ABSTRACT
I. Introduction................................................................................. 191 II. Multiple GnRH Systems............................................................. 192
III. Intracellular Recording and Labeling of Single TN-GnRH Neurons ..................................................................... 193
IV. Behavioral Functions of TN-GnRH Cells.................................. 194 V. Modulation of Pacemaker Frequencies of TN-GnRH
Cells by GnRH ............................................................................ 195 VI. Mechanisms of Modulation of Pacemaker Frequencies
by GnRH...................................................................................... 196 VII. Working Hypothesis ................................................................... 198
VIII. Acknowledgments ...................................................................... 200 References ............................................................................................. 200
Gonadotropin-releasing hormone (GnRH) has been conventionally regarded as a hypophysiotropic hormone that facilitates the release of gonadotropins from the pituitary. We have demonstrated, by taking advantage of the distinctive anatomical features of the GnRH neuronal systems of the dwarf gourami (freshwater tropical fish) that, besides this conventional GnRH system (preoptic GnRH system), there are GnRH neuronal systems that do not project to the pituitary and may serve as neuromodulators.
