RESUMO
We investigated the influence of ibotenic acid lesions of the medial hypothalamus (MH) on salt appetite and arterial blood pressure responses induced by angiotensinergic and adrenergic stimulation of the median preoptic nucleus (MnPO) of rats. Previous injection of the adrenergic agonists norepinephrine, clonidine, phenylephrine, and isoproterenol into the MnPO of sham MH-lesioned rats caused no change in the sodium intake induced by ANG II. ANG II injected into the MnPO of MH-lesioned rats increased sodium intake compared with sham-lesioned rats. Previous injection of clonidine and isoproterenol increased, whereas phenylephrine abolished the salt intake induced by ANG II into the MnPO of MH-lesioned rats. Previous injection of norepinephrine and clonidine into the MnPO of sham MH-lesioned rats caused no change in the mean arterial pressure (MAP) induced by ANG II. Under the same conditions, previous injection of phenylephrine increased, whereas isoproterenol reversed the increase in MAP induced by angiotensin II (ANG II). ANG II injected into the MnPO of MH-lesioned rats induce a decrease in MAP compared with sham-lesioned rats. Previous injection of phenylephrine or norepinephrine into the MnPO of MH-lesioned rats induced a negative MAP, whereas pretreatment with clonidine or isoproterenol increased the MAP produced by ANG II injected into the MnPO of sham- or MH-lesioned rats. These data show that ibotenic acid lesion of the MH increases the sodium intake and pressor responses induced by the concomitant angiotensinergic, alpha 2 and beta adrenergic activation of the MnPO, whereas alpha 1 activation may have opposite effects. MH involvement in excitatory and inhibitory mechanisms related to sodium intake and MAP control is suggested.
Assuntos
Pressão Sanguínea/efeitos dos fármacos , Ingestão de Alimentos/fisiologia , Agonistas de Aminoácidos Excitatórios/toxicidade , Hipotálamo Médio/fisiologia , Ácido Ibotênico/toxicidade , Área Pré-Óptica/fisiologia , Sódio na Dieta , Agonistas Adrenérgicos/farmacologia , Angiotensina II/farmacologia , Animais , Agonistas de Aminoácidos Excitatórios/administração & dosagem , Hipotálamo Médio/anatomia & histologia , Hipotálamo Médio/efeitos dos fármacos , Ácido Ibotênico/administração & dosagem , Injeções , Masculino , Área Pré-Óptica/anatomia & histologia , Área Pré-Óptica/efeitos dos fármacos , RatosRESUMO
Thirty six female mice were injected on the 12th day of the gestational period with 0.2 ml of distilled water (control group) or of an acqueous solution containing either 30 mg/Kg or 50 mg/Kg of body weight of cyclophosphamide (treated group). The animal were killed at 24, 48, 72, 96 and 120 hours after the injection and 3 days after birth. It was verified that cyclophosphamide interferes on the tooth germ development and that this effect is in directly ratio of the doses used.
Assuntos
Ciclofosfamida/toxicidade , Odontogênese/efeitos dos fármacos , Germe de Dente/efeitos dos fármacos , Animais , Feminino , Incisivo/efeitos dos fármacos , Incisivo/crescimento & desenvolvimento , Camundongos , GravidezRESUMO
Mice foetus were killed between 13 and 16 days of the gestational period and their molar tooth germs grafted into the anterior chamber of the eye. The hosts were injected either with 6.25 mg/Kg or with 125 mg/Kg of cyclophosphamide and killed 15 days later. The cyclophosphamide irreversibly, interferes on tooth germ development causing either its total degeneration or an alteration on its morphology forming hypodeveloped tooth germs; its action is directly proportional to the foetus age and to the dose used; it does not induce the formation of osteodentin while some predentin partial cell inclusion may occur.