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ABSTRACT 



Victor J. CeMoble and Paul C. fete. Intravenous Nicotine Sel f-A<imini- 

 stration in Rats' Effects of fecamylamine, Hexarr.ethonium ard '.'aloxone. 

 Psychcpharracology CCO.OOO. ^ 



The rdte and pattern of lever pressing were studied in eighteen rats 

 dur-ng 24 h sessions in which responding resulted in intravenous fiv) 

 infusions of nicotine. There were four iniUcations (Df the positv/e 

 reinforclrg effect o' nicotine: 1} a g-eater ror.ber cf lever presses 

 w^-en nicotine was resporse-contingent compared tc when saline was avai':- 

 able; 2) a greater r^'^tr.ber of responses on the lever resulting in an 

 infusion of nicotine than en the control lever; 3) systetratic decreases 

 in the number of conti'"gent nicotine infusicrs when nicotine was deliv- 

 ered nonccntirgently, ^) systeratic changes in the frequency of lever 

 pressing as a funct:on of dose. L'nder a fixed-ratio 1 (FR 1) schedule 

 the I uinber o^ infusions first increased and then decreased as the dose 

 of nicotine was decreased (64, 32, 16, 8 ug/kg infusion) and nicotine 

 intake (mg/kg/24 h) was directly related to the infusion dose. As the 

 FP size was increased from 1 to 6, the number of lever presses 

 increased and the number of infusions (32 '.-g/kg) remained stable. At 

 FP. values greater t'"an six, both the nuirber cf lever presses and infu- 

 sions decreased. Presession injections of me caryl amine (0.75, 1.5 and 

 3.0 mg/kg sc) decreased the number of in'usicns in a dose related irar- 

 ne"*. Presession injections of hexaTPthoniuir ^..5 and 3.C mg/kg sc) or 



