Caffeine and propranolol block the increase in rat pineal melatonin production produced by stimulation of adenosine receptors.
The adenosine agonist 5'-N-ethylcarboxamidoadenosine (NECA) injected i.p. during the light period increased rat pineal melatonin levels and this increase was blocked by simultaneous administration of the non-selective adenosine receptor antagonist caffeine. A single dose of the adenosine A1 agonist cyclopentyladenosine had no effect on nocturnal melatonin production. The NECA-stimulated increase was also blocked by the beta-adrenergic receptor antagonist propranolol. Given alone, neither caffeine nor propranolol had any effect on melatonin levels. The results point to an intermediate role for beta-adrenergic receptors in the adenosine-stimulated increase of melatonin production.
Department of Biology, McGill University, Montreal, Canada.
A M
AM
Babey
R M
RM
Palmour
S N
SN
Young
D000241:Adenosine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology; D019830:Adenosine-5'-(N-ethylcarboxamide); D000704:Analysis of Variance; D000818:Animals; D001667:Binding, Competitive; D002110:Caffeine / Q000494:pharmacology*; D002421:Caudate Nucleus / Q000187:drug effects / Q000378:metabolism; D002940:Circadian Rhythm; D008297:Male; D008550:Melatonin / Q000096:biosynthesis*; D010870:Pineal Gland / Q000187:drug effects / Q000378:metabolism*; D011433:Propranolol / Q000494:pharmacology*; D011699:Putamen / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018047:Receptors, Purinergic P1 / Q000187:drug effects / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology
D018047:Receptors, Purinergic P1; D014665:Vasodilator Agents; D019830:Adenosine-5'-(N-ethylcarboxamide); D002110:Caffeine; D011433:Propranolol; D008550:Melatonin; D000241:Adenosine