Title:
Effects of short- and long-duration hypothyroidism on function of the rat hypothalamic-pituitary-adrenal axis
Languages of Item:
English
Abstract:
The effects of hypothyroidism on the functional integrity of the hypothalamic-pituitary-adrenal (HPA) axis were investigated in adult male rats. HPA axis function was examined in vivo in sham-thyroidectomized male Sprague-Dawley rats or in thyroidectomized rats for 7 (short-term hypothyroidism) or 60 (long-term hypothyroidism) days. Peripheral ACTH and corticosterone responses to insulin-induced hypoglycemia and interleukin (IL)-1 stimulation were used to indirectly assess the hypothalamic CRH neuron. Hypothyroidism resulted in exaggerated ACTH responses to both hypoglycemic stress and IL-1 administration. The adrenal cortex of hypothyroid animals showed a significant reduction in adrenal reserves, as assessed by its response to low-dose ACTH, following suppression of the HPA axis with dexamethasone. Hypothyroid rats were also associated with significant decreases in cerebrospinal fluid corticosterone concentrations and decreased adrenal weights. The findings suggest that experimentally induced hypothyroidism is associated with a mild, yet significant, adrenal insufficiency, which involves abnormalities in all components of the HPA axis.
Authors:
Johnson, E.O.
Kamilaris, T.C.
Calogero, A.E.
Konstandi, M.
Chrousos, G.P.
Journal:
Journal of Endocrinological Investigation
Keywords:
corticosterone; corticotropin; dexamethasone; insulin; interleukin 1alpha; liothyronine; tetracosactide; thyrotropin; thyroxine, adrenal cortex; adrenal gland; adrenal insufficiency; animal experiment; animal model; animal tissue; article; cerebrospinal fluid; controlled study; corticosterone blood level; corticotropin blood level; disease duration; hypoglycemia; hypothalamus hypophysis adrenal system; hypothyroidism; in vivo study; liothyronine blood level; male; nonhuman; rat; thymus; thyrotropin blood level; thyroxine blood level, Adrenal Insufficiency; Animals; Hypothalamo-Hypophyseal System; Hypothyroidism; Insulin; Male; Pituitary-Adrenal System; Rats; Rats, Sprague-Dawley; Thyroid Hormones; Thyroidectomy
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