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Immunohistochemical and biochemical studies of the enkephalins, β-endorphin, and related peptides

1979; Palgrave Macmillan; Linguagem: Inglês

10.1007/978-1-349-04015-5_3

Stanley J. Watson, Huda Akil, Jack D. Barchas,

Chemical Synthesis and Analysis

There are several hypotheses concerning the relationships between the various endorphins and enkephalins (Hughes et al., 1975; Li and Chung, 1976; Guillemin et al., 1976; Bradbury et al., 1976). Such hypotheses include the possibility that β-endorphin or a similar pituitary peptide is primarily a precursor of met-enkephalin (Cox et al., 1975), that met-enkephalin and other peptides such as α and γ-endorphin are breakdown products of β-endorphin (Austen et al., 1977), or that the enkephalins and β-endorphin constitute two distinct endogenous opioid systems (Watson et al., 1977a, b, c; Akil et al., 1978; Bloom et al., 1977b). Furthermore, because of the history of their discovery, the enkephalins have been primarily associated with the brain (Hughes et al., 1975; Simantov and Snyder, 1976), while α, β, and γ-endorphin have been primarily linked to the intermediate and anterior lobes of the pituitary (Cox et al., 1975; Guillemin et al., 1976; Li and Chung, 1976; Bloom et al., 1977a; Bradbury et al., 1976; Graf et al., 1976; Teschemacher, 1975), and particularly to β-lipotropin (β-LPH) their putative prohormone (Moon et al., 1973; Pelletier et al., 1977). Elucidation of the relationships between these endogenous opioid peptides is a crucial first step towards a better understanding of their biosynthetic and degradative pathways, and as a prerequisite for the study of their physiological functions.