Effects of antidepressants on thyroid stimulating hormone release in rats under ether stress

We found inhibitory effects of antidepressants (clomipramine, maprotyline, mianserin and zimelidine) and 5-hydroxytryptophan (5-HTP) on thyroid stimulating hormone (TSH) release induced by ether stress in freely moving rats. We confirmed that ether stress suppressed the plasma TSH levels after 30 min. We then injected intravenously 250 ng thyrotropin releasing hormone (TRH), 0.1 mg/kg clomipramine, 2.5 mg/kg maprotyline, 2.5 mg/kg mianserin, 0.5 mg/kg zimelidine and 25 mg/kg 5-HTP simultaneously. These materials blocked the influences on plasma TSH levels by the ether stress. Serotonergic antidepressants (clomipramine, zimelidine) and 5-HTP (precursor of serotonin) had a higher potency against the ether stress. These results suggest that antagonizing effects against the ether stress may involve the serotonergic system in the pituitary gland.