title: Prostaglandins of the E Series Stimulate Cyclic AMP Accumulation and N-Acetylation of Serotonin in Chick Pineal Cells.
abstract: We investigated the effects of prostaglandins on cyclic AMP (cAMP) levels and on the activity of the rate-limiting enzyme of melatonin biosynthesis, arylalkylamine-N-acetyltransferase (NAT). The study was performed on primary cultures of dispersed chick pineal cells. Prostaglandin E, (PGE,) increased cAMP levels 2-fold and this stimulation went up to 4-fold in the presence of a phosphodiesterase inhibitor. The PGE,- evoked increase in cAMP levels did not desensitize over 6 h. The potency order of a series of prostaglandins to increase cAMP levels (PGE(1) PGE(1) >PGA2>PGD(2) ≃PGF(2) α) agreed with the pharmacological profile of the adenylate cyclase-coupled prostaglandin receptor. Inhibition of endogenous prostaglandin synthesis by two cyclooxygenase inhibitors (indomethacin and aspirin) caused a 30% decrease in cAMP levels. This effect was completely reversed by the addition of exogenous PGE(1) or PGE(2) . Indomethacin and aspirin also caused a 50% decrease in NAT activity. Prostaglandins of the E series increased NAT activity up to 2-fold above basal level and restored NAT activity after inhibition by indomethacin or aspirin. These results are the first illustration of a role for prostaglandins in chick pineal cells. The correlations observed between cAMP levels and NAT activity suggest that the regulation of NAT activity by prostaglandins of the E series might be mediated by changes in cAMP concentration.
authors.affiliation: Laboratoire de Neurobiologie et Neuroendocrinologie Cellulaires, LIRA CNRS N° 290, UFR Sciences, 40 avenue du Recteur Pineau, 86022 Poitiers Cedex, France. Division of Biomédical Sciences, King's College London, Campden Hill Road, London W8 7AH, UK. INSERM U 207, URIA, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris Cedex 15, France.
authors.forename: G
authors.initials: G
authors.lastname: Camp
authors.forename: P
authors.initials: P
authors.lastname: Voisin
authors.forename: D
authors.initials: D
authors.lastname: Sugden
authors.forename: F
authors.initials: F
authors.lastname: Dray
authors.forename: J P
authors.initials: JP
authors.lastname: Coilin