Wilson K M, Rowland N, Fregly M J
Appetite. 1984 Mar;5(1):31-8. doi: 10.1016/s0195-6663(84)80047-1.
Administration of either naloxone, an opioid antagonist (1 mg/kg i.p.), or clonidine, an alpha 2 adrenoceptor agonist (12 micrograms/kg i.p.), attenuated the dipsogenic responses of female rats to both angiotensin II (200 micrograms/kg s.c.) and isoproterenol (25 micrograms/kg s.c.). The effect of simultaneous administration of naloxone and clonidine at these submaximal doses was an additive attenuation of both angiotensin II- and isoproterenol-induced water intakes. The absence of a significant interaction between naloxone and clonidine to inhibit drinking suggests that they act by a similar mechanism. Yohimbine, an alpha 2 adrenoceptor antagonist (300 micrograms/kg i.p.), administered in combination with naloxone, reversed the antidipsogenic effect on angiotensin II-induced drinking. These results provide further support for a role for alpha 2-adrenoceptors in laboratory-induced drinking in rats, and suggest the possibility that the antidipsogenic effect of naloxone is related to alpha 2 adrenergic mechanisms. A model to support these observations is presented in which two separate pathways for the induction of drinking (osmoreceptor- and angiotensin II-induced) converge on a final common pathway. Since both naloxone and clonidine inhibit responses to stimulation of both pathways for drinking, these results suggest that their actions are likely to be at some point as yet undetermined on the final common pathway.
给予阿片受体拮抗剂纳洛酮（1毫克/千克，腹腔注射）或α2肾上腺素能受体激动剂可乐定（12微克/千克，腹腔注射），均可减弱雌性大鼠对血管紧张素II（200微克/千克，皮下注射）和异丙肾上腺素（25微克/千克，皮下注射）的致渴反应。以这些次最大剂量同时给予纳洛酮和可乐定，对血管紧张素II和异丙肾上腺素诱导的饮水量具有相加性的减弱作用。纳洛酮和可乐定在抑制饮水方面不存在显著的相互作用，这表明它们通过相似的机制发挥作用。α2肾上腺素能受体拮抗剂育亨宾（300微克/千克，腹腔注射）与纳洛酮联合给药，可逆转对血管紧张素II诱导饮水的抗致渴作用。这些结果进一步支持了α2肾上腺素能受体在大鼠实验性诱导饮水过程中的作用，并提示纳洛酮的抗致渴作用可能与α2肾上腺素能机制有关。本文提出了一个支持这些观察结果的模型，其中诱导饮水的两条独立途径（渗透压感受器诱导和血管紧张素II诱导）汇聚于一条最终的共同途径。由于纳洛酮和可乐定均抑制对两条饮水诱导途径刺激的反应，这些结果表明它们的作用可能在最终共同途径上的某个尚未确定的点上。
