Postnatal maternal separation during the stress hyporesponsive period enhances the adrenocortical response to novelty in adult rats by affecting feedback regulation in the CA1 hippocampal field
Postnatal maternal separation during the stress hyporesponsive period enhances the adrenocortical response to novelty in adult rats by affecting feedback regulation in the CA1 hippocampal field
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DOI：
10.1016/s0736-5748(98)00019-7
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发表时间：
1998-06-01
影响因子：
1.8
通讯作者：
Agnati, LF
中科院分区：
文献类型：
--
作者：
Biagini, G;Pich, EM;Agnati, LF
本实验的目的是研究出生后早期母体分离对成年大鼠对新奇事物的行为和肾上腺皮质反应的影响。从出生后第2天到第6天，在应激低反应期，SD大鼠幼鼠每天暴露于母体隔离(5h/d)。由于这一过程需要与动物进行身体接触，因此引入了第一组每日处理的幼崽。第二个对照组，由从未抚育过或与母亲分离的幼崽组成，也被考虑在内。在出生后45天，在两室探索仪中进行了测试：母亲分离的大鼠和未处理的大鼠的行为表现没有差异，表现出比处理的大鼠更高的情绪行为(P<；0.05)，这表明处理程序而不是母亲的分离提高了适应新奇事物的能力。无论是在安静状态下，还是在新奇刺激后30分钟，母系分离大鼠的血浆皮质酮水平均高于其他两组(P<；0.05)。正如预期的那样，在处理过的和未处理过的大鼠中，CA1区海马区的核糖皮质激素受体免疫反应性水平受到新奇暴露的调节，但在母系分离的大鼠中不受影响。总而言之，在出生的第一周，每天5小时的重复母婴隔离时间对海马体对下丘脑-垂体-肾上腺皮质轴的调节产生了长期的影响，这似乎与成年后对应激刺激的反应增强有关。(C)1998年综合业务数字网。爱思唯尔科学有限公司出版。
The aim of the present experiment was to study the effects of early postnatal maternal separation on behavioural and adrenocortical responses to novelty in rats tested as adults. Sprague-Dawley rat pups were exposed to daily maternal separation (5 h/day) from postnatal day 2 to 6, during the stress hyporesponsive period. Since this procedure requires physical contact with the animals, a first control group of daily handled pups was introduced. A second control group, consisting of pups never handled or separated from the mother, was also considered. At postnatal day 45, the rats were tested in a two-compartment exploratory apparatus: the maternally separated and the non-handled rats, whose behavioural performance did not differ, showed higher emotional behaviour when compared with the handled rats (P < 0.05), suggesting that the handling procedure hut not maternal separation improved the capacity to cope with novelty. Corticosterone plasma levels were found to be higher in the maternally separated rats than in the other two groups (P < 0.05), either at resting conditions or at 30 min after novelty exposure (P < 0.05). Levels of nuclear glucocorticoid receptor immunoreactivity in the CA1 hippocampal field were shown to be regulated by novelty exposure, as expected, in both the handled and the non-handled rats but not in the maternally separated rats. In conclusion, repeated maternal separation periods of 5 h/day during the first week of life produced long-lasting effects on the hippocampal regulation of the hypothalamic-pituitary-adrenocortical axis, which appear to be associated with increased responsiveness to stress stimuli in adulthood. (C) 1998 ISDN. Published by Elsevier Science Ltd.