Mescaline-induced motor impairment in rats, assessed by two different methods

Mescaline, at moderate to large doses, produces a biphasic effect on rodent behavior—first depressant, then stimulant. During the depressant phase, motor impairment was measured using two objective methods. An ataxia test analyzing footprints revealed few irregularities in gait splay but a dose-related reduction in step length (stride). A tilt plane test for general motor control showed that 25 mg/kg mescaline decreased the animals' ability to cling to a tilted plane at 30 and 40 minutes after administration. These motor deficits are relevant for interpreting drug effects on behaviors involving movement and have research potential in their own right.

Study at a glance

Abstract

Motor impairment, especially ataxia, is often mentioned as a 'side effect' of doses of psychoactive drugs which depress animal behaviour; it is difficult to determine it accurately from visual observation, but relatively few attempts have been made to measure it objectively and quantitatively. Mescaline, in moderate to large doses, can induce biphasic--depressant followed by stimulant--effects on learnt and other performance of laboratory rodents. Motor impairment, using three doses, was accordingly measured during the depressant phase by two methods. An 'ataxia' test, involving analyses of footprints, showed few irregularities of gait splay due to mescaline, but the drug markedly reduced the length of steps ('stride') in a dose-related manner. In a 'tilt plane' test for general motor control, the animals' ability to cling to a tilted plane decreased with 25 mg/kg mescaline, at 30 and 40 minutes after administration. Deficits of this kind can be relevant to interpreting drug actions on forms of behaviour which involve movements for responding, and they also have interesting potential in their own right.