Purinergic and noradrenergic cotransmission in the rat pineal gland.
ATP is coreleased with noradrenaline in several noradrenergic synapses, and P2-like receptors were shown to be present in rat pineal glands. A new method of functional investigation was developed to assess the importance of both transmitters (noradrenaline and ATP) in eliciting the synthesis of melatonin and its precursor N'-acetyl-5-hydroxytryptamine (N'-acetyl-5-HT) through transmural electrical field stimulation of cultured pineal glands. Incubation with the beta-adrenoceptor antagonist propranolol (>10(-7) M) blocked almost completely the production of N'-acetyl-5-HT, whilst the P2 receptor antagonists pyridoxalphosphate-6 azophenyl-2',4'-disulfonic acid (PPADS, >3x10(-6) M) and suramin (>10(-6) M) blocked it partially. These findings indicate a physiologically relevant role for the purinergic cotransmission in this system.
Department of Physiology, Institute of Bioscience, University of São Paulo, Rua do Matão, travessa 14, 05508-900, São Paulo, Brazil.
E J
EJ
Mortani Barbosa
Z S
ZS
Ferreira
R P
RP
Markus
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008550:Melatonin / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D010870:Pineal Gland / Q000187:drug effects / Q000294:innervation / Q000378:metabolism*; D011433:Propranolol / Q000494:pharmacology; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000031:analogs & derivatives* / Q000378:metabolism; D013498:Suramin / Q000494:pharmacology; D009435:Synaptic Transmission / Q000502:physiology*; D013997:Time Factors
D000319:Adrenergic beta-Antagonists; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D012701:Serotonin; D011732:Pyridoxal Phosphate; D013498:Suramin; D000255:Adenosine Triphosphate; D011433:Propranolol; D008550:Melatonin; C006389:N-acetylserotonin; D009638:Norepinephrine