小鼠腹外侧视前区神经元的鉴定及其昼夜发放频率

Identification of ventrolateral preoptic nucleus and their different firing rate within day and night

目的鉴定腹外侧视前区（VLPO）的神经元,记录神经元在昼夜的动作电位（AP）的发放频率,揭示不同VLPO神经元昼夜发放的规律。方法 4~6周龄野生型小鼠新鲜脑片,根据形态、对药物去甲肾上腺素的响应及电特性对VLPO的神经元进行鉴定;膜片钳方式记录VLPO区域的神经元在白天的11：00~16：00以及夜间的22：00~02：00动作电位的发放;采用t检验对神经元动作电位的发放频率进行统计学分析。结果成功在VLPO鉴定出两类神经元,一类为多极三角形、去甲肾上腺素抑制性神经元,其阈值有低阈值发放（LTS）特性;一类呈两极梭形、去甲肾上腺素兴奋性神经元,其阈值无LTS特性。在记录的59个VLPO区域的神经元中,LTS特性的神经元有44个,非LTS特性的有15个;t检验分析显示去甲肾上腺素抑制的、有LTS特性的神经元在白天动作电位的发放频率明显高于夜间神经元动作电位的发放频率（P〈0.01）;去甲肾上腺素兴奋的、非LTS特性的神经元白天动作电位的发放频率也明显高于夜晚动作电位的发放频率（P〈0.05）。结论 VLPO存在两类神经元,这两类神经元的白天动作电位发放频率皆高于夜间动作电位发放频率,提示两类神经元都参与了昼夜节律的调控。

Objective To identificate the types of ventrolateral preoptic nucleus（ VLPO） and recorde the action potential（ AP） of this neurons within day and night for investigating their firing roles during day and light. Methods The fresh slices were made from WT mice aged 4 ~ 6 weeks,and the neurons were identified by their shape,different reaction to noradrenaline（ NA） and electrical characteristics. AP firings of neurons were recorded during 11： 00~ 16： 00 and 22： 00 ~ 02： 00 with patch-clamp recording. The firing rates of these neurons were analyzed using ttest. Results The neurons in VLPO were successfully identified into two types. One type neurons with triangular and multipolar shape could be hyperpolarized by NA and had the electrical property of low-threshold spike（ LTS）.The other type neurons with fusiform and bipolar shape could be depolarized by NA and lacked the electrical property of LTS（ non-LTS）. Of 59 recorded neurons in VLPO,44 neurons had the character of LTS,and 15 neurons were non-LTS. Using t-test of statistics,AP firing rate of LTS neurons which were hyperpolarized by NA showed higher at day time than that at night（ P〈 0. 01）. Non-LTS neurons which were depolarized by NA showed the similar tendency,that AP firing rate at day time was higher than that at night（ P 〈0. 05）. Conclusion There are two types of neurons in VLPO. Both of them show high firing rate at day time and low firing rate at night time,which indicates they participate in regulating circadian rhythem.