Vasoactive intestinal peptide stimulates melatonin release from perifused pineal glands of rats

Abstract

The rat pineal gland is known to release melatonin in response to noradrenergic stimulation. The effect of vasoactive intestinal peptide (VIP), one of the neuropeptides present in the pineal, was examined on perifused rat pineal glands. VIP stimulated melatonin release with a dose-dependent effect above 10(-7) M. In regard of kinetic characteristics, the pattern of melatonin release after VIP stimulation was similar to that after isoproterenol stimulation. 10(-6) M VIP-stimulated melatonin release was not altered when the pineal glands were treated with 10(-5) M propranolol (a beta-adrenergic antagonist) or 10(-5) M prazosin (an alpha 1-adrenergic antagonist). Thus VIP has a noradrenergic-independent effect on melatonin secretion. Conversely, this VIP effect is greatly inhibited by the specific action of a VIPergic antagonist. This suggests that VIP acts on melatonin synthesis through its own binding sites. This study demonstrates that melatonin secretion from rat pineal glands may be elicited through a VIPergic system which is independent of the well-known noradrenergic system.

Accumulation of rat pineal serotonin N-acetyltransferase mRNA induced by pituitary adenylate cyclase activating polypeptide and vasoactive intestinal peptide in vitro

“…Among the peptides of the secretin superfamily, VIP and PACAP proved to be the most potent in stimulating MT synthesis and release (Simonneaux et al 1990, 1993, Rekasi et al 1994, Pfeffer et al 1999). …”

“…The pineal VIP content, like that of NE, oscillates over a 24-h period (Kaku et al 1986). Functional studies have demonstrated that VIP also stimulates adenylate cyclase activity (Kaneko et al 1980a), cAMP production (Kaneko et al 1980b, Chik et al 1988, Rekasi et al 1998, CREB phosphorylation (Schomerus et al 1996), AA-NAT activity (Kaneko et al 1980a, Yuwiler 1983) and MT secretion (Simonneaux et al 1990, Rekasi et al 1994 with, however, much less potency than NE. PACAP also stimulates cAMPinduced AA-NAT activity and MT secretion (Simonneaux et al 1993, Chik & Ho 1995, Yuwiler et al 1995 in rat pineal gland in a similar manner to VIP.…”

Delta-Sleep-Inducing Peptide Stimulates Melatonin, 5-Methoxytryptophol and Serotonin Secretion from Perifused Rat Pineal Glands

“…Numerous peptides [vasoactive intestinal peptide (VIP), vasopressin (VP), oxytocin (OT), neuropep tide Y, calcitonin-gene-related peptide, deltasleep-inducing peptide (DSIP) ...] have also been found in the pineal gland [5][6][7][8]. Recent ly, we reported that VIP stimulates, whereas AVP and OT potentiate MEL secretion from rat pineal glands [9,10], Other pineal peptides may also modulate MEL synthesis, but their exact function has yet to be determined.…”

Generation of the Melatonin Endocrine Message in Mammals: A Review of the Complex Regulation of Melatonin Synthesis by Norepinephrine, Peptides, and Other Pineal Transmitters

“…VIP was the first and most studied neuropeptide in the pineal gland. VIP increases the intracellular levels (Kaneko et al, 1980;Yuwiler, 1983a;Simonneaux et al, 1997b) and efflux (Rekasi et al, 1998) of cAMP and therefore activates all cAMP-related events: phosphorylation of CREB Schomerus et al, 1996), increase in Aa-nat gene expression Rekasi and Czompoly, 2002), activation of AA-NAT activity in vitro (Kaneko et al, 1980;Yuwiler, 1983a) and in vivo (Schröder et al, 1989), stimulation of the synthesis and release of 5-HT probably following TPOH activation (Simonneaux et al, 1997c), long-term activation of HIOMT (Ribelayga et al, 1997), and stimulation of MEL release (Simonneaux et al, 1990c. These effects, however, are always lower than what has been reported following ␤-AR stimulation.…”