CHANGES IN SERUM TSH LEVEL AFTER INTRAVENTRICULAR INJECTION OF VARIOUS NEUROMEDIATORS IN RATS

Abstract

The influence of various neuromediators on pituitary TSH [thyrotropin] secretion in rats was investigated. Noradrenaline [norepinephrine] 50 .mu.g/rat, dopamine 50 .mu.g/rat, serotonin-creatinine-sulfate 100 .mu.g/rat, .gamma.-aminobutyric acid 100 .mu.g/rat, pilocarpine 1 mg/rat, histamine 100 .mu.g/rat were administered into the lateral ventricle of the brain. All agents were dissolved in Parker''s fluid. Two control groups of animals were given Parker''s fluid and subjected to surgical manipulations, respectively. Plasma TSH level was estimated after 30 min by means of radioimmunoassay. The increase in the TSH level was observed after the injection of serotonin and noradrenaline (4.0 and 3.1 ng/ml, respectively) compared with the control group (0.7 ng/ml).