RESUMEN
All forms of stress, including restraint stress (RS) and lipopolysaccharide (LPS) administration, activate the hypothalamic-pituitary-adrenal (HPA) axis. LPS binds to a recognition protein (CD14) and toll-like receptor 2/4 in different cells and tissues, including the adrenal gland, to induce the production of cytokines and cause upregulation of cyclooxygenase and nitric oxide synthase (NOS) enzymes. Acute ethanol exposure activates the HPA axis, but in some conditions prolonged administration can dampen this activation as well as decrease the inflammatory responses to LPS. Therefore, this study was designed to evaluate the adrenal response to a challenge dose of LPS (50 µg/kg) injected i.p., after submitting male rats to RS, twice a day (2 h each time) for 5 days and/or ethanol administration (3 g/kg) by gavage also for 5 days, twice daily. At the end of the experiment, plasma corticosterone concentrations and adrenal gland content of prostaglandin E (PGE) and NOS activity were measured as stress mediators. The results showed that repetitive ethanol administration attenuated the adrenal stress response to LPS challenge alone and after RS, by preventing the increase in plasma corticosterone concentrations and by decreasing the PGE content and NOS activity in the adrenal gland. Therefore, we conclude that moderate alcohol consumption could attenuate the effects of psychophysical stress and impair an inflammatory response.
Asunto(s)
Glándulas Suprarrenales/efectos de los fármacos , Glándulas Suprarrenales/fisiología , Etanol/farmacología , Lipopolisacáridos/farmacología , Animales , Corticosterona/sangre , Ciclooxigenasa 1/biosíntesis , Ciclooxigenasa 2/biosíntesis , Inflamación/prevención & control , Receptores de Lipopolisacáridos/metabolismo , Lipopolisacáridos/antagonistas & inhibidores , Masculino , Proteínas de la Membrana/biosíntesis , Óxido Nítrico Sintasa/metabolismo , Prostaglandinas E/metabolismo , Ratas , Ratas Sprague-Dawley , Restricción Física , Estrés Psicológico/tratamiento farmacológico , Receptor Toll-Like 4/metabolismoRESUMEN
Our objective was to determine the effect of arachidonylethanolamide (anandamide, AEA) injected intracerebroventricularly (icv) into the lateral ventricle of the rat brain on submandibular gland (SMG) salivary secretion. Parasympathetic decentralization (PSD) produced by cutting the chorda tympani nerve strongly inhibited methacholine (MC)-induced salivary secretion while sympathetic denervation (SD) produced by removing the superior cervical ganglia reduced it slightly. Also, AEA (50 ng/5 µL, icv) significantly decreased MC-induced salivary secretion in intact rats (MC 1 µg/kg: control (C), 5.3 ± 0.6 vs AEA, 2.7 ± 0.6 mg; MC 3 µg/kg: C, 17.6 ± 1.0 vs AEA, 8.7 ± 0.9 mg; MC 10 µg/kg: C, 37.4 ± 1.2 vs AEA, 22.9 ± 2.6 mg). However, AEA did not alter the significantly reduced salivary secretion in rats with PSD, but decreased the slightly reduced salivary secretion in rats with SD (MC 1 µg/kg: C, 3.8 ± 0.8 vs AEA, 1.4 ± 0.6 mg; MC 3 µg/kg: C, 14.7 ± 2.4 vs AEA, 6.9 ± 1.2 mg; P < 0.05; MC 10 µg/kg: C, 39.5 ± 1.0 vs AEA, 22.3 ± 0.5 mg; P < 0.001). We showed that the inhibitory effect of AEA is mediated by cannabinoid type 1 CB1 receptors and involves GABAergic neurotransmission, since it was blocked by previous injection of the CB1 receptor antagonist AM251 (500 ng/5 µL, icv) or of the GABA A receptor antagonist, bicuculline (25 ng/5 µL, icv). Our results suggest that parasympathetic neurotransmission from the central nervous system to the SMG can be inhibited by endocannabinoid and GABAergic systems.
Asunto(s)
Animales , Masculino , Ratas , Ácidos Araquidónicos/farmacología , Endocannabinoides/farmacología , Ventrículos Laterales/efectos de los fármacos , Alcamidas Poliinsaturadas/farmacología , Saliva , Transmisión Sináptica/efectos de los fármacos , Ácidos Araquidónicos/administración & dosificación , Endocannabinoides/administración & dosificación , Inyecciones Intraventriculares , Alcamidas Poliinsaturadas/administración & dosificación , Ratas Wistar , Saliva/efectos de los fármacos , Glándula SubmandibularRESUMEN
Our objective was to determine the effect of arachidonylethanolamide (anandamide, AEA) injected intracerebroventricularly (icv) into the lateral ventricle of the rat brain on submandibular gland (SMG) salivary secretion. Parasympathetic decentralization (PSD) produced by cutting the chorda tympani nerve strongly inhibited methacholine (MC)-induced salivary secretion while sympathetic denervation (SD) produced by removing the superior cervical ganglia reduced it slightly. Also, AEA (50 ng/5 microL, icv) significantly decreased MC-induced salivary secretion in intact rats (MC 1 microg/kg: control (C), 5.3 +/- 0.6 vs AEA, 2.7 +/- 0.6 mg; MC 3 microg/kg: C, 17.6 +/- 1.0 vs AEA, 8.7 +/- 0.9 mg; MC 10 microg/kg: C, 37.4 +/- 1.2 vs AEA, 22.9 +/- 2.6 mg). However, AEA did not alter the significantly reduced salivary secretion in rats with PSD, but decreased the slightly reduced salivary secretion in rats with SD (MC 1 microg/kg: C, 3.8 +/- 0.8 vs AEA, 1.4 +/- 0.6 mg; MC 3 microg/kg: C, 14.7 +/- 2.4 vs AEA, 6.9 +/- 1.2 mg; P < 0.05; MC 10 microg/kg: C, 39.5 +/- 1.0 vs AEA, 22.3 +/- 0.5 mg; P < 0.001). We showed that the inhibitory effect of AEA is mediated by cannabinoid type 1 CB1 receptors and involves GABAergic neurotransmission, since it was blocked by previous injection of the CB1 receptor antagonist AM251 (500 ng/5 microL, icv) or of the GABA A receptor antagonist, bicuculline (25 ng/5 microL, icv). Our results suggest that parasympathetic neurotransmission from the central nervous system to the SMG can be inhibited by endocannabinoid and GABAergic systems.
