Multiplicity of Opioidergic Pathways Related to Cardiovascular Innervation: Differential Contribution of All Three Opioid Precursors

The endogenous opioid family consists of the three precursors proenkephalin (proenkephalin A), prodynorphin (proenkephalin B), and proopiomelanocortin (POMC), from which various opioid and nonopioid peptides can be processed, apparently in a tissue-specific manner (cf. Civelli et al. 1984; Goldstein 1984; Herz 1984; Udenfriend and Kilpatrick 1984; Civelli et al. 1985; Khachaturian et al. 1985; Kosterlitz 1985). Their distribution in areas of the CNS which are involved in cardiovascular regulation is well documented. The biochemistry and functions of endocrine (pituitary and adrenal) opioids have also been well characterized (cf. Millan and Herz 1985). The conception that endocrine and CNS o…