Production of corticotrophin releasing hormone by the isolated hypothalamus of the rat.

Abstract

The ability of the rat hypothalamus to produce corticotropin releasing hormone (CRH) in vitro was studied in the presence and absence of neurotransmitter substances, angiotensin and corticosterone. Acetylcholine, 5-hydroxytryptamine (5-HT) and angiotensin II increased hypothalamic CRH release and content. Noradrenaline [norepinephrine] and glycine decreased the spontaneous release of CRH from the hypothalamus but neither of these substances affected hypothalamic CRH content. Dopamine, GABA [gamma aminobutyric acid], adrenaline [epinephrine], melatonin, histamine, glutamic acid and corticosterone did not affect the basal CRH activity of the hypothalamus in vitro. Noradrenaline, GABA and corticosterone reduced the acetylcholine- and 5-HT-induced increases in the release of CRH from the hypothalamus. The rises in CRH content induced by acetylcholine and 5-HT were reduced by noradrenaline and GABA but increased by corticosterone. The physiological significance of the results and the potential value of the technique are discussed.