RESUMEN
The cardinal tetra Paracheirodon axelrodi is a species of the family Characidae of great interest as an ornamental fish. Many aspects of the biology of this species are still unknown. The present work presents a complete description of the different components of the digestive tract of P. axelrodi, analyzing its global anatomical arrangement, the adjacent glands (liver and pancreas) and the previously ignored pyloric caeca, using histological and histochemical techniques with light microscopy and scanning electron microscopy. Three levels of analysis were performed: macroscopic anatomy, histology of the gastrointestinal tract and scanning electron microscopy of mucosal surfaces. The intestinal coefficient (Ci) of P. axelrodi calculated here (0.94) is within the expected range for a carnivorous species. The anatomy of the alimentary and the resulting Ci is consistent with carnivorous diet in line with dietary studies in the wild in this species. The digestive tract, including adjacent glands (liver and pancreas), presented a relatively conserved general pattern within that described for other species of the family Characidae, especially at the histological level.(AU)
El tetra cardenal Paracheirodon axelrodi es una especie de la familia Characidae de gran interés como pez ornamental. Muchos aspectos de la biología de esta especie son aún desconocidos. En este trabajo se presenta una descripción completa de los diferentes componentes del tracto digestivo de P. axelrodi, analizando su disposición anatómica global, las glándulas adyacentes (hígado y páncreas) y la presencia de ciegos pilóricos, mediante técnicas histológicas e histoquímicas con microscopía óptica y electrónica de barrido. Se realizaron tres niveles de análisis: anatomía macroscópica, histología del tracto gastrointestinal y microscopía electrónica de barrido de las superficies mucosas. El coeficiente intestinal (Ci) de P. axelrodi calculado aquí (0,94) está dentro del rango esperado para una especie carnívora. Los estudios anatómicos del tracto alimentario y el Ci son consistentes con una dieta carnívora en línea con los estudios de la dieta en ejemplares silvestres en esta especie. El tracto digestivo, incluyendo las glándulas adyacentes (hígado y páncreas), presentó un patrón general relativamente conservado dentro de lo descrito para otras especies de la familia Characidae, especialmente a nivel histológico.(AU)
Asunto(s)
Animales , Tracto Gastrointestinal/anatomía & histología , Characidae/fisiologíaRESUMEN
In amphibians, intra- or interspecific chemical cues are an important source of information about possible predation risk. In anuran tadpoles, this information causes changes at different levels including behavior, morphology, and growth and development. It has been shown that chemical alarm cues trigger antipredator behaviors, such as decreased exploratory activity, in a wide variety of anuran species; however, the cellular origin of the chemical cues has not yet been confirmed by new evidence. Previous works have suggested that the alarm cues originate from a particular cell type in the skin in tadpoles of the family Bufonidae: the epidermal giant cells (GCs). Here, we confirm the presence of GCs in the epidermis of Rhinella arenarum larvae from developmental stages as early as G22, when free-swimming larvae show gregarious behavior. In addition, larval skin homogenates trigger antipredator behaviors in conspecifics from stage G22 onwards, but not at early stages (G19 and G21). This fact exposes experimental evidence for the coexistence between the appearance of GCs and the production of chemical alarm cues during the development of R. arenarum. Furthermore, the antipredator behavioral response of R. arenarum larvae triggered by skin preparations of other species that belong to the same family who also exhibit GCs allows us to speculate that chemical cues appear to be conserved among phylogenetically related species, allowing them to cross-respond to heterospecific cues. Our experimental approaches support the role of GCs as the source of alarm cues in anuran larvae of the family Bufonidae.
Asunto(s)
Señales (Psicología) , Conducta Predatoria , Animales , Bufonidae , Epidermis , Células Gigantes , Larva/fisiologíaRESUMEN
The cardinal tetra Paracheirodon axelrodi belongs to the family Characidae, an economically important and morphologically diverse family of fishes. Information on the olfactory system of this species is scattered and scarce. Among teleost fishes, differences exist in the shape, number, and arrangement of the olfactory lamellae, in the distribution of the sensory and nonsensory epithelium, as well as in the abundance of various receptor cell types. Here, an anatomical and morphological description of the olfactory system was carried out using light microscopic histology, immunohistochemistry, scanning electron microscopy, and transmission electron microscopy. P. axelrodi is a ditremous and isosmat species. It has an arrow-shaped olfactory rosette arrangement. The olfactory epithelium is covering the 12-14 lamellae of the olfactory rosette and, using scanning electron microscopy, we observed that the apical surface of the olfactory epithelium carries a dense layer of mucus. Based on the histological, immunohistochemical, and ultrastructural descriptions, all characteristic sensory and nonsensory cell types of the olfactory epithelium of teleost fish were identified. Three types of olfactory receptor neurons were identified: ciliated, microvilli, and crypt cells. The distribution of sensory and nonsensory cell types is like that described in Aphyocharax anisitsi, another species of the Characidae family. A. anisitsi inhabits slow-flowing water bodies with high-density vegetation such as P. axelrodi.
