[Thyroxine depression of compensatory hypertrophy of the thyroid gland in rats of different ages].

It was shown on hemithyroidectomized male rats (2--2.5, 8--10 and 14--16--month-old) that with the advance of age there occurred an increase in the inhibitory effect of the same (as per 100 g of body weight) dose of the exogenous thyroxine on the thyroid compensatory hypertrophy. It is supposed that the threshold of hypothalamo-pituitary-thyroid system to homeostatic inhibition decreased with ageing.