Effect of adenosine on melatonin and norepinephrine release in rat pineal explants.
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 x 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.
Vacas
M I
MI
Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
Sarmiento
M I
MI
Pereyra
E N
EN
Cardinali
D P
DP
D015762:2-Chloroadenosine / Q000378:metabolism; D000241:Adenosine / Q000378:metabolism*; D000243:Adenosine Deaminase / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D008297:Male; D008550:Melatonin / Q000096:biosynthesis*; D009638:Norepinephrine / Q000378:metabolism*; D010507:Periodicity; D010870:Pineal Gland / Q000378:metabolism*; D051381:Rats; D014020:Tissue Extracts / Q000378:metabolism
D014020:Tissue Extracts; D015762:2-Chloroadenosine; D000243:Adenosine Deaminase; D008550:Melatonin; D000241:Adenosine; D009638:Norepinephrine