A kinematic comparison of L-DOPA-induced air-stepping and swimming in developing rats.
In Experiment 1, rats of 5, 10, 15, and 20 days of age were injected with L-DOPA to elicit stepping and videotaped while suspended in air and in warm water. Inter- and intralimb coordination were similar for L-DOPA-induced air-stepping and swimming at all ages. Other parameters of locomotion, such as step length and step rate, varied by substrate. In Experiment 2, pups of 5 to 20 days of age received an injection of L-DOPA or the vehicle and were videotaped while freely swimming. L-DOPA-induced free swimming was more stereotyped and "automatonlike" than that of vehicle-injected animals. Through 15 days of age, all pups swam using all four limbs, but L-DOPA induced stricter synchrony of movement in diagonal limbs than was used by pups injected with the vehicle. At postnatal Day 20, vehicle-injected pups adopted the adult swimming pattern in which only the hindlimbs were used, whereas L-DOPA-injected pups continued to use the immature pattern, diagonal progression with all four limbs. These results suggest that L-DOPA-induced air-stepping and swimming are manifestations of the same central mechanisms and that parameters of L-DOPA-induced stepping are modified by the sensory and/or biomechanical effects of the substrate. Although the free swimming of L-DOPA-injected pups was kinematically similar to vehicle-treated pups, L-DOPA retarded transition to the adult swimming pattern.
McEwen
M L
ML
Department of Psychology, University of Florida, Cainesville 32611, USA.
Van Hartesveldt
C
C
Stehouwer
D J
DJ
D000375:Aging / Q000187:drug effects*; D000818:Animals; D000831:Animals, Newborn; D015259:Dopamine Agents / Q000494:pharmacology*; D005260:Female; D007980:Levodopa / Q000494:pharmacology*; D008124:Locomotion / Q000187:drug effects; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D009048:Motor Skills / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013239:Stereotyped Behavior / Q000187:drug effects; D013550:Swimming
D015259:Dopamine Agents; D007980:Levodopa