Fig. 3.

Acute nicotine exposure desensitizes nicotinic receptors in young postnatal CA1 pyramidal neurons in a concentration-dependent manner. A: receptor desensitization by nicotine was calculated in neurons of mice aged postnatal day 5–10 by measuring the peak inward current response to 1 mM ACh (15 s; in the presence of 200 nM atropine and 10 nM MLA) before and after a 10-min exposure to 100, 300, or 500 nM nicotine. Nicotine was allowed to wash out of the brain slice for 10 min before ACh was reapplied, and nicotine was applied only once to each brain slice. The percent decrease/desensitization for the ACh response was significantly affected by nicotine concentration (1-way ANOVA, P = 0.04), with percent desensitization following 500 nM nicotine application being greater than that following 100 nM nicotine application (Tukey's post hoc test, P = 0.03). All values are means ± SE. ^a,bDifferent letters indicate statistically significant differences among data sets. B: representative voltage-clamp traces showing inward current responses to ACh (gray horizontal bars) before and after 10-min exposure to 100, 300, or 500 nM nicotine.