Changes in hypothalamic noradrenaline and 5-hydroxytryptamine levels during the development of warm- and cold-adaptation in the rat
Hahn, Z.; Szelényi, Z.
Acta Physiologica Academiae Scientiarum Hungaricae 54(3): 245-249
1979
ISSN/ISBN: 0001-6756 PMID: 554440 Document Number: 143065
Hypothalamic 5-hydroxytryptamine (5-HT) and noradrenaline (NA) as well as plasma corticosterone levels were studied in male rats after 1, 2, 4 and 6 weeks of exposure to 4--7 or 30--31 degrees C. An increase of the NA concentration and a decrease of the 5-HT level was observed after the first week in both cold and warm environment together with an increase of plasma corticosterone levels in both groups. NA, 5-HT and plasma corticosterone levels returned to normal in cold-exposed animals by the 6th week whereas in warm-acclimated rats NA and corticosterone levels regained their initial values and 5-HT concentrations remained low. Changes by the end of the first week of exposure may result from the thermal stress. The low 5-HT levels of warm-adapted animals at the end of the 6th week were probably secondary to the process of adaptation.