A study on the central osmoreceptor mechanism controlling drinking

我们证明了终板血管器官(OVLT)、正中视前核(MnPO)和视上核之间存在渗透敏感性神经回路，提示该回路控制着加压素和催产素的释放。我们研究了渗透受体复合体是否在控制饮酒方面发挥作用。在雄性大鼠OVLT、MnPO或SON内植入套管，分别向各部位注射0.2µl等渗或高渗脑脊液，观察其对10min饮水量的影响。OVLT、MnPO或SON内注射高渗脑脊液可诱发饮酒。然后，这些大鼠被剥夺了15小时的水，并测试了利多卡因注射到每个脑区的效果。利多卡因阻断OVLT、MnPO或SON的活性，可减少恢复自由饮水后前10分钟的饮水量。这些结果表明，连接OVLT、MnPO和SON的渗透敏感神经回路在饮酒的渗透控制和加压素的释放中发挥作用。室旁核在血管紧张素II(AII)的促糖尿病作用中具有重要意义(Gutman等，1988)。因此，我们试图调查儿子是否也参与了口渴的中枢控制。SON内微量注射(0.2mu1)10℃~(-6)-6~mAII可显著增加大鼠的摄水量。而SON内微量注射AII拮抗剂10^-4-M Saralasin对缺水15小时大鼠的摄水量无影响。由此可见，SON中的血管紧张素能机制在缺水脱水大鼠的饮水中不起作用。

We have demonstrated that there is an osmosensitive neural circuit connecting the organum vasculosum of the lamina terminalis(OVLT),median preoptic nucleus(MnPO)and supraoptic nucleus and suggested that the circuit controls the vasopressin and oxytocin release. We examined whether the osmoreceptor complex plays a role in control of drinking. Cannulae were implanted into the OVLT,MnPO or SON of male rats and the effects of injections(0.2mu1)of isotonic or hypertonic CSF into each of the regions on the volume of water drunk in 10 min were measured. Hypertonic CSF injected into the OVLT,MnPO or SON was found to induce drinking. The rats were then deprived of water 15 hours and tested for the effect of lidocaine injection into each of the brain regions. The lidocain block of the activity of the OVLT,MnPO or SON reduced the volume of water drunk during the first 10 min after resuming free access to water. These results suggest that the osmosensitive neural circuit connecting the OVLT,MnPO and SON plays a role in the osmotic control of drinking as well as vasopressin release.The significance of the paraventricular nucleus for the dipsogenic effect of angiotensin II(AII) has been shown(Gutman et al, 1988). So we made attempt to investigate whether or not the SON is also involved in the central AII control of thirst. The microinjection(0.2mu1)of 10^<-6>M AII into the SON significantly increased water-intake. However,the microinjection of 10^<-4>M saralasin(AII antagonist)into the SON did not influence water intake in 15 hour water-deprived rats. Thus it is concluded that the angiotensinergic mechanism in the SON does not play a role in drinking in water-deprived dehydrated rat.