早孕大鼠下丘脑催乳素释放肽的表达及对血催乳素分泌的调节

Role of prolactin-releasing peptide in pregnancy maintained by regulation of pituitary prolactin

目的探讨早孕期大鼠下丘脑催乳素(PRL)释放肽(PrRP)的表达及对血PRL的调节作用。方法于大鼠孕6～8d皮下注射溴隐亭,造成溴隐亭致大鼠流产模型(A组);B组为模型鼠于孕1～11d注射PRL;C组为正常妊娠组。于孕4、7、10、12d剪尾采静脉血,采用放射免疫法检测血PRL、孕酮(P)。孕12d处死大鼠,逆转录聚合酶链反应(RTPCR)检测下丘脑PrRP及垂体、胎盘、蜕膜PrRP受体(PrRPR)mRNA表达。结果A组下丘脑PrRPmRNA表达明显低于B、C组(P<0.05),垂体PrRPRmRNA表达明显高于B、C组(P<0.05);蜕膜及胎盘也检测到PrRPR表达,但差异无显著性(P>0.05)。3组大鼠孕4d血PRL、P水平的差异无显著性(P>0.05);随孕日递增,A组血PRL、P水平无明显变化,而B、C组血PRL、P水平明显增加;A组孕7、10、12d血PRL、P水平明显低于B、C组同期激素水平(P<0.05)。结论孕期下丘脑PrRP特异性调节垂体PRL释放,后者调节卵巢绒毛膜促性腺激素(HCG)受体表达,进而调节P分泌,维持早期妊娠。

Objective To investigate the expression of prolaetin releasing peptide （PrRP） in rat hypothalamus and it＇s regulation on blood prolactin （PRL） during early pregnancy. Methods Sprague-Dawley rats were randomly divided into three groups. Group A rats were injected with bromocriptine qd subcutaneously at day 6, 7, 8 of pregnancy, group 13 rats were added PRL and group C rats were pregnant rats without given treatment. The venous blood was collected by scissoring rat tails at d 4, 7, 10, 12 of pregnancy. Serum PRL, progesterone （P） levels were measured by RIA （Radioimmunoassay）. The rats were sacrificed on day 12 of pregnancy. The expressions of PrRP mRNA in the hypothalamus, PrRP R mRNA in the pituitary body, PrRP and PrRP-R mRNA in the placenta and deciduas were determined by semiquantitied RT-PCR. Results Expression of PrRP mRNA in group A was significantly lower than those in group B and C, but the expression of its receptor was higher than those in the other groups （P〈0.05）. The expression of PrRP mRNA was also found in the placenta and the deciduas but there were no significant differences among the three groups. There were no differences in serum PRL and P levels at d4 in group A-C （P〉0.05）. Serum PRL and P in group B and C at d12 were significantly higher than those on d4 （P〉0.05）, while serum PRL, P levels in group A on dT, d10, d12 were significantly lower than those in group B and C （P〈0.05）. Conclusions The release of PrRP from the hypothalamus can reg ulate the production of pituitary PRL. Pituitary PRL up-regulates the human chorionic gonadotropin （HCG） receptor expression which induces high level of progesterone. （Shanghai Med J, 2006,29..22 25）