THE EFFECT OF CHOLINERGIC MODIFICATIONS ON RESPONSE OF NEUROENDOCRINE PARAMETERS TO STRESS

MOHAMMED MATAR ALHARBI, Purdue University

Abstract

The objective of this project was twofold. First, to investigate the effects of acute or subchronic dosage of cholinergic blockers and stimulants and their interaction with stress on the response of various neuroendocrine parameters, namely plasma corticosterone (PCS), plasma free fatty acids (PFA), and plasma glucose (PGL). Second, to study the effects of subchronic dosage of cholinergic blockers and stimulants on 24 hour water consumption. A single 2 hour immobilization exposure was used in the experiments. Subchronic treatments were for 7 days; on the 8th day, the rats were given either test drug(s) or water, prior to exposure to immobilization for 2 hours and then immediately decapitated. Acute, subchronic, or combined treatment with atropine, but not methylatropine or procyclidine, enhanced the PCS response to stress but had no consistent effect on the PGL and PFA responses. Subchronic physostigmine or neostigmine had no effect per se and did not alter the atropine effect on PCS and PFA responses to stress. Physostigmine, but not neostigmine, potentiated the atropine effect on the PGL response to immobilization. Subchronic dosage of centrally active cholinergic blockers increased 24 hour water consumption starting after the second day of treatment and maintained consistently through the 7 th day of treatment. In contrast, similar treatment with methylatropine, depressed 24 hour water intake only on the first day of treatment. Subchronic treatment with physostigmine or neostigmine had no effect on 24 hour water intake. In summary, central cholinergic systems play an important role in the response to stress; prolonged central cholinergic blockade may exaggerate the response to stressful situations.

Degree

Ph.D.

Subject Area

Pharmacology

COinS