Motor activity of rats with peripheral nerve lesion

The crucial factor for the locomotion of rats is the activity of forelimbs. Impairment of the control of a single forelimb brings alteration of motor activity of a degree that could be identified in the open field test. Three groups of adult Wistar rats were used: A Control group A (healthy animals), Marcain group B (blockade of the nerves of the right forelimb plexus by Marcain), Sham group C (Aqua for injection was used instead of Marcain). For the horizontal locomotion the average time spent in locomotion (s), average distance travelled (m) and average speed of locomotion (m/s) during one hour, at time intervals of ten minutes were recorded. Results confirm the role of forelimbs for locomotion of rats - inactivation of one forelimb brings reduction of all parameters of locomotion (p <0.001). Paradoxically, no difference in any of the studied parameters of locomotion was found between the experimental groups B (Marcain) and C (Sham). The malfunction of the forelimb in sham group could be explained by volumetric effect of the fluid injection. Open field test is sufficiently sensitive method for registration of functional impairment of a single forelimb but it is not adequate to distinguish effect of local anaesthesia from the fluid compression.