Asunto(s)
Characidae , Characiformes , Neuronas Receptoras Olfatorias , Animales , Characidae/anatomía & histología , Microscopía Electrónica de Rastreo , Mucosa OlfatoriaRESUMEN
Chemical communication can induce a multitude of behaviours when detected by fish olfactory systems, from parental care, predation and alarm signalling, to foraging, schooling, reproduction, and migration. Chemical cues provide information that visual traits cannot and fish can respond to chemical cues without any additional sensory cue. In this way, pheromones play an essential role in the fitness of fishes. Given that Aphyocharax anisitsi inhabits environments characterized by cloudy and highly vegetated waters, it is interesting to evaluate the olfactory contribution in their communication. Here, we investigated the relevance of chemical cues in the types of behaviours triggered in A anisitsi by two experimental contexts: 1) non-social and olfactory context (conspecific-chemical cues), and 2) social context (conspecific female or male presence). Non-social context experiments suggest that males of A. anisitsi respond to both male and female-chemical cues even in the absence of other sensory inputs. The high olfactory sensitivity of characids in general and of A. anisitsi, in particular, could facilitate vital functions, such as foraging and conspecific recognition in habitats that impose severe restrictions on the visual system.
Asunto(s)
Characidae , Animales , Señales (Psicología) , Femenino , Masculino , Feromonas , Conducta Predatoria , OlfatoRESUMEN
Anuran amphibians (frogs and toads) typically have a complex life cycle, involving aquatic larvae that metamorphose to semi-terrestrial juveniles and adults. However, the anuran olfactory system is best known in Xenopus laevis, an animal with secondarily aquatic adults. The larval olfactory organ contains two distinct sensory epithelia: the olfactory epithelium (OE) and vomeronasal organ (VNO). The adult organ contains three: the OE, the VNO, and a "middle cavity" epithelium (MCE), each in its own chamber. The sensory epithelia of Xenopus larvae have overlapping sensory neuron morphology (ciliated or microvillus) and olfactory receptor gene expression. The MCE of adults closely resembles the OE of larvae, and senses waterborne odorants; the adult OE is distinct and senses airborne odorants. Olfactory subsystems in other (non-pipid) anurans are diverse. Many anuran larvae show a patch of olfactory epithelium exposed in the buccal cavity (bOE), associated with a grazing feeding mode. And other anuran adults do not have a sensory MCE, but many have a distinct patch of epithelium adjacent to the OE, the recessus olfactorius (RO), which senses waterborne odorants. Olfaction plays a wide variety of roles in the life of larval and adult anurans, and some progress has been made in identifying relevant odorants, including pheromones and feeding cues. Increased knowledge of the diversity of olfactory structure, of odorant receptor expression patterns, and of factors that affect the access of odorants to sensory epithelia will enable us to better understand the adaptation of the anuran olfactory system to aquatic and terrestrial environments.
Asunto(s)
Neuronas Receptoras Olfatorias/fisiología , Anfibios , AnimalesRESUMEN
Among teleost fishes, differences exist in the shape, number, and arrangement of the olfactory lamellae, the distribution of the sensory and non-sensory epithelium, as well as, the abundance of various receptor cells. The objective of this work was to describe the morphology, immunohistochemistry, and scanning electron microscopy ultrastructure of the olfactory epithelium of the bloodfin tetra, Aphyocharax anisitsi. This is the first complete description including the anatomy, histology, and immunohistochemistry of the peripheral olfactory organ from a Characiformes. Based on the external morphology of the olfactory organ, A. anisitsi was classified as a ditermous species, with an olfactory cavity containing two openings divided by a skin flap that separates the anterior and posterior nostril. This species belongs to the group of isosmates, since the presence of accessory olfactory sacs was not observed, and non-sensory ciliated cells were identified. A. anisitsi has an olfactory rosette with an arrow-shaped arrangement, with differences in length between the anterior and posterior lamellae. In the olfactory epithelium, three types of olfactory receptor neurons were identified using histology and confirmed by immunohistochemistry, that is, ciliated olfactory receptor neurons in the basal region of the epithelium, microvillar olfactory receptor neurons in the middle region; and Crypt cells, in smaller numbers compared to the other neuronal types, present in the apical region. Sensory and non-sensory areas were scattered and mixed along the lamellar lateral surface but the nasal cavity and the midline raphe lacked olfactory receptor neurons. The presence of abundant kinocilia in the non-sensory cells could be related in A. anisitsi with ventilation and quality control of water entering the olfactory cavity. The spatial organization of the sensory and non-sensory areas in A. anisitsi was similar to that observed in other species that also inhabit still and slow-flowing bodies of water with high-density vegetation.
