title: Enhanced function in the good forelimb of hemi-parkinson rats: compensatory adaptation for contralateral postural instability?
abstract: In this paper we present two new assays of rat motor behavior which can be used to assess function linked to postural stability in each forelimb independently. Postural instability is a major deficit in Parkinson's disease that is resistant to levodopa therapy and contributes to the risk of falling. We applied both tests, one forelimb at a time, to normal rats as well as rats extensively depleted of dopamine by unilateral infusion of 6-hydroxydopamine (6-OHDA, given in the medial forebrain bundle) to produce a hemi-parkinsonian syndrome. The 6-OHDA rats showed severe postural instability in the impaired forelimb, but unexpectedly showed enhanced function in the non-impaired forelimb. The data suggest that the intact hemisphere may undergo rapid reorganization subsequent to unilateral dopamine depletion, which allows for compensatory function of the "intact" limb. Measurements of amphetamine-induced striatal c-fos expression, as well as behavior results gathered when animals were under the influence of apomorphine or haloperidol, indicate that this potential reorganization may require non-dopaminergic neural plasticity. The relevance of these findings for unilateral rat models of neurological disease is discussed.
authors.affiliation: Institute for Neuroscience, The University of Texas at Austin, Austin, TX, USA.
authors.forename: Martin T
authors.initials: MT
authors.lastname: Woodlee
authors.forename: Jacqueline R
authors.initials: JR
authors.lastname: Kane
authors.forename: Jitsen
authors.initials: J
authors.lastname: Chang
authors.forename: Lawrence K
authors.initials: LK
authors.lastname: Cormack
authors.forename: Timothy
authors.initials: T
authors.lastname: Schallert
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D005552:Forelimb / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology*; D008297:Male; D010300:Parkinson Disease / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley