Effect of narcotics on enzymes of acetylcholine metabolism in cultured cells from embryonic chick brains

Abstract

The addition of 2.5 × 10 −4 M morphine sulphate to cultures of cells dissociated from the brains of chick embryos brought about 25–50% increases in the activities of neuronal choline acetyltransferase (ChA) and acetylcholinesterase (AChE). Narcotic drugs also increased the activities of these two enzymes in the brains of developing chicks in vivo. The effects of morphine on the cultures were antagonized by naloxone but not by propranolol. Both l(+)-dextrorphan and d(−)-levorphanol produced similar increments in the enzyme activities of cultured cells. The activities of ChA and AChE in cultured cells from embryos that had been previously exposed to narcotics were unaffected by the addition of morphine to the cultures. Dissociated brain cells from treated embryos also exhibited tolerance to the inhibition of leucine incorporation by high concentrations of morphine.