Colocalization of NMDA Receptor and Estrogen Receptor Alpha in the Mating-activated Cells of the Medial Amygdala

Cassandra Weaver
Boston University

In the female rat the summation of vaginocervical stimulation (VCS) triggers the release of a twice-daily surge of prolactin (PRL) for 10-12 days. This PRL surge is characteristic of early pregnancy. The prolonged release of PRL (without further VCS) suggests there is a neuroendocrine memory storing mating stimuli in the brain. The glutamatergic cells of the medial amygdala (MEA), via the NMDA receptor (NMDAR), are involved in the activation of the PRL surge and may also play a role in the storage of the mating stimuli. It has been shown that the presence of estrogen is necessary for reproductive behavior in the female and we propose that estrogen may also interact with the glutamatergic cells of the MEA causing the induction of the neuroendocrine memory. A triple-label fluorescence immunocytochemistry study was performed on brain tissue of female rats that had received varying amounts of VCS. The tissue was labeled for estrogen receptor ? (ER?), NMDAR, and FOS protein, an indicator of mating-induced cell activation. The presence of a significant amount of triple-labeled cells within the MEA suggests there is an interaction between glutamate and estrogen that may lead to the formation of a neuroendocrine memory.