低渗刺激下大鼠视上核星形胶质细胞对神经元反应的调控机制

目的观察低渗刺激后大鼠视上核(SON)星形胶质细胞对神经元反应的调节机制,以及牛磺酸拮抗剂(TAG)和缝隙连接阻断剂-甘珀酸(CBX)对反应的影响。方法成年SD大鼠20只,对照组经尾静脉注射0.9%盐水;低渗组经尾静脉注射低渗盐水(0.83%葡萄糖 0.3%NaCl);TAG 低渗组和CBX 低渗组分别经侧脑室注射TAG或CBX,2h后经尾静脉注射低渗盐水。常规固定取材制片。切片进行抗Fos、抗加压素(VP)、抗甘氨酸受体(GlyR)、抗胶质原纤维酸性蛋白(GFAP)、抗缝隙连接蛋白43(Cx43)免疫荧光染色,镜下观察在视上核神经元和星形胶质细胞的表达。结果低渗组视上核星形胶质细胞的GFAP和Cx43表达高于对照组,GlyR阳性神经元较对照组多,Fos和VP阳性神经元较对照组少;TAG 低渗组和CBX 低渗组,星形胶质细胞的反应同低渗组,而GlyR阳性神经元较低渗组少,VP-、Fos-阳性神经元较低渗组均有所增加。结论低渗刺激激活视上核星形胶质细胞,被激活的星形胶质细胞可能经缝隙连接释放牛磺酸而抑制神经元,减少VP的释放,此过程可被TAG和CBX所阻断。

THE MECHANISMS OF ASTROCYTES MODULATING NEURONS IN RAT SUPRAOPTIC NUCLEUS INDUCED BY HYPOTONIC STIMULATION

Objective To investigate the mechanisms of astrocytes modulating neurons in rat supraoptic nucleus induced by hypotonic stimulation and the effect of 6-aminomethyl-3-methyl-4H-1，2，4-benzothiadiazine-1,1-dioxide HCl (TAG, a antagonist for taurine) or carbenoxolone (CBX, a gap junction blocker)on the responses of astrocytes and neurons in SON. Methods Adult male Sprague Dawley rats were divided into four groups: the control group was injected with 5.5ml/kg 0.9% NaCl solution into the caudal vein; the hypotonic group was injected with 5.5 ml/kg hypo-saline (0.83% glucose plus 0.3% NaCl); TAG + hypotonic and CBX + hypotonic groups were injected with TAG (100μmol/L) or CBX (10g/L) into the lateral ventricle respectively, and were injected 2 hours later with hypotonic saline into the caudal vein. With anti-Fos, anti-vasopressin (VP), anti-glycine receptor (GlyR), anti-glial fibrillary acidic protein (GFAP) and anti-connexin43 (Cx43) immunofluorescent staining methods, the responses of neurons and astrocytes in SON were studied. Results In control rats, Fos-, VP-, and GlyR-expression in the neurons and GFAP- or Cx43-expression in the astrocytes were lower. In hypotonic rats, GFAP-, Cx43- and GlyR signals were more than those in control rats, while Fos- and VP- signals were less. Compared with those in hypotonic rats in TAG + hypotonic or CBX + hypotonic rats, GFAP- and Cx43- signals in the astrocytes were the same, GlyR signals in the neurons decreased, and Fos- and VP-signals increased. Conclusion Hypotonic stimulation activates SON astrocytes, which then release taurine through gap junction signaling to the neurons