Effects of nicotine, nornicotine and cotinine, alone or in combination, on locomotor activity and ultrasonic vocalization emission in adult rats.

Rationale: The behavioral effects of the nicotine metabolites nornicotine and cotinine have not been investigated extensively.

Objectives: To evaluate the effects of nicotine, cotinine, and nornicotine, given alone or in combination, on locomotor activity and emission of ultrasonic vocalizations in male adult rats.

Methods: Rats were first given home cage nicotine injections to make them tolerant to the drug's locomotor depressant effects.