Asunto(s)
Ácidos Araquidónicos/farmacología , Moduladores de Receptores de Cannabinoides/farmacología , Ventrículos Laterales/efectos de los fármacos , Alcamidas Poliinsaturadas/farmacología , Saliva/metabolismo , Transmisión Sináptica/efectos de los fármacos , Animales , Ácidos Araquidónicos/administración & dosificación , Moduladores de Receptores de Cannabinoides/administración & dosificación , Endocannabinoides , Inyecciones Intraventriculares , Masculino , Alcamidas Poliinsaturadas/administración & dosificación , Ratas , Ratas Wistar , Saliva/efectos de los fármacos , Glándula Submandibular/metabolismoRESUMEN
Genital tract bacterial infections could induce abortion and are some of the most common complications of pregnancy; however, the mechanisms remain unclear. We investigated the role of prostaglandins (PGs) in the mechanism of bacterial lipopolysaccharide (LPS)-induced pregnancy loss in a mouse model, and we hypothesized that PGs might play a central role in this action. LPS increased PG production in the uterus and decidua from early pregnant mice and stimulated cyclooxygenase (COX)-II mRNA and protein expression in the decidua but not in the uterus. We also observed that COX inhibitors prevented embryonic resorption (ER). To study the possible interaction between nitric oxide (NO) and PGs, we administered aminoguanidine, an inducible NO synthase inhibitor. NO inhibited basal PGE and PGF(2alpha) production in the decidua but activated their uterine synthesis and COX-II mRNA expression under septic conditions. A NO donor (S-nitroso-N-acetylpenicillamine) produced 100% ER and increased PG levels in the uterus and decidua. LPS-stimulated protein nitration was higher in the uterus than in the decidua. Quercetin, a peroxynitrite scavenger, did not reverse LPS-induced ER. Our results suggest that in a model of septic abortion characterized by increased PG levels, NO might nitrate and thus inhibit COX catalytic activity. ER prevention by COX inhibitors adds a possible clinical application to early pregnancy complications due to infections.
Asunto(s)
Reabsorción del Feto/inducido químicamente , Reabsorción del Feto/metabolismo , Lipopolisacáridos/farmacología , Óxido Nítrico/metabolismo , Prostaglandinas/metabolismo , Animales , Inhibidores de la Ciclooxigenasa/farmacología , Femenino , Isoenzimas/genética , Isoenzimas/metabolismo , Masculino , Ratones , Ratones Endogámicos BALB C , Óxido Nítrico Sintasa/metabolismo , Embarazo , Prostaglandina-Endoperóxido Sintasas/genética , Prostaglandina-Endoperóxido Sintasas/metabolismo , ARN Mensajero/genética , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal , Tirosina/metabolismoRESUMEN
We have previously reported that intrauterine (i/u) administration of epidermal growth factor (EGF 500 ng) on day (d) 21 of pregnancy delayed 19.0 +/- 0.6 h the onset of labor. Progesterone (P) is secreted by ovarian corpora lutea (CL) throughout gestation in the rat. Prepartum CL regression due to increased uterine cyclooxygenase I and prostaglandin F(2alpha) results in P withdrawal followed by labor. The aims of the present work were (i) to study whether EGF delayed-onset of labor was mediated by a mechanism that prevented CL regression; (ii) to determine amniotic fluid (AF) EGF in pregnant rats. Rats on d21 of pregnancy received i/u EGF (500 ng) and were killed 0, 4, 8, 12, 24, and 48 h later. Control AF from rats on d13 and 18-22 of pregnancy was obtained. EGF decreased uterine prostaglandin F(2alpha) synthesis 8 h after treatment. Twelve hours after EGF injection, P reached its highest serum level and uterine cyclooxygenase I expression was undetectable. CL from rats killed 8 and 12 h after EGF were similar to those from rats on d13 of pregnancy, when serum P is maximum. EGF in AF increased throughout gestation, reached a maximum on d21, and decreased before the onset of labor. We suggest that the effect of EGF on the onset of labor was mediated by an early effect on the uterus that prevented prepartum CL regression.
