Abstract

The toxicological evaluation of aqueous and methanolic leaf extract of Cannabis sativa (marijuana) was investigated in liver and brain of male rats. Twenty seven (27) male albino rats were divided into three groups (A, B and C) comprising nine rats each. Animals in group A (115.43±2.45g), B (135.56±3.27g) and C (145.92±2.13g) were administered 0.5 ml of distilled water, 700 mg/kg body weight aqueous and methanolic extract of C. sativa leaves respectively. Treatment was done once daily during which 3 rats from each group were sacrificed at interval of 7 days until the 21st day. Phytoconstituents present in the methanolic extract are alkaloids, steroids, phenolics, terpenoids, saponins, flavonoids, carbohydrates, tannins, cardiac glycosides, starch and reducing sugars while the aqueous extract contains all except phenolics, tannins and starch. From week1, week2 and week3, while treatment with both aqueous and methanolic extract significantly (p< 0.05) decreased WBC, MCV, monocyte, lymphocytes, total and direct bilirubin as well as the activities of ALP, AST, ALT in the aqueous and methanol group when compared with the control group, it increased platelet count. However, treatment with both extract from week1 to week3 did not significantly (p> 0.05) affect the levels of PCV and hemoglobin when compared with the control group. Histological section of the liver and brain were normal for the control group from week1 to week3. However, it showed acute hepatocellular necrosis and central vein inflammation for both aqueous and methanol treated groups from week1, week2 and week3. In the brain, it showed neurosis, neuronal degeneration and perivascular congestion in both groups throughout the exposure period. The effect of methanolic extract was greater than that of the aqueous extract both in liver and brain. Overall, the various alterations in biomolecules which do not compare favourably with the control values as evidenced with degeneration in histology suggest that the plant extract has both functional and structural toxicity. This study also supports the speculation that consumption of Cannabis sativa may contribute to increasing incidence of liver failure and brain damage.