Bastos R, Menani J V, Saad W A, Renzi A, Silveira J E, Camargo L A
Department of Physiology, School of Dentistry, Paulista State University (UNESP), Araraquara, SP, Brazil.
Physiol Behav. 1997 Aug;62(2):311-6. doi: 10.1016/s0031-9384(97)88986-x.
In this study, we investigated the participation of adrenergic receptors of the median preoptic area (MnPO) and the participation of ventromedial hypothalamus (VMH) in angiotensin II-(ANG II)-induced water intake and pressor responses. Male rats with sham or electrolytic VMH lesions and a stainless steel cannula implanted into the MnPO were used. Noradrenaline, clonidine (an alpha2-adrenergic receptor agonist), or phenylephrine (an alpha1-adrenergic receptor agonist) injected into the MnPO of sham-lesioned rats reduced water ingestion induced by ANG II injected into the same area. In VMH-lesioned rats ANG II-induced water intake increased with a previous injection of noradrenaline, phenylephrine, or isoproterenol. The pressor response induced by ANG II injected into the MnPO was reduced in VMH-lesioned rats, whereas the pressor response induced by clonidine was abolished. Previous treatment with noradrenaline and phenylephrine into the MnPO of sham-lesioned rats produced a pressor response, and a hypotensive response was obtained with the previous administration of noradrenaline, phenylephrine or isoproterenol into the MnPO of VMH-lesioned rats. These results show that VMH is essential for the dipsogenic and pressor responses induced by adrenergic and angiotensinergic activation of the MnPO in rats.
在本研究中，我们调查了正中视前区（MnPO）肾上腺素能受体的参与情况以及腹内侧下丘脑（VMH）在血管紧张素II -（ANG II）诱导的饮水和升压反应中的参与情况。使用了接受假手术或VMH电解损伤且在MnPO植入不锈钢套管的雄性大鼠。向假手术大鼠的MnPO注射去甲肾上腺素、可乐定（一种α2肾上腺素能受体激动剂）或去氧肾上腺素（一种α1肾上腺素能受体激动剂）可减少向同一区域注射ANG II所诱导的饮水。在VMH损伤的大鼠中，预先注射去甲肾上腺素、去氧肾上腺素或异丙肾上腺素会使ANG II诱导的饮水增加。向MnPO注射ANG II所诱导的升压反应在VMH损伤的大鼠中减弱，而可乐定诱导的升压反应则被消除。向假手术大鼠的MnPO预先注射去甲肾上腺素和去氧肾上腺素会产生升压反应，而向VMH损伤大鼠的MnPO预先注射去甲肾上腺素、去氧肾上腺素或异丙肾上腺素则会产生降压反应。这些结果表明，VMH对于大鼠中由MnPO的肾上腺素能和血管紧张素能激活所诱导的饮水和升压反应至关重要。
