催产素对孕鼠强迫游泳后母爱行为的保护作用

目的:探讨大鼠产前应激对其母爱行为的影响及其神经内分泌机制。方法:于母鼠怀孕14d至分娩当日,每日进行一次强迫游泳应激,每次2 min,然后随机分为大剂量催产素保护组(A组):皮下注射1 ml含40 IU催产素的生理盐水;小剂量催产素保护组(B组):皮下注射1 ml含20IU催产素的生理盐水,单纯应激组(C组):仅注射1 ml生理盐水;正常孕鼠对照组(D组)不给予任何刺激,令其正常自然分娩。在分娩当天各组均进行母爱行为测试,分别观察母鼠的舔仔、回收幼仔、弓背哺乳、建穴4种母爱行为的时间,比较各组母鼠母爱行为的差异,并用免疫组织化学方法检测下丘脑室旁核(PVN)催产素(OT)神经元、中脑腹侧被盖区(VTA)多巴胺(DA)神经元数量变化。结果:A、B、C组母鼠的4种母爱行为持续时间均较D组有显著差异(P<0.01和P<0.05);而A组的母爱行为持续时间较C组有显著差异(P<0.01和P<0.05)。与D组比较,B组和C组OT神经元及DA神经元阳性细胞数减少(P<0.05)。结论:怀孕后期持续应激会明显损伤母鼠的母爱行为,而催产素对孕鼠的母爱行为有一定的保护作用。

Protection of Oxytocin in the Maternal care from Forced-swimming Rats during Pregnancy

Objective: To explore the effects and the mechanism of antepartum stress on maternal behavior of rats. Methods: The female rats were stimulated by forced-swimming 2 min/d from pregnancy 14th day to the delivery. After delivery, maternal behavior (arched-back nursing, licking, nesting, grouping) were monitored by VHS. In the present study, we compare the effects of oxytocin with physiological saline on the maternal behaviors of rats. The oxytocin were administrated by hypodermic. The number of oxytocinergic neuron in paraventricular nucleus (PVN) of hypothalamus and the number of dopaminergic neuron in ventral tegmental area (VTA) were observed by immunohistochemistry. Results: Compared with control group, the four types of maternal behaviors of model groups was decreased (P<0.01 and P<0.05).The meternal behaviors of the large dosage oxytocin treated group was increased (P<0.01 and P<0.05). The number of oxytocinergic neuron in paraventricular nucleus of hypothalamus and the number of opaminergic neuron in ventral tegrnental area were lower in model group than that of control group (P<0.01 and P<0.05). Conclusion: Antepartum stress can decrease the maternal behaviors, and oxytocin can improve the maternal behaviors.