74 



Nicotine-maintained lever pressing was studied over a range of dos- 

 es in 7 rats. As the dose of nicotine was decreased responding 

 increased then decreased resulting in an inverted V shaped dose- 

 response function. The general relationship between magnitude of rein- 

 forcer and frequency of responding found in the present study was simi- 

 lar to that obtained with other reinforcers (Reynolds 1958; Golcbera 

 1973; Griffiths et al. 19:^9; CeNoble et al. 1981). In contrast tc the 

 inverted V shaped dose-resporse function, the nicotine intake ffrg/kg of 

 body weight) increased directly as a function of dose. At the raximum 

 daily intake f3.2 mg/kg) the rats d'd not show any signs of 'cxicity as 

 noted by Hanson et al. f!979). 



Mecamylamine is an effective and specific antagonist for the behav- 

 ioral effects of nicotine. Presessior treatment with irecamylarpine has 

 been shown to antagonize both t^e rate-increasing and the rate- 

 decreasing effects of nicotine when behavior was maintained in rats cr 

 squirrel monkeys under a FI and FR schedule of food presentation, water 

 presentation or tenrination of a stimulus associated with electric 

 shock (Morrison et al. 1969; Stitzer et al . 1970; Spealnan and Goldberg 

 1982). f'ecamylamine has also been used to antagonize the dlscriaina- 

 tive stimulus effect of nicotine in rats (Schecter and Posecrans 1972; 

 Hirshorn and Rosecrans 1974; Keltzer et al. 1980;) and antagonize the 

 effects of intraventricular infusions c' nicotine on behavior main- 

 tained under FR schedules o' food presentation (DeKoble et al. 1982). 

 When behavior of squirrel ironkeys or dogs was maintained under FI sched- 



16 



