ABSTRACT
Cannabis (marijuana) abuse has become a source of concern globally affecting almost every nation for decades. Medical use of marijuana is also on the increase being legalized in some countries. Despite extensive research on smoked Cannabis, little is known about the psychotropic effects of marijuana wax (similar to n-butanol extract), a high potency form of Cannabis that is gaining in popularity. The present study examined the effect of n-butanol extract of Cannabis sativa L. on the frontal cortex of adult Wistar rats which involved the following investigations: acute toxicity study, routine histological and histochemical studies using haematoxylin & eosin and cresyl fast violet staining techniques; neurobehavioral studies using ladder rung walking (LRW) to assess motor function and acetylcholinesterase (AChE) activity using brain tissue homogenate. Thirty (30) Wistar rats (male and female) were divided into two experimental categories: twelve (12) rats for acute toxicity studies using Lorke's method and eighteen (18) rats for the main experiment were divided into three (3) groups. Group I served as the control group and was administered 1 ml of distilled water, while group II and III were administered 250 mg/kg and 500 mg/kg of n-butanol extract of Cannabis sativa L. respectively for 21 days via oral route. The result for acute toxicity study showed no mortality within 24 hours after oral administration of the extract. Reduced distribution of Nissl substance and distortion in cytoarchitecture of frontal cortex (layer V) with vacuolation, pyknosis and dissolution of nucleolus was observed in the treatment groups. The result for neurobehavioral study also showed a significant decrease (p<0.05) in foot fault scoring, increase in latency and foot placement accuracy of Wistar rats administered 250 mg/kg and 500 mg/kg n-butanol extract of Cannabis sativa L. when compared to the control. Neurotoxicity of cannabis exposure was also evident as it increased acetylcholinesterase activity in the treatment group. In conclusion, findings suggest that, n-butanol extract of Cannabis sativa L. at 250 mg/kg and 500 mg/kg is capable of causing neurotoxicity in the frontal lobe of adult Wistar rats which may leads to motor deficit.