EFFECTS OF DEXAMETHASONE ON NEUROTRANSMITTER ENZYMES IN CHROMAFFIN TISSUE OF THE NEWBORN RAT

—Dexamethasone administration to newborn rats resulted in an increase in phenylethanolamine N-methyltransferase activity in superior cervical ganglia. The same treatment resulted in a decrease in tyrosine hydroxylase and choline acetyltransferase activities. The decline in choline acetyltransferase activity after dexamethasone treatment was only seen when the drug was given before 5 days of age. When dexamethasone was given to pregnant rats it caused an age-dependent decrease in choline acetyltransferase in the adrenals, superior cervical ganglia and para-aortic chromaffin tissue of the offspring. These results suggest that dexamethasone administration may delay the development of the preganglionic neurons of sympathetic ganglia. This in turn would delay the development of tyrosine hydroxylase but not phenylethanolamine N-methyltransferase.