L-dopa reverses castration-induced disruption of dishabituation responses to female chemical cues in male rats.

In the present experiment, habituation/dishabituation behavioral tests were conducted to measure discriminatory olfactory recognition responses to chemical cues among control, castrated, and castrated+L-3,4-dihydroxyphenylalanine (L-DOPA)-treated male rats. Castration produced a disruption of dishabituation responses to female urine, and this effect was reversed by treatment with L-DOPA. In the posterior olfactory bulb, 3,4-dihydroxyphenlacetic acid (DOPAC) levels were significantly increased in L-DOPA-treated animals compared with the vehicle-treated control and castrated groups. No significant differences in olfactory bulb norepinephrine or dopamine concentrations among the three treatment groups were obtained. The restoration of behavioral dishabituation responses following L-DOPA treatment suggests that the catecholaminergic system of the olfactory bulb may play a critical role in the recognition and possibly attractions for or preferences to female chemical cues.