Table 1.

Lever responses and nicotine intake averaged across the final three self-administration/conditioning sessions and body weight measured after completion of self-administration/conditioning training

Group/dose (mg/kg/infusion)	0 (n=10)	0.015 (n=9)	0.03 (n=9)	0.06 (n=9)
Active lever responses	14.3±2.0	60.9±8.8**	79.8±7.2**,+	72.5±7.5**
Inactive lever responses	3.5±0.7	5.7±2.0	4.9±1.3	6.5±1.7
Nicotine intake (mg/kg/h)		0.80±0.13	1.48±0.13+	2.97±0.34++,^^
Body weight (g)	269±7	273±4	267±6	269±8

^**p<0.01 different from 0 group

⁺p<0.05,

⁺⁺p<0.01 different from 0.015 group

^{^^}p<0.01 different from 0.03 group