Olfacto-protective roles of Nigella sativa oil in Harmaline-induced essential tremor modelling

Abstract

Background: Harmaline is a tremorgenic beta-carboline, reported to induce acute postural and kinetic tremor. Essential Tremor (ET) is an idiopathic slowly neurodegenerative tremor disorder which also compromises olfactory acuity. Nigella sativa (NS) is a therapeutic agent widely used in the treatment of various ailments. Objective: To determine the effect of NSon olfactory functions of mice treated with harmaline. Methods: Seventy-five BALB/c male mice weighing 20g-25g, were equally divided into five groups, namely CNTRL (received only Normal saline), NS (received NS oil1ml/kg), HML(received Harmaline 20mg/kg), HNS (received Harmaline and Nigella sativa concurrently), and NSH (received NSfollowed by Harmaline). Olfactory sensitivity and discrimination were assayed through buried food test. The olfactory bulb was assayed neurochemically for glutamate and dopamine, and histologically for neuronal architecture using haematoxylin and eosin stain. Differences in neurochemical and histological data, body weight, appetite, relative brain weight, sensitivity and discrimination indices were statistically analysed. Results: NS was significantly protective against the negative effects of Harmaline. It also effected quick olfactory discrimination, increased dopamine level, decrease in weight difference and increased food consumption in the animals. However, Harmaline increased relative brain weight and GPX levels. The concurrent administration aided in the reduction of neuronal density while neuronal average size reduced on pre-treatment with NS. Conclusion: Harmaline did not induce tremor in the animals, though it resulted in histological and neurochemical deficits. However, it resulted in olfactory insensitivity and indiscrimination, both of which were prevented and ameliorated by Nigella sativa oil.