Effect of Acute Exposure to Cold on Blood Thyrotrophin (TSH) and Corticosterone Concentrations in the Rabbit

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Abstract
Leppäluoto, J., H. Lybeck, T. Ranta and P. Virkkunen. Effect of acute exposure to cold on blood thyrotrophin (TSH) and corticosterone concentrations in the rabbit. Acta physiol. scand. 1973. 89. 423–428.Rabbits were exposed to various degrees of cold and plasma TSH concentration was measured by the McKenzie bioassay method (McKenzie 1958) and plasma corticosterone by a fluoro‐metric method. After the transfer of 19 rabbits to a cold room (10o C) no consistent change (p > 0.05) in the plasma TSH level could be seen up to 3 h, whereas the plasma corticosterone level rose transiently from 6.8 to 15.8 μg/100 ml (p 0.05) and plasma corticosterone levels had risen from 5.9 to 27.4 μg/100 ml (p < 0.001, 10 cases), or were unchanged (p > 0.05) but high i nanimals pretreated with stereotactically around the preoptic area provoked a decrease in hypothalamic temperature by 3o C (8 cases), while plasma TSH fell to an undetectable level adn corticosterone rose from 18.7 to 26.2 (p < 0.05) μg/100 ml. We conclude that in the rabbit the hypothalamus is refractory to cold stimulus, possibly through a mechanism associated with the secretion of ACTH.