Journal of Krishna Institute of Medical Sciences University (Jul 2018)
Pro-Neurogenic and Antioxidant Efficacy of Nigella sativa Oil Reduced Vulnerability Cholinesterase Dysfunction and Disruption in Amygdala-Dependent Behaviours in Chlorpyrifos Exposure
Abstract
Background: Organophosphorus Pesticides (OPs) are compounds with irreversible cholinesterase activity which induce cholinergic neurotoxicity, but still remain a widely used pesticide in household and agriculture. Aim and Objectives: This study investigated the efficacy of a natural antioxidant Nigella sativa Oil (NSO) against Chlorpyrifos (CPF) induced oxidative stress and implications on emotionality behaviours. Material and Methods: Thirty-two adult Wistar rats were randomly divided into four groups, and exposed to (1 ml/kg b w) of normal saline, (14.9 mg/kg b w) of CPF, (14.9 mg/kg b w) of CPF plus (1 ml/kg b w) of NSO and (1 ml/kg b w) of NSO respectively for 14 consecutive days. Body weight were recorded at day 1 and 15 of the experiment, the rats were exposed to trials in both Open Field Test (OFT) and Elevated Plus Maze (EPM) to asses anxiety-like behaviours and fear related learning respectively on the 13th day. Rats were euthanized by the 15th day, the brains excised, and the amygdala area of brains were removed, homogenized to analyse for total Reactive Oxygen Species (ROS), Nitrous Oxide (NO) levels and Acetylcholinesterase (AChE) activities, while the other three were processed for histology (Nissl stain) and Proliferative marker (Ki67 immunohistochemistry). Results: Repeated CPF exposure caused an increase in NO and ROS levels, reduction in AChE activities and a loss in the neurogenic cells in the amygdala. It was also a prolonged freezing period, centre squares avoidance and delayed transfer latency with CPF exposure. However, NSO prevented the overproduction of ROS and NO, and markedly reactivated AChE activities in the amygdala either with or without CPF exposure. NSO treatment was also, able to preserve neurogenic cells in the amygdala and subsequently improved amygdala-dependent behaviours in the treated rats. Conclusion: The antioxidant efficacy of NSO could be efficacious in CPF induced neuro-cognitive toxicity in rats.
