精氨酸加压素对大鼠下丘脑视前区NMDA受体亚单位表达的影响

Effects of Arginine Vasopressin on the Expression of NMDA Receptor Subunits in Preoptic Area of Rat Hypothalamus

目的研究精氨酸加压素(arginine vasopressin,AVP)对大鼠下丘脑视前区(preoptic area,POA)N-甲基-D-门冬氨酸(NMDA)受体mRNA和蛋白质表达的影响。方法腹腔注射AVP或AVP V1a受体抑制剂0.5h后,采用实时荧光定量逆转录PCR和Western blot技术分析大鼠视前区AVP V1a受体、NMDA受体NR2A、NR2B、NR1亚单位mRNA和蛋白表达的变化。结果与对照组相比,注射AVP或V1a受体抑制剂组大鼠视前区NR2A、NR2B和V1a受体mRNA表达均无显著变化(均P>0.05);AVP对NR1mRNA表达也无影响,但V1a受体抑制剂明显降低了NR1mRNA表达(P<0.01);AVP能明显下调视前区NMDA受体亚单位(NR2A、NR2B、NR1)蛋白水平(均P<0.05),但不影响V1a受体蛋白表达(P>0.05)。结论外源性AVP不影响AVP V1a受体的表达,其主要通过抑制NMDA受体亚单位蛋白质翻译而不是基因转录,减少大鼠视前区NMDA受体介导的谷氨酸能突触传递。

Objective To investigate the effects of arginine vasopressin(AVP)on the mRNA and protein expression of N-methyl-D-aspartate(NMDA)receptor subunits in the preoptic area(POA)of the rat hypothalamus.Methods After intraperitoneal injection of AVP or AVP receptor V1a antagonist for 0.5 h,the mRNA and protein expression of AVP receptor V1a and NMDA receptor subunits NR2A,NR2B and NR1 in POA were analyzed by fluorescence-based reverse-transcription real-time quantitative PCR(RT-qPCR)and Western blotting.Results The mRNA expression levels of NR2A,NR2B and V1a receptor in rats treated with AVP or V1a receptor antagonist were not significantly different from those in control group(P>0.05).AVP had no significant effect on the expression of NR1.The injection of V1a receptor antagonist however significantly led to the decrease in the NR1 mRNA level(P<0.01).Additionally,AVP could down-regulate the protein level of POA NMDA receptor subunits(NR2A,NR2B,NR1)(P<0.05 for all),but it did not affect the expression of V1a receptor protein(P>0.05).Conclusion Exogenous AVP has no significant effect on the mRNA and protein expression of POA V1a receptor;it is involved in the inhibition of glutamatergic synaptic transmission in the POA by down-regulation of the translation of NMDA receptor proteins rather than gene transcription.