Hormonal influences on RNA and DNA synthesis in developing rat brain

In recent years, authors' interest was focussed on the role of hormones in the brain biochemical maturation during the early postnatal life. One-day-old rats were used in the investigation of the following hormones: thyroxine (T4), hydrocortisone, aldosterone and ACTH, in unique or repeated administration. Dynamics of cerebral RNA and DNA synthesis, a realiable indicator of central nervous system (CNS) maturation, was investigated. Authors' research led to the following conclusions: In infant rats, cerebral RNA and DNA synthesis exhibits a continuous increase, with a peak between 7 and 14 days after birth. Hydrocortisone induces a significant inhibition of cerebral RNA and DNA synthesis, more important in 7-day-old rats. In ACTH-treated newborn rats, RNA and DNA synthesis presents a high stimulation in 7- and 14-day-old rats. Aldosterone elicits an enhancement of brain nucleic acid synthesis, more marked in 7- and 14-day-old rats. Thyroxine administration induces a marked stimulation of cerebral RNA and DNA synthesis, greatest at 7 and 14 days after birth. The results confirm the important, even decisive, role of endocrine secretions during the early postnatal life, as far as the subsequent individual development is concerned.