METABOTROPIC GLUTAMATE-RECEPTOR IN GHRH AND BETA-ENDORPHIN NEURONS OFTHE HYPOTHALAMIC ARCUATE NUCLEUS

GROWTH hormone-releasing hormone (GHRH) and beta-endorphin are mainly synthesized in neurones of the hypothalamic arcuate nucleus. Arcuate n eurones also contain both ionotropic and metabotropic glutamate recept ors. The aim of present study was to investigate whether glutamate rec eptors are present in GHRH and beta-endorphin containing nerve cells o f this hypothalamic area. Using double-label immunocytochemistry as we ll as the mirror technique, we found that almost all GHRH and beta-end orphin immunoreactive arcuate neurones contain the metabotropic glutam ate receptor 1a. The observations provide morphological evidence for t he view that glutamate, which appears to be a major excitatory neurotr ansmitter in the hypothalamus, may directly stimulate GHRH and beta-en dorphin neurones of the medial hypothalamus.