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NOREPINEPHRINE INCREASES THE [ 32 P]LABELLING OF A SPECIFIC PHOSPHOLIPID FRACTION OF POST‐SYNAPTIC PINEAL MEMBRANES
Author(s) -
Berg G. R.,
Klein D. C.
Publication year - 1972
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1972.tb01311.x
Subject(s) - norepinephrine , melatonin , medicine , endocrinology , phospholipid , postsynaptic potential , biology , stimulation , pineal gland , labelling , chemistry , biochemistry , membrane , receptor , dopamine
— Cultured pineal glands incorporated 32 P into membrane phospholipids. Treatment of cultured glands with norepinephrine, which is known to stimulate membrane‐ bound pineal adenyl cyclase and to increase the production and secretion of melatonin, stimulated the incorporation of 32 P into a phospholipid fraction of membranes and particulates containing phosphatidyl serine and phosphatidyl inositol. The labelling of other phospholipid fractions and the total 32 P in the gland were not changed by norepinephrine treatment. Experiments with chronically‐denervated pineal glands indicated that the effect of norepinephrine on the [ 32 P]labelling of phospholipids occurred at a postsynaptic site. When norepinephrine‐stimulated secretion of melatonin was partially inhibited by p ‐chlorophenylalanine (a compound which blocks the synthesis of melatonin precursors), the norepinephrine‐stimulated labelling of phospholipids was still observed. Conversely, when melatonin secretion was stimulated in the absence of norepinephrine by treatment with the immediate precursor of melatonin, N ‐acetylserotonin, a stimulation of 32 P‐ labelling of phospholipids did not occur. These observations suggest that the increased [ 32 P]‐ labelling of a phospholipid fraction caused by the norepinephrine treatment is not related to the secretion of melatonin. This effect on phospholipids may be associated with the interaction of norepinephrine with a membrane‐bound postsynaptic receptor. Stimulation by norepinephrine of [ 32 P]‐incorporation into phospholipids has not been previously reported to occur in a tissue in which cholinergic fibres are absent.