title: Docosahexaenoic acid reduces both cyclic nucleotide and melatonin synthesis in rat pinealocytes.
abstract: The effect of docosahexaenoic acid (22:6n-3) on melatonin (MT) production in rat pinealocytes was measured. In pinealocytes, supplementation with 50 microM 22:6n-3 for 48 h decreased MT production after a norepinephrine (NE)-stimulation (1 and 10 microM). Using co-treatment with IBMX (1 mM), a cyclic nucleotide phosphodiesterase inhibitor known to increase NE-stimulated cAMP and prazosin (1 microM), an alpha 1 antagonist, the results indicate that a) 22:6n-3 did not act on cyclic nucleotide phosphodiesterase activities to decrease both cAMP (-64%) and cGMP (-45%) levels and b) the inhibition of cGMP was higher (-70%) in presence of prazosin. These results confirm that in rat pinealocytes the lowering effect of 22:6n-3 supplementation on cAMP is likely to be dependent on alpha 1-adrenoceptor modulation whereas the decrease of cGMP seems to involve other intracellular mechanisms. The absence of 22:6n-3 effect on serotonin metabolites suggest that the lowering effect on MT may be also correlated with alterations of O-methylation step.
authors.affiliation: Laboratoire de Physiologie de l'Environnement, Faculté de Médecine Grange-Blanche, Lyon, France.
authors.forename: Z A
authors.initials: ZA
authors.lastname: Monia
authors.forename: G
authors.initials: G
authors.lastname: Abdallah
authors.forename: G
authors.initials: G
authors.lastname: Claude
authors.forename: N
authors.initials: N
authors.lastname: Sarda
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000096:biosynthesis; D006152:Cyclic GMP / Q000096:biosynthesis; D004281:Docosahexaenoic Acids / Q000494:pharmacology*; D008297:Male; D008550:Melatonin / Q000096:biosynthesis*; D009638:Norepinephrine / Q000494:pharmacology; D009712:Nucleotides, Cyclic / Q000096:biosynthesis*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010870:Pineal Gland / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051381:Rats
chemical_list: D009712:Nucleotides, Cyclic; D010726:Phosphodiesterase Inhibitors; D004281:Docosahexaenoic Acids; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D006152:Cyclic GMP; D008550:Melatonin; D015056:1-Methyl-3-isobutylxanthine; D009638:Norepinephrine