Asunto(s)
Characidae/anatomía & histología , Mucosa Olfatoria/anatomía & histología , Mucosa Olfatoria/citología , Animales , Cilios/ultraestructura , Femenino , Inmunohistoquímica , Masculino , Mucosa Olfatoria/ultraestructura , Neuronas Receptoras Olfatorias/metabolismoRESUMEN
Cardinal tetra Paracheirodon axelrodi and bloodfin tetra Aphyocharax anisitsi are two species of characids with high trade value as ornamental fish in South America. Although both species inhabit middle water layers, cardinal neon exhibits a tropical distribution and bloodfin tetra a subtropical one. Generally, these species are difficult to grow, so it becomes essential to know some key components of the neuroendocrine system to achieve their reproduction in captivity. Considering the importance of deepening the knowledge of the reproductive physiology through functional morphology, for the first time in this work we performed an anatomical, morphological and immunohistochemical analysis of the pituitary gland of these two species. In both species, a leptobasic type pituitary is found in the ventral zone of the hypothalamus and it is characterized by a neurohypophysis which has a well-developed pituitary stalk and a globular adenohypophysis. The pituitary components, characterized by histochemistry and immunohistochemistry, shows a distribution pattern of cells types similar to other teleost species, with only slight differences in the distribution of βFSH and βLH for P. axelrodi.(AU)
El cardenal tetra Paracheirodon axelrodi y el tetra Aphyocharax anisitsi son dos especies de carácidos con alto valor comercial como peces ornamentales en América del Sur. Aunque ambas especies habitan en las capas medias de agua, el neón cardenal exhibe una distribución tropical, mientras que el tetra cola roja una distribución subtropical. En general estas especies son difíciles de cultivar, por lo que es esencial conocer algunos componentes clave de los sistemas neuroendocrinos para lograr su reproducción en cautiverio. Considerando la importancia de profundizar en el conocimiento de la fisiología reproductiva a través de la morfología funcional, en este trabajo realizamos, por primera vez, un análisis anatómico, morfológico e inmunohistoquímico de la glándula pituitaria de estas dos especies. En ambas especies, la hipófisis, del tipo leptobásica, se encontró en la zona ventral del hipotálamo y se caracteriza por una neurohipófisis con un tallo hipofisario bien desarrollado y una adenohipófisis globular. Los componentes hipofisarios, caracterizados por la histoquímica y la inmunohistoquímica, mostraron un patrón de distribución de tipos de células similares a otras especies de teleósteos, con solo pequeñas diferencias en la distribución de βFSH y βLH para P. axelrodi.(AU)
Asunto(s)
Animales , Hipófisis/enzimología , Inmunohistoquímica/veterinaria , Characiformes/anatomía & histología , Characiformes/inmunología , HistologíaRESUMEN
Cardinal tetra Paracheirodon axelrodi and bloodfin tetra Aphyocharax anisitsi are two species of characids with high trade value as ornamental fish in South America. Although both species inhabit middle water layers, cardinal neon exhibits a tropical distribution and bloodfin tetra a subtropical one. Generally, these species are difficult to grow, so it becomes essential to know some key components of the neuroendocrine system to achieve their reproduction in captivity. Considering the importance of deepening the knowledge of the reproductive physiology through functional morphology, for the first time in this work we performed an anatomical, morphological and immunohistochemical analysis of the pituitary gland of these two species. In both species, a leptobasic type pituitary is found in the ventral zone of the hypothalamus and it is characterized by a neurohypophysis which has a well-developed pituitary stalk and a globular adenohypophysis. The pituitary components, characterized by histochemistry and immunohistochemistry, shows a distribution pattern of cells types similar to other teleost species, with only slight differences in the distribution of βFSH and βLH for P. axelrodi.(AU)
El cardenal tetra Paracheirodon axelrodi y el tetra Aphyocharax anisitsi son dos especies de carácidos con alto valor comercial como peces ornamentales en América del Sur. Aunque ambas especies habitan en las capas medias de agua, el neón cardenal exhibe una distribución tropical, mientras que el tetra cola roja una distribución subtropical. En general estas especies son difíciles de cultivar, por lo que es esencial conocer algunos componentes clave de los sistemas neuroendocrinos para lograr su reproducción en cautiverio. Considerando la importancia de profundizar en el conocimiento de la fisiología reproductiva a través de la morfología funcional, en este trabajo realizamos, por primera vez, un análisis anatómico, morfológico e inmunohistoquímico de la glándula pituitaria de estas dos especies. En ambas especies, la hipófisis, del tipo leptobásica, se encontró en la zona ventral del hipotálamo y se caracteriza por una neurohipófisis con un tallo hipofisario bien desarrollado y una adenohipófisis globular. Los componentes hipofisarios, caracterizados por la histoquímica y la inmunohistoquímica, mostraron un patrón de distribución de tipos de células similares a otras especies de teleósteos, con solo pequeñas diferencias en la distribución de βFSH y βLH para P. axelrodi.(AU)
Asunto(s)
Animales , Hipófisis/enzimología , Inmunohistoquímica/veterinaria , Characiformes/anatomía & histología , Characiformes/inmunología , HistologíaRESUMEN
