Research articleThe therapeutic potential of Berberine chloride hydrate against harmaline-induced motor impairments in a rat model of tremor

•Harmaline significantly increased step width and tremor scores.•Muscle strength and time on rod decreased in harmaline group.•BBR partially reversed the effects of harmaline on motor and balance function.•Berberine in a dose dependent manner improved harmaline - induced neurotoxicity.•High dose of berberine had the same tremor score as compared to harmaline.

Essential tremor (ET) is a progressive neurological disorder with motor and non-motor symptoms. It has conclusively been shown that modulation of glutamate receptors could ameliorate ET. Recent studies have suggested that Berberine (BBR) has an inhibitory effect on glutamate receptors. Therefore, BBR may have therapeutic effects on ET. In this study, male Wistar rats (n = 10 in each group) weighing 40-60 g were divided into control, harmaline (30 mg/kg, i.p.) and berberine (10, 20 or 50 mg/kg, i.p, 15 min before harmaline injection) groups. Open field, rotarod, wire grip and foot print tests were used to evaluate motor performance. The results indicated that the administration of BBR (10 and 20 mg/kg) attenuated harmaline-induced tremor in rats, but the beneficial effects of BBR could not be identified at dose 50 mg/kg. In addition, BBR ameliorated gait disturbance in doses of 10 and 20 mg/kg. The high dose of BBR not only failed to recover step width but also showed an adverse effect on left and right step length. The results indicate that BBR only in dose of 20 mg/kg recovers mobility duration. The current study found a dose-dependent manner for the therapeutic effects of BBR in ET. Our study provides the initial evidence for the effects of BBR on motor function. Since BBR exerts its effects mainly through regulation of neurotransmitter release or blocke of NMDA receptors, thus, it is predicted that BBR ameliorate harmaline effect through blockade of NMDA receptors or glutamate release. This is an important issue for future research to evaluate the possible mechanisms involved.