61 



naloxone (0.75, 1.5 and 3.0 mg/kg sc) did not alter the within op 

 between session patterns of nicotine selfadninistration. Under the con- 

 ditions of the present experiment nicotine served as an effective rein- 

 forcer and the behavior was shown to be sensitive to both FP size and 

 infusion dose. In addition, the results suggest that nicotine self- 

 administration involves csntral nicotinic receptors and that cpioid 

 receptor antagonism has no effect on nicotine's reinforcing e^^'ects in 

 rats. , ^ 



Key Vcrds : r.Mcotine self-administration, F? schedules, ncncontin^ent 

 nicotine infusions, mecamyl amine, hsxa-rethoniun, naloxone, 

 rats. ' - • • 



'r : '■ -'J • f "4 ■•1.' 



