Opiates and Neuroendocrine Regulation
Following reports of the presence of endogenous opiate activity in the brain (Pasternak et al., 1977; Terenius and Wahlstrom, 1975), two pentapeptides having the following structures: H-tyr-gly-gly-phe-met-OH (met-enkephalin) and H-tyr-gly-gly-phe-leu-OH (leu-enkephalin) have been isolated from porcine (Bradbury et al., 1976) and calf (Simantov and Snyder, 1976) brain and shown to possess high opiate-agonist activity. The sequence of met-enkephalin is the same as the N-terminus of β-endorphin (Smith et al., 1976), the C-fragment (β-LPH61-91) of β-lipotropin first isolated from sheep pituitary gland (Smith et al., 1976). It has been possible to isolate and characterize β-endorphin from camel pituitary glands (Li and Chung, 1976), as well as from many other species including the human, and both in vitro (Bradbury et al.,1976; Cox et al., 1976; Li and Chung, 1976) and in vivo (Loh et al., 1976) methods have shown it to be an analgesic agent.
KeywordsMedian Eminence Arcuate Nucleus Suprachiasmatic Nucleus Prolactin Secretion Prolactin Release
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