Callera J C, Camargo L A, De Luca Júnior L A, Menani J V, Renzi A, Saad W A
Department of Physiology, School of Dentistry, Paulista State University, Araraquara, SP, Brazil.
Pharmacol Biochem Behav. 1993 Sep;46(1):39-43. doi: 10.1016/0091-3057(93)90314-j.
In the present study, we investigated the effect of phenylephrine and clonidine (alpha 1- and alpha 2-adrenoceptor agonists, respectively) injected into the lateral preoptic area (LPOA) on the water intake induced by water deprivation in rats. In addition, the effects of prior injections of prazosin and yohimbine (alpha 1- and alpha 2-adrenoceptor antagonists, respectively) into the LPOA on the antidipsogenic action of phenylephrine and clonidine were investigated. After 30 h of water deprivation, the water intake of rats in a control experiment (saline injection) was 10.5 +/- 0.8 ml/h. Injection of clonidine (5, 10, 20, and 40 nmol) into the LPOA reduced water intake to 6.3 +/- 0.9, 4.9 +/- 0.8, 3.6 +/- 1.0, and 2.2 +/- 0.7 ml/h, respectively. Similar reductions occurred after injection of 80 and 160 nmol phenylephrine into the LPOA (6.2 +/- 1.6 and 4.8 +/- 1.3 ml/h, respectively). Pretreatment with prazosin (40 nmol) abolished the antidipsogenic action of an 80-nmol dose of phenylephrine (11.3 +/- 1.1 ml/h) and reduced the effect of a 20-nmol dose of clonidine (7.4 +/- 1.4 ml/h). Yohimbine (20, 40, and 80 nmol), previously injected, produced no significant changes in the effects of either phenylephrine or clonidine. The present results show that phenylephrine and clonidine injected into the LPOA induce an antidipsogenic effect in water-deprived rat. They also suggest an involvement of alpha 1-adrenoceptors in this effect. A possible participation of imidazole receptors in the effect of clonidine should also be taken into account.
在本研究中，我们调查了分别注射到视前外侧区（LPOA）的去氧肾上腺素和可乐定（分别为α1和α2肾上腺素能受体激动剂）对大鼠禁水诱导的饮水的影响。此外，还研究了预先向LPOA注射哌唑嗪和育亨宾（分别为α1和α2肾上腺素能受体拮抗剂）对去氧肾上腺素和可乐定的抗饮水作用的影响。禁水30小时后，对照实验（注射生理盐水）中大鼠的饮水量为10.5±0.8 ml/h。向LPOA注射可乐定（5、10、20和40 nmol）分别使饮水量降至6.3±0.9、4.9±0.8、3.6±1.0和2.2±0.7 ml/h。向LPOA注射80和160 nmol去氧肾上腺素后也出现了类似的饮水量减少（分别为6.2±1.6和4.8±1.3 ml/h）。预先用哌唑嗪（40 nmol）处理可消除80 nmol剂量去氧肾上腺素的抗饮水作用（11.3±1.1 ml/h），并减弱20 nmol剂量可乐定的作用（7.4±1.4 ml/h）。预先注射的育亨宾（20、40和80 nmol）对去氧肾上腺素或可乐定的作用均未产生显著影响。目前的结果表明，注射到LPOA的去氧肾上腺素和可乐定在禁水大鼠中诱导出抗饮水作用。它们还提示α1肾上腺素能受体参与了这一作用。还应考虑咪唑受体可能参与可乐定的作用。