Asunto(s)
Factor de Crecimiento Epidérmico/farmacología , Trabajo de Parto/metabolismo , Luteólisis/efectos de los fármacos , Luteólisis/fisiología , Líquido Amniótico/metabolismo , Análisis de Varianza , Animales , Western Blotting , Dinoprost/sangre , Factor de Crecimiento Epidérmico/metabolismo , Femenino , Técnicas Histológicas , Ovario/anatomía & histología , Ovario/metabolismo , Embarazo , RatasRESUMEN
Bacterial and viral products, such as bacterial lipopolysaccharide (LPS), cause inducible (i) NO synthase (NOS) synthesis, which in turn produces massive amounts of nitric oxide (NO). NO, by inactivating enzymes and leading to cell death, is toxic not only to invading viruses and bacteria, but also to host cells. Injection of LPS induces interleukin (IL)-1beta, IL-1alpha, and iNOS synthesis in the anterior pituitary and pineal glands, meninges, and choroid plexus, regions outside the blood-brain barrier. Thereafter, this induction occurs in the hypothalamic regions (such as the temperature-regulating centers), paraventricular nucleus (releasing and inhibiting hormone neurons), and the arcuate nucleus (a region containing these neurons and axons bound for the median eminence). Aging of the anterior pituitary and pineal with resultant decreased secretion of pituitary hormones and the pineal hormone melatonin, respectively, may be caused by NO. The induction of iNOS in the temperature-regulating centers by infections may cause the decreased febrile response in the aged by loss of thermosensitive neurons. NO may play a role in the progression of Alzheimer's disease and parkinsonism. LPS similarly activates cytokine and iNOS production in the cardiovascular system leading to coronary heart disease. Fat is a major source of NO stimulated by leptin. As fat stores increase, leptin and NO release increases in parallel in a circadian rhythm with maxima at night. NO could be responsible for increased coronary heart disease as obesity supervenes. Antioxidants, such as melatonin, vitamin C, and vitamin E, probably play important roles in reducing or eliminating the oxidant damage produced by NO.
Asunto(s)
Envejecimiento/fisiología , Óxido Nítrico/metabolismo , Animales , Aterosclerosis/metabolismo , Sistema Nervioso Central/fisiología , Corticosterona/metabolismo , Hormona Liberadora de Gonadotropina/metabolismo , Humanos , Hipotálamo/anatomía & histología , Hipotálamo/metabolismo , Isoenzimas/metabolismo , Leptina/metabolismo , Lipopolisacáridos/metabolismo , Modelos Biológicos , Enfermedades Neurodegenerativas/metabolismo , Óxido Nítrico Sintasa/metabolismo , Glándula Pineal/metabolismo , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Nitric oxide (NO) is synthesized in a variety of tissues, including rat uterus, from L-arginine by NO synthase (NOS), of which there are three isoforms, namely neuronal, endothelial and inducible NOS (nNOS, eNOS and iNOS, respectively). Nitric oxide is an important regulator of the biology and physiology of the organs of the reproductive system, including the uterus. Some studies have shown increased variation in NO production and NOS expression during the oestrous cycle. However, the factors that regulate NO production in the uterus remain unclear. Therefore, in the present study, we investigated the effect of sex steroids on NOS expression and activity in the ovariectomized rat uterus. Ovariectomized rats received progesterone (4 mg per rat) or 17beta-oestradiol (1 microg per rat). All rats were killed 18 h after treatment. Both progesterone and oestradiol were able to augment NOS activity. The effect of oestradiol was abolished by pre-incubation with 500 micro M aminoguanidine, an iNOS inhibitor, or by coadministration of oestradiol with 3 mg kg(-1) dexamethasone, but the effect of progesterone was not affected by these treatments. Uterine nNOS, eNOS and iNOS protein levels were assessed using Western blots. Ovariectomized rat uteri expressed iNOS and eNOS. Progesterone increased the expression of eNOS and iNOS, whereas oestradiol increased iNOS expression only. These results suggest that oestradiol and progesterone are involved in the regulation of NOS expression and activity during pregnancy and implantation in the rat.
Asunto(s)
Estradiol/farmacología , Hormonas Esteroides Gonadales/farmacología , Óxido Nítrico Sintasa/metabolismo , Progesterona/farmacología , Útero/efectos de los fármacos , Animales , Western Blotting , Calcio , Inhibidores Enzimáticos/farmacología , Estradiol/fisiología , Femenino , Hormonas Esteroides Gonadales/fisiología , Guanidinas/farmacología , Isoenzimas/análisis , Isoenzimas/antagonistas & inhibidores , Isoenzimas/metabolismo , Óxido Nítrico Sintasa/análisis , Óxido Nítrico Sintasa/antagonistas & inhibidores , Ovariectomía , Progesterona/fisiología , Ratas , Ratas Wistar , Regulación hacia Arriba , Útero/enzimologíaRESUMEN
The aim of this study was to investigate the relationship between beta-endorphin and nitric oxide (NO) during the ovulatory process in rats. Immature rats were treated with equine chorionic gonadotrophin-hCG to induce ovulation. An intrabursal injection of beta-endorphin stimulated nitric oxide synthase (NOS) activity. This effect was completely reversed when naltrexone was co-injected with beta-endorphin. The stimulatory action of beta-endorphin on NOS activity was studied to determine whether it was exerted via prostaglandins. Treatment with prostaglandin E(2) (PGE(2)) completely reversed the beta-endorphin-induced stimulation of NOS activity. Moreover, intrabursal injection of meloxicam, an inhibitor of cyclooxygenase 2, increased NOS activity, but this effect was not altered by co-injection with beta-endorphin. The presence of both endothelial NOS (eNOS) and inducible NOS (iNOS) in the ovary at 10 h after hCG treatment was studied by western blot analysis. Local administration of beta-endorphin inhibited the expression of eNOS protein, whereas expression of iNOS protein was not detectable. Ovarian beta-endorphin content was diminished at 10 h after hCG injection. Treatment with prostaglandin synthesis inhibitors in vivo augmented the ovarian beta-endorphin content. In conclusion, these results indicate that beta-endorphin stimulates the activity of ovarian NOS indirectly by inhibiting prostaglandin production.
