TY - JOUR
T1 - Cold-induced changes in thyroid function in a poikilothermic mammal, the naked mole-rat
AU - Buffenstein, Rochelle
AU - Woodley, Ryan
AU - Thomadakis, Cleopatra
AU - Daly, T. Joseph M.
AU - Gray, David A.
PY - 2001/1
Y1 - 2001/1
N2 - Cold acclimation induces very divergent responses in thyroid function in reptiles and mammals reflective of their different thermoregulatory modes. Naked mole-rats, unlike other small mammals, are unable to effectively employ endothermy and are operatively poikilotherms. We therefore investigated changes in their thyroid status with chronic cold exposure. Under simulated burrow conditions, free thyroxine (T4; 0.39 ± 0.09 ng/dl) and thyroid stimulating hormone (TSH; 1.12 ± 0.56 μIU/ml) levels fell within the reptilian range, one order of magnitude lower than mammalian levels. However, cold induced typical mammalian responses: free T4 levels (0.55 ± 0.09 ng/dl) and thyroid follicular cell height were significantly greater. Although TSH levels (1.28 ± 0.83 μIU/ml) were not significantly elevated, thyrotrophs exhibited ultrastructural signs of increased secretory activity. Low thyroid hormone concentrations may contribute substantially to the unusual thermoregulatory mode exhibited by naked mole-rats.
AB - Cold acclimation induces very divergent responses in thyroid function in reptiles and mammals reflective of their different thermoregulatory modes. Naked mole-rats, unlike other small mammals, are unable to effectively employ endothermy and are operatively poikilotherms. We therefore investigated changes in their thyroid status with chronic cold exposure. Under simulated burrow conditions, free thyroxine (T4; 0.39 ± 0.09 ng/dl) and thyroid stimulating hormone (TSH; 1.12 ± 0.56 μIU/ml) levels fell within the reptilian range, one order of magnitude lower than mammalian levels. However, cold induced typical mammalian responses: free T4 levels (0.55 ± 0.09 ng/dl) and thyroid follicular cell height were significantly greater. Although TSH levels (1.28 ± 0.83 μIU/ml) were not significantly elevated, thyrotrophs exhibited ultrastructural signs of increased secretory activity. Low thyroid hormone concentrations may contribute substantially to the unusual thermoregulatory mode exhibited by naked mole-rats.
KW - Follicular cell height
KW - Thyroid-stimulating hormone
KW - Thyrotrophs
KW - Thyroxine
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U2 - 10.1152/ajpregu.2001.280.1.r149
DO - 10.1152/ajpregu.2001.280.1.r149
M3 - Article
C2 - 11124146
AN - SCOPUS:0035010561
VL - 280
SP - R149-R155
JO - American Journal of Physiology
JF - American Journal of Physiology
SN - 0363-6119
IS - 1 49-1
ER -