Behavioral and biochemical studies in rats following prenatal treatment with β-adrenoceptor antagonists

Increased motor activity and poor performance in the active avoidance test were observed in the offspring of rats treated with d1-propranolol or sotalol during pregnancy, but not with atenolol and d-propranolol. All substances were administered in drinking water from days 8-22 of gestation. A significant increase in the density of muscarinic acetylcholine receptors in the hippocampus was found for dl-propranolol and sotalol, at 35 and 20 days of age, respectively. Twenty-day-old pups bom to dl-propranolol-treated rats exhibited a non-significant decrease in the number of β-adrenoceptors in the frontal cortex. Assuming that all the β-adrenoceptor antagonists tested had access to the developing fetal brain, the effect of dl-propranolol and sotalol on behavior could stem from central β₂-adrenoceptor blockade. In view of the lack of behavioral changes after atenolol, a β₁-selective adrenoceptor antagonist, it is suggested that the clinical use of β₁-selective adrenoceptor antagonists during pregnancy might be safer for the fetus than β₂-adrenoceptor antagonists.