ABSTRACT
I. Introduction................................................................................. 169 II. GABA and the LH Surge ........................................................... 169
III. The SCN, POA, and the GnRH Surge Generator..................... 171 IV. Summary...................................................................................... 174
References ............................................................................................. 174
Luteinizing hormone (LH) secretion is controlled by gonadotropin-releasing hormone (GnRH) containing neurons in the hypothalamus, and is essential for maintaining the estrous cycle in female rodents. Luteinizing hormone is secreted in two markedly different patterns. One is a pulsatile secretion, and another is a pre-ovulatory surge secretion. We have hypothesized that these patterns of LH secretion are controlled by different neural circuits: the GnRH pulse generator, previously known as a tonic center, and the GnRH surge generator, previously known as a phasic or a cyclic center (Figure 14.1). In this chapter, we focus on the putative GnRH surge generator of rats.
