低雌激素经5-羟色胺通路致体温调节中枢功能紊乱的机制

Estrogen deficiency is correlated with thermoregulation disorder，of which the mechanism is still unclear. Our preparatory work showed rats with estrogen deficiency had abnormal core temperature and their temperature sensitive nuclei were less sensitive. We also found that with estrogen deficiency, serotonin concentration and the number of serotonin receptors in thermoregulation center were higher. Our project intents to prove that the abnormal change of firing frequency and ion channels opening or closing in the temperature sensitive neurons derived from the serotonin pathway in the thermoregulation center is the mechanism of the temperature regulation disorder in estrogen deficiency condition. First, the brain slices of rats which have disordered temperature regulation in estrogen deficiency condition will be selected, the effect of estrogen deficiency on spontaneous firing rate and the thermoregulation relevant ion channels of temperature sensitive neurons will be measured. Then the distribution of 5-hydroxytryptamine receptors on temperature sensitive neurons will be shown in rats which have abnormal temperature regulation related to estrogen deficiency. Third, certain subtypes of 5-hydroxytryptamine receptors on temperature sensitive neurons will be excited or blocked according to the experiment above and see if the spontaneous firing rate and the opening or closing of thermoregulation relevant ion channels change in estrogen deficiency condition.Finally, the utility of estrogen in vivo or in vitro on the disorder of temperature sensitive neurons derived from estrogen deficiency. We aim to explain the mechanism of estrogen deficiency-induced disorders of hypothalamus in temperature regulation and provide new ideas for treatment.

低雌激素致体温调节紊乱，但机制尚未明确。本项目组前期工作显示，低雌激素大鼠中心体温异常，温度敏感神经核团对温度敏感性降低，且体温调节中枢5-羟色胺浓度、受体数量均增加。本项目拟论证5-羟色胺通路异常致体温调节中枢温度敏感神经元放电频率变化及离子通道异常开闭是低雌激素状态下体温调节紊乱的机制。首先选取低雌激素体温调节紊乱大鼠脑片，测定不同温度下低雌激素对温度敏感神经元自发放电频率及体温调节相关离子通道的影响。第二，阐明5-羟色胺受体在低雌激素体温调节异常大鼠温度敏感神经元的分布特点。第三，根据上述实验结果选取温度敏感神经元上特定5-羟色胺受体亚型激动剂和拮抗剂，观察在低雌激素时，特定受体亚型激动或抑制是否改变温度敏感神经元自发放电频率及相关离子通道开闭。最后，在体内和体外明确雌激素改善低雌激素致温度敏感神经元功能紊乱的效用。本项目旨在阐明低雌激素致下丘脑体温调节中枢功能紊乱的神经递质机制。

低雌激素致体温调节紊乱的机制尚未完全阐明。本项目组前期工作显示，低雌激素大鼠中心体温异常，温度敏感神经核团对温度敏感性降低，且体温调节中枢5-羟色胺受体数量增加。本项目拟在前期工作基础上论证5-羟色胺通路异常致体温调节中枢温度敏感神经元放电频率变化及离子通道异常开闭是低雌激素状态下体温调节紊乱的机制。1.我们切取脑片并选取体温调节中枢下丘脑视前区神经元，检测神经元电压依赖性钙通道，加入与体温调节有关的5-羟色胺受体激动剂和阻断剂来判断5-羟色胺受体对钙通道的作用。结果发现，5-羟色胺1A和7受体能够明显降低高电压激活钙电流而不改变低电压激活钙电流，从而抑制神经元的兴奋性和放电频率，参与体温调节。而5-羟色胺2A和5-羟色胺3受体对高电压激活钙电流和低电压激活钙电流均无明显作用。2.本课题组通过体温植入子检测去卵巢大鼠中心和外周体温的变化情况结果发现，大鼠去卵巢后可发生体温调节异常，单位时间内外周体温的波动频次和幅度明显升高，雌激素治疗后能恢复正常。3. 本课题组研究了低雌激素状态下对大鼠糖脂代谢的影响，结果发现，大鼠去卵巢后体重增加，甘油三酯水平增高，腹部和肝脏脂肪含量增加，脂肪细胞增生，雌激素能够改善上述异常情况。4.本课题组使用微透析-高效液相色谱法检测去卵巢大鼠下丘脑视前区5-羟色胺、去甲肾上腺素、多巴胺及其代谢产物的变化，结果发现大鼠去卵巢后，三者含量均有所降低，雌激素补充治疗后有回升。5. 本课题组使用免疫荧光化学方法发现，去卵巢大鼠中缝背核5-羟色胺染色阳性神经元数目明显减少，下丘脑视前区5-羟色胺阳性神经纤维数量也明显减少，雌激素治疗4周后能恢复正常。本课题组研究发现，低雌激素状态下，5-羟色胺通路改变，导致下丘脑体温调节中枢功能紊乱，进而发生潮热。