Differential recovery of sensorimotor function in GM1 ganglioside-treated vs. spontaneously recovered MPTP-treated cats: partial striatal dopaminergic reinnervation vs. neurochemical compensation

Administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to ca ts results in a parkinsonian syndrome characterized by rigidity, akinesia, bradykinesia, decreased response to external sensory stimuli and depletion of nigrostriatal dopamine. Cats spontaneously recover gross sensorimotor fu nctions despite little recovery of the dopaminergic innervation of the stri atum. in contrast, GM1 ganglioside administration accelerates gross behavio ral recovery and causes an increased dopaminergic innervation of the striat um. This study examined whether these two recovery conditions are character ized by different degrees of functional recovery. Cats were trained to perf orm a sensorimotor reaching task prior to MPTP exposure and were then re-te sted on the task 6 weeks later after spontaneously recovering gross motor f unctioning or after 6 weeks of GM1 treatment. Gross motor recovery was simi lar in both groups. However, the spontaneously recovered cats had significa nt difficulty in performing the task while GM1-treated cats performed norma lly. GM1-treated cats also had significant increases in striatal [H-3]mazin dol binding compared to spontaneously recovered cats. These results suggest that while gross motor functions may improve to a similar extent with spon taneous and GM1-induced recovery from experimental parkinsonism, complex se nsorimotor behavior recovers to different extents under the different recov ery conditions. More complete behavioral recovery may depend upon at least a partial recovery of striatal dopaminergic terminals rather than neurochem ical compensation. (C) 1998 Elsevier Science B.V. All rights reserved.