75 



ules (Spealman and Goldberg 1962) or FR schedules (Riser and Goldberg 

 1983) of iv nicotine infusions, presession treatment wUh 1.0 irg/kg of 

 necamylamine reduced responding maintained by nicotine infusions to 

 saline-control levels. Infusions of nicotine (iv) and the delivery of 

 electric shock both serve as punishers to suppress food maintained 

 lever pressing in squirrel monkeys (Goldberg and Spealr.an 1983). 

 Presession treatment with 0.1 to 0.3 mg/kg of Tecanylamine reversed the 

 suppression of respording produced by nicotine but did rot alter the 

 suppression produced by electric shock. In the present exper'r.ent, mec- 

 enylamine was also an effective antagonist of the behavioral effects of 

 nicotine. . When mecamylarine was administered at the beginning of a ses- 

 sion, responding maintained by nicotine infusions was reduced and the 

 anount of reduction was directly related tc the mecamylamine dose. In 

 contrast nicotine maintained responding in the same rats was not 

 altered by presession treatment with hexarethonium. This combined with 

 previous reports would suggest that the behavioral effects cf nicotine 

 i.T^ mediated by nicotine's effects on the central nicotinic receptors. 



Opioid antagonists have been shown to reduce the intake of positive 

 reinforcers such as food, water and ethanol fKarquies et al. 197C; 

 Hcltzran 1?74-, Altschuler et al . 1980). The reduction does not appear 

 to be "-elated to an abstinence syndrome, or of a general suppression of 

 behavior (Stein and Beiluzii 1979), unless high doses (>5.C irg/kg) cf 

 the antagonist are used (Segal et al. 1979). Naloxone has also been 

 shown to reduce the amount of cigarettes smoked during a 3 h test per- 



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