Lever pressing

Rat (Wistar) 4 hr 250 M (decreased shock avoidance and Skinner box lever press) Kishi et al. 1993... 

Other additional studies or pertinent information which lend support to this MRL Rats exposed to 1,000 ppm trichloroethylene for 3 days showed disturbed sleep cycles (Arito et al. 1993). Rats exposed to 250 ppm for less than 8 hours showed decreased electric shock avoidance and frequency of Skinner box lever press (Kishi et al. 1991). Humans exposed to 27 ppm trichloroethylene for up to 4 hours noted drowsiness, and headache was reported at 81 ppm (Nomiyama and Nomiyama 1977). Humans exposed for 8 hours to 110 ppm showed decreased performance on perception, memory, reaction time, and manual dexterity tests (Salvini et al. 1971). 

As a result of these observations it has been suggested that DA released in the nucleus accumbens is important in motivation by linking reward (especially when it is food) with the motor activity required to achieve it (Mogenson, Jones and Yim 1980). It is difficult, however, to distinguish a pure behavioural role for DA in actually initiating the sense of reward and motivation from its undisputed part in facilitating the motor response necessary to obtain the reward, e.g. a lever press in rats. 

Salmon, P, Tsaltas, E and Gray, JE (1989) Disinhibition by propranolol and chlordiazepoxide of nonrewarded lever-pressing in the rat is unaffected by dorsal noradrenergic bundle lesion. Neuropharmacology 28 207-210. 

Yokel, R.A., and Wise, R.A. Increased lever pressing for amphetamine after pimozide in rats Implications for a dopamine theory of reward. Science 187 547-549, 1975. 

Makriyannis and Liu claimed a series of pyrazole analogues in a patent application published in 2003 [272]. Of the 29 compounds specifically exemplified in the patent application, compound (389) was demonstrated to reduce lever presses when administered to rats that were trained to expect delivery of a food pellet as the outcome. It was proposed that the reduction in lever pressing was the result of decreased appetite brought about by CBi receptor antagonism. 

Wise, Roy A., Aileen Murray, and Michael A. Bozarth. 1990. "Bromocriptine Self-Administration and Bromocriptine Reinstatement of Cocaine-Trained and Heroin-Trained Lever Pressing in Rats." Psychopharmacology 100 355-60. 

In addition, it was shown that treatment with EGb (100 mg/kg, in 5% ethanol) reduces the development of the polydipsia induced by the stress of daily handling, anesthetization with ether and oral intubation [112], Rap in et al. [113] have reported that oral treatment with EGb (50 or 100 mg/kg/day, for 20 days) suppresses auditory stress-induced alterations of discrimination learning in both young and old rats EGb was especially effective in decreasing the number of inefficient lever presses and in reducing the reaction time in older animals. Furthermore, treatment with EGb counteracted the auditory stress-induced increases in the plasma concentrations of epinephrine, norepinephrine and corticosterone in both young and old rats. 

Differential reinforcement of low rate (DRL) responding in a Skinnerbox has been used in different studies as a test for teratogenic effects on behavior. Prenatal treatment of rats vith haloperidol resulted in normal baseline level of lever pressing in a Skinnerbox for a water reward. However, like after postnatal haloperidol treatment, an increase in the number of sessions to criterion for DRL responding was observed in these animals (ref. 41). Simple acquisition of the bar-press response for water reward was shown to be affected by prenatal treatment vith chlorpromazine, but not by prenatal amphetamine treatment (ref. 137). The response rate, but not response accuracy, in a left-right alternation learning test in a Skinnerbox was increased after neonatal clomipramine treatment ref. 34). 

At the end of this phase between 80 and 100% of the animals acquire the lever-press response. Animals which fail to learn are discarded from the experiments. If some animals are close to establishing steady lever-pressing behavior they are given extra training with the aim of attaining at least 10 animals per group. 

Subsequent to lever-press acquisition, all animals are submitted to delayed alternation sessions over 10 days. During this phase the Skinner Boxes are fitted with two retractable levers one on each side of the food distributor. 

A training session consists of 36 successive trials separated by 10 seconds. Each trial starts by presenting the animal with one lever (left or right). When the animal presses on the lever, it is given a food pellet, the lever is retracted and 5 seconds later two levers are presented. The animal has to learn to press on the lever not previously presented in order to gain a food reward (delayed alternation). If the animal does not lever-press within 20 seconds of a one- or two-lever presentation, the lever(s) are withdrawn and the next trial commences 10 seconds later. 

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