Responses of hypothalamo-pituitary-adrenal axis to a cholinesterase inhibitor

Acute gastrointestinal events (mostly manifested by nausea, vomiting, or loss of appetite) are class effects of all cholinesterase inhibitors, which are prescribed for the treatment of Alzheimer's disease. The underlying mechanism, however, has been unclear. Because corticotropin-releasing hormone is related to appetite control, we focused on the activation of the hypothalamo-pituitary-adrenal system and food intake following the administration of the cholinesterase inhibitor, donepezil, in rats. We monitored the plasma concentrations of adrenocorticotropic hormone, c-Fos, in the paraventricular nucleus, and intakes of rat chow for 3 h after the first administration of donepezil, and 2 weeks later, after daily administration of donepezil. The intragastric administration of 3 mg/kg of donepezil significantly increased the plasma adrenocorticotropic hormone levels and c-Fos expression in the paraventricular nucleus, and decreased the food intake on the first day. The increase in adrenocorticotropic hormone and loss of appetite after oral administration of the drug were attenuated after daily administration for 2 weeks.