Studies on neuroendocrinological mechanisms of memory in the Hatano rats

Hatano高回避（HAA）和低回避（LAA）品系大鼠最初是从Sprague-Dawley大鼠中选择和繁殖的，用于穿梭箱任务。本研究观察了束缚应激对HAA和LAA大鼠下丘脑-垂体-肾上腺皮质轴（HPA）活动的影响。束缚应激引起血浆ACTH、催乳素、皮质酮和孕酮浓度升高，肾上腺皮质酮和孕酮浓度升高。在应激条件下，血浆ACTH的峰值水平显着高于HAA大鼠比LAA大鼠，而催乳素的峰值水平显着低于HAA大鼠比LAA大鼠。应激时HAA大鼠垂体前叶ACTH和催乳素合成显著高于LAA大鼠。应激时HAA大鼠血浆皮质酮浓度（以初始值百分比表示）显著高于LAA大鼠。肾上腺皮质酮和孕酮的浓度增加，在两个菌株的压力，虽然没有显着的应变差异之间观察到HAA和LAA。结果表明，急性束缚应激时HAA大鼠HPA轴活性高于LAA大鼠，而催乳素分泌活性则相反。这些内分泌对应激反应的差异可能与记忆的调节有关。

Hatano high avoidance (HAA) and low avoidance (LAA) strains rats have been originally selected and bred from Sprague-Dawley rats for their shuttle-box task. The present study focused on the activity of the hypothalamo-pituitary-adrenocortical axis (HPA) of HAA and LAA rats in response to restraint stress. The restraint stress induced an elevation of plasma concentrations of ACTH, prolactin, corticosterone and progesterone, and in adrenal concentrations of coricosterone and progesterone. Peak levels of plasma ACTH during stress condition were significantly higher in HAA rats than LAA rats, while peak levels of prolactin were significantly lower in HAA rats than LAA rats. ACTH and prolactin syntheses in anterior pituitary glands were significantly higher in HAA rat than LAA rats during stress. The plasma concectrations of corticosterone, as shown bv percentage of initial values, during stress were significantly higher in HAA rats than LAA rats. Adrenal concentrations of corticosterone and progesterone increased during stress in both strains, although no significant strain deference was observed between HAA and LAA. These results indicate that the activities of HPA axis to acute restraint stress are higher in HAA rats than LAA rats, whereas prolactin secretory activity is vice versa. These endocrine differences in response to stress may be involved in regulation of memory.