RESUMEN
The renin-angiotensin system (RAS) is composed of a series of peptides, receptors, and enzymes that play a pivotal role in maintaining cardiovascular homeostasis. Among the most important players in this system are the angiotensin-II and angiotensin-(1-7) peptides. Our group has recently demonstrated that alamandine (ALA), a peptide with structural and functional similarities to angiotensin-(1-7), interacts with cardiomyocytes, enhancing contractility via the Mas-related G protein-coupled receptor member D (MrgD). It is currently unknown whether this modulation varies along the distinct phases of the day. To address this issue, we assessed the ALA-induced contractility response of cardiomyocytes from mice at four Zeitgeber times (ZTs). At ZT2 (light phase), ALA enhanced cardiomyocyte shortening in an MrgD receptor-dependent manner, which was associated with nitric oxide (NO) production. At ZT14 (dark phase), ALA induced a negative modulation on the cardiomyocyte contraction. ß-Alanine, an MrgD agonist, reproduced the time-of-day effects of ALA on myocyte shortening. NG-nitro-l-arginine methyl ester, an NO synthase inhibitor, blocked the increase in fractional shortening induced by ALA at ZT2. No effect of ALA on myocyte shortening was observed at ZT8 and ZT20. Our results show that ALA/MrgD signaling in cardiomyocytes is subject to temporal modulation. This finding has significant implications for pharmacological approaches that combine chronotherapy for cardiac conditions triggered by disruption of circadian rhythms and hormonal signaling.NEW & NOTEWORTHY Alamandine, a member of the renin-angiotensin system, serves critical roles in cardioprotection, including the modulation of cardiomyocyte contractility. Whether this effect varies along the day is unknown. Our results provide evidence that alamandine via receptor MrgD exerts opposing actions on cardiomyocyte shortening, enhancing, or reducing contraction depending on the time of day. These findings may have significant implications for the development and effectiveness of future cardiac therapies.
Asunto(s)
Contracción Miocárdica , Miocitos Cardíacos , Óxido Nítrico , Oligopéptidos , Receptores Acoplados a Proteínas G , Animales , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/efectos de los fármacos , Contracción Miocárdica/efectos de los fármacos , Contracción Miocárdica/fisiología , Ratones , Receptores Acoplados a Proteínas G/metabolismo , Receptores Acoplados a Proteínas G/agonistas , Óxido Nítrico/metabolismo , Oligopéptidos/farmacología , Ratones Endogámicos C57BL , Ritmo Circadiano/fisiología , Ritmo Circadiano/efectos de los fármacos , Receptores de Neuropéptido/metabolismo , Receptores de Neuropéptido/agonistas , Receptores de Neuropéptido/antagonistas & inhibidores , Masculino , Células Cultivadas , Sistema Renina-Angiotensina/efectos de los fármacos , Sistema Renina-Angiotensina/fisiologíaRESUMEN
Mast cells have long been recognized for their involvement in allergic pathology through the immunoglobulin E (IgE)-mediated degranulation mechanism. However, there is growing evidence of other "non-canonical" degranulation mechanisms activated by certain pathogen recognition receptors. Mast cells release several mediators, including histamine, cytokines, chemokines, prostaglandins, and leukotrienes, to initiate and enhance inflammation. The chemical nature of activating stimuli influences receptors, triggering mechanisms for the secretion of formed and new synthesized mediators. Mast cells have more than 30 known surface receptors that activate different pathways for direct and indirect activation by microbes. Different bacterial strains stimulate mast cells through various ligands, initiating the innate immune response, which aids in clearing the bacterial burden. Mast cell interactions with adaptative immune cells also play a crucial role in infections. Recent publications revealed another "non-canonical" degranulation mechanism present in tryptase and chymase mast cells in humans and connective tissue mast cells in mice, occurring through the activation of the Mas-related G protein-coupled receptor (MRGPRX2/b2). This receptor represents a new therapeutic target alongside antibiotic therapy. There is an urgent need to reconsider and redefine the biological role of these MASTer cells of innate immunity, extending beyond their involvement in allergic pathology.
Asunto(s)
Antiinfecciosos , Hipersensibilidad , Humanos , Animales , Ratones , Antiinfecciosos/metabolismo , Citocinas/metabolismo , Inmunoglobulina E , Inmunidad Innata , Mastocitos , Proteínas del Tejido Nervioso/metabolismo , Receptores de Neuropéptido/metabolismo , Receptores Acoplados a Proteínas G/metabolismoRESUMEN
Growth hormone (GH) deficiency is a common cause of late sexual maturation and fertility issues. To determine whether GH-induced effects on reproduction are associated with alterations in hypothalamic kisspeptin system, we studied the male reproduction in two distinct GH deficiency mouse models. In the first model, mice present GH deficiency secondary to arcuate nucleus of the hypothalamus (ARH) lesions induced by posnatal monosodium glutamate (MSG) injections. MSG-induced ARH lesions led to significant reductions in hypothalamic Ghrh mRNA expression and consequently growth. Hypothalamic Kiss1 mRNA expression and Kiss1-expressing cells in the ARH were disrupted in the MSG-treated mice. In contrast, kisspeptin immunoreactivity remained preserved in the anteroventral periventricular and rostral periventricular nuclei (AVPV/PeN) of MSG-treated mice. Importantly, ARH lesions caused late sexual maturation and infertility in male mice. In our second mouse model, we studied animals profound GH deficiency due to a loss-of-function mutation in the Ghrhr gene (Ghrhrlit/lit mice). Interestingly, although Ghrhrlit/lit mice exhibited late puberty onset, hypothalamic Kiss1 mRNA expression and hypothalamic kisspeptin fiber density were normal in Ghrhrlit/lit mice. Despite presenting dwarfism, the majority of Ghrhrlit/lit male mice were fertile. These findings suggest that spontaneous GH deficiency during development does not compromise the kisspeptin system. Furthermore, ARH Kiss1-expressing neurons are required for fertility, while AVPV/PeN kisspeptin expression is sufficient to allow maturation of the hypothalamic-pituitary-gonadal axis in male mice.
