Effects of corticosterone and metyrapone on gastrointestinal neurotransmitter enzyme activities

Adrenal glucocorticoids have been shown to produce alterations in the enzymes which synthesize and degrade cholinergic and catecholaminergic neurotransmitters in the central and peripheral nervous system. The present study examined the impact of altering plasma corticosterone levels via corticosterone or metyrapone ingestion, via the drinking water, on the developmental profile of choline acetyltransferase (ChAT), acetylcholine esterase (AChE), tyrosine hydroxylase (TH) and monoamine oxidase (MAO) in various gastrointestinal (GI) segments of rats. Three groups were studied: non-treated, corticosterone treated and metyrapone treated. Drug intake of pregnant (i.e., beginning on the 15th day of gestation), lactating and weaned rats was monitored until the male pups were sacrificed at 1, 3, 7, 14, 21, 35 and 50 days of age. Results showed that ChAT and TH activities peaked earlier in development in corticosterone treated rats as compared to non-treated and metyrapone treated rats. During the early postnatal period plasma corticosterone levels were inversely related to AChE and MAO activities in most GI segments. These results indicate that neurotransmitter enzyme activities in various GI segments are influenced by corticosterone during a critical period of development.