In many amphibians, the granular glands can be grouped in special regions forming macroglands. This is the case of toads, characterized by the presence of a pair of parotoid macroglands, strategically located to give protection by poison release in case of attacks. The product secreted consists of a wide variety of chemical compounds including proteins, peptides, biogenic amines, toxic steroidal bufadienolides, and various alkaloids, depending on the species. In this work, using Rhinella arenarum, we have performed, for the first time, the matrix assisted-ultraviolet laser desorption/ionization mass spectrometry and tandem mass spectrometry characterization of the components of the secretion used as crude material, just suspended in MeOH (or MeCN). The crude sample as a whole (whole suspension) was spotted on the matrix assisted-ultraviolet laser desorption plate for analysis. Electrospray ionization-Orbitrap was used for cross-checking experiments. The pattern of signals obtained at m/z ranges 600 to 800 and 1200 to 1600 could be assigned as the argininyl bufadienolide esters fingerprint characteristic of female and male. Variation patterns for gender (female, male), age (non-reproductive, reproductive), and season (non-reproductive, reproductive) are described.
Asunto(s)
Arginina/análogos & derivados , Arginina/análisis , Bufanólidos/análisis , Cordados/fisiología , Glándula Parótida/metabolismo , Animales , Arginina/metabolismo , Bufanólidos/metabolismo , Cordados/crecimiento & desarrollo , Cromatografía Líquida de Alta Presión/métodos , Ésteres/análisis , Ésteres/metabolismo , Femenino , Masculino , Análisis de Componente Principal/métodos , Estaciones del Año , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Espectrometría de Masas en Tándem/métodosRESUMEN
The anuran peripheral olfactory system is composed of a number of subsystems, represented by distinct neuroepithelia. These include the main olfactory epithelium and vomeronasal organ (found in most tetrapods) and three specialized epithelia of anurans: the buccal-exposed olfactory epithelium of larvae, and the olfactory recess and middle chamber epithelium of postmetamorphic animals. To better characterize the developmental changes in these subsystems across the life cycle, morphometric changes of the nasal chemosensory organs during larval development and metamorphosis were analyzed in three different anuran species (Rhinella arenarum, Hypsiboas pulchellus, and Xenopus laevis). We calculated the volume of the nasal chemosensory organs by measuring the neuroepithelial area from serial histological sections at four different stages. In larvae, the vomeronasal organ was relatively reduced in R. arenarum compared with the other two species; the buccal-exposed olfactory epithelium was absent in X. laevis, and best developed in H. pulchellus. In postmetamorphic animals, the olfactory epithelium (air-sensitive organ) was relatively bigger in terrestrial species (R. arenarum and H. pulchellus), whereas the vomeronasal and the middle chamber epithelia (water-sensitive organs) was best developed in X. laevis. A small olfactory recess (likely homologous with the middle chamber epithelium) was found in R. arenarum juveniles, but not in H. pulchellus. These results support the association of the vomeronasal and middle chamber epithelia with aquatic olfaction, as seen by their enhanced development in the secondarily aquatic juveniles of X. laevis. They also support a role for the larval buccal-exposed olfactory epithelium in assessment of oral contents: it was absent in X. laevis, an obligate suspension feeder, while present in the two grazing species. These initial quantitative results give, for the first time, insight into the functional importance of the peripheral olfactory subsystems across the anuran life cycle.
Asunto(s)
Anuros/crecimiento & desarrollo , Metamorfosis Biológica , Mucosa Olfatoria/crecimiento & desarrollo , Órgano Vomeronasal/crecimiento & desarrollo , Animales , Epitelio/anatomía & histología , Procesamiento de Imagen Asistido por Computador , Inmunohistoquímica , Larva/crecimiento & desarrollo , Mucosa Olfatoria/anatomía & histología , Especificidad de la Especie , Órgano Vomeronasal/anatomía & histología , Xenopus laevis/crecimiento & desarrolloRESUMEN
Exposure to adverse environmental conditions can elicit a stress response, which results in an increase in endogenous corticosterone levels. In early life stages, it has been thoroughly demonstrated that amphibian larval growth and development is altered as a consequence of chronic stress by interfering with the metamorphic process, however, the underlying mechanisms involved have only been partially disentangled. We examined the effect of intraspecific competition on corticosterone levels during larval development of the toad Rhinella arenarum and its ultimate effects on cell proliferation in particular brain areas as well as the pituitary gland. While overcrowding altered the number of proliferating cells in the pituitary gland, hypothalamus, and third ventricle of the brain, no differences were observed in areas which are less associated with neuroendocrine processes, such as the first ventricle of the brain. Apoptosis was increased in hypothalamic regions but not in the pituitary. With regards to pituitary cell populations, thyrotrophs but not somatoatrophs and corticotrophs showed a decrease in the cell number in overcrowded larvae. Our study shows that alterations in growth and development, produced by stress, results from an imbalance in the neuroendocrine systems implicated in orchestrating the timing of metamorphosis.
