ABSTRACT
Objective @#To investigate the effect of Arginine Vasopressin (AVP) on the median preoptic glutamatergic (MnPOVglut2 ) neurons and its mechanism．@*Methods @#Brain slices were prepared from male Vglut2-tdTomato mice．MnPOVglut2 neurons expressing red fluorescent protein were located by using fluorescence microscope．Wholecell patch clamp technique was used to observe the effect of AVP on the firing frequency of MnPOVglut2 neurons，the effect of synaptic transmission blockers ( STBs) on the AVP-induced change in the firing frequency of MnPOVglut2 neurons，and the effect of AVP V1a receptor antagonist on the AVP-induced change in the firing frequency of MnPOVglut2 neurons. @*Results@#The mean firing frequency of MnPOVglut2 neurons increased during perfusion with artificial cerebrospinal fluid (ACSF) and AVP compared with that during perfusion with ACSF (P＜0. 01) ，indicating that AVP excited the MnPOVglut2 neurons．The mean firing frequency of MnPOVglut2 neurons still increased during perfusion with ACSF，STBs，and AVP compared with that during perfusion with ACSF and STBs (P＜0. 001) ; moreover，the magnitude of AVP-induced increase in firing frequency didn't change significantly during perfusion with ACSF，STBs，and AVP compared with that during perfusion with ACSF and AVP (P ＞0. 05 ) ，suggesting that AVP excited the MnPOVglut2 neurons directly in a postsynaptic manner．The magnitude of AVP-induced increase in the firing frequency of MnPOVglut2 neurons declined during perfusion with ACSF，STBs，AVP，and V1areceptor antagonist compared with that during perfusion with ACSF，STBs，and AVP (P＜0. 01) ，suggesting that AVP excited MnPOVglut2 neurons directly via V1a receptor．@*Conclusion @#AVP can excite MnPOVglut2 neurons via V1areceptor directly in a postsynaptic manner．This study reveals the molecular marker of MnPO neurons which AVP act on.