Asunto(s)
Dinoprostona/farmacología , Óxido Nítrico/metabolismo , Ovario/metabolismo , Ovulación/fisiología , betaendorfina/farmacología , Animales , Western Blotting/métodos , Gonadotropina Coriónica/farmacología , Dinoprostona/metabolismo , Femenino , Indometacina/farmacología , Meloxicam , Modelos Animales , Naltrexona/farmacología , Óxido Nítrico Sintasa/análisis , Óxido Nítrico Sintasa/antagonistas & inhibidores , Óxido Nítrico Sintasa/metabolismo , Óxido Nítrico Sintasa de Tipo II , Óxido Nítrico Sintasa de Tipo III , Ovario/química , Antagonistas de Prostaglandina/farmacología , Ratas , Ratas Sprague-Dawley , Tiazinas/farmacología , Tiazoles/farmacología , betaendorfina/análisis , betaendorfina/metabolismoRESUMEN
The central nervous system plays an important role in the control of renal sodium excretion. We present here a brief review of physiologic regulation of hydromineral balance and discuss recent results from our laboratory that focus on the participation of nitrergic, vasopressinergic, and oxytocinergic systems in the regulation of water and sodium excretion under different salt intake and hypertonic blood volume expansion (BVE) conditions. High sodium intake induced a significant increase in nitric oxide synthase (NOS) activity in the medial basal hypothalamus and neural lobe, while a low sodium diet decreased NOS activity in the neural lobe, suggesting that central NOS is involved in the control of sodium balance. An increase in plasma concentrations in vasopressin (AVP), oxytocin (OT), atrial natriuretic peptide (ANP), and nitrate after hypertonic BVE was also demonstrated. The central inhibition of NOS by L-NAME caused a decrease in plasma AVP and no change in plasma OT or ANP levels after BVE. These data indicate that the increase in AVP release after hypertonic BVE depends on nitric oxide production. In contrast, the pattern of OT secretion was similar to that of ANP secretion, supporting the view that OT is a neuromodulator of ANP secretion during hypertonic BVE. Thus, neurohypophyseal hormones and ANP are secreted under hypertonic BVE in order to correct the changes induced in blood volume and osmolality, and the secretion of AVP in this particular situation depends on NOS activity.
Asunto(s)
Factor Natriurético Atrial/sangre , Óxido Nítrico/metabolismo , Oxitocina/sangre , Solución Salina Hipertónica/farmacología , Sodio/metabolismo , Vasopresinas/sangre , Animales , Factor Natriurético Atrial/metabolismo , Volumen Sanguíneo , Riñón/metabolismo , Masculino , NG-Nitroarginina Metil Éster/farmacología , Óxido Nítrico Sintasa/efectos de los fármacos , Óxido Nítrico Sintasa/metabolismo , Concentración Osmolar , Oxitocina/metabolismo , Ratas , Vasopresinas/metabolismo , Agua/metabolismo , Equilibrio HidroelectrolíticoRESUMEN
The central nervous system plays an important role in the control of renal sodium excretion. We present here a brief review of physiologic regulation of hydromineral balance and discuss recent results from our laboratory that focus on the participation of nitrergic, vasopressinergic, and oxytocinergic systems in the regulation of water and sodium excretion under different salt intake and hypertonic blood volume expansion (BVE) conditions. High sodium intake induced a significant increase in nitric oxide synthase (NOS) activity in the medial basal hypothalamus and neural lobe, while a low sodium diet decreased NOS activity in the neural lobe, suggesting that central NOS is involved in the control of sodium balance. An increase in plasma concentrations in vasopressin (AVP), oxytocin (OT), atrial natriuretic peptide (ANP), and nitrate after hypertonic BVE was also demonstrated. The central inhibition of NOS by L-NAME caused a decrease in plasma AVP and no change in plasma OT or ANP levels after BVE. These data indicate that the increase in AVP release after hypertonic BVE depends on nitric oxide production. In contrast, the pattern of OT secretion was similar to that of ANP secretion, supporting the view that OT is a neuromodulator of ANP secretion during hypertonic BVE. Thus, neurohypophyseal hormones and ANP are secreted under hypertonic BVE in order to correct the changes induced in blood volume and osmolality, and the secretion of AVP in this particular situation depends on NOS activity
Asunto(s)
Animales , Masculino , Ratas , Factor Natriurético Atrial , Oxitocina , Solución Salina Hipertónica , Sodio en la Dieta , Vasopresinas , Factor Natriurético Atrial , Volumen Sanguíneo , NG-Nitroarginina Metil Éster , Óxido Nítrico Sintasa , Concentración Osmolar , Oxitocina , VasopresinasRESUMEN
Inducible (calcium-independent) nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) are important in the regulation of the function of different organs during infection. A single dose of lipopolysaccharide (LPS; 5 mg/kg ip) within 6 h increased NOS activity (20%) and prostaglandin E (PGE) content (100%) in submandibular glands (SMG) and blocked stimulated salivary secretion in adult male rats. The administration of an iNOS synthesis inhibitor, aminoguanidine (AG), with LPS decreased NOS activity and PGE content. Furthermore, the administration of meloxicam (MLX), an inhibitor of COX-2, blocked the increase in PGE and the production of NO. The incubation of slices of SMG in the presence of 3-morpholinosydnonimine, a donor of NO, increased the release of PGE highly significantly. The incubation of SMG in the presence of a PGE(1) analog (alprostadil) increased the production of NO. These results indicate that LPS activates NOS, leading to NO release, which activates COX, generating PGEs that act back to further activate NOS, causing further generation of PGEs by activation of COX. Because the alprostadil administration inhibited stimulated salivation, LPS-induced inhibition of salivation appears to be caused by increased PGE production. Diminished salivary secretion produces poor oral health; thus the use of COX-2 inhibitors to counteract the effects of inhibited salivation should be considered.
