Effect of adenosine on melatonin and norepinephrine release in rat pineal explants
Vacas, M.I.; Sarmiento, M.I.; Pereyra, E.N.; Cardinali, D.P.
Acta Physiologica et Pharmacologica Latinoamericana Organo de la Asociacion Latinoamericana de Ciencias Fisiologicas y de la Asociacion Latinoamericana de Farmacologia 39(2): 189-195
1989
ISSN/ISBN: 0326-6656 PMID: 2618756 Document Number: 343697
To study adenosine effect on melatonin production, rat pineal explants were incubated for 6 h with 10-4 M adenosine or 2-chloroadenosine in the presence or absence of 5 .times. 10-5 M norepinephrine (NE). Melatonin content in pineal gland and medium was measured by RIA. Both adenosine and 2-chloroadenosine increased melatonin production rate by 3-4-fold, and augmented NE stimulation by 30-40%. Addition of adenosine deaminase prior to NE reduced stimulated melatonin release by 40-46%. 2-Chloroadenosine counteracted the inhibition of NE response given by adenosine deaminase. Either adenosine or its A1 receptor agonist cyclohexyl adenosine (CHA) decreased by 20-22% 3H-transmitter release induced by a K+ depolarizing stimulus in rat pineal incubated with 3H-NE. These results suggest that adenosine affects both pre- and postsynaptic pineal mechanisms.