Asunto(s)
Núcleo Arqueado del Hipotálamo/metabolismo , Hormona del Crecimiento/deficiencia , Sistema Hipotálamo-Hipofisario/metabolismo , Kisspeptinas/metabolismo , Reproducción , Maduración Sexual , Animales , Enanismo/genética , Enanismo/metabolismo , Fertilidad , Kisspeptinas/genética , Masculino , Ratones , Neuronas/metabolismo , Receptores de Neuropéptido/genética , Receptores de Neuropéptido/metabolismo , Receptores de Hormona Reguladora de Hormona Hipofisaria/genética , Receptores de Hormona Reguladora de Hormona Hipofisaria/metabolismoRESUMEN
Isolated growth hormone (GH) deficiency (IGHD) affects approximately 1 in 4,000 to 1 in 10,000 individuals worldwide. We have previously described a large cohort of subjects with IGHD due to a homozygous mutation in the GH releasing hormone (GHRH) receptor gene. These subjects exhibit throughout the life very low levels of GH and its principal mediator, the Insulin Growth Factor-I (IGF-I). The facilitating role of IGF-I in the infection of mouse macrophages by different Leishmania strains is well-known. Nevertheless, the role of IGF-I in Leishmania infection of human macrophages has not been studied. This study aimed to evaluate the behavior of Leishmania infection in vitro in macrophages from untreated IGHD subjects. To this end, blood samples were collected from 14 IGHD individuals and 14 age and sex-matched healthy controls. Monocytes were isolated and derived into macrophages and infected with a strain of Leishmania amazonensis. In addition, IGF-I was added to culture medium to evaluate its effect on the infection. Cytokines were measured in the culture supernatants. We found that macrophages from IGHD subjects were less prone to Leishmania infection compared to GH sufficient controls. Both inflammatory and anti-inflammatory cytokines increase only in the supernatants of the control macrophages. Addition of IGF-I to the culture medium increased infection rates. In conclusion, we demonstrated that IGF-I is crucial for Leishmania infection of human macrophages.
Asunto(s)
Enanismo Hipofisario/metabolismo , Factor I del Crecimiento Similar a la Insulina/metabolismo , Leishmania mexicana/metabolismo , Leishmaniasis/inmunología , Macrófagos/metabolismo , Mutación , Receptores de Neuropéptido/metabolismo , Receptores de Hormona Reguladora de Hormona Hipofisaria/metabolismo , Adulto , Animales , Citocinas/metabolismo , Femenino , Humanos , Leishmaniasis/microbiología , Masculino , Ratones , Persona de Mediana Edad , Fagocitosis , ARN Mensajero/metabolismo , Receptores de Neuropéptido/genética , Receptores de Hormona Reguladora de Hormona Hipofisaria/genética , Adulto JovenRESUMEN
Kisspeptin has been shown to stimulate prolactin secretion. We investigated whether kisspeptin acts through the Kiss1 receptor (Kiss1r) to regulate dopamine and prolactin. Initially, we evaluated prolactin response in a Kiss1r-deficient mouse line, in which Kiss1r had been knocked into GnRH neurons (Kiss1r-/-R). Intracerebroventricular kisspeptin-10 (Kp-10) increased prolactin release in wild-type but not in Kiss1r-/-R female mice. In ovariectomized, estradiol-treated rats, the Kiss1r antagonist kisspeptin-234 abolished the Kp-10-induced increase in prolactin release but failed to prevent the concomitant reduction in the activity of tuberoinfundibular dopaminergic (TIDA) neurons, as determined by the 3,4-dihydroxyphenylacetic acid/dopamine ratio in the median eminence. Using whole-cell patch clamp recordings in juvenile male rats, we found no direct effect of Kp-10 on the electrical activity of TIDA neurons. In addition, dual-label in situ hybridization in the hypothalamus of female rats showed that Kiss1r is expressed in the periventricular nucleus of the hypothalamus (Pe) and arcuate nucleus of the hypothalamus (ARC) but not in tyrosine hydroxylase (Th)-expressing neurons. Kisspeptin also has affinity for the neuropeptide FF receptor 1 (Npffr1), which was expressed in the majority of Pe dopaminergic neurons but only in a low proportion of TIDA neurons in the ARC. Our findings demonstrate that Kiss1r is necessary to the effect of kisspeptin on prolactin secretion, although TIDA neurons lack Kiss1r and are electrically unresponsive to kisspeptin. Thus, kisspeptin is likely to stimulate prolactin secretion via Kiss1r in nondopaminergic neurons, whereas the colocalization of Npffr1 and Th suggests that Pe dopaminergic neurons may play a role in the kisspeptin-induced inhibition of dopamine release.
