“…For example, the stimulation of DA release in the nucleus accumbens after several nicotine injections remains controversial Balfour et al, 1998;Di Chiara, 2000), and repeated nicotine treatments in rats induce a behavioral sensitisation, which vanishes quicker than for other drugs of abuse (Ksir et al, 1985;Villégier et al, 2003). Similarly, although self-administration of nicotine is observed in rodents (Corrigall and Coen, 1989;Donny et al, 1995;Martellotta et al, 1995;Shoaib et al, 1997;Caggiula et al, 2001) and monkeys (Goldberg et al, 1981;Wakasa et al, 1995), its development seems slower and weaker than for other drugs of abuse (Manzardo et al, 2002), and often needs facilitation by the use of food restriction (Corrigall et al, 2002;Rauhut et al, 2002) or cocaine pre-treatment (Picciotto et al, 1998). These differences suggest either that nicotine possesses both aversive and rewarding properties (Risinger and Brown, 1996;Shoaib et al, 2002), or that the addictive effects of tobacco are not only due to nicotine.…”