Objective: The aim of this study was to evaluate the effect of orexin-A (OX-A) and the orexin-1 receptor antagonist SB-334867 (SB) on motor and cognitive functions in a rat model of Parkinson’s disease. Methods: Parkinson was induced by intracerebroventricular (i.c.v) injection of 6- hydroxydopamine (6-OHDA) (200 μg/rat). 72 h later, the treatment was initiated by i.c.v administration of SB (30 nmol/rat) and/or OX-A (0.3 nmol/rat) for 10 days. Motor functions were monitored using rotarod and hanging tests. Cognitive function was assessed by passive avoidance test (Shuttle box). Results: OX-A administration in 6-OHDA treated rats remarkably increased the time which animals run on rod (in rotarod test) and also the latency to fall (in hanging test) (P < 0.01 and P < 0.001, respectively). Conversely, administration of SB in 6-OHDA-treated rats decreased the mentioned indices (P < 0.05 for latency to fall). Administration of agonist and/or antagonist of orexin-1 receptors had no significant effect on 6-OHDA induced cognitive impairment in rats. Conclusion: Results of this study suggest that the orexinergic system might be involved in sensory-motor deficits of Parkinson’s disease.

Diabetes mellitus is associated with the development of neuronal tissue damage in different central and peripheral nervous system regions. A common complication of diabetes is painful diabetic peripheral neuropathy. We have explored the antihyperalgesic and neuroprotective properties of Rosmarinus officinalis L. extract (RE) in a rat model of streptozotocin (STZ)-induced diabetes. The nociceptive threshold and motor coordination of these diabetic rats was assessed using the tail-flick and rotarod treadmill tests, respectively. Activated caspase-3 and the Bax:Bcl-2 ratio, both biochemical indicators of apoptosis, were assessed in the dorsal half of the lumbar spinal cord tissue by western blotting. Treatment of the diabetic rats with RE improved hyperglycemia, hyperalgesia and motor deficit, suppressed caspase-3 activation and reduced the Bax:Bcl-2 ratio, suggesting that the RE has antihyperalgesic and neuroprotective effects in this rat model of STZ-induced diabetes. Cellular mechanisms underlying the observed effects may, at least partially, be related to the inhibition of neuronal apoptosis.