Delta-sleep-inducing peptide stimulates melatonin, 5-methoxytryptophol and serotonin secretion from perifused rat pineal glands.
The pineal gland is known to synthesize numerous indolamines. Since delta-sleep-inducing peptide (DSIP, a tryptophan nonapeptide) is found in the pineal gland, its effect on the secretion of indolamines was investigated. DSIP stimulated melatonin (MEL), 5-methoxytryptophol (5-ML) and serotonin (5-HT) synthesis and release, whereas it did not affect pineal cyclic AMP levels. The stimulatory effect of DSIP on MEL secretion was dose dependent between 5 x 10(-6) and 10(-4) M, whereas the minimal effective concentration of DSIP on 5-ML secretion was higher than 10(-5) M. The effect of DSIP (10(-4) M) was compared to the effect of isoproterenol (ISO, 10(-6) M) on MEL and 5-HT release. ISO stimulated MEL secretion and concomitantly decreased 5-HT release. With regard to kinetic characteristics, the effect of DSIP (10(-4) M) on MEL release was faster and of shorter duration than the effect of ISO (10(-6) M; 2 and 4 h, respectively). At 10(-4) M, DSIP potentiated the ISO-induced increase of MEL secretion. The DSIP-stimulated release of MEL was not significantly altered when the pineal glands were treated with 10(-5) M propranolol (a beta-adrenergic antagonist), 10(-5) M prazosin (an alpha 1-adrenergic antagonist) or 10(-5) M naloxone (an opioidergic antagonist). This study demonstrates that the DSIP-induced secretion of indolamines from rat pineal glands may not be elicited through the well-known noradrenergic or opioid systems.
Ouichou
A
A
URA-CNRS 1332 Neurobiologie des fonctions rythmiques et saisonnières, Université Louis Pasteur, Strasbourg, France.
Zitouni
M
M
Raynaud
F
F
Simonneaux
V
V
Gharib
A
A
Pévet
P
P
D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D003701:Delta Sleep-Inducing Peptide / Q000494:pharmacology*; D066298:In Vitro Techniques; D007211:Indoles / Q000378:metabolism*; D008297:Male; D008550:Melatonin / Q000378:metabolism; D010477:Perfusion; D010870:Pineal Gland / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism
D007211:Indoles; D012701:Serotonin; D003701:Delta Sleep-Inducing Peptide; C002465:methoxytryptophol; D000242:Cyclic AMP; D008550:Melatonin