Study of the biochemical processing of the biowarning information through the hypothalamu

本研究旨在研究应激刺激下大鼠脑内5-羟色胺(5-羟色胺)和去甲肾上腺素(NA)水平的动态变化。(1)束缚--应激引起的厌食症伴随着下丘脑5-羟色胺释放的即刻增加。注射5-羟色胺受体拮抗剂可显著减轻应激引起的食欲减退，提示应激时下丘脑5-羟色胺能系统被激活，5-羟色胺是摄食行为的抑制性递质。(2)束缚组大鼠内侧前额叶皮质(PFC)NA水平升高。预先注射苯二氮卓类受体激动剂地西潘显著减弱固定诱导的NA释放，而注射引起焦虑的化合物FG7142则促进非应激状态下的NA释放。因此，应激刺激激活了内侧PFC的NA系统，这可能是通过激活大脑中的苯二氮卓类受体来调节的。(3)束缚应激可显著提高小鼠脾NA水平，同时抑制自然杀伤细胞的杀伤活性。手术切除脾交感神经后，NA水平的升高和NK细胞毒性的抑制均明显减弱，提示束缚抑制脾N/K细胞毒性主要是通过增强脾交感神经的活性来实现的。

This study was designed to study the dynamic changes in serotonin (5HT) and noradrenaline (NA) levels during the stressful stimuli, and have reached the following conclusions in rats. (1) Immobilization-stress caused anorexia in conjunction with an immediate increase in thehypothalamic 5HT release. Injection of 5HT receptor antagonist significantly reduced the immobilization-induced anorexia, suggesting that the hypothalamic serotonergic ystem is activated during stress and 5HT is an inhibitory transmitter in feeding behavior. (2) Immobilization elevated NA levels in the medial prefrontal cortex (PFC). Pre-injection of a benzodiazepine receptor agonist, diazepam, significantly attenuated the immobilization-induced NA release, while the injection of an anxiogenic compound, FG7142, facilitated it in non-stressed condition. Thus the stressfull stimuli activate the NA system in the medial PFC which may be modulated by an activation of the benzodiazepine receptors in the brain. (3) Immobilization-stress rapidly increased NA levels of spleen in conjunction with the suppression of natural killer (NK) cytotoxicity. Both theincreased levelsof NA ad he suppresion of NK cytotoxicity were significantly attenuated after surgical denervation of the splenic sympathetic nerve, indicating that immobilization-induced suppression of splenic N/K cytotoxicity was mediated predominantly through enhanced activity of the splenic sympathetic nerve..These results suggest that both 5HT and NA may act asneurotransmitters and/or neuromodlators which regulate biowarning processes in the living body.