Asunto(s)
Dopamina/metabolismo , Kisspeptinas/metabolismo , Núcleo Hipotalámico Paraventricular/metabolismo , Prolactina/metabolismo , Receptores de Kisspeptina-1/metabolismo , Animales , Neuronas Dopaminérgicas/fisiología , Femenino , Masculino , Ratones Noqueados , Ratas Wistar , Receptores de Neuropéptido/metabolismo , Tirosina 3-Monooxigenasa/metabolismoRESUMEN
RFamide-related peptide (RFRP-3) is a regulator of GnRH secretion from the brain, but it can also act in human ovary to influence steroidogenesis. We aimed to study the putative local role of RFRP-3 in the ovary and its potential participation in the development of a polycystic ovary phenotype induced by chronic sympathetic stress (cold stress). We used adult SpragueDawley rats divided into control and stressed groups. In both groups, we studied the effect of intraovarian exposure to RFRP-3 on follicular development and plasma ovarian steroid concentrations. We also tested the effect of RFRP-3 on ovarian steroid production in vitro. Chronic in vivo intraovarian exposure to RFRP-3 decreased basal testosterone concentrations and cold stress-induced progesterone production by the ovary. In vitro, RFRP-3 decreased hCG-induced ovarian progesterone and testosterone secretion. Immunohistochemistry and mRNA expression analysis showed a decrease in Rfrp and expression of its receptor in the ovary of stressed rats, a result which is in line with the increased testosterone levels found in stressed rats. In vivo application of RFRP-3 recovered the low levels of secondary and healthy antral follicles found in stressed rats. Taken together, our data indicate a previously unknown response of hypothalamic and ovarian RFRP-3 to chronic cold stress, influencing ovarian steroidogenesis and follicular dynamics. Thus, it is likely that RFRP-3 modulation in the ovary is a key component of development of the polycystic ovary phenotype.
Asunto(s)
Hormonas Hipotalámicas/metabolismo , Hipotálamo/metabolismo , Ovario/metabolismo , Síndrome del Ovario Poliquístico/metabolismo , Animales , Frío , Femenino , Síndrome del Ovario Poliquístico/etiología , Progesterona/sangre , Ratas Sprague-Dawley , Receptores de Neuropéptido/metabolismo , Estrés Fisiológico , Testosterona/sangreRESUMEN
Sympathetic activity displays rhythmic oscillations generated by brainstem inspiratory and expiratory neurons. Amplification of these rhythmic respiratory-related oscillations is observed in rats under enhanced central respiratory drive or during development of neurogenic hypertension. Herein, we evaluated the involvement of ventral medullary sympatho-excitatory catecholaminergic C1 neurons, using inhibitory Drosophila allatostatin receptors, for the enhanced expiratory-related oscillations in sympathetic activity in rats submitted to chronic intermittent hypoxia (CIH) and following activation of both peripheral (hypoxia) and central chemoreceptors (hypercapnia). Pharmacogenetic inhibition of C1 neurons bilaterally resulted in reductions of their firing frequency and amplitude of inspiratory-related sympathetic activity in rats in normocapnia, hypercapnia or after CIH. In contrast, hypercapnia or hypoxia-induced enhanced expiratory-related sympathetic oscillations were unaffected by C1 neuronal inhibition. Inhibition of C1 neurons also resulted in a significant fall in arterial pressure and heart rate that was similar in magnitude between normotensive and CIH hypertensive rats, but basal arterial pressure in CIH rats remained higher compared to controls. C1 neurons play a key role in regulating inspiratory modulation of sympathetic activity and arterial pressure in both normotensive and CIH hypertensive rats, but they are not involved in the enhanced late-expiratory-related sympathetic activity triggered by activation of peripheral or central chemoreceptors.
Asunto(s)
Hipertensión/patología , Neuronas/metabolismo , Sistema Nervioso Simpático/metabolismo , Animales , Barorreflejo/fisiología , Presión Sanguínea/fisiología , Modelos Animales de Enfermedad , Drosophila , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Vectores Genéticos/metabolismo , Frecuencia Cardíaca/fisiología , Proteínas de Homeodominio/genética , Hipercapnia/patología , Hipertensión/metabolismo , Hipoxia , Masculino , Bulbo Raquídeo/metabolismo , Neuronas/patología , Técnicas de Placa-Clamp , Ratas , Ratas Wistar , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Receptores de Neuropéptido/genética , Receptores de Neuropéptido/metabolismoRESUMEN
We studied potential changes in the subventricular zone (SVZ) stem cell niche of the senescence-accelerated mouse prone-8 (SAM-P8) aging model. Bromodeoxyuridine (BrdU) assays with longtime survival revealed a lower number of label-retaining stem cells in the SAM-P8 SVZ compared with the SAM-Resistant 1 (SAM-R1) control strain. We also found that in SAM-P8 niche signaling is attenuated and the stem cell pool is less responsive to the self-renewal niche factor pigmented epithelium-derived factor (PEDF). Protein analysis demonstrated stable amounts of the PEDF ligand in the SAM-P8 SVZ niche; however, SAM-P8 stem cells present a significant expression decrease of patatin-like phospholipase domain containing 2, a receptor for PEDF (PNPLA2-PEDF) receptor, but not of laminin receptor (LR), a receptor for PEDF (LR-PEDF) receptor. We observed changes in self-renewal related genes (hairy and enhancer of split 1 (Hes1), hairy and enhancer of split 1 (Hes5), Sox2] and report that although these genes are down-regulated in SAM-P8, differentiation genes (Pax6) are up-regulated and neurogenesis is increased. Finally, sheltering mammalian telomere complexes might be also involved given a down-regulation of telomeric repeat binding factor 1 (Terf1) expression was observed in SAM-P8 at young age periods. Differences between these 2 models, SAM-P8 and SAM-R1 controls, have been previously detected at more advanced ages. We now describe alterations in the PEDF signaling pathway and stem cell self-renewal at a very young age, which could be involved in the premature senescence observed in the SAM-P8 model.
