Effects of intravenous nicotine on prepulse inhibition in smokers and non-smokers: relationship with familial smoking

Abstract

Rationale: The reinforcing properties of nicotine may be, in part, derived from its ability to enhance certain forms of cognitive processing. Several animal and human studies have shown that nicotine increases prepulse inhibition (PPI) of the startle reflex. However, it remains unclear whether these effects are related to smoking susceptibility.

Objectives: The current study examined the effects of intravenously delivered nicotine on PPI in smokers and non-smokers, as well as its association with a quantitative index of familial smoking.

Methods: The sample consisted of 30 non-smokers and 16 smokers, who completed an initial assessment, followed on a separate day by a laboratory assessment of PPI prior to and following each of two intravenous nicotine infusions. Separate doses were used in smoker and non-smoker samples.

Results: Analyses indicated that both nicotine infusions acutely enhanced PPI among non-smokers, and this enhancement was positively related to the degree of smoking among first and second-degree relatives. Smokers also displayed PPI enhancement after receiving the first infusion, but this effect was unrelated to familial smoking.

Conclusions: These data suggest that the PPI paradigm may have utility as an endophenotype for cognitive processes which contribute to smoking risk.

Figure 1

Nicotine blood levels (ng/ml) before and after two nicotine infusions in nonsmokers and smokers. Bars represent standard errors. There were significant quadratic patterns for each group, reflecting increases following each infusion that quickly dissipated by the second post-infusion measurement.

Figure 2

Prepulse inhibition (as percentage of response reduction when startle probe was preceded by a prepulse) before and after two nicotine infusions in nonsmokers and smokers. Bars represent standard errors. For non-smokers, nicotine was associated with a significant increase in PPI following each infusion; this effect was significant only upon the first infusion for smokers.