Effect of intrastriatal injection of soman on acetylcholine, dopamine and serotonin metabolism.

Intrastriatal injection of soman (14.85 nmol) inhibits cholinesterase (ChE) activity in the striatum with much smaller decreases in ChE activity in other brain areas of the rat. As would be expected, there is a substantial increase in striatal acetylcholine (ACh) content shortly after soman injection. However, this increase is no longer significant 1 h following intrastriatal injection. There is no change in striatal KACh 20 min, 1 h or 24 h following soman injection. ACh content is not affected in the parietal cortex, hippocampus, or medulla/pons following intrastriatal soman injection. However, KACh and/or ACh turnover are reduced in these brain areas following soman injection. There is no consistent effect on dopamine (DA) metabolism in any of the brain areas studied. However, serotonin (5-HT) metabolism appears to be affected in the cortex, hippocampus and medulla/pons following intrastriatal injection of soman. Possible mechanisms of the actions of local injection of soman on brain Ach and 5-HT metabolism are discussed, as well as the differences observed between the effects of local and peripheral administration of soman on DA metabolism in the striatum.