Chronic prenatal morphine treatment decreases G alpha s mRNA levels in neonatal frontal cortex.

G alpha s mRNA levels were measured in brain regions of newborn pups following prenatal morphine treatment. A significant decrease (24%) in G alpha s mRNA levels was observed in the frontal cortex. No changes were observed in other regions. This report demonstrates the first in vivo study of opiate effects on G-protein gene expression in neonates. The development of tolerance in vivo may involve complex interactions between several neurotransmitter systems having opposing actions on the G-protein system.