Asunto(s)
Encéfalo/crecimiento & desarrollo , Bufo arenarum/crecimiento & desarrollo , Proliferación Celular , Aglomeración , Sistemas Neurosecretores/crecimiento & desarrollo , Hipófisis/crecimiento & desarrollo , Estrés Fisiológico , Animales , Apoptosis , Encéfalo/citología , Corticosterona/análisis , Larva/citología , Larva/crecimiento & desarrollo , Metamorfosis Biológica , Sistemas Neurosecretores/citología , Hipófisis/citologíaRESUMEN
We investigated the occurrence and anatomy of the vomeronasal system (VNS) in tadpoles of 13 different anuran species. All of the species possessed a morphologically fully developed VNS with a highly conserved anatomical organisation. We found that a bean-shaped vomeronasal organ (VNO) developed early in the tadpoles, during the final embryonic stages, and was located in the anteromedial nasal region. Histology revealed the presence of bipolar chemosensory neurones in the VNO that were immunoreactive for the Gαo protein. Tract-tracing experiments demonstrated that chemosensory neurones from the VNO reach specific areas in the brain, where a discernible accessory olfactory bulb (AOB) could be observed. The AOB was located in the ventrolateral side of the anterior telencephalon, somewhat caudal to the main olfactory bulb. Synaptophysin-like immunodetection revealed that synaptic contacts between VNO and AOB are established during early larval stages. Moreover, using lectin staining, we identified glomerular structures in the AOB in most of the species that we examined. According to our findings, a significant maturation in the VNS is achieved in anuran larvae. Recent published evidence strongly suggests that the VNS appeared early in vertebrate evolution and was already present in the aquatic last common ancestor of lungfish and tetrapods. In this context, tadpoles may be a good model in which to investigate the anatomical, biochemical and functional aspects of the VNS in an aquatic environment.
Asunto(s)
Anuros/anatomía & histología , Órgano Vomeronasal/anatomía & histología , Animales , Anuros/crecimiento & desarrollo , Inmunohistoquímica , Larva/anatomía & histología , Bulbo Olfatorio/anatomía & histología , Especificidad de la Especie , Órgano Vomeronasal/crecimiento & desarrolloRESUMEN
Angiotensin II (AngII), the main effector peptide of the renin-angiotensin system (RAS), participates in multiple biological processes, including cell growth, apoptosis, and tissue remodeling. Since AngII activates, in different cell types, signal transducing pathways that are critical for mammary gland postlactational regression, we investigated the role of the RAS during this process. We found that exogenous administration of AngII in mammary glands of lactating Balb/c mice induced epithelium apoptosis [2.9±0.5% (control) vs. 9.6±1.1% (AngII); P < 0.001] and activation of the proapoptotic factor STAT3, an effect inhibited by irbesartan, an AT(1) receptor blocker. Subsequently, we studied the expression kinetics of RAS components during involution. We found that angiotensin-converting enzyme (ACE) mRNA expression peaked 6 h after weaning (5.7-fold; P<0.01), while induction of angiotensinogen and AT(1) and AT(2) receptors expression was detected 96 h after weaning (6.2-, 10-, and 6.2-fold increase, respectively; P<0.01). To assess the role of endogenously generated AngII, mice were treated with losartan, an AT(1) receptor blocker, during mammary involution. Mammary glands from losartan-treated mice showed activation of the survival factors AKT and BCL-(XL), significantly lower LIF and TNF-α mRNA expression (P<0.05), reduced apoptosis [12.1±2.1% (control) vs. 4.8±0.7% (losartan); P<0.001] and shedding of epithelial cells, inhibition of MMP-9 activity in a dose-dependent manner (80%; P<0.05; with losartan IC(50) value of 6.9 mg/kg/d] and lower collagen deposition and adipocyte invasion causing a delayed involution compared to vehicle-treated mice. Furthermore, mammary glands of forced weaned AT(1A)- and/or AT(1B)-deficient mice exhibited retarded apoptosis of epithelial cells [6.3±0.95% (WT) vs. 3.3±0.56% (AT(1A)/AT(1B) DKO); P<0.05] with remarkable delayed postlactational regression compared to wild-type animals. Taken together, these results strongly suggest that AngII, via the AT(1) receptor, plays a major role in mouse mammary gland involution identifying a novel role for the RAS. angiotensin system.
