Effect of isoprenaline on the output of melatonin from fetal and newborn lamb pineals glands in vitro

I. C. McMillen, H. C. Parkington, I. McCance

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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 β-adrenergic agonist, isoprenaline (105 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 plus minus 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 β-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.

Original languageEnglish
Pages (from-to)773-776
Number of pages4
JournalActa Endocrinologia
Issue number6
Publication statusPublished - 1 Dec 1989

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