An Animal Model of Drug-Induced Thermoregulatory and Endurance Decrements

Effects of the neurotransmitter acetylcholine are divided into muscarinic or nicotinic depending on the receptors that are activated. Stimulation of muscarinic receptors results in vasodilation, decreased heart rate and cardiac contractility, increased secretions of exocrine glands including sweat and salivary, increased intestinal and gastric contractions, and increased bronchial secretions. Agonists at nicotinic receptors stimulate autonomic ganglia and neuromuscular junctions. Over-stimulation results in asynchronous excitation, fatigability, and involuntary twitching. Anticholinergic drugs are commonly used as antihistamines, tranquilizers, cold medications, antidiarrheal medications, as well as treatments for motion sickness and anticholinesterase poisoning. Use of anticholinergic drugs has detrimental effects on thermoregulation particularly in hot environments due to sweat suppression. Anticholinesterase drugs are used clinically for treatment of myasthenia gravis, Alzheimers disease, anticholinergic syndrome, and as a pretreatment against potential organophosphorus exposure.