Effects of caffeine, theophylline and theobromine on scheduled controlled responding in rats.
1 Rats were trained to respond under a variable interval 30 s (VI 30) schedule of food  reinforcement.  Caffeine (0.32-32 mg/kg), theophylline (1.0-56 mg/kg) and theobromine (10-320 mg/kg) in general produced dose-related decreases in operant responding. At relatively low doses, caffeine (1.0 mg/kg) and theophylline (3.2 mg/kg) produced slight but nonsignificant increases in VI 30 responding. 3 The rank order of potency for producing decreases in responding was caffeine greater than theophylline greater than theobromine. 4 Daily caffeine injections (32 mg/kg, i.p.) resulted in the development of caffeine tolerance. This tolerance was characterized by a 6 fold shift to the right in the caffeine dose-effect curve. Saline substitution for the 32.0 mg/kg caffeine maintenance dose resulted in a substantial decrease in responding.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D002110:Caffeine / Q000494:pharmacology; D003216:Conditioning, Operant / Q000187:drug effects; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012055:Reinforcement Schedule; D013805:Theobromine / Q000494:pharmacology; D013806:Theophylline / Q000494:pharmacology; D014970:Xanthines / Q000494:pharmacology*
D014970:Xanthines; D002110:Caffeine; D013806:Theophylline; D013805:Theobromine