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. Author manuscript; available in PMC: 2010 Nov 1.
Published in final edited form as: Pharmacol Biochem Behav. 2009 Jul 18;94(1):43–50. doi: 10.1016/j.pbb.2009.07.004

Figure 5.

Figure 5

(Top Panels) The average number of active and inactive lever responses observed during the progressive-ratio nicotine self-administration sessions as function of postnatal day across the adolescent testing period under the 5 and 10 µg/kg nicotine dose conditions. The asterisk indicates a significant interaction of sex by time (P<0.05). Each data point represents an N of 7 females and 5 males under the 5 µg/kg nicotine dose condition and an N of 6 females and 8 males under the 10 µg/kg nicotine dose condition. Vertical bars with asterisks represents a significant effect of sex for last three sessions (P<0.05). (Bottom Panel) The average number of active and inactive lever responses observed under the progressive-ratio schedule as function of phase of the estrous cycle (Met/Die = metestrus/diestrus; Pro = proestrus; Est = estrus). The asterisk indicates a significant difference in the number of infusions obtained between estrus and the other 2 phases (P’s≤0.05). Each bar represents an N of 12.