RESUMEN
The dopamine D2-type receptor agonist quinpirole (QNP) facilitates the development of conditioned same-sex partner preference in males during cohabitation, but not in ovariectomized (OVX) females, primed with estradiol benzoate (EB) and progesterone (P). Herein we tested the effects of QNP on OVX, EB-only primed females. Females received a systemic injection (every four days) of either saline (Saline-conditioned) or QNP (QNP-conditioned) and then cohabited for 24h with lemon-scented stimulus females (CS+), during three trials. In test 1 (female-female) preference was QNP-free, and females chose between the CS+ female and a novel female. In test 2 (male-female) they chose between the CS+ female and a sexually experienced male. In test 1 Saline-conditioned females displayed more hops & darts towards the novel female, but QNP-conditioned females displayed more sexual solicitations towards the CS+ female. In test 2 Saline-conditioned females displayed a clear preference for the male, whereas QNP-conditioned females displayed what we considered a bisexual preference. We discuss the effect of dopamine and ovarian hormones on the development of olfactory conditioned same-sex preference in females.
Asunto(s)
Condicionamiento Psicológico/fisiología , Hormonas Gonadales/fisiología , Homosexualidad Femenina , Preferencia en el Apareamiento Animal/fisiología , Percepción Olfatoria/fisiología , Animales , Condicionamiento Psicológico/efectos de los fármacos , Dopamina/farmacología , Agonistas de Dopamina/farmacología , Femenino , Hormonas Gonadales/metabolismo , Hormonas Gonadales/farmacología , Homosexualidad Femenina/psicología , Preferencia en el Apareamiento Animal/efectos de los fármacos , Percepción Olfatoria/efectos de los fármacos , Ovario/metabolismo , Progesterona/farmacología , Ratas , Ratas Wistar , Receptores de Dopamina D2/metabolismo , Conducta Sexual Animal/efectos de los fármacos , OlfatoRESUMEN
BACKGROUND: We have previously demonstrated that blockade of ß-adrenoreceptors (ß-AR) located in the temporomandibular joint (TMJ) of rats suppresses formalin-induced TMJ nociceptive behaviour in both male and female rats, but female rats are more responsive. In this study, we investigated whether gonadal hormones modulate the responsiveness to local ß-blocker-induced antinociception in the TMJ of rats. METHODS: Co-administration of each of the selective ß1 (atenolol), ß2 (ICI 118.551) and ß3 (SR59230A)-AR antagonists with equi-nociceptive concentrations of formalin in the TMJ of intact, gonadectomized and hormone-treated gonadectomized male and female rats. RESULTS: Atenolol, ICI 118.551 and SR59230A significantly reduced formalin-induced TMJ nociception in a dose response fashion in all groups tested. However, a lower dose of each ß-AR antagonist was sufficient to significantly reduce nociceptive responses in gonadectomized but not in intact and testosterone-treated gonadectomized male rats. In the female groups, a lower dose of ß1 -AR antagonist was sufficient to significantly reduce nociceptive responses in gonadectomized but not in intact or gonadectomized rats treated with progesterone or a high dose of oestradiol; a lower dose of ß2 -AR antagonist was sufficient to significantly reduce nociceptive responses in gonadectomized but not in intact and gonadectomized rats treated with low or high dose of oestradiol. CONCLUSION: Gonadal hormones may reduce the responsiveness to local ß-blocker-induced antinociception in the TMJ of male and female rats. However, their effect depends upon their plasma level, the subtype of ß-AR and the dose of ß-blockers used.
Asunto(s)
Antagonistas Adrenérgicos beta/farmacología , Hormonas Gonadales/farmacología , Nocicepción/efectos de los fármacos , Dolor/tratamiento farmacológico , Propanolaminas/farmacología , Trastornos de la Articulación Temporomandibular/tratamiento farmacológico , Articulación Temporomandibular/efectos de los fármacos , Antagonistas de Receptores Adrenérgicos beta 3/farmacología , Animales , Atenolol/farmacología , Femenino , Masculino , Dimensión del Dolor/métodos , Ratas WistarRESUMEN
Several studies have demonstrated that gonadal hormones show significant effects on the brain and signaling pathways of effector organs/cells that respond to neurotransmitters. Since little information is available concerning the impact of male and female gonadal hormones on the renal and peripheral sympathetic system, the objective of this study was to further assess whether and how the renal content and plasma concentration of catecholamines are influenced by gender and the estrous cycle in rats. To achieve this, males Wistar rats were divided into 4 groups: (i) sham (i.e., control), (ii) gonadectomized, (iii) gonadectomized and nandrolone decanoate replacement at physiological levels or (iv) gonadectomized and nandrolone decanoate replacement at high levels. Female Wistar rats were divided into 6 groups: (i) ovariectomized (OVX), (ii) estrogen replacement at physiological levels and (iii) estrogen replacement at at high levels, (iv) progesterone replacement at physiological levels and (v) progesterone replacement at at high levels, and (vi) sham. The sham group was subdivided into four subgroups: (i) proestrus, (ii) estrus, (iii) metaestrus, and (iv) diestrus. Ten days after surgery, the animals were sacrificed and their plasma and renal catecholamine levels measured for intergroup comparisons. Gonadectomy led to an increase in the plasma catecholamine concentration in females, as well as in the renal catecholamine content of both male and female rats. Gonadectomized males also showed a lower level of plasma catecholamine than the controls. The urinary flow, and the fractional excretion of sodium and chloride were significantly increased in gonadectomized males and in the OVX group when compared with their respective sham groups.