Asunto(s)
Lipopolisacáridos/administración & dosificación , Prostaglandinas E/metabolismo , Saliva/metabolismo , Glándula Submandibular/efectos de los fármacos , Glándula Submandibular/fisiología , Alprostadil/farmacología , Animales , Antiinflamatorios no Esteroideos/farmacología , Ácido Araquidónico/metabolismo , Fármacos del Sistema Nervioso Autónomo/farmacología , Ciclooxigenasa 2 , Inhibidores Enzimáticos/farmacología , Guanidinas/farmacología , Técnicas In Vitro , Inyecciones Intraperitoneales , Isoenzimas/antagonistas & inhibidores , Isoenzimas/metabolismo , Masculino , Meloxicam , Cloruro de Metacolina/farmacología , Óxido Nítrico/metabolismo , Donantes de Óxido Nítrico/farmacología , Óxido Nítrico Sintasa/antagonistas & inhibidores , Óxido Nítrico Sintasa/metabolismo , Óxido Nítrico Sintasa de Tipo II , Norepinefrina/farmacología , Prostaglandina-Endoperóxido Sintasas/metabolismo , Ratas , Tiazinas/farmacología , Tiazoles/farmacologíaRESUMEN
Little is known of the consequences of ethanol intake prior to fertilization on preimplantation embryo development. Recently we showed that chronic 10 and 5% w/v ethanol intake by young female mice reduces in vitro fertilization (IVF) rates. The purpose of the present work was to investigate whether the adverse effects of preconceptional low-dose chronic ethanol intake by sexually maturing female mice affects preimplantation embryo growth in vitro or in vivo in subsequent pregnancy. Prepubertal female mice were given 5% ethanol in their drinking water for 30 days. On day 27 and 29 of the ethanol treatment, females were superovulated. IVF-derived cultured embryos (in vitro development) or embryos obtained from oviducts and uteri (in vivo development) were evaluated. Whether analyzed on a per embryo or per dam basis, ethanol treatment was associated with a significant decrease in progression through embryo stages during the seven days of in vitro development and with an increase in morphologically abnormal embryos. Progression through embryo stages during four days of in vivo development was also inhibited by ethanol pretreatment of dams At 99 h post-hCG of in vivo development, there were fewer total, hatched, and expanded blastocysts, and a complete absence of implanting blastocysts among females treated with ethanol. In summary, low-dose chronic ethanol consumption of sexually maturing female mice prior to conception has adverse effects on preimplantation embryo development, both under in vitro and in vivo conditions, manifested as retarded development, embryo anormalities, and a reduction in expansion and hatching of the preimplantation blastocyst.
Asunto(s)
Anomalías Inducidas por Medicamentos , Consumo de Bebidas Alcohólicas/efectos adversos , Blastocisto/efectos de los fármacos , Desarrollo Embrionario y Fetal/efectos de los fármacos , Etanol/toxicidad , Maduración Sexual/efectos de los fármacos , Animales , Etanol/administración & dosificación , Femenino , Fertilización In Vitro , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos CBA , Técnicas de Cultivo de Órganos , Embarazo , Maduración Sexual/fisiologíaRESUMEN
BACKGROUND/OBJECTIVE: Injection of bacterial lipopolysaccharide (LPS) into male rats activates genes that in turn induce many enzymes that participate in the animals' response to LPS. There is induction of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) in many tissues. This induction could result from combination with cell surface LPS receptors that directly induce both genes, or the nitric oxide (NO) released as a result of iNOS induction could induce COX-2. METHODS: To distinguish between these two possibilities, specific inhibitors of iNOS and COX-2 activity, aminoguanidine (AG) and meloxicam (MLX), respectively, were injected either peripherally or intracerebroventricularly (i.c.v.), and their effect on NO and prostaglandin E (PGE) production induced by LPS in the medial basal hypothalamus (MBH) and anterior pituitary gland (AP) were determined. RESULTS: Peripheral injection of AG blocked iNOS-derived NO production in the AP but not in the MBH. When AG was injected i.c.v., iNOS-derived NO production in the MBH was blocked. MLX injected peripherally blocked COX-2-derived PGE(2) production in the MBH and AP, whereas AG injected peripherally or i.c.v. was ineffective. Since AG was only effective in blocking iNOS-derived NO production in the MBH when injected i.c.v., AG apparently does not effectively cross the blood brain barrier, whereas MLX injected peripherally inhibited PGE production, probably by inhibiting COX-2 activity in both the MBH and AP. AG was ineffective in preventing the increase in PGE derived from COX-2 in either the MBH or AP. CONCLUSION: LPS directly induces both enzymes, iNOS and COX-2, in the hypothalamus and AP.