Asunto(s)
Bloqueadores del Receptor Tipo 1 de Angiotensina II/farmacología , Glándulas Mamarias Animales/efectos de los fármacos , Receptor de Angiotensina Tipo 1/efectos de los fármacos , Sistema Renina-Angiotensina , Angiotensina II/metabolismo , Animales , Apoptosis/efectos de los fármacos , Línea Celular , Relación Dosis-Respuesta a Droga , Femenino , Etiquetado Corte-Fin in Situ , Lactancia , Glándulas Mamarias Animales/metabolismo , Glándulas Mamarias Animales/fisiología , Ratones , Ratones Endogámicos BALB C , Reacción en Cadena de la Polimerasa , Transducción de SeñalRESUMEN
The mammary epithelium undergoes cyclical periods of cellular proliferation, differentiation, and regression. During lactation, the signal transducer and activator of transcription factor (STAT)-5A and the glucocorticoid receptor (GR) synergize to induce milk protein expression and also act as survival factors. During involution, STAT3 activation mediates epithelial cell apoptosis and mammary gland remodeling. It has been shown that the administration of glucocorticoids at weaning prevents epithelial cell death, probably by extracellular matrix breakdown prevention. Our results show that the synthetic glucocorticoid dexamethasone (DEX) modulates STAT5A and STAT3 signaling and inhibits apoptosis induction in postlactating mouse mammary glands, only when administered within the first 48 h upon cessation of suckling. DEX administration right after weaning delayed STAT5A inactivation and degradation, preserving gene expression of target genes as ß-casein (bcas) and prolactin induced protein (pip). Weaning-triggered GR down-regulation is also delayed by the hormone treatment. Moreover, DEX administration delayed STAT3 activation and translocation into epithelial cells nuclei. In particular, DEX treatment impaired the increment in gene expression of signal transducer subunit gp130, normally up-regulated from lactation to involution and responsible for STAT3 activation. Therefore, the data shown herein indicate that glucocorticoids are able to modulate early involution by controlling the strong cross talk that GR, STAT5, and STAT3 pathways maintains in the mammary epithelium.
Asunto(s)
Dexametasona/farmacología , Glándulas Mamarias Animales/fisiología , Factor de Transcripción STAT3/metabolismo , Factor de Transcripción STAT5/metabolismo , Transducción de Señal/fisiología , Animales , Receptor gp130 de Citocinas/genética , Receptor gp130 de Citocinas/metabolismo , Fragmentación del ADN , Dexametasona/administración & dosificación , Femenino , Regulación de la Expresión Génica/fisiología , Glucocorticoides/administración & dosificación , Glucocorticoides/farmacología , Lactancia/fisiología , Factor Inhibidor de Leucemia/genética , Factor Inhibidor de Leucemia/metabolismo , Glándulas Mamarias Animales/efectos de los fármacos , Ratones , Ratones Endogámicos BALB C , Factor de Transcripción STAT3/genética , Factor de Transcripción STAT5/genéticaRESUMEN
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) play key roles in vertebrate gametogenesis and steroidogenesis. They are mainly synthesized in the pituitary gland. While investigating the ontogeny of FSH and LH cells in the cichlid fish Cichlasoma dimerus by immunohistochemistry (IHC), we unexpectedly found immunoreactive neurons in the preoptic area, sending their projections through different brain areas and neurohypophysis. Our previous work using Western blot and IHC techniques applied to the adult brain confirmed these findings. To further demonstrate the extrapituitary expression of these hormones, we performed RT-PCR detecting sequences coding for beta-FSH and beta-LH subunits in the C. dimerus pituitary and brain (preoptic-hypothalamic area). The expression of these transcripts in both organs was consistent with their peptide expression showing a high sequence homology when compared with other phylogenetically related fish. An individual pituitary in vitro culture system was utilized to study the possible modulatory effect of brain-derived gonadotropins on pituitary hormone secretion. Pituitary explants were cultured with different concentrations of LH or FSH, and the culture media were analyzed by Western blot. Exogenous LH produced a dose-dependent increase in pituitary beta-LH, beta-FSH and somatolactin (SL) releases. No effect was observed on growth hormone (GH). The effect on prolactin (PRL) was not consistent among treatments. Exogenous FSH produced an inhibition in beta-LH release, dose-dependent increases in beta-FSH and SL releases, and no effect on PRL and GH releases. These findings support the concept of regulation of pituitary trophic hormones by brain-derived gonadotropins.
