Comparison of plasma thyroxine levels following short exposure to cold and TRH administration in intact and pituitary autografted quail (Coturnix coturnix japonica).

The thyrotropic functional abilities of ectopically transplanted anterior pituitaries were tested by subjecting quail bearing their adenohypophysis in juxtarenal position either to a short cold exposure or to an intravenous injection of TRH. Thyroxine was determined in plasma samples collected from 20 to 120 min after treatment. Intact birds exhibited increasing T4 levels up to a peak at 40 min, then decreasing slowly within 2 hr after either cold or TRH stimulation. Autografted birds exhibited significant although lower and delayed increase of plasma thyroxine following both stimuli.