Asunto(s)
Dinoprostona/biosíntesis , Endotoxemia/complicaciones , Hipotálamo/enzimología , Inflamación/enzimología , Inflamación/etiología , Óxido Nítrico/biosíntesis , Adenohipófisis/enzimología , Animales , Ciclooxigenasa 2 , Inhibidores de la Ciclooxigenasa 2 , Inhibidores de la Ciclooxigenasa/farmacología , Guanidinas/farmacología , Hipotálamo/efectos de los fármacos , Hipotálamo/fisiopatología , Inflamación/fisiopatología , Isoenzimas/antagonistas & inhibidores , Isoenzimas/metabolismo , Lipopolisacáridos/farmacología , Masculino , Meloxicam , Óxido Nítrico Sintasa/antagonistas & inhibidores , Óxido Nítrico Sintasa/metabolismo , Adenohipófisis/efectos de los fármacos , Adenohipófisis/fisiopatología , Prostaglandina-Endoperóxido Sintasas/metabolismo , Ratas , Ratas Sprague-Dawley , Tiazinas/farmacología , Tiazoles/farmacología , Factores de Tiempo , Regulación hacia Arriba/efectos de los fármacos , Regulación hacia Arriba/fisiologíaRESUMEN
In order to determine whether ionotropic (iGluRs) and metabotropic (mGluRs) glutamate receptor activation modulates oxytocin release in male rats, we investigated the effect of agonists of both types of glutamate receptors on oxytocin release from hypothalamus and posterior pituitary. Kainate and quisqualate (1 mM) increased hypothalamic oxytocin release. Their effects were prevented by selective AMPA/kainate receptor antagonists. NMDA (0.01-1 mM) did not modify hypothalamic oxytocin release. Group I mGluR agonists, such as quisqualate and 3-HPG, significantly increased hypothalamic oxytocin release. These effects were blocked by AIDA (a selective antagonist of group I mGluRs). In the posterior pituitary, oxytocin release was not modified by kainate, quisqualate, trans-ACPD (a broad-spectrum mGluR agonist) and L-SOP (a group III mGluR agonist). However, NMDA (0.1 mM) significantly decreased oxytocin release from posterior pituitary. D-Aspartate significantly increased oxytocin release from the hypothalamus, while it decreased oxytocin release from posterior pituitary. AP-5 (a specific NMDA receptor antagonist) reduced the D-Aspartate effect in the hypothalamus, but not in the posterior pituitary. Our data indicate that the activation of non-NMDA receptors and group I mGluRs stimulates oxytocin release from hypothalamic nuclei, whereas NMDA inhibits oxytocinergic terminals in the posterior pituitary. D-Aspartate also has a dual effect on oxytocin release: stimulatory at the hypothalamus and inhibitory at the posterior pituitary. These results suggest that excitatory amino acids differentially modulate the secretion of oxytocin at the hypothalamic and posterior pituitary levels.
Asunto(s)
Ácido Aspártico/farmacología , Agonistas de Aminoácidos Excitadores/farmacología , Hipotálamo/metabolismo , Oxitocina/metabolismo , Neurohipófisis/metabolismo , Animales , Hipotálamo/efectos de los fármacos , Técnicas In Vitro , Masculino , Neurohipófisis/efectos de los fármacos , Ratas , Ratas Wistar , Receptores AMPA/agonistas , Receptores de Glutamato Metabotrópico/metabolismo , Receptores de N-Metil-D-Aspartato/antagonistas & inhibidoresRESUMEN
The aim of the present study was to test whether the contractile responses elicited by KCl in the rat mesenteric bed are coupled to the release of nitric oxide (NO). Contractions induced by 70 mM KCl were coincident with the release of NO to the perfusate. The in vitro exposure to the nitric oxide synthase (NOS) inhibitor L-N(omega)-nitro-L-arginine methyl ester, L-NAME (1-100 microM) potentiated the vascular responses to 70 mM KCl and, unexpectedly, increased the KCl-stimulated release of NO. Moreover, even after the chronic treatment with L-NAME (70 mg/kg/day during 4 weeks), the KCl-induced release of NO was not reduced, whereas the potentiation of contractile responses was indeed achieved. The possibility that NOS had not been completely inhibited under our experimental conditions can be precluded because NOS activity was significantly inhibited after both L-NAME treatments. After the in vitro treatment with 1 to 100 microM L-NAME, the inhibition of NOS was concentration-dependent (from 50% to 90%). With regard to the basal release of NO, the inhibition caused by L-NAME was not concentration-dependent and reached a maximum of 40%, suggesting that basal NO outflow is only partially dependent on NOS activity. An eventual enhancement of NOS activity caused by KCl was disregarded because the activity of this enzyme measured in homogenates from mesenteric beds perfused with 70 mM KCl was significantly reduced. On the other hand, endothelium removal, employed as a negative control, almost abolished NOS activity, whereas the incubation with the Ca(2+) ionophore A23187, employed as a positive control, induced an increase in NOS activity. It is concluded that in the mesenteric arterial bed of the rat, the contractile responses elicited by depolarization through KCl are coincident with a NOS-independent release of NO. This observation, which differs from the results obtained with noradrenaline, do not support the use of KCl as an alternative contractile agent whenever the participation of NO is under study.
