GABA- and Glutamate-Activated Channels in Green Fluorescent Protein-Tagged Gonadotropin-Releasing Hormone Neurons in Transgenic Mice

TLDR

GABA‑A, AMPA, and NMDA receptor channels on GnRH neurons may modulate GnRH secretory oscillations. Transgenic mice were created that express green fluorescent protein under the GnRH promoter, enabling visualization of GnRH neurons. In these mice, GFP was confined to GnRH‑positive somata, dendrites, and axons across multiple hypothalamic and olfactory regions, and whole‑cell recordings revealed that GFP‑positive neurons exhibited a distinct firing pattern and robust GABA‑evoked responses, with smaller glutamate/AMPA responses and NMDA responses in about one‑fifth of the patches.

Abstract

Mice were generated expressing green fluorescent protein (GFP) under the control of the gonadotropin-releasing hormone (GnRH) promoter. Green fluorescence was observed in, and restricted to, GnRH-immunopositive neuronal somata in the olfactory bulb, ganglion terminale, septal nuclei, diagonal band of Broca (DBB), preoptic area (POA), and caudal hypothalamus, as well as GnRH neuronal dendrites and axons, including axon terminals in the median eminence and organum vasculosum of the lamina terminalis (OVLT). Whole-cell recordings from GFP-expressing GnRH neurons in the OVLT-POA-DBB region revealed a firing pattern among GFP-expressing GnRH neurons distinct from that of nonfluorescent neurons. Nucleated patches of GFP-expressing GnRH neurons exhibited pronounced responses to fast application of GABA and smaller responses to L-glutamate and AMPA. One-fifth of the nucleated patches responded to NMDA. The GABA-A, AMPA, and NMDA receptor channels on GnRH neurons mediating these responses may play a role in the modulation of GnRH secretory oscillations.