Asunto(s)
Envejecimiento/metabolismo , Envejecimiento/patología , Proteínas del Ojo/metabolismo , Ventrículos Laterales/metabolismo , Ventrículos Laterales/patología , Factores de Crecimiento Nervioso/metabolismo , Células-Madre Neurales/metabolismo , Células-Madre Neurales/patología , Serpinas/metabolismo , Envejecimiento/genética , Animales , Bromodesoxiuridina/metabolismo , Recuento de Células , Proteínas del Ojo/genética , Ratones , Modelos Animales , Modelos Neurológicos , Factores de Crecimiento Nervioso/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Receptores de Neuropéptido/genética , Receptores de Neuropéptido/metabolismo , Serpinas/genética , Transducción de Señal , Nicho de Células MadreRESUMEN
RFamide-related peptide-3 (RFRP-3), the orthologue of avian gonadotrophin-inhibitory hormone, and its receptor GPR147 have been recently identified in the human hypothalamus, and their roles in the regulation of reproductive axis has been studied. The present study aimed to investigate whether the presence of variants in the genes encoding human RFRP-3 (NPVF gene) and its receptor, GPR147 (NPFFR1 gene), is associated with the occurrence of gonadotrophin-releasing hormone-dependent pubertal disorders. Seventy-eight patients with idiopathic central precocious puberty (CPP) and 51 with normosmic isolated hypogonadotrophic hypogonadism (nIHH) were investigated. Fifty healthy subjects comprised the control group. The coding sequences of the NPVF and NPFFR1 genes were amplified and sequenced. Odds ratios (OR) were used to estimate the likelihood of CPP or nIHH in the presence of the described polymorphisms. All such polymorphisms have already been registered in the National Center for Biotechnology Information database. A three-nucleotide in frame deletion was identified in the NPVF gene (p.I71_K72), with a smaller proportion in the CPP (5%) compared to the nIHH (15%) group (P = 0.06). This results in the deletion of the isoleucine at position 71, adjacent to lysine at an endoproteolytic cleavage site of the precursor peptide. This polymorphism was associated with a lower risk of CPP (OR = 0.33; 95% confidence interval = 0.08-0.88); interestingly, only two men with nIHH were homozygotes for this variant. A total of five missense polymorphisms were found in the NPFFR1 gene, which encodes GPR147, with similar frequencies among groups and no association with pubertal timing. Our data suggest that RFRP-3/GPR147 may play secondary, modulatory roles on the regulation of pubertal development; a restraining modulatory effect of the NPVF p.I71_K72 variant on the activation of the gonadotrophic axis cannot be ruled out and deserves further investigation.
Asunto(s)
Hipogonadismo/genética , Neuropéptidos/genética , Polimorfismo Genético , Pubertad Precoz/genética , Receptores de Neuropéptido/genética , Adolescente , Niño , Preescolar , Análisis Mutacional de ADN , Femenino , Humanos , Hipogonadismo/metabolismo , Hipotálamo/metabolismo , Masculino , Neuropéptidos/metabolismo , Pubertad Precoz/metabolismo , Receptores de Neuropéptido/metabolismo , Adulto JovenRESUMEN
Shohat-Ophir et al. (1) demonstrate a connection between sexual behaviour and ethanol consumption in male Drosophila flies, and how the neuropeptide F system regulates ethanol preference. Their results are rightly discussed only in a physiological context, but this has facilitated erroneous anthropomorphic interpretations by the media. Here we discuss the link between male sexual behaviour and ethanol consumption from an evolutionary perspective, providing a broader context to interpret their results.
Asunto(s)
Conducta Animal , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/fisiología , Etanol/administración & dosificación , Neuropéptidos/metabolismo , Receptores de Neuropéptido/metabolismo , Conducta Sexual Animal , Animales , Femenino , MasculinoRESUMEN
BACKGROUND: Cell-cell interactions are a basic principle for the organization of tissues and organs allowing them to perform integrated functions and to organize themselves spatially and temporally. Peptidic molecules secreted by neurons and epithelial cells play fundamental roles in cell-cell interactions, acting as local neuromodulators, neurohormones, as well as endocrine and paracrine messengers. Allatotropin (AT) is a neuropeptide originally described as a regulator of Juvenile Hormone synthesis, which plays multiple neural, endocrine and myoactive roles in insects and other organisms. METHODS: A combination of immunohistochemistry using AT-antibodies and AT-Qdot nanocrystal conjugates was used to identify immunoreactive nerve cells containing the peptide and epithelial-muscular cells targeted by AT in Hydra plagiodesmica. Physiological assays using AT and AT- antibodies revealed that while AT stimulated the extrusion of the hypostome in a dose-response fashion in starved hydroids, the activity of hypostome in hydroids challenged with food was blocked by treatments with different doses of AT-antibodies. CONCLUSIONS: AT antibodies immunolabeled nerve cells in the stalk, pedal disc, tentacles and hypostome. AT-Qdot conjugates recognized epithelial-muscular cell in the same tissues, suggesting the existence of anatomical and functional relationships between these two cell populations. Physiological assays indicated that the AT-like peptide is facilitating food ingestion. SIGNIFICANCE: Immunochemical, physiological and bioinformatics evidence advocates that AT is an ancestral neuropeptide involved in myoregulatory activities associated with meal ingestion and digestion.
