Passive exposure to tobacco smoke sensitizes the locomotor effects of nicotine but not of amphetamine in rats

Nicotine is the primary psychoactive component of tobacco smoke (TS) attributed to the development of tobacco dependence. However, there are several chemical components in TS that may also contribute its addictive properties. Thus, exposing subjects to TS may be a better model of tobacco addiction. Nicotine is similar to other drugs of abuse in that it can stimulate locomotor activity. Repeated nicotine administration can lead to locomotor sensitization, a behavioral measure of neuroadaptive changes. It is unknown whether or not TS exposure induces similar adaptive behaviors. In the current studies, rodents were exposed to air or TS for 14 days. Locomotor behavior was assessed at day 1, day 7, and day 14. We hypothesized that chronic TS would lead to locomotor sensitization. TS induced a sensitized locomotor response after 7 and 14 days of exposure. To determine if repeated TS exposure would potentiate the locomotor effects of nicotine, rodents were exposed to repeated air or TS for 13 days and injected with saline or nicotine on day 14 and locomotor behavior was assessed. TS potentiated the locomotor response to nicotine. An additional study was conducted to investigate if TS potentiated the locomotor effects of a low dose of amphetamine. TS smoke had no effect on the locomotor effects of amphetamine. Supported by FAMRI Grant 52312 .