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Catecholaminergic Mechanisms Mediate Hypothermia‐Induced Elevations in Pineal Gland N‐Acetyltransferase in Neonatal Rats
Author(s) -
Torres German,
Haak Katherine A.,
Lytle Loy D.
Publication year - 1989
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/j.1600-079x.1989.tb00401.x
Subject(s) - pineal gland , endocrinology , medicine , catecholaminergic , biology , melatonin , thermoregulation , ectotherm , catecholaminergic cell groups , pituitary gland , endocrine gland , catecholamine , hormone , zoology
The newly born of many mammalian species are ectothermic, and it is possible that biochemical processes important for the metabolism of endocrine hormones might vary with alterations in the environmental temperature. Temperature‐induced fluctuations in pineal gland N‐acetyltransferase activity were investigated in 4‐, 12‐, and 20‐day‐old rats placed for 4 hr in 23 or 34°C environments. Enzyme activity increased dramatically in ectothermic 4‐ and 12‐day‐old animals exposed to the 23°C environment, but not in endothermic 20‐day‐old rats. The elevations in daytime pineal gland NAT activity seen in cold‐exposed animals were absent in rats previously subjected to chemical sympathectomy induced by 6‐hydroxydopamine, or in animals treated with the beta‐noradrenoceptor antagonist drug propranolol. Catecholaminergic nerves and beta‐noradrenoceptors known to be important for light‐induced changes in mammalian pineal gland biochemistry also appear essential for environmental temperature‐dependent elevations in neonatal pineal N‐acetyltransferase activity.