Different sensitivity of rat pineal N-acetyltransferase to alpha- and beta-adrenergic receptor agonists during development: in vitro studies.

Herein, we investigate the mechanisms involved in the adrenergically mediated stimulation of rat pineal N-acetyltransferase (NAT) activity during development using an in vitro model. Compared with adults, results suggest a different regulation of pineal NAT activity in growing rats where a similar efficiency of alpha- and beta-adrenergic receptor agonists is observed during the 1st weeks of age for activating the enzyme. In adult rats, beta- but not alpha-adrenergic receptors appear to play the preeminent role. The results indicate that the adrenergic receptor agonists used acted in a non-specific manner by binding to relatively immature receptors early during development.