Spontaneous functional recovery from parkinsonism is not due to reinnervation of the dorsal striatum by residual dopaminergic neurons.
Cats exposed to MPTP experience severe motor deficits that spontaneously recover after 4-6 weeks. This recovery occurs despite a persistent deficit (approximately 95%) in dorsal striatal DA levels. To determine whether residual DA neurons that previously did not innervate the dorsal caudate nucleus (CD) have innervated this area in recovered MPTP-treated animals, HRP was injected into the dorsal lateral and dorsal medial CD and the locations of retrogradely labeled neurons in ventral mesencephalon were mapped in normal and recovered MPTP-treated cats. Tyrosine hydroxylase (TH) positive cells were also counted in ventral mesencephalic DA-containing cell groups in normal, symptomatic, and recovered MPTP-treated cats. Results showed no difference in the pattern of HRP labeling in normal and recovered cats except for the loss of labeled substantia-nigra pars compacta (SNc) cells in MPTP-treated cats. Cell counts revealed no significant difference in the degree of TH-positive cell loss in all ventral mesencephalic areas studied in both symptomatic and recovered cats. The results suggest that spontaneous recovery of gross motor function in MPTP-treated cats is most likely not dependent upon reinnervation of the dorsal striatum from residual DAergic neurons.
Rothblat
D S
DS
Department of Neurology, Hahnemann University, Philadelphia, PA 19102.
Schneider
J S
JS
D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; D000818:Animals; D002415:Cats; D003342:Corpus Striatum / Q000503:physiopathology*; D004298:Dopamine / Q000502:physiology*; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D009416:Nerve Regeneration; D009474:Neurons / Q000502:physiology*; D010302:Parkinson Disease, Secondary / Q000139:chemically induced / Q000503:physiopathology*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; D014446:Tyrosine 3-Monooxygenase; D004298:Dopamine