Role of Excitatory Amino Acid Neurotransmission during Puberty in the Female Rat

The purpose of the present study was to determine the contribution to and role of N-methyl-d-aspartate (NMDA) and non-NMDA receptor-mediated neurotransmission in the initiation of puberty in the female rat. The ability of NMDA and the non-NMDA receptor agonist kainate to facilitate puberty was compared, the effect of a non-NMDA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX) on the timing of puberty was investigated, and the question of whether NMDA or kainate receptor binding in the hypothalamus changes during sexual maturation was examined. NMDA treatment effectively and significantly advanced puberty by an average of 2.5 days compared to that in vehicle controls (P < 0.001). The body weight of NMDA-treated rats at the time of vaginal opening was significantly lower than that of vehicle controls, reflecting that puberty had occurred at an earlier age. In contrast to NMDA, kainate treatment had no effect on the timing of puberty in female rats. Body weights of kainate-treated rats at the time of vaginal opening were also similar to those of vehicle controls. Treatment with the non-NMDA receptor antagonist DNQX (15 nmol at 1400 and 1600 h) through third ventricle administration from Days 29 to 36 had no effect on the timing of puberty in female rats, further suggesting that non-NMDA receptor activation may not play a critical role in puberty. Finally, it was demonstrated that neither NMDA nor kainate receptor binding in the hypothalamus changes during sexual maturation in the female rat. The results of these studies suggest that NMDA receptors are more important than kainate receptors in the process of puberty in the female rat.