Brain cholinesterase activity in animals and birds.

Normal cholinesterase activity in brain tissue was measured in various mammalian and avain species. The cholinesterase activity in the cerebrum of cattle, swine, sheep and horses was approximately 2-3 umoles/min/g of tissue in each instance. The whole brain cholinesterase activity of small feral mammals was approximately 2 to 5 fold greater than the domestic animals. Considerable interspecies variability was present in the feral mammals. Similar variability was also observed in the avian brain cholinesterase determinations. The avian whole brain cholinesterase activities ranged from 9.78 to 21.35 umoles/min/g of tissue. The substantial species variability associated with normal brain cholinesterase emphasizes the need for baseline values for each animal or avian species. Routine diagnosis or monitoring of exposure to anticholinesterase agents is extremely limited unless these baseline or normal values are known.