Asunto(s)
Conducta Alimentaria , Hormonas de Insectos/metabolismo , Neuropéptidos/metabolismo , Animales , Biología Computacional , Regulación de la Expresión Génica , Hydra/metabolismo , Hormonas de Insectos/química , Neuropéptidos/química , Puntos Cuánticos , Receptores de Neuropéptido/metabolismoRESUMEN
Orexin-A and orexin-B are neuropeptides controlling sleep-wakefulness, feeding and neuroendocrine functions via their G protein-coupled receptors, orexin-1R and orexin-2R. They are synthesized in the lateral hypothalamus and project throughout the brain. Orexins and orexin receptors have also been described outside the brain. Previously we demonstrated the presence of both receptors in the ovary, their increased expression during proestrous afternoon and the dependence on the gonadotropins. Here we studied the effects of orexins on the mRNA expression of both receptors, by quantitative real-time PCR, on luteal cells from superovulated rat ovaries and granulosa cells from diethylstilbestrol-treated rat ovaries. Effects on progesterone secretion were also measured. In luteal cells, 1 nM of either orexin-A or orexin-B decreased progesterone secretion. Orexin-A treatment increased expression of both orexin-1R and orexin-2R mRNA. The effect on orexin-1R mRNA expression was abolished by an orexin-1R selective receptor antagonist SB-334867 and the effect on orexin-2R mRNA expression was abolished by a selective orexin-2R antagonist JNJ-10397049. Orexin-B did not modify orexin-1R mRNA expression, but increased orexin-2R mRNA expression. The effect of orexin-B on orexin-2R was abolished by a selective orexin-2R antagonist. Neither the expression of orexin receptors nor progesterone secretions by granulosa cells were affected by orexins. FSH, as positive control, increased both steroid hormones secretion, but did not induce the expression of OX receptors in granulosa cells isolated from late preantral/early antral follicles. Finally in ovaries obtained immediately after sacrifice, the expression of orexin-1R and orexin-2R was higher in superovulated rat ovaries compared to control or diethylstilbestrol treated rat ovaries. A selective presence and function of both orexinergic receptors in luteal and granulosa cells is described, suggesting that the orexinergic system may have a functional role in the ovary.
Asunto(s)
Células de la Granulosa/metabolismo , Péptidos y Proteínas de Señalización Intracelular/fisiología , Células Lúteas/metabolismo , Neuropéptidos/fisiología , Progesterona/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Receptores de Neuropéptido/metabolismo , Animales , Benzoxazoles/farmacología , Células Cultivadas , Dietilestilbestrol/farmacología , Dioxanos/farmacología , Estradiol/metabolismo , Estrógenos no Esteroides/farmacología , Femenino , Expresión Génica , Naftiridinas , Receptores de Orexina , Orexinas , Ovario/citología , Ovario/metabolismo , Compuestos de Fenilurea/farmacología , Progesterona/sangre , Ratas , Ratas Sprague-Dawley , Receptores Acoplados a Proteínas G/antagonistas & inhibidores , Receptores Acoplados a Proteínas G/genética , Receptores de Neuropéptido/antagonistas & inhibidores , Receptores de Neuropéptido/genética , Urea/análogos & derivados , Urea/farmacologíaRESUMEN
Appropriate nutritional and vigilance states are needed for reproduction. In previous works, we described the influence of the hormonal milieu of proestrus on the orexinergic system and we found that orexin receptor 1 expression in the hypothalamus, but not other neural areas, and the adenohypophysis was under the influence of oestradiol and the time of the day. Information from the sexual hormonal milieu of proestrous afternoon impacts on various components of the orexinergic system and alertness on this particular night of proestrus would be of importance for successful reproduction. In this review, we summarize the available experimental data supporting the participation of orexins in the hypothalamic-pituitary-ovarian relationships. All together, these results suggest a role of the orexinergic system as an integrative link among vital functions such as reproduction, food intake, alertness and the inner biological clock.
