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Interaction Between Adrenergic and Peptide Stimulation in the Rat Pineal: Pituitary Adenylate Cyclase‐Activating Peptide
Author(s) -
Yuwiler A.,
Brammer G. L.,
Bennett B. L.
Publication year - 1995
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1995.64052273.x
Subject(s) - vasoactive intestinal peptide , medicine , endocrinology , stimulation , forskolin , biology , melatonin , receptor , pituitary adenylate cyclase activating peptide , adenylate kinase , chemistry , neuropeptide
The 27 amino acid peptide, pituitary adenylate cyclase‐activating polypeptide (PACAP‐27), and its 38 amino acid analogue, PACAP‐38, stimulate serotonin‐ N ‐acetyltransferase (NAT) activity and N ‐acetylserotonin (NAS) and melatonin content of pineal glands from adult rats. Maximal stimulation of rat pineal NAT by PACAP‐38 is not increased further significantly by concurrent stimulation with the two related peptides, vasoactive intestinal polypeptide (VIP) and/or peptide N‐terminal histidine C‐terminal isoleucine (PHI). Isoproterenol was a more potent inducer of NAT activity than any of these peptides alone or in combination. PACAP‐38 also stimulates melatonin production by chicken pineal cells in culture as does VIP. Stimulation by both was not greater than after either alone. Prior stimulation of rat pineal NAT activity with VIP, PHI, or PACAP‐38 reduces the magnitude of subsequent stimulation with PACAP‐38 or forskolin. Concurrent stimulation of α‐receptors or treatment with active phorbol ester augments rat pineal response to PACAP‐38 stimulation just as it increases the response to VIP, PHI, and β‐receptor stimulation. Pineals from newborn rats respond to PACAP‐38 with an increase in NAT activity and the increase is augmented by concomitant α 1 ‐adrenergic stimulation. The putative PACAP inhibitor PACAP (6–38) and the putative VIP inhibitor (Ac‐Tyr, d ‐Phe)‐GRF 1–29 amide, in 100–1,000‐fold excess, did not affect the stimulatory activity of any of the peptides. Pineal melatonin concentration parallels changes in pineal NAT activity.