EVALUATING THE NEUROPROTECTIVE POTENTIAL OF AQUEOUS ASPALATHUS LINEARIS (ROOIBOS) LEAF EXTRACT ON MERCURY CHLORIDE-INDUCED TOXICITY IN THE CEREBELLUM OF ADULT WISTAR RATS
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ABSTRACT
Mercury is a common element in the environment that causes oxidative stress in those who are exposed, which in turn causes tissue damage. The role of natural antioxidants, especially those derived from plants is gaining a lot of attention with scientific evidence showing that vegetables, fruits and teas have protective effects and promote good health. Aspalathus linearis, commonly known as Rooibos, is well known for its rich content of different compounds with antioxidant properties. Studies have shown that it has anticarcinogenic, antimutagenic, anti-diabetic, antioxidant, cardio-protective effects. In this study, the neuroprotective activities of Aspalathus linearis (rooibos) was investigated in mercury chloride-induced neurotoxicity in experimental animals. Forty two adult Wistar rats, which weighed an average of 161g, were used for this study. The rats were grouped into seven groups (A, B, C, D, E, F and G), of six rats each. Group A served as the control and were given 1ml of sterile water, Group B (HgCl2) were given 4mg/kg bodyweight of Mercury chloride only, Group C (RBT + HgCl2) were administered 250mg/kg bodyweight aqueous leaf extract of Aspalathus linearis and 4mg/kg bodyweight of Mercury chloride, Group D (RBT + HgCl2) were administered 500mg/kg bodyweight aqueous leaf extract of Aspalathus linearis and 4mg/kg bodyweight of Mercury chloride, Group E (RBT) were administered 500mg/kg bodyweight aqueous leaf extract of Aspalathus linearis only, Group F (Vit E + HgCl2) were administered 500mg/kg bodyweight of vitamin E and 4mg/kg bodyweight of Mercury chloride and Group G(Vit E) were administered 500mg/kg bodyweight of vitamin E only. All administrations were given orally, through an orogastric tube and the experiment lasted for 28 days. At the end of the study period, the rats were weighed and open field test was performed. The rats were euthanized through cervical dislocation and their brains dissected out. Brain weight was recorded and antioxidant parameters such as MDA, GPx and SOD was investigated. Histology of the cerebellum was also examined in all groups. Result shows, in the neurobehavoural activity, for rearing and ambulation a decrease (P < 0.05) was observed in group B when compared with control, however in rearing and ambulation an increase (P > 0.05) was observed in group C, D and F when compared with group B. For grooming and immobility an increase (P > 0.05) was observed in group B when compared with control, however in grooming and immobility a decrease (P < 0.05) was observed in group C, D and F when compared with group B. Result for antioxidant activity showed oxidative stress ( low antioxidant activity) in group B whereas the Control, RBT and Vit. E groups increase in antioxidant activity. Result from histology showed degeneration of the purkinje cells in the purkinje cell layer of the cerebellum in group B when compared with control, however treatment with RBT and Vit. E reversed the effect. In conclusion the findings showed Aspalathus linearis (rooibos) help to attenuate the neurotoxic effect of mercury-chloride on the cerebellum of adult Wistar rat
Mercury is a common element in the environment that causes oxidative stress in those who are exposed, which in turn causes tissue damage. The role of natural antioxidants, especially those derived from plants is gaining a lot of attention with scientific evidence showing that vegetables, fruits and teas have protective effects and promote good health. Aspalathus linearis, commonly known as Rooibos, is well known for its rich content of different compounds with antioxidant properties. Studies have shown that it has anticarcinogenic, antimutagenic, anti-diabetic, antioxidant, cardio-protective effects. In this study, the neuroprotective activities of Aspalathus linearis (rooibos) was investigated in mercury chloride-induced neurotoxicity in experimental animals. Forty two adult Wistar rats, which weighed an average of 161g, were used for this study. The rats were grouped into seven groups (A, B, C, D, E, F and G), of six rats each. Group A served as the control and were given 1ml of sterile water, Group B (HgCl2) were given 4mg/kg bodyweight of Mercury chloride only, Group C (RBT + HgCl2) were administered 250mg/kg bodyweight aqueous leaf extract of Aspalathus linearis and 4mg/kg bodyweight of Mercury chloride, Group D (RBT + HgCl2) were administered 500mg/kg bodyweight aqueous leaf extract of Aspalathus linearis and 4mg/kg bodyweight of Mercury chloride, Group E (RBT) were administered 500mg/kg bodyweight aqueous leaf extract of Aspalathus linearis only, Group F (Vit E + HgCl2) were administered 500mg/kg bodyweight of vitamin E and 4mg/kg bodyweight of Mercury chloride and Group G(Vit E) were administered 500mg/kg bodyweight of vitamin E only. All administrations were given orally, through an orogastric tube and the experiment lasted for 28 days. At the end of the study period, the rats were weighed and open field test was performed. The rats were euthanized through cervical dislocation and their brains dissected out. Brain weight was recorded and antioxidant parameters such as MDA, GPx and SOD was investigated. Histology of the cerebellum was also