Effects of cold exposure or TRH on the serum TSH levels in the iron-deficient rat.
Normal and iron-deficient rats were exposed to cold at 4 degrees C for 1 hr or 5 hrs and the serum TSH, T3 and T4 levels were compared with those in rats kept at room temperature (20 degrees C). There was a rise in serum TSH, T3 and T4 levels in response to 1 hr and 5 hrs of cold exposure in normal, but not in iron-deficient rats. Although pituitary TSH contents were lower in iron-deficient rats, the increases in serum levels of TSH following administration of TRH were similar in both normal and iron-deficient rats. The results suggest that the inability to respond to cold in iron-deficient rats may be due to a reduction in the release of TRH from the hypothalamus.
Tang
F
F
Department of Physiology, Faculty of Medicine, University of Hong Kong.
Wong
T M
TM
Loh
T T
TT
D000818:Animals; D003080:Cold Temperature / Q000009:adverse effects*; D000090463:Iron Deficiencies; D051381:Rats; D011919:Rats, Inbred Strains; D013963:Thyroid Hormones / Q000097:blood*; D013972:Thyrotropin / Q000097:blood*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*; D013997:Time Factors
D013963:Thyroid Hormones; D013973:Thyrotropin-Releasing Hormone; D013972:Thyrotropin