Effect of stress and glucocorticoids on the gastrointestinal cholinergic enzymes.

Male Sprague-Dawley rats maintained under controlled lighting and temperature conditions were used in this experiment. Animals were exposed to acute cold (4 degrees C) and immobilization stress for one hour, exposed to cold stress for 7 days (chronic stress) or treated with corticosterone (2 mg/kg) 1 hr prior to sacrificing. Animals with their proper controls were sacrificed and the stomach, duodenum, ileum and colon were separated and assayed for choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) activities. The data obtained indicated that exposure to acute stress resulted in significant decline in ChAT activity in all tissues studied. The administration of corticosterone resulted in significant decline in ChAT activity in all tissues studied except for the duodenum. Meanwhile, the exposure to chronic stress did not have any significant effect on ChAT activity. On the other hand, acute stress caused significant increase in AChE activity in all tissues studied except for the ileum and stomach. The duodenal AChE activity of stressed animals increased thirty-fold when compared to control. The administration of glucocorticoids significantly reduced AChE in all tissues studied, except for the duodenum and stomach where there was thirty-two-fold increase as compared to the control levels. The exposure to chronic stress also caused significant increase in AChE of all tissues studied, except for the colon. The results of this experiments indicate that the duodenal AChE is extremely sensitive to stress or glucocorticoids and that stress induced changes in the cholinergic enzymes of the gastrointestinal tract may be mediated by adrenal steroids.