title: Effect of isoprenaline on the output of melatonin from fetal and newborn lamb pineal glands in vitro.
abstract: We have measured the output of melatonin in vitro from the pineal glands of lambs in late gestation (135-143 days) and the early newborn period (4-8 days). The basal output of melatonin/mg pineal tissue was significantly lower in the fetal group (16.3 +/- 3.9 pg melatonin.(30 min)-1.mg-1) than in the newborn group (148.1 +/- 43.6 pg melatonin.(30 min)-1.mg-1). Addition of the beta-adrenergic agonist, isoprenaline (10(-5) mol/l) significantly stimulated melatonin output from both the fetal (to 24.9 +/- 3.9 pg melatonin.(30 min)-1.mg-1) and newborn pineals (to 247.7 +/- 67.3 pg melatonin.(30 min)-1.mg-1). Pineals from newborn lambs produced 9-10-fold more melatonin than the fetal pineal glands, before, during and after addition of isoprenaline. These results show that functional beta-adrenergic receptors are present before birth on the sheep pinealocyte and that there is a marked increase in the melatonin synthetic capacity of the pineal in the newborn period.
authors.affiliation: Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors.forename: I C
authors.initials: IC
authors.lastname: McMillen
authors.forename: H C
authors.initials: HC
authors.lastname: Parkington
authors.forename: I
authors.initials: I
authors.lastname: McCance
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D005260:Female; D007545:Isoproterenol / Q000494:pharmacology*; D008550:Melatonin / Q000096:biosynthesis* / Q000378:metabolism; D010477:Perfusion; D010870:Pineal Gland / Q000196:embryology / Q000378:metabolism*; D011247:Pregnancy; D011863:Radioimmunoassay; D012756:Sheep
chemical_list: D000319:Adrenergic beta-Antagonists; D008550:Melatonin; D007545:Isoproterenol