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Thyroxine feed‐back on the regulation of thyrotrophin secretion *
Author(s) -
Panda J. N.,
Turner C. W.
Publication year - 1968
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1968.sp008444
Subject(s) - endocrinology , medicine , hypothalamus , thyroid , hypothalamic–pituitary–thyroid axis , pituitary gland , hormone , secretion , chemistry , thyroid hormones
1. The role of thyroid hormone as a feed‐back at the hypothalamic level in the control of thyrotrophin (TSH) secretion and release has been investigated by estimating the plasma and pituitary TSH levels following intrahypophysial and intrahypothalamic thyroid autotransplants. 2. Thyroidectomized rats bearing thyroid autotransplants in the pituitary had a significantly lower ( P < 0·001) plasma TSH than that of controls at 26° C but not at 4° C. 3. Thyroidectomized rats bearing thyroid autotransplants in the supraoptic area showed a significantly lower ( P < 0·001) level of plasma TSH and higher pituitary TSH at 4° C but not at 26° C. 4. Study with both unilaterally and bilaterally thyroidectomized rats bearing thyroid autotransplants either in the pituitary or in the hypothalamus revealed that thyroxine feed‐back operates at pituitary level in normal situations (26° C) and there exists a feed‐back through higher centres, specifically the TSR secreting area of the hypothalamus, in situations demanding higher thyroid function, as in cold exposure.