Caffeine and nicotine improve visual tracking by rats: a comparison with amphetamine, cocaine and apomorphine

Abstract

Psychomotor stimulant drugs such as caffeine, nicotine, amphetamine and cocaine, have been shown to improve vigilance in man under conditions of fatigue. Nicotine has also been shown to improve performance in some cognitive tests in patients with Alzheimer's disease. In rodents these drugs increase activity which may confound "performance enhancing effects" in rodent models. However, improvements have been found in a number of tests that do not seem to be directly dependent upon an enhancement of locomotor activation. In one example, Evenden and Robbins (1985) reported consistent improvements in a visual tracking test following amphetamine. The present study was undertaken to determine whether these performance enhancing effects of amphetamine could also be obtained with cocaine and apomorphine, which both have psychomotor stimulant effects through their actions as, respectively, indirect and direct dopamine agonists, and by caffeine and nicotine, which do not have a direct dopaminergic mechanism of action. The results of the study indicate that all five drugs improved tracking performance at one or more doses. The most consistent effects were obtained with amphetamine which, like cocaine and nicotine, improved tracking at a dose which did not produce other changes in behaviour. Taking into account previous studies (Evenden and Robbins 1983, 1985), these results were interpreted as indicating that psychomotor stimulant drugs produce a general activation of behaviour. At all but the highest doses of such drugs, the form of behaviour that is observed depends upon the environment.(ABSTRACT TRUNCATED AT 250 WORDS)

Facilitation of stimulus detection performance of rats with d -amphetamine: a function of dose and level of training

“…The results of the present experiment and of previous studies (Evenden and Robbins 1985;Grilly and Gowans 1988;Grilly et al 1989;Grilly and Grogan 1990;Grilly and Nocjar 1990;Grilly 1992;Evenden et al 1993;Grilly and Simon 1994;Grilly and Pistell 1997) indicate that there are a variety of conditions under which psychostimulants such as amphetamine and cocaine may enhance the choice performance of normal, non-fatigued adult animals in visual stimulus detection tasks. In general, these findings are consistent with the conclusions from studies with humans that psychostimulants can improve overall level of performance (both accuracy and speed) in vigilance-dependent tasks (Koelega 1993).…”

“…Whether choice task performance is facilitated or disrupted by psychostimulants may also depend on the degree to which the animal's behavior is adequately controlled by the stimulus-reinforcement contingencies of the task before drug testing, i.e., well-trained performance, under strong stimulus control, is more likely to be improved with low doses of psychostimulants (Lyon and Robbins 1975;Grilly 1977;Robbins and Sahakian 1983;Grilly and Nocjar 1990;Evenden et al 1993). On the other hand, if the contingencies between the stimuli, the choice behavior(s) and reinforcers are not well established prior to testing, irrelevant behaviors activated by psychostimulants, e.g., general motor activity, may increase and compete with the reinforcement-contingent behavior.…”

“…Two studies have reported psychostimulant-induced facilitation on the light-tracking efficiency of rats trained to move from pressing one of two levers to the other depending on the location of a cue light (Evenden and Robbins 1985;Evenden et al 1993). In the first study, d-amphetamine (AMP) increased tracking efficiency consistently over a dose range of 0.2-1.6 mg/kg, although at a high dose (3.2 mg/kg), AMP significantly impaired tracking.…”

Immunohistochemical localization of caffeine-induced c-Fos protein expression in the rat brain

“…than after the lower (1-30 mg/kg) doses of caffeine because of stress induced by the higher caffeine dose. To test this possibility would require a more precise definition of ''arousal'' and carefully designed behavioral tests that would allow differentiation of multiple aspects of arousal (e.g., Evenden et al, 1993). Despite these conceptual problems, however, the response to stress may involve an increase in certain aspects of arousal, and therefore, some of the Fos expression seen at 75 mg/kg may be related to stress-induced arousal.…”

Assessing a vigilance decrement in aged rats: effects of pre-feeding, task manipulation, and psychostimulants

“…Recently, some enhancement in performance has been detected with nicotine as indexed by increases in response accuracy and/or speed (Mirza and Stolerman 1998;Blondel et al 2000;Grottick and Higgins 2000), although these effects were not dosedependent, and were only found under specific task conditions. For amphetamine, other tests of vigilance in rats have detected either performance disruption (McGaughty and Sarter 1995) or improvements (Evenden et al 1993), whilst in the 5-CSRTT, performance improvement has been restricted to increases in response speed Robbins 1987, 1989). It has been suggested that the relatively low demands in processing required for these tasks result in high levels of performance, thus rendering them insensitive to various manipulations (Moore et al 1992).…”