The effects of smoking high nicotine cigarettes on prepulse inhibition, startle latency, and subjective responses

Rationale: Several previous investigations with animals and humans have sug gested that nicotine enhances prepulse inhibition of the startle reflex (PP I). However, the administration of nicotine activates mesolimbic dopamine, and activation of mesolimbic dopamine is known to attenuate prepulse inhibi tion of the startle reflex (PPI), which might suggest that nicotine would d ecrease PPI. Objective: The primary aim of this study was to test rigorousl y the effects of smoking high nicotine cigarettes on PPI and other measures (e.g., heart rate, craving, and mood) when the concentration of nicotine p eaks in the brain (i.e., immediately after smoking). Methods: Thirty smoker s participated in two experimental sessions 1 week apart. Two high nicotine cigarettes were smoked in one session, and two control cigarettes were smo ked in the other session after overnight deprivation. Results: The results indicated that smoking the high nicotine cigarettes decreased PPI and that PPI increased across trials in both conditions. The interaction between nic otine dose and trial was not significant, although it appeared that high ni cotine may have reversed an increase in PPI across trials in the control co ndition. High nicotine cigarettes also significantly increased heart rate, decreased the latency to peak startle response on control trials, but did n ot alter the magnitude of the startle response. Discussion: The findings su ggest that either high nicotine cigarettes reduced PPI, or possibly, that h igh nicotine cigarettes may have reversed an increase in PPI across trials as evident in the control condition.