Abstract
The effect of dexamethasone pretreatment on TSH release induced by synthetic TRF was investigated in rats.
Plasma TSH levels were measured by means of McKenzie's method with a slight modification.
Dexamethasone was injected 4 hours before TRF administration. Blood samples were withdrawn from the jugular vein 10 min after TRF injection.
In a group received single dexamethasone pretreatment, TSH release following the TRF administration was significantly enhanced when compared with those observed in the saline pretreated group.
However, the increase in TSH release was not observed in the rats treated chronically by dexamethasone for 15 days.
The mechanism responsible for this dexamethasone effect on TSH secretion induced by TRF exists at hypothalamic level.