Asunto(s)
Catecolaminas/sangre , Catecolaminas/metabolismo , Ciclo Estral/sangre , Ciclo Estral/metabolismo , Riñón/metabolismo , Animales , Cloruros/orina , Relación Dosis-Respuesta a Droga , Estradiol/administración & dosificación , Estradiol/farmacología , Femenino , Hormonas Gonadales/administración & dosificación , Hormonas Gonadales/farmacología , Riñón/efectos de los fármacos , Riñón/fisiopatología , Masculino , Nandrolona/administración & dosificación , Nandrolona/análogos & derivados , Nandrolona/farmacología , Nandrolona Decanoato , Orquiectomía/métodos , Orquiectomía/estadística & datos numéricos , Ovariectomía/métodos , Ovariectomía/estadística & datos numéricos , Progesterona/administración & dosificación , Progesterona/farmacología , Ratas , Ratas Wistar , Caracteres Sexuales , Sodio/orina , Micción/efectos de los fármacos , Micción/fisiologíaRESUMEN
Previously we have demonstrated that medial nucleus of the amygdala, which is part of medial extended amygdala, is damaged by status epilepticus induced by kainic acid (KA) and this neurodegeneration was prevents by estrogen replacement. The medial bed nucleus of stria terminalis (BSTM) also belong to medial extended amygdala and it is uncertain whether the gonadal hormones are protective or not against this neurotoxicity in the BSTM. Here we show that a single i.p. injection of KA (9 mg/kg) induces neurodegeneration in the subnuclei of the BSTM of rats with different degrees of intensity in males and females. A differential neuroprotective effect of the gonadal hormones was also observed. In diestrous rats, massive neuronal death similar to that in the ovariectomized females was detected. BSTM neurons of proestrous rats, like the ovariectomized treated with estrogen, were significantly less affected by the KA. Testosterone produced a mild neuroprotective action, but dihydrotestosterone did not protect. A similar pattern was observed in all male groups. This results show that estrogen protects BSTM neurons from KA neurotoxicity and androgens are partially neuroprotective; and probably this effect of androgens is due to conversion to estrogen.
Asunto(s)
Agonistas de Aminoácidos Excitadores/toxicidad , Hormonas Gonadales/metabolismo , Ácido Kaínico/toxicidad , Neuronas/efectos de los fármacos , Núcleos Septales/efectos de los fármacos , Animales , Conducta Animal/efectos de los fármacos , Castración , Diestro/efectos de los fármacos , Modelos Animales de Enfermedad , Estrógenos/metabolismo , Estrógenos/farmacología , Agonistas de Aminoácidos Excitadores/administración & dosificación , Femenino , Hormonas Gonadales/farmacología , Inyecciones Intraperitoneales , Ácido Kaínico/administración & dosificación , Masculino , Neuronas/metabolismo , Neuronas/patología , Ratas , Ratas Wistar , Núcleos Septales/patología , Factores Sexuales , Estado Epiléptico/inducido químicamente , Estado Epiléptico/metabolismo , Estado Epiléptico/patología , Testosterona/metabolismo , Testosterona/farmacologíaRESUMEN
MK801, PCP, and ketamine are non-competitive NMDA receptor-antagonists drugs that in humans produce psychomimetic effects and neurocognitive disturbances reminiscent to those of schizophrenia. The administration of these drugs in animals has been used as a pharmacological model to study the NMDA receptor hypofunction-hypothesis of schizophrenia. In animals, the biological effect of MK801 is dose-dependent. Low doses induce behavioral disturbances and higher doses, in addition, promote neurotoxicity in many brain regions, particularly the granular retrosplenial cortex (RSG). The neurotoxic effect of MK801 is sexually dimorphic, being females markedly more sensitive than males; however, the involvement of gonadal hormones is elusive. Here we show that a single intraperitoneal injection of 5 mg/kg of MK801 induced overt neurodegeneration in RSG of female rats, including abundant somatic degeneration in layer 4, and somatodendritic and terminal degeneration in layers 1, 4, and 5. MK801-degeneration in males was scarce and mainly evidenced by the presence of few argirophilic somas in layer 4. Ovariectomized rats were not significantly different than intact females, while orchiectomized rats showed robust MK801-toxicity. Testosterone and dihydrotestosterone (DHT) inhibit MK801-toxicity in orchiectomized rats. In ovariectomized rats only DHT, but not testosterone, prevented MK801-induced degeneration, while in intact females, DHT was only partially protective. Treatment of intact males with estradiol benzoate significantly enhanced MK801-toxicity. Altogether, our experiments indicate that non-aromatizable androgens protect RSG from MK801-toxicity, while estrogens counteract this protection. Thus, the balance of androgens and estrogens delineate the sexual dimorphism of the RSG to the toxic effect of MK801.