Asunto(s)
Mesenterio/metabolismo , Óxido Nítrico Sintasa/metabolismo , Óxido Nítrico/metabolismo , Cloruro de Potasio/farmacología , Antagonistas Adrenérgicos alfa/farmacología , Animales , Inhibidores Enzimáticos/farmacología , Mediciones Luminiscentes , Masculino , Mesenterio/efectos de los fármacos , Contracción Muscular/efectos de los fármacos , Músculo Liso Vascular/efectos de los fármacos , Músculo Liso Vascular/metabolismo , NG-Nitroarginina Metil Éster/farmacología , Óxido Nítrico Sintasa/antagonistas & inhibidores , Norepinefrina/metabolismo , Perfusión , Prazosina/farmacología , Ratas , Ratas Sprague-DawleyRESUMEN
In infection bacterial products such as lipopolysaccharides (LPS) induce inducible nitric oxide synthase (iNOS) that produces large quantities of NO toxic to the invading organisms, but also often has toxic effects on host cells. Therefore, inhibition of iNOS activity might be beneficial in combatting these adverse effects. To determine if methylene blue (MB), an oxidizing agent that inactivates iNOS, would reduce the iNOS levels in the medial basal hypothalami (MBH) of conscious male rats, LPS (5 mg/kg) was injected intravenously (i.v.), and after 3 h they were injected i.v. with either MB (3 mg/kg) or saline and the effects on iNOS in the MBH determined. iNOS was measured by conversion of labeled arginine into citrulline by incubating MBH in the absence of calcium (Ca(2+)) since iNOS does not require Ca(2+) for activation. The results indicate that iNOS was induced by the injection of saline, but the induction by LPS was much greater, an increase of 10-fold above that of control sham-operated animals. Both the induction of iNOS from the stress of saline injections and LPS were completely eliminated by MB indicating that MB might be beneficial in preventing injury to brain tissue following LPS injection. There was no effect of either LPS or MB on the Ca(2+)-dependent constitutive NOS activity.
Asunto(s)
Hipotálamo Medio/enzimología , Lipopolisacáridos/farmacología , Azul de Metileno/farmacología , Óxido Nítrico Sintasa/antagonistas & inhibidores , Óxido Nítrico Sintasa/biosíntesis , Estrés Fisiológico/enzimología , Animales , Calcio/fisiología , Colorantes/metabolismo , Inducción Enzimática , Hipotálamo Medio/efectos de los fármacos , Inyecciones Intraventriculares , Lipopolisacáridos/administración & dosificación , Masculino , Azul de Metileno/administración & dosificación , Nitratos/sangre , Óxido Nítrico Sintasa/metabolismo , Óxido Nítrico Sintasa de Tipo II , Nitritos/sangre , Ratas , Ratas Wistar , Cloruro de Sodio/administración & dosificaciónRESUMEN
Neurokinin A (NKA) is a tachykinin that participates in the control of neuroendocrine functions. The posterior pituitary lobe (PP) contains abundant nitric oxide synthase (NOS), suggesting that nitric oxide (NO) may play a role in controlling the release of neuropeptides and neurotransmitters. In the present project, we investigated the in vitro effect of NKA on oxytocin release from hypothalamic explants and PP of male rats and the possible involvement of NO in the action of NKA. Since NKA inhibits gamma-aminobutyric acid (GABA) release from PP, we also examined the role of NO in the effect of NKA on basal and K(+)-evoked GABA release. NKA (10(-7)-10(-5) M) significantly decreased oxytocin release from PP, whereas it did not affect its release from hypothalamic explants. The inhibitory effect of NKA on oxytocin release from PP was completely blocked by the NOS inhibitors N(G)-monomethyl-L-arginine (L-NMMA, 0.5 mM) or N(G)-nitro-L-arginine-methyl-ester (L-NAME, 1 mM). Sodium nitroprusside (0.5 mM), an NO releaser, had no effect on basal GABA release but significantly decreased K(+)-evoked GABA release. L-NMMA (0.3 mM) and L-NAME (0.5 mM) increased K(+)-evoked GABA release, indicating that NO plays an inhibitory role in GABA release from PP. The inhibition in both basal and K(+)-evoked GABA release induced by NKA (10(-7) M) was reduced by L-NAME (1 mM). Also, NKA (10(-7) M) increased NO synthesis as measured by [(14)C] citrulline production. Considered all together, our data indicate that NO may mediate the inhibitory effect of NKA on the release of both oxytocin and GABA from PP.
Asunto(s)
GMP Cíclico/análogos & derivados , Neuroquinina A/farmacología , Óxido Nítrico Sintasa/efectos de los fármacos , Oxitocina/efectos de los fármacos , Neurohipófisis/efectos de los fármacos , Ácido gamma-Aminobutírico/efectos de los fármacos , Animales , GMP Cíclico/farmacología , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/farmacología , Hipotálamo/efectos de los fármacos , Hipotálamo/metabolismo , Técnicas In Vitro , Masculino , NG-Nitroarginina Metil Éster/farmacología , Óxido Nítrico/fisiología , Óxido Nítrico Sintasa/metabolismo , Oxitocina/metabolismo , Neurohipófisis/metabolismo , Potasio/farmacología , Ratas , Ratas Wistar , Tionucleótidos/farmacología , Ácido gamma-Aminobutírico/metabolismo , omega-N-Metilarginina/farmacologíaRESUMEN
The release of adrenocorticotropin (ACTH) from the corticotrophs is controlled principally by vasopressin and corticotropin-releasing hormone (CRH). Oxytocin may augment the release of ACTH under certain conditions, whereas atrial natriuretic peptide acts as a corticotropin release-inhibiting factor to inhibit ACTH release by direct action on the pituitary. Glucocorticoids act on their receptors within the hypothalamus and anterior pituitary gland to suppress the release of vasopressin and CRH and the release of ACTH in response to these neuropeptides. CRH neurons in the paraventricular nucleus also project to the cerebral cortex and subcortical regions and to the locus ceruleus (LC) in the brain stem. Cortical influences via the limbic system and possibly the LC augment CRH release during emotional stress, whereas peripheral input by pain and other sensory impulses to the LC causes stimulation of the noradrenergic neurons located there that project their axons to the CRH neurons stimulating them by alpha-adrenergic receptors. A muscarinic cholinergic receptor is interposed between the alpha-receptors and nitric oxidergic interneurons which release nitric oxide that activates CRH release by activation of cyclic guanosine monophosphate, cyclooxygenase, lipoxygenase and epoxygenase. Vasopressin release during stress may be similarly mediated. Vasopressin augments the release of CRH from the hypothalamus and also augments the action of CRH on the pituitary. CRH exerts a positive ultrashort loop feedback to stimulate its own release during stress, possibly by stimulating the LC noradrenergic neurons whose axons project to the paraventricular nucleus to augment the release of CRH.
