Benzodiazepine Receptor and Thyroid Hormones: In Vivo and In Vitro Modulation
- 1 May 1985
- journal article
- research article
- Published by Wiley in Journal of Neurochemistry
- Vol. 44 (5), 1340-1344
- https://doi.org/10.1111/j.1471-4159.1985.tb08767.x
Abstract
In rats rendered hyperthyroid by chronic treatment with L-triiodothyronine (T3) hormone there was a 21 and 27% decrease, respectively, in the number of binding sites for [3H]flunitrazepam ([3H]FNZ) and [3H]ethyl-β-carboline-3-carboxylate ([3H]β-CCE) without changes in affinity for the two ligands. Two weeks after thyroidectomy there was a 44% increase in [3H]FNZ sites and a 17% increase in [3H]β-CCE binding sites. In vitro we found that T3 produces a decrease in Bmax and an increase in KD, both changes being characteristic of a mixed type of inhibition. Thyroid status dramatically affected the Ki of T3 in displacing [3H]FNZ from sites on isolated membranes of the cerebral cortex: in hypothyroid rats the Ki value was 0.9 μM, whereas in hyperthyroid rats it was 83 μM, a 92-fold difference. In control rats, the Ki was 11 μM These findings are discussed in relation to a possible modulation of benzodiazepine receptors by thyroid hormones.Keywords
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