[Effect of drugs on cyclic AMP levels in the tissues of animals at different stages of ontogenesis. I. Experimental studies on the effect of adrenomimetic drugs on cyclic AMP concentration in the brain of 7-day-old and adult rats].

The purpose of the investigations was the comparison of the adrenergic receptors excitability in brain of 7-days-old and adult rats after adrenaline and isoprenaline administration. The excitation was evaluated biochemically by measurement of the beta receptor-mediated increase in brain cAMP concentration. There was no significant difference in brain tissue cAMP concentration of 7-days-old and adult rats in physiological conditions. The concentration of cAMP in brain of adult rats was not affected after administration both adrenaline and isoprenaline. On the contrary, the concentration of cAMP in brain of 7-days-old rats was significantly increased after each of two examined drugs, indicating that blood-brain barrier is permeable for catecholamines at this age.