Asunto(s)
Hormona Folículo Estimulante de Subunidad beta/análisis , Hormona Folículo Estimulante de Subunidad beta/genética , Hormona Luteinizante de Subunidad beta/análisis , Hormona Luteinizante de Subunidad beta/genética , Hipófisis/metabolismo , Área Preóptica/química , ARN Mensajero/análisis , Secuencia de Aminoácidos , Animales , Cíclidos , Relación Dosis-Respuesta a Droga , Femenino , Proteínas de Peces/metabolismo , Hormona Folículo Estimulante/farmacología , Hormona Folículo Estimulante de Subunidad beta/metabolismo , Expresión Génica , Glicoproteínas/metabolismo , Hormona del Crecimiento/metabolismo , Inmunohistoquímica , Hormona Luteinizante/farmacología , Hormona Luteinizante de Subunidad beta/metabolismo , Masculino , Datos de Secuencia Molecular , Técnicas de Cultivo de Órganos , Hormonas Hipofisarias/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Homología de Secuencia de AminoácidoRESUMEN
We detected a close morphological association between melanin-concentrating hormone (MCH)-immunoreactive (ir) fibers and somatolactin (SL)-ir cells in the pars intermedia of the cichlid fish Cichlasoma dimerus by double-label immunofluorescence. Male pituitaries obtained from adult C. dimerus were incubated with 0.1-10 microM salmon MCH, and the amount of SL released into the culture medium was semi-quantified by Western blot. This assay showed an increase of SL release in a dose-dependent manner (linear regression: P<0.05). A close association of GnRH-ir fibers with SL-ir cells was also detected at the pars intermedia level. Male pituitaries were also incubated with 0.1-10 microM of mammalian GnRH, and SL release was semi-quantified by Western blot, showing an increase of released SL levels in a dose-dependent manner (linear regression: P<0.05). In contrast, SL release was unaffected from female pituitaries incubated with salmon MCH; however, an increasing tendency was observed when mammalian GnRH was used. Hypothalamic close association of MCH-ir perikarya and GnRH-ir fibers was found by double-label immunofluorescence indicating a possible relationship between them. These results suggest that SL, like other pituitary hormones, is under hypothalamic control and is involved in diverse physiological processes including background adaptation and reproduction. This study has also shown that the in vitro culture of a single C. dimerus pituitary is a feasible method for studying the control of SL release and other pituitary hormones.
Asunto(s)
Cíclidos/fisiología , Proteínas de Peces/metabolismo , Hormona Liberadora de Gonadotropina/farmacología , Hormona del Crecimiento/metabolismo , Hormonas Hipotalámicas/farmacología , Melaninas/farmacología , Hormonas Hipofisarias/farmacología , Animales , Células Cultivadas , Medios de Cultivo/química , Relación Dosis-Respuesta a Droga , Estudios de Factibilidad , Femenino , Hormona del Crecimiento/química , Cinética , Masculino , Peso Molecular , Hipófisis/citología , Isoformas de Proteínas , Reproducibilidad de los Resultados , Salmón , Factores de TiempoRESUMEN
In the last years several studies have shown that vascular endothelial growth factor (VEGF) is present in neural stem cells and mature neurons from different neural tissues where it may play an important role as a neuroproliferative and/or antiapoptotic factor. The olfactory neuroepithelium has the capability to replace dying neurons with new neurons formed by cell division from stem cells in the basal region of the epithelium. The present study demonstrates, for the first time, that VEGF is present in the olfactory epithelium, nerves and bulbs (both main and accessory) during the development of the toad Bufo arenarum. In this report, we detected VEGF immunoreactivity in mature olfactory neurons from early larval stages until the beginning of the metamorphic climax. VEGF expression decreases dramatically after metamorphosis. VEGF receptor Flk-1 was localized by immunohistochemistry, from premetamorphic larval stages until the climax in the neurons of the olfactory epithelium with a more intense labeling in the basal cell layer. Double-label immunofluorescence studies localized VEGF to the cytoplasm and the nucleus of mature neurons whereas Flk-1 was expressed in cell membranes. Flk-1 was present in neurons of both the main and accessory olfactory bulbs. After the end of metamorphosis, Flk-1 expression was limited to basal cells in the olfactory epithelium and Bowman's glands. The main and accessory olfactory bulbs showed the same pattern of Flk-1 immunostaining before and after the end of metamorphosis. The presence of VEGF and its receptor in the olfactory system suggests that VEGF may play an important role during neural development.
