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  • Title: Acetylcholine and norepinephrine stimulate the release of corticotropin-releasing factor-41 from the rat hypothalamus in vitro.
    Author: Tsagarakis S, Holly JM, Rees LH, Besser GM, Grossman A.
    Journal: Endocrinology; 1988 Oct; 123(4):1962-9. PubMed ID: 2970959.
    Abstract:
    The effects of the two putative neurotransmitters acetylcholine and norepinephrine on immunoreactive CRF-41 release from incubated rat hypothalami were studied. Acetylcholine at concentrations of 10(-11) to 10(-7) M stimulated CRF-41 release. This effect was blocked in a dose-dependent manner by the muscarinic antagonist atropine (10(-9) to (-7) M). The nicotinic antagonist hexamethonium was ineffective at a dose of 10(-7) M, but produced slight inhibition of this response at 10(-5) M. Norepinephrine at concentrations of 10(-10) to 10(-6) M also produced a dose-dependent stimulation of CRF-41 release. The beta-adrenoceptor antagonists propranolol (10(-5) M) and timolol (10(-6) M) blocked norepinephrine-induced CRF-41 release. The alpha 1-adrenoceptor antagonists thymoxamine (10(-5) M), prazosin (10(-5) M), and corynanthine (10(-4) M), and the alpha 2-antagonist idazoxan (10(-5) M), were ineffective. Potassium depolarization (56 mM) caused stimulation of CRF-41 release which was dependent on the presence of calcium in the incubation medium. Authenticity of immunoreactive CRF-41 released was demonstrated by chromatographic criteria using gel filtration and reversed phase HPLC. These results provide evidence for a stimulatory role of acetylcholine and norepinephrine on CRF-41 release, and consequently on hypothalamo-pituitary-adrenal axis in the rat, through actions at a hypothalamic level. The stimulatory effect of acetylcholine is mediated principally through muscarinic receptors and that of norepinephrine through beta-adrenoceptors.
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