[Effect of cortisol administration and stress actions in early ontogeny on hormonal induction in adult rats].

The influence of cortisole injections and stress ("handling") in the early ontogenesis (during the first 9 or 16 days of life) on the process of thyrosine aminotransferase induction by cortisol in the adult rats has been studied. It was shown that both the injection of the hormone in the young rats and "handling" led to the manifested trace effects: (1) stable increase of thyrosine aminotransferase activity in the liver of adult (5-6 months) rats and (2) appearance of peculiar tolerance to cortisol in the form of decrease in the ability of cells to induce thyrosine aminotransferase in response to the hormone injection. The data obtained suggest that the sensitive period of postnatal ontogenesis when cortisol or "handling" exert such a stable effect is limited by the 3rd and 9th days after birth. The causes of such "biochemical imprinting" are considered with respect to the increased sensitivity of the genetical system of cells-targets to the transcription inducers during the early postnatal development.