Asunto(s)
Bufo arenarum/embriología , Mucosa Olfatoria/embriología , Mucosa Olfatoria/metabolismo , Factor A de Crecimiento Endotelial Vascular/metabolismo , Receptor 2 de Factores de Crecimiento Endotelial Vascular/metabolismo , Animales , Western Blotting , Diferenciación Celular , Inmunohistoquímica , Larva/metabolismo , Mucosa Olfatoria/citologíaRESUMEN
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) expressing cells were detected in pituitary, brain and ovary of the Perciform cichlid fish Cichlasoma dimerus. This detection was carried out by immunohistochemistry (IHC) and Western blot techniques using antisera of the Cyprinodontiform Fundulus heteroclitus raised against the conservative region of the teleost betaFSH and the betaLH subunits. The estimated molecular weights were 24 kDa for LH and 19 and 15 kDa for FSH. In the adult pituitary, both cell types were distributed along mid and ventral zones of the proximal pars distalis (PPD, mid-immunoreactive cells), and along the ventral and dorsal external border of the pars intermedia (PI, high-immunoreactive cells). Double IHC showed that FSH and LH are mainly expressed in different pituitary cells. FSH cells were detected in the pituitary around day 21 after hatching (ah) (prior to sex differentiation), while LH cells were detected by day 60 ah (during the sexual differentiation period). A correlation between gonadal sex differentiation and FSH was demonstrated in a 15 days organ culture system. FSH and LH neurons were localized in the nucleus lateralis tuberis and their fibers project through the ventral hypothalamus, preoptic area and neurohypophysis. FSH neurons differentiated on day 21 ah, while LH neurons appeared on day 15 ah. In the ovary, the immunoreactivity for both FSH and LH was restricted to the cytoplasm of previtellogenic and early vitellogenic oocytes.
Asunto(s)
Cíclidos/embriología , Hormona Folículo Estimulante/metabolismo , Hormona Luteinizante/metabolismo , Ovario/embriología , Hipófisis/embriología , Diferenciación Sexual , Factores de Edad , Animales , Encéfalo/citología , Encéfalo/embriología , Encéfalo/metabolismo , Femenino , Hormona Folículo Estimulante/farmacología , Hormona Liberadora de Gonadotropina/metabolismo , Inmunohistoquímica , Masculino , Fibras Nerviosas/metabolismo , Técnicas de Cultivo de Órganos , Ovario/citología , Ovario/metabolismo , Hipófisis/citología , Hipófisis/metabolismo , Testículo/citología , Testículo/embriología , Testículo/metabolismo , Vitelogénesis/efectos de los fármacos , Vitelogénesis/fisiologíaRESUMEN
The present study employs an in vitro system to analyse the role of steroid hormones in hCG-induced spermiation in two species of anuran amphibian: Rana catesbeiana and Leptodactylus ocellatus. In vitro spermiation was induced with 10 IU hCG and the effect of different steroid-biosynthesis inhibitors was analysed. Cyanoketone (10(-5)M), an inhibitor of 3-oxo-4-ene steroid biosynthesis, did not block hCG-inducing activity even when biosynthesis of androgen was significantly reduced. These results clearly showed that, in both species, spermiation-inducing action of hCG does not depend on the biosynthesis of 3-oxo-4-ene steroids. Moreover, when combined inhibitors, aminoglutethimide (10(-5)M) plus cyanoketone (10(-5)M), were employed, spermiation evoked by hCG was not modified while hCG-induced androgen secretion significantly decreased. Additionally, none of the steroids used, progesterone, 17, 20 alpha-dihydroxy-4-pregnen-3-one, testosterone and 5 alpha-dihydrotestosterone, were able to induce spermiation in the absence of hCG, confirming that steroids are not involved in that process. In conclusion, as previously described in Bufo arenarum, in L. ocellatus and R. catesbeiana hCG-induced spermiation does not depend on steroid biosynthesis.
Asunto(s)
Anuros/fisiología , Rana catesbeiana/fisiología , Espermatogénesis , Esteroides/biosíntesis , Andrógenos/metabolismo , Animales , Gonadotropina Coriónica/farmacología , Dihidrotestosterona/farmacología , Humanos , Hidroxiprogesteronas/farmacología , Masculino , Progesterona/farmacología , Testosterona/farmacologíaRESUMEN
This paper analyzes, in the toad Bufo arenarum, the effect on spermiation and androgen secretion of two human recombinant gonadotropins, human recombinant LH (hrLH) and human recombinant FSH (hrFSH) as well as the well-known spermiation-inducing hormone, human chorionic gonadotropin (hCG). For this purpose, testes were incubated with different concentrations of hrLH (0.01-2.5 microg/ml) and hrFSH (0.05-5 microg/ml), and results were compared with those obtained with 2.5 microg/ml hCG. Spermiation was most efficiently stimulated by hrFSH, which elicited a higher response than either hrLH or hCG. Both hrFSH and hrLH produced a bell-shaped dose-response curve, with a 50% inhibition on spermiation at a concentration twice higher than that necessary to get the highest response. However, none of the gonadotropins yielded a biphasic response on androgen secretion, hrLH producing the highest response at a concentration that evoked a 70% inhibition in the spermiation test. Regarding steroidogenesis, hrLH and hrFSH were more active than hCG. Taken together, the results described in this paper suggest that, in B. arenarum, spermiation and androgen secretion are mediated by different receptors. After comparing the effects of recombinant hormones, we conclude that hrFSH has a greater effect on spermiation than hCG or hrLH.