Combined ipsilateral limb use score as an index of motor deficits and neurorestoration in parkinsonian rats

Abstract

Our aim was to apply a robust non-drug induced sensorimotor test battery to assess the efficacy of neurorestorative therapies on the motor deficits caused by partial unilateral 6-OHDA lesion mimicking early stage PD. Since the 6-OHDA lesion protocols to induce partial DA depletion in striatum vary extensively between laboratories, we evaluated the associations between different intrastriatal 6-OHDA doses (1 X 0-20 and 2 X 0-30 µg), striatal DA depletion (HPLC-ECD) and D-amphetamine induced rotation to identify a lesion protocol that would produce 40-60% striatal DA depletion. Doses ≥ 6 µg produced a significant DA depletion (ANOVA, P < 0.0001). 6-OHDA dose range (6-14 µg) causing 40-60% DA depletion induced very variable rotational responses. Next, intrastriatal 1 × 10 and 1 × 14 µg doses were compared with a full lesion (10 µg into the medial forebrain bundle) with regard to their effects on adjusting step, cylinder, and vibrissae test performance. A combined ipsilateral score (average of each test) was found more sensitive in distinguishing between different lesions than any test alone. Finally, five-week treadmill exercise starting two weeks post-lesion was able to restore impaired limb use (combined score; mixed model, P < 0.05) and striatal DA depletion (ANOVA, P < 0.05) in rats with partial lesion (1 × 10 µg). Notably, D-amphetamine induced rotation significantly decreased between weeks one to seven post-lesion (t-test, P < 0.01). In conclusion, intrastriatal 1 × 10 µg of 6-OHDA produces 40-60% striatal DA depletion robustly, and the combined ipsilateral score provides an efficient means for testing of the efficacy of neurorestorative or neuroprotective treatments for PD. © 2017 Wiley Periodicals, Inc.

Brief isoflurane anesthesia regulates striatal AKT‐GSK3β signaling and ameliorates motor deficits in a rat model of early‐stage Parkinson′s disease

“…We utilized our recently validated unilateral 6‐OHDA rat model of early‐stage PD (Leikas et al . ) to determine whether repeated brief isoflurane anesthesia exposures (20‐min anesthesia exposure every 48 h for a total of four times; starting 7 days after 6‐OHDA infusion) influences the emergence of sensorimotor impairments induced by intrastriatal 6‐OHDA (Fig. a).…”

“…Our recently described intrastriatal unilateral 6‐OHDA infusion protocol reproducibly produces 40–60% depletion of striatal DA in the lesioned hemisphere, and causes motor deficits that can be quantified by a sensitive sensorimotor test battery (Leikas et al . ). Importantly, isoflurane anesthesia readily regulated AKT‐GSK3β signaling in the 6‐OHDA‐lesioned striatum and ameliorated motor deficits observed in this model.…”

“…; Leikas et al . ). Power analyses were conducted using online tools (http://www.powerandsamplesize.com) to determine a sufficient sample size using an alpha of 0.05, a power of 0.80, and estimated effect size of two in biochemical assays and 1.5 in behavioral tests as calculated by Cohen's d value (estimated mean difference between groups/pooled standard deviation).…”

“…Lesions were performed as described (Leikas et al . ). Briefly, the rats were anesthetized with pentobarbital (50 mg/kg, i.p.).…”

“…(), and this approach has been shown to be more sensitive in detecting motor deficits in partially 6‐OHDA‐lesioned rats compared to individual tests alone (Leikas et al . ). The battery consisted of sensorimotor tests with proven ability to detect diverse and varying levels of motor deficits caused by 6‐OHDA lesion.…”