GABAA receptor epsilon subunit expression in identified peptidergic neurons of the rat hypothalamus.

Dual-labeling immunohistochemical or in situ hybridization studies for the recently cloned epsilon-subunit and several neuropeptides were performed in the rat hypothalamus. We revealed an extensive co-expression (>90%) with hypocretin (Hcrt), oxytocin (OT), the gonadotropin-releasing hormone (GnRH), and the melanin-concentrating hormone (MCH) peptides, whereas occasional co-expression (<10%) with cocaine-amphetamine-regulated transcript (CART) was found. Our results suggest that novel GABA(A) receptor subtypes comprising epsilon-subunit are important for metabolic and neuroendocrine functions.