Suppression of mating behaviour in the male rat by intracerebroventricular infusions of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.

Acute microinfusions of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) into the third cerebral ventricle (III V) of sexually experienced male rats produced a dose-related suppression of masculine sexual behaviour. This inhibition of male sexual performance could be reversed by simultaneous infusions of small doses of pargyline. Three analogues of MPTP, namely, 4-phenyl-1,2,3,6-tetrahydropyrididine, 4-cyano-4-phenylpiperidine and 4-hydroxy-4-phenylpiperidine had no significant effects on any of the parameters of male sexual behaviour. These findings suggest that MPTP may have potent effects on the mechanisms regulating male sexual behaviour in the rat by acting on sites around the third ventricle (arcuate and periventricular hypothalamic nuclei) where there are high MPTP receptor densities and thus provide further evidence for MPTP in neuroendocrine regulation. These responses depend upon the unique structural properties of the MPTP molecule.