Asunto(s)
Humanos , Animales , Infecciones del Sistema Nervioso Central/metabolismo , Sistema Hipotálamo-Hipofisario/fisiología , Sistema Hipófiso-Suprarrenal/fisiología , Estrés Fisiológico/metabolismo , Hormona Adrenocorticotrópica/metabolismo , Factor Natriurético Atrial/metabolismo , Factor Natriurético Atrial/fisiología , Sistema Nervioso Central/metabolismo , Hormona Liberadora de Corticotropina/metabolismo , Hormona Liberadora de Corticotropina/fisiología , Lipopolisacáridos/farmacología , Óxido Nítrico/fisiología , Oxitocina/metabolismo , Oxitocina/fisiología , Vasopresinas/metabolismo , Vasopresinas/fisiologíaRESUMEN
The release of adrenocorticotropin (ACTH) from the corticotrophs is controlled principally by vasopressin and corticotropin-releasing hormone (CRH). Oxytocin may augment the release of ACTH under certain conditions, whereas atrial natriuretic peptide acts as a corticotropin release-inhibiting factor to inhibit ACTH release by direct action on the pituitary. Glucocorticoids act on their receptors within the hypothalamus and anterior pituitary gland to suppress the release of vasopressin and CRH and the release of ACTH in response to these neuropeptides. CRH neurons in the paraventricular nucleus also project to the cerebral cortex and subcortical regions and to the locus ceruleus (LC) in the brain stem. Cortical influences via the limbic system and possibly the LC augment CRH release during emotional stress, whereas peripheral input by pain and other sensory impulses to the LC causes stimulation of the noradrenergic neurons located there that project their axons to the CRH neurons stimulating them by alpha-adrenergic receptors. A muscarinic cholinergic receptor is interposed between the alpha-receptors and nitric oxidergic interneurons which release nitric oxide that activates CRH release by activation of cyclic guanosine monophosphate, cyclooxygenase, lipoxygenase and epoxygenase. Vasopressin release during stress may be similarly mediated. Vasopressin augments the release of CRH from the hypothalamus and also augments the action of CRH on the pituitary. CRH exerts a positive ultrashort loop feedback to stimulate its own release during stress, possibly by stimulating the LC noradrenergic neurons whose axons project to the paraventricular nucleus to augment the release of CRH.
Asunto(s)
Infecciones del Sistema Nervioso Central/metabolismo , Sistema Hipotálamo-Hipofisario/fisiología , Sistema Hipófiso-Suprarrenal/fisiología , Estrés Fisiológico/metabolismo , Hormona Adrenocorticotrópica/metabolismo , Animales , Factor Natriurético Atrial/fisiología , Sistema Nervioso Central/metabolismo , Hormona Liberadora de Corticotropina/fisiología , Humanos , Lipopolisacáridos/farmacología , Óxido Nítrico/fisiología , Oxitocina/fisiología , Vasopresinas/fisiologíaRESUMEN
Although many studies have explored the effects of acute or chronic ethanol exposure during the postimplantation period on embryo/fetal development, few reports have described the ethanol effects on preimplantation embryo development. Little is known about the effects of ethanol consumption prior to gestation on embryo growth. Recently, we have shown that chronic moderate ethanol intake by prepubertal female mice reduces the ovulatory response and impairs in vitro fertilization and in vitro embryo preimplantation development. The purpose of the present work was to evaluate the effects of preconceptional chronic moderate ethanol ingestion on preimplantation embryo morphology and differentiation, the timing of cleavage and embryo growth in vivo, and to determine the time pattern in which alterations appear. Prepubertal female mice were treated with 10% (w/v) ethanol for 30 days prior to conception. After inducing ovulation on day 27 and 29 of the ethanol treatment, females were mated with control males and the day of presence of vaginal plug was day 1. On day 1, a decreased percentage of normal fertilized oocytes, elevated parthenogenetic oocyte activation and unfertilized eggs with abnormal metaphase II were found in ethanol-treated, compared to control females. On day 2, while any differences in the total percentage of 2-cell embryos were observed, the treated females had a significantly higher percentage of morphologically abnormal embryos, compared to control females. On day 3, the preconceptional consumption of ethanol produced significantly reduced percentages of compacted morulae and an increased percentage of uncompacted morulae. The total percentage of morulae in the treated females was lower than in controls. On day 4, ethanol-treated females showed significantly decreased percentages of hatched attached blastocysts and increased early blastocyst and morula percentages, compared to controls. Thus, preconceptional chronic moderate ethanol ingestion by prepubertal female mice produced retarded development, impaired blastocyst hatching, abnormal embryo morphology and embryo loss by fragmentation due to alterations induced in the female gamete.