RESUMO
Inhibin administered to adult male rats delayed the in-vivo pituitary responsiveness to thyrotrophin releasing hormone (TRH) as observed in terms of prolactin release in the serum. It also decreased the sensitivity of the pituitary gland to TRH, in terms of TSH release. However, inhibin alone did not alter the serum levels of prolactin and TSH, although it significantly suppressed serum FSH levels. In addition, the inhibin effect on FSH release was blocked by TRH.
Assuntos
Inibinas/farmacologia , Hormônio Liberador de Tireotropina/farmacologia , Animais , Interações Medicamentosas , Hormônio Foliculoestimulante/sangue , Hormônio Foliculoestimulante/metabolismo , Masculino , Prolactina/sangue , Prolactina/metabolismo , Ratos , Ratos Endogâmicos , Tireotropina/sangue , Tireotropina/metabolismoRESUMO
In order to investigate whether inhibin could modulate the action of luteinizing hormone releasing hormone (LHRH), the in vitro effect of inhibin of LHRH bindings to the pituitaries from intact adult male rats was studied. The inhibin preparations suppressed the binding of labeled LHRH to pituitary receptors in a dose-related manner. In vivo administration of inhibin decreased the pituitary LHRH receptor concentration, with an apparent increase in the affinity of these receptors. A dose-related decrease was observed in serum follicle stimulating hormone (FSH) levels in the same group whereas the serum luteinizing hormone (LH) levels remained unaltered. There may be a direct action of inhibin at the pituitary level to suppress FSH levels specifically.
Assuntos
Hipófise/metabolismo , Proteínas/farmacologia , Receptores de Superfície Celular/metabolismo , Hormônios Testiculares/farmacologia , Animais , Bacitracina/farmacologia , Ligação Competitiva , Citocromos/farmacologia , Relação Dose-Resposta a Droga , Hormônio Foliculoestimulante/sangue , Humanos , Inibinas , Hormônio Luteinizante/sangue , Masculino , Ratos , Receptores LHRH , OvinosRESUMO
Subcutaneous administration of delta-9-tetrahydrocannabinol (delta 9-THC) in adult male rats caused a decrease in serum luteinizing hormone (LH) levels with unchanged serum prolactin, pituitary LH and pituitary prolactin content. Response of pituitary to in vitro gonadotropin releasing hormone (GnRH) remained unaltered while the response to in vivo GnRH treatment was markedly increased with the drug indicating the pituitary to be functionally normal. Differences in the in vitro and in vivo response could be due to the endogenous steroid levels. The hypothalamic LH-RH content concommitantly increased. Delta-9-tetrahydrocannabinol may inhibit the release of luteinizing hormone releasing hormone (LHRH).
Assuntos
Dronabinol/farmacologia , Sistema Hipotálamo-Hipofisário/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Hormônio Liberador de Gonadotropina/metabolismo , Hormônio Luteinizante/sangue , Masculino , Hormônios Liberadores de Hormônios Hipofisários , Prolactina/sangue , RatosRESUMO
The effects of both high and low molecular weight inhibin preparations on testicular and pituitary receptors were studied. Both these preparations were able to inhibit the binding of labelled hFSH to testicular receptor in a dose related manner, but were unable to affect the binding of labelled hCG to its receptor, suggesting that the observed inhibition of FSH binding was specific to inhibin. In addition, the binding of LHRH to pituitary receptors was affected by inhibin preparations. Interestingly, the antiserum raised against high molecular weight inhibin was able to neutralize, totally, the biological effect of high molecular weight inhibin, and only, partially, the biological effect of low molecular weight inhibin.
Assuntos
Hipófise/efeitos dos fármacos , Proteínas/farmacologia , Receptores de Superfície Celular/efeitos dos fármacos , Hormônios Testiculares/farmacologia , Testículo/efeitos dos fármacos , Animais , Gonadotropina Coriônica/metabolismo , Hormônio Foliculoestimulante/metabolismo , Hormônio Liberador de Gonadotropina/metabolismo , Inibinas , Masculino , Peso Molecular , Hipófise/metabolismo , Ratos , Receptores de Superfície Celular/metabolismo , Testículo/metabolismoRESUMO
The LD50 values were utilized to assess the relative rate of absorption of two very poorly soluble drugs. Formulations of these drugs were studied by micronization; addition of surfactant, alkaline or buffering agents, and/or bile salts; coprecipitation; melt or fusion techniques; or granulation with hydrophilic agents. Differences in toxicities were demonstrated from formulations compared to pure drugs by the LD50 method. This study shows that the LD50 is a practical, rapid method of achieving comparative evaluations of drug formulations.