Asunto(s)
Sistema Hipotálamo-Hipofisario/fisiología , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Neuropéptidos/metabolismo , Neurotransmisores/metabolismo , Ovario/fisiología , Animales , Nivel de Alerta/fisiología , Relojes Biológicos/fisiología , Ingestión de Alimentos/fisiología , Metabolismo Energético/fisiología , Estradiol/metabolismo , Estro/metabolismo , Femenino , Humanos , Hipotálamo/fisiología , Receptores de Orexina , Orexinas , Adenohipófisis/fisiología , Proestro/fisiología , Receptores Acoplados a Proteínas G/metabolismo , Receptores de Neuropéptido/metabolismo , Reproducción/fisiologíaRESUMEN
Orexins A and B (hypocretins A and B) are regulatory peptides that control a variety of neuroendocrine and autonomic functions including feeding and sleep-wakefulness. Previously, we described a clear relationship between the hormonal milieu of the estrous cycle and the mRNA expression of the components of the orexinergic system, in the hypothalamus, pituitary and ovary. Here, we investigate whether steroid hormones are involved in the modulation of the hypocretin/orexin type-1 receptor expression at the protein level, and its time of the day dependence, in hypothalamus and pituitary of castrated male and female rats and castrated receiving hormone replacement. Orchidectomy decreased the hypocretin/orexin type-1 receptor expression in anterior hypothalamus, but not in mediobasal hypothalamus or cortex; in pituitary this treatment resulted in an increase. Testosterone and dihydrotestosterone were able to restore receptor expression and gonadotropins. In females, pituitary and ovarian hormones increased during proestrous afternoon. Hypocretin/orexin type-1 receptor expression was higher at 19:00 of proestrus in hypothalamus and pituitary. Ovariectomized treated with estradiol or oil and sacrificed at 11:00 h showed the receptor expression similar to 11:00 h of proestrus in hypothalamus and pituitary. At 19:00 h, low expression persisted in these areas in oil-treated ovariectomized rats; in contrast, estradiol replacement increased the expression to high levels of normal cycling rats at 19:00 h. Sexual steroids modulate the orexinergic system and the anatomical regions, hormones and times of the day all have to be considered when the roles of orexins, and probably other peptides, are under consideration.
Asunto(s)
Encéfalo/metabolismo , Hormonas Esteroides Gonadales/fisiología , Receptores Acoplados a Proteínas G/metabolismo , Receptores de Neuropéptido/metabolismo , Animales , Western Blotting , Femenino , Masculino , Orquiectomía , Receptores de Orexina , Ovariectomía , Ratas , Ratas Sprague-DawleyRESUMEN
In 5-month-old male and female dopamine receptor 2 (D2R) knockout mice food intake per animal was unaltered while food per g BW was increased. We wished to evaluate the effect of D2R disruption on different components of energy balance and food intake regulation. We determined hypothalamic orexin precursor (PPO) expression, its receptor OX1, serum leptin levels, hypothalamic leptin receptor (OBR), circulating and pituitary alpha MSH levels, as well as central MC3 and MC4 receptors and NPY mRNA in wildtype and D2R knockout mice (KO). Loss of D2R caused a marked increase in serum prolactin levels, to higher levels in females compared to male KO mice. On the other hand, it produced a female-specific increase in circulating alphaMSH, and hypothalamic alphaMSH content, while neurointermediate alphaMSH content was decreased in both sexes. No differences were found in hypothalamic NPY, MC3R or MC4R concentration. Hypothalamic PPO mRNA expression was significantly decreased only in female KOs, while OX1 mRNA was not different between genotypes. Serum leptin levels were also similar in both genotypes. Our results show that in female and not in male mice disruption of the D2R produces two potentially anorexigenic events: an increase in serum and hypothalamic alphaMSH, and a decrease in hypothalamic orexin expression. Very high prolactin levels, which are orexigenic, probably counterbalance these effects, so that food intake is slightly altered. In males, on the other hand, hypothalamic PPO, and serum or hypothalamic alphaMSH are not modified, and increased prolactin levels may account for increased food intake per g BW. These results suggest a sexually dimorphic participation of the D2R in food intake regulation.
Asunto(s)
Hipotálamo/metabolismo , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Neuropéptido Y/metabolismo , Neuropéptidos/metabolismo , Receptor de Melanocortina Tipo 3/metabolismo , Receptor de Melanocortina Tipo 4/metabolismo , Receptores de Dopamina D2 , Receptores Acoplados a Proteínas G/metabolismo , Receptores de Neuropéptido/metabolismo , alfa-MSH/metabolismo , Animales , Ingestión de Alimentos , Metabolismo Energético , Femenino , Masculino , Ratones , Ratones Noqueados , Receptores de Orexina , Orexinas , Precursores de Proteínas/metabolismo , Receptores de Dopamina D2/genética , Receptores de Dopamina D2/metabolismoRESUMEN
Orexins are peptides controlling feeding, sleep, and neuroendocrine functions. They are synthesized by the hypothalamus with projections throughout the brain. Orexins and their orexin 1 (OX(1)) and orexin 2 receptors (OX(2)) are present outside the central nervous system. Here the expression of preproorexin (PPO), OX(1), and OX(2) was studied in rat ovaries. PPO, OX(1), and OX(2) were determined by quantitative real-time RT-PCR in ovaries of cycling Sprague-Dawley rats on all days of the cycle. Serum hormones and food consumption were determined. Ovarian OX(1) and OX(2) expression was then studied after ovulation blockade with Cetrorelix or Nembutal. Finally, proestrous rats were treated at 1400 and 1900 with a selective OX(1) antagonist (SB-334867-A) and/or a selective OX(2) antagonist (JNJ-10397049), and hormone levels, ovulation, and ovarian histology were studied. Both receptors' expression increased in the ovary between 1700 and 2300 of proestrus exclusively, in coincidence with hormone peaks, but not with the dark-light cycle or food intake. PPO was not detected. Cetrorelix or Nembutal prevented the increases of OX(1) and OX(2) while blunting gonadotropin peaks. SB-334867-A and JNJ-10397049, alone or combined, decreased serum gonadotropins and reduced ova number the following morning; ovaries showed a bloody (hyperemic and/or hemorrhagic) reaction with more preovulatory follicles and less corpora lutea. Here we demonstrate for the first time an increased ovarian expression of both OX(1) and OX(2), only during proestrous afternoon, and its hormone dependence but not dependence on the dark-light cycle. Two new receptor antagonists reduced proestrous gonadotropins and/or ova number while producing ovarian structural changes.
