Reza Vajdi-Hokmabad
1, Mojtaba Ziaee
2, Saeed Sadigh-Eteghad
3, Siamak Sandoghchian Shotorbani
4, Javad Mahmoudi
3*1 Department of veterinary, Miyaneh branch, Islamic Azad University, Miyaneh, Iran.
2 Medicinal Plant Research Center, Institute of Medicinal Plants, ACECR, Karaj, Iran.
3 Neurosciences Research Center (NSRC), Tabriz University of Medical Sciences, Tabriz, Iran.
4 Department of Immunology, Tabriz Branch, Islamic Azad University, Tabriz, Iran.
Abstract
Purpose: Modafinil is a vigilance-enhancing drug licensed for narcolepsy. The use of modafinil leads to various neuromodulatory effects with very low abuse potential. A body of evidence suggested that modafinil may have anti-parkinsonian effects. This study was designed to evaluate whether modafinil could improve motor dysfunction in the 6-hydroxydopamine (6-OHDA)-induced rat model of Parkinson’s disease. Methods: Male Wistar rats (180-220 g, n= 98) were used in this study. Parkinsonism was induced by injection of 6-hydroxydopamine (10 μg/2μl in 0.2 % ascorbic acid-saline) into the right striatum. Parkinsonian rats received intraperitoneal (ip) injections of modafinil (50, 75, and 100 mg/kg) and catalepsy-like immobility was assessed by the bar test (BT). Furthermore, involvement of dopamine D1 and D2 receptors in modafinil’s anti-parkinsonian effects was studied. For this purpose, parkinsonian animals were pretreated with SCH23390 and raclopride (the dopamine D1 and D2 receptor anatgonists, respectively) or SCH23390 + raclopride, and then assessed by the BT. Results: Modafinil (100 mg/kg) showed anti-cataleptic effects in the BT. Notably, the effect of modafinil in the BT was reversed in parkinsonian rats pretreated with raclopride (1.25 mg/kg) and/or SCH23390 + raclopride (0.75 and 1.25 mg/kg, respectively), but not in those pretreated with SCH23390 (0.75 mg/kg). Conclusion: Acute administration of modafinil improves 6-OHDA-induced motor impairment possibly through activation of dopamine D2 receptors.