Responses to central oxotremorine and scopolamine support the cholinergic control of male mating behavior in hamsters

DARK Classics in Chemical Neuroscience: Atropine, Scopolamine, and Other Anticholinergic Deliriant Hallucinogens

Anticholinergic drugs based on tropane alkaloids, including atropine, scopolamine, and hyoscyamine, have been used for various medicinal and toxic purposes for millennia. These drugs are competitive antagonists of acetylcholine muscarinic (M-) receptors that potently modulate the central nervous system (CNS). Currently used clinically to treat vomiting, nausea, and bradycardia, as well as alongside other anesthetics to avoid vagal inhibition, these drugs also evoke potent psychotropic effects, including characteristic delirium-like states with hallucinations, altered mood, and cognitive deficits. Given the growing clinical importance of anti-M deliriant hallucinogens, here we discuss their use and abuse, clinical importance, and the growing value in preclinical (experimental) animal models relevant to modeling CNS functions and dysfunctions.

Role of acetylcholine in control of sexual behavior of male and female mammals

The results of studies using systemic or central applications of cholinergic drugs suggest that acetylcholine makes important contributions to the neurochemical control of male- and female-typical reproductive behaviors. In males, cholinergic control seems largely specific to some elements or aspects of copulatory behavior that can vary significantly across species. Synapses in or near the medial preoptic area represent part of this mechanism, but the entire system appears to extend more widely, perhaps especially to one or more structures flanking some part of the lateral ventricle. In females, the lordosis response that essentially defines sexual receptivity is clearly responsive to cholinergic drugs. The same seems likely to be true of other elements of female sexual behavior, but additional studies will be needed to confirm this. Changes in cholinergic activity may help to mediate estrogenic effects on female sexual behavior. However, estrogen exposure can increase or decrease cholinergic effects, suggesting a relationship that is complex and requires further analysis. Also presently unclear is the localization of the cholinergic effects on female sexual responses. Though periventricular sites again have been implicated, their identity is presently unknown. This review discusses these and other aspects of the central cholinergic systems affecting male and female sexual behaviors.