Asunto(s)
Benzoxazoles/farmacología , Dioxanos/farmacología , Ciclo Estral/genética , Gonadotropinas/metabolismo , Ovario/metabolismo , Ovulación/efectos de los fármacos , Compuestos de Fenilurea/farmacología , Receptores Acoplados a Proteínas G/antagonistas & inhibidores , Receptores Acoplados a Proteínas G/genética , Receptores de Neuropéptido/antagonistas & inhibidores , Receptores de Neuropéptido/genética , Urea/análogos & derivados , Animales , Ingestión de Alimentos/efectos de los fármacos , Ciclo Estral/efectos de los fármacos , Ciclo Estral/metabolismo , Femenino , Regulación de la Expresión Génica/efectos de los fármacos , Hormona Liberadora de Gonadotropina/análogos & derivados , Hormona Liberadora de Gonadotropina/farmacología , Gonadotropinas/sangre , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Naftiridinas , Neuropéptidos/genética , Neuropéptidos/metabolismo , Receptores de Orexina , Orexinas , Ovulación/sangre , Pentobarbital/farmacología , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Receptores Acoplados a Proteínas G/metabolismo , Receptores de Neuropéptido/metabolismo , Urea/farmacologíaRESUMEN
Orexins and their receptors OX1 and OX2 regulate energy balance and the sleep-wake cycle. We studied the expression of prepro-orexin (PPO), OX1, and OX2 in brain and pituitary under the influence of the hormonal status in adult rats. Primarily, PPO, OX1, and OX2 expression was determined in Sprague-Dawley female cycling rats during proestrus and in males. Animals were killed at 2-h intervals. Anterior (AH) and mediobasal (MBH) hypothalamus, anterior pituitary (P), and frontoparietal cortex (CC) were homogenized in TRIzol, and mRNAs were obtained for screening of PPO, OX1, OX2 expression by semiquantitative RT-PCR. Main findings were confirmed and extended to all days of the cycle by quantitative real-time RT-PCR. Hormones and food consumption were determined. Finally, OX1, OX2, and PPO were measured by real-time RT-PCR in tissues collected at 1900 of proestrus after treatments at 1400 with ovulation-blocking agents Cetrorelix or pentobarbital. OX1 and OX2 expression increased at least threefold in AH, MBH, and P, but not in CC, between 1700 and 2300 of proestrus, without variations in estrus, diestrus, or in males. PPO in AH and MBH showed a fourfold or higher increase only during proestrus afternoon. Cetrorelix or pentobarbital prevented increases of OX1 and OX2 only in the pituitary and blunted gonadotropin surges, but left OX1, OX2, and PPO brain expression unchanged. Reproduction, energy balance, and sleep-wake cycle are integrated. Here, we demonstrate that, in the physiological neuroendocrine condition leading to ovulation, information to the orexinergic system acts in hypothalamus and pituitary by different mechanisms.
Asunto(s)
Hormona Liberadora de Gonadotropina/análogos & derivados , Hipotálamo/metabolismo , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Neuropéptidos/metabolismo , Pentobarbital/farmacología , Hipófisis/metabolismo , Proestro/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Receptores de Neuropéptido/metabolismo , Animales , Anticonceptivos/farmacología , Femenino , Hormona Liberadora de Gonadotropina/antagonistas & inhibidores , Hormona Liberadora de Gonadotropina/farmacología , Hormonas/sangre , Hipotálamo/efectos de los fármacos , Masculino , Receptores de Orexina , Orexinas , Hipófisis/efectos de los fármacos , Proestro/sangre , Proestro/efectos de los fármacos , Ratas , Ratas Sprague-DawleyRESUMEN
Recently, the importance of the dopaminergic D2 receptor (D2R) subtype in normal body growth and neonatal GH secretion has been highlighted. Disruption of D2R alters the GHRH-GH-IGF-I axis and impairs body growth in adult male mice. The D2R knockout (KO) dwarf mouse has not been well characterized; we therefore sought to determine somatotrope function in the adult pituitary. Using immunohistochemistry and confocal microscopy, we found a significant decrease in the somatotrope population in pituitaries from KO mice (P=0.043), which was paralleled by a decreased GH output from pituitary cells cultured in vitro. In cells from adult mice the response amplitude to GHRH differed between genotypes (lower in KO), but this difference was less dramatic after taking into account the lower basal release and hormone content in the KO cells. Furthermore, there were no significant differences in cAMP generation in response to GHRH between genotypes. By Western blot, GHRH-receptor in pituitary membranes from KO mice was reduced to 46% of the level found in wildtype (WT) mice (P=0.016). Somatostatin induced a concentration-dependent decrease in GH and prolactin (PRL) secretion in both genotypes, and 1x10(-7) M ghrelin released GH in cells from both genotypes (P=0.017) in a proportionate manner to basal levels. These results suggest that KO somatotropes maintain a regulated secretory function. Finally, we tested the direct effect of dopamine on GH and PRL secretion in cells from both genotypes at 20 days and 6 months of life. As expected, we found that dopamine could reduce PRL levels at both ages in WT mice but not in KO mice, but there was no consistent effect of the neurotransmitter on GH release in either genotype at the ages studied. The present study demonstrates that in the adult male D2R KO mouse, there is a reduction in pituitary GH content and secretory activity. Our results point to an involvement of D2R signaling at the hypothalamic level as dopamine did not release GH acting at the pituitary level either in 1-month-old or adult mice. The similarity of the pituitary defect in the D2R KO mouse to that of GHRH-deficient models suggests a probable mechanism. A loss of dopamine signaling via hypothalamic D2Rs at a critical age causes the reduced release of GHRH from hypophyseotropic neurons leading to inadequate clonal expansion of the somatotrope population. Our data also reveal that somatotrope cell number is much more sensitive to changes in neonatal GHRH input than their capacity to develop properly regulated GH-secretory function.
Asunto(s)
Enanismo/metabolismo , Hormona Liberadora de Hormona del Crecimiento/farmacología , Hormona del Crecimiento/metabolismo , Hipófisis/metabolismo , Receptores de Dopamina D2/genética , Somatostatina/farmacología , Animales , Western Blotting/métodos , Células Cultivadas , AMP Cíclico/análisis , AMP Cíclico/biosíntesis , Dopamina/farmacología , Relación Dosis-Respuesta a Droga , Ghrelina , Inmunohistoquímica/métodos , Masculino , Ratones , Ratones Noqueados , Microscopía Confocal , Hormonas Peptídicas/farmacología , Hipófisis/citología , Hipófisis/efectos de los fármacos , Prolactina/metabolismo , Receptores de Dopamina D2/metabolismo , Receptores de Neuropéptido/análisis , Receptores de Neuropéptido/metabolismo , Receptores de Hormona Reguladora de Hormona Hipofisaria/análisis , Receptores de Hormona Reguladora de Hormona Hipofisaria/metabolismoRESUMEN
Orexins (hypocretins) have been implicated in the regulation of the normal sleep-wake cycle, in sensorimotor programming, and in other homeostatic and neuroregulatory processes. The present study examined the effects of sleep deprivation (SD) and sleep recovery on the expression of orexin 1 receptors (OX1R) and orexin 2 receptors (OX2R) throughout the brain. Rats were sacrificed either immediately after 96 h of sleep deprivation (SD group) or after SD followed by 24 h of sleep recovery (Rebound group). Prepro-orexin mRNA showed a non-significant increase in the SD group relative to controls, but a pronounced and significant increase in the Rebound group (+88%, P < 0.007). Similarly, sleep deprivation produced no effect on OX1R or OX2R mRNA levels. However, in the Rebound group, OX1R mRNA levels increased significantly, compared to either control or SD groups, in 37 of 92 brain regions analyzed, with particularly strong effects in the amygdala and hypothalamus. Changes in OX2R mRNA levels were also seen only in the sleep Rebound group, but they were fewer in number (10 out of 86 regions), were in the direction of decreased rather than increased expression, and were predominantly confined to cerebral cortical areas. These observations indicate that some factor associated with sleep recovery, possibly the compensatory increase in REM sleep, has strong effects on the orexin system at the mRNA level. They further indicate that,pOX1 and OX2 receptors are affected in opposite way and that the former are more vulnerable to these effects than the latter.
Asunto(s)
Encéfalo/metabolismo , Expresión Génica/fisiología , Receptores de Neuropéptido/metabolismo , Sueño/fisiología , Animales , Encéfalo/anatomía & histología , Regulación de la Expresión Génica/fisiología , Hibridación in Situ/métodos , Péptidos y Proteínas de Señalización Intracelular , Masculino , Neuropéptidos/genética , Neuropéptidos/metabolismo , Receptores de Orexina , Orexinas , Precursores de Proteínas/genética , Precursores de Proteínas/metabolismo , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Receptores Acoplados a Proteínas G , Receptores de Neuropéptido/genética , Privación de Sueño/metabolismo , Factores de TiempoRESUMEN
We have previously shown that experimental hyperthyroidism produces premature and difficult delivery and absence of lactation in spite of apparently adequate luteolysis and lactogenesis. To study the possible causes of these alterations we measured the effect of treatment with T4 (0.25 or 1 mg kg(-1), s.c., daily, started 10-15 days before mating, HT0.25 and HT1) on serum hormones and their receptor (R) concentrations in reproductive tissues on day 20 of pregnancy (1800 hours), comparing them with controls on the same day (C20), or on day 21 of pregnancy (1800 hours) (C21). Serum prolactin (PRL) and corticosterone (B) concentrations increased in the HT groups, progesterone (Pg) and GH decreased and estradiol (E2) did not change, compared with C20 group. C21 rats had increased serum PRL and decreased Pg and GH. In HT rats mammary DNA and protein tissue content was doubled. Receptor concentrations were expressed per mg DNA. Mammary PRL-R were increased in HT1 rats, while E-R and Pg-R were significantly lower in both HT groups. HT0.25 and HT1 rats had increased uterine E-R and Pg-R and decreased liver PRL-R and GH-R as well as their mRNAs. Liver E-R, PRL-R and GH-R were decreased in C21 rats, while uterine Pg-R were increased. Thus, some of the observed changes (serum Pg and GH, mammary and uterine Pg-R, and liver GH-R and PRL-R decreases and serum PRL increase) may be due at least partially to the advancement in luteolysis and delivery, being similar to the changes observed between days 20 and 21. The changes in serum B, mammary PRL-R, and mammary and uterine E-R may be caused solely by the T4 treatments and may play a role in the alterations previously observed.