大鼠双侧海马伞离断对脂多糖诱导的下丘脑催产素能神经元功能活动的影响

为观察去海马传入对免疫应激时下丘脑室旁核、视上核催产素能神经元功能活动的影响 ,以探索海马调控外周免疫反应的脑内环路 ,本研究预先切断大鼠双侧海马伞 ,2 8d后腹腔内注射细菌内毒素脂多糖 (lipopolysaccharide,LPS,75 0μg/kg) ,用免疫组织化学双标记方法 ,以 F os蛋白作为神经元功能活动的标记物 ,观察下丘脑催产素能神经元中即刻早期基因的表达变化。结果显示 :双侧海马伞离断后 ,下丘脑室旁核中因腹腔脂多糖刺激而发生活化的催产素能神经元活化百分率显著下降 ;而视上核中催产素能神经元的活化未受明显影响。上述结果表明 ,海马对下丘脑 -垂体 -肾上腺轴以及免疫系统的抑制作用部分是通过其支配的下丘脑室旁核的催产素能神经元来完成的。

THE EFFECT OF BILATERAL FIMBRIA TRANSECTION ON ACTIVATION OF HYPOTHALAMIC OXYTOCINERGIC NEURONS IN THE INTRAPERITONEALLY LPS-ADMINISTERED RAT

In order to understand the hippocampus-related neural circuit in the brain responsible for regulating immune function, effect of eliminating hippocampal afferents on the activation of oxytocin (OT)-nergic neurons in the hypothalamic paraventricular nucleus (PVN) and supraoptic nucleus (SON) induced by immune challenge was studied. Bilateral fimbria of the rats were transected and lipopolysaccharide (LPS, 750 μg/kg) was administered intraperitoneally 28 days later. PVN and SON neurons containing oxytocin and Fos protein, an immediately early gene product served as a neuronal activation marker, were demonstrated by using double staining immunohistochemical method. We found the percentage of activated OT neurons followed by LPS administration in PVN in the group of fimbria transection was lower than that of the sham operated group, whereas no detectable change was found in SON. These results show that inhibition of hippocampal formation on HPA axis and peripheral immune response may be partly mediated by OT neurons in PVN.