Interleukin-1 inhibits NMDA-stimulated GnRH secretion: Associated effects on the release of hypothalamic inhibitory amino acid neurotransmitters

Immune system activation is often accompanied by alterations in the reprodu ctive axis. Interleukin-1 (IL-1), a polypeptide cytokine, has been postulat ed as a chemical messenger between the immune and the neuroendocrine system s. Using superfused hypothalamic fragments explanted from intact male rats, we evaluated the effects of IL-1 (0.5 and 5 nM) on basal and N-methyl-D-as partate (NMDA)-stimulated release of gonadotropin-releasing hormone (GnRH), and the associated modifications in the output of inhibitory amino acid ne urotransmitters involved in the control of GnRH secretion, IL-1 did not mod ify basal GnRH release, but markedly restrained the stimulatory effect of N MDA on GnRH secretion. gamma-Aminobutyric acid, glycine and taurine concent rations significantly increased in the superfusion medium only after pretre atment with the higher dose of IL-1 (p < 0.05). Our results indicate that t his cytokine inhibits NMDA-stimulated GnRH release, affecting the activity and/or the release of hypothalamic excitatory and inhibitory amino acid neu rotransmitters participating in the regulation of GnRH secretion, Copyright (C) 1999 S. Karger AG, Basel.