Cyclic adenosinemonophosphate in cerebrospinal fluid. Effects of theophylline, L-dopa and a dopamine receptor stimulant in rats.
The effects of L-Dopa and the dopamine receptor stimulant ET-495 on cisternal cAMP levels were studied in rats. L-dopa (100-200 mg/kg) increased cisternal cAMP levels by 60 to 80% of controls. When peripheral Dopa-decarboxylase was inhibited, smaller doses of L-Dopa were effective. Fla-63, an inhibitor of dopamine-beta-hydroxylase lowered the increase induced by L-Dopa which was completely suppressed by propranolol, not by phentolamine, suggesting that the cAMP increase is mediated through a central beta-adrenoceptor stimulation. ET-495 failed to influence cAMP levels which argues against a dopamine-sensitive adenylate cyclase involved in the L-Dopa effect. Moreover, large increases of cisternal cAMP were observed after treatment with theophylline , not papaverine which suggests different effects of these "phosphodiesterase inhibitors" on the cyclic AMP systems in the central nervous system or on transport mechanisms.
D000818:Animals; D005406:Bis(4-Methyl-1-Homopiperazinylthiocarbonyl)disulfide / Q000494:pharmacology; D000242:Cyclic AMP / Q000134:cerebrospinal fluid*; D004305:Dose-Response Relationship, Drug; D007980:Levodopa / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D010208:Papaverine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology*; D010891:Piribedil / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011955:Receptors, Drug / Q000187:drug effects; D013268:Stimulation, Chemical; D013997:Time Factors
D010879:Piperazines; D011955:Receptors, Drug; D005406:Bis(4-Methyl-1-Homopiperazinylthiocarbonyl)disulfide; D007980:Levodopa; D011433:Propranolol; D010208:Papaverine; D010891:Piribedil; D000242:Cyclic AMP; D010646:Phentolamine