Abstract

The nigrostriatal degeneration underlying Parkinson’s disease is commonly studied in experimental animals by injection of the neurotoxin 6-hydroxydopamine (6-OHDA). The present study describes a modified version of a beam traversal test which allows the quantification of the motor deficit through the time spent to arrive to the platform once all four paws of the animals are in contact with the beam (escape latency), the time spent before falling (tumbled down latency) and the number of errors committed for the animals in each beam. The shape and the diameter of the cross section of the beams were modified from rectangular and circular cross section with 2.5 cm of diameter to the same shape with 1 cm of diameter, which induced a high difficulty to the execution of the test. Three groups of Wistar rats were examined: untreated (n = 15), lesioned with 6-hydroxydopamine (n = 14), and sham-operated (n = 14). All variables studies showed significant differences between control and hemiparkinsonian rats. The escape latency and the error were increased and the tumbled down latency was decreased in hemiparkinsonian rats for all beams in comparison with control rats. In tumbled down latency, the significant differences between groups were more evident (p < 0.001) for the beams with high cross section irrespective of the shape of the cross section (rectangular or circular). The beam traversal test is a convenient sensorimotor test that does not need to be trained extensively, and require averse motivation or food deprivation and appears to be very useful in evaluating the motor deficits in established unilateral model of Parkinson’s disease and also other experimental models.

Key words: Beam traversal test, 6-OHDA, dopamine.