Department of Human Physiology, School of Medical Sciences, Faculty of Health Sciences, University of KwaZulu-Natal, Durban 4000, South Africa.
Behav Brain Res. 2010 Jul 29;211(1):16-22. doi: 10.1016/j.bbr.2010.02.045. Epub 2010 Mar 3.
Maternal separation has been associated with development of anxiety-like behaviour and learning impairments in adult rats. This has been linked to changes in brain morphology observed after exposure to high levels of circulating glucocorticoids during the stress-hyporesponsive period (P4-P14). In the present study, adult rats that had been subjected to maternal separation (180 min/day for 14 days) during the stress-hyporesponsive period, received unilateral infusions of a small dose of 6-hydroxydopamine (6-OHDA, 5 microg/4 microl saline) into the medial forebrain bundle. The results showed that voluntary exercise had a neuroprotective effect in both non-stressed and maternally separated rats in that there was a decrease in forelimb akinesia (step test) and limb use asymmetry (cylinder test). Maternal separation increased forelimb akinesia and forelimb use asymmetry and reduced the beneficial effect of exercise on forelimb akinesia. It also reduced exploratory behaviour, consistent with anxiety-like behaviour normally associated with maternal separation. Exercise appeared to reduce dopamine neuron destruction in the lesioned substantia nigra when expressed as a percentage of the non-lesioned hemisphere. However, this appeared to be due to a compensatory decrease in completely stained tyrosine hydroxylase-positive neurons in the contralateral, non-lesioned substantia nigra. In agreement with reports that maternal separation increases the 6-OHDA-induced loss of dopamine terminals in the striatum, there was a small increase in dopamine neuron destruction when expressed as a percentage of the non-lesioned hemisphere but there was no difference in dopamine cell number, suggesting that exposure to maternal separation did not exacerbate dopamine cell loss.
母体分离与成年大鼠焦虑样行为和学习障碍的发展有关。这与在应激反应期（P4-P14）暴露于高水平循环糖皮质激素后观察到的大脑形态变化有关。在本研究中，在应激反应期（14 天，每天 180 分钟）接受母体分离的成年大鼠接受了内侧前脑束中 6-羟多巴胺（6-OHDA，5 微克/4 微升盐水）的小剂量单侧输注。结果表明，自愿运动对非应激和母体分离大鼠均具有神经保护作用，表现为前肢运动减少（步测）和肢体使用不对称（圆筒测试）。母体分离增加了前肢运动减少和前肢使用不对称，并降低了运动对前肢运动减少的有益作用。它还减少了探索行为，这与通常与母体分离相关的焦虑样行为一致。当表达为未损伤半球的百分比时，运动似乎减少了损伤的黑质中多巴胺神经元的破坏。然而，这似乎是由于对侧未损伤黑质中完全染色的酪氨酸羟化酶阳性神经元的代偿性减少所致。与母体分离增加纹状体中 6-OHDA 诱导的多巴胺末梢损失的报道一致，当表达为未损伤半球的百分比时，多巴胺神经元破坏略有增加，但多巴胺细胞数量没有差异，这表明暴露于母体分离并未加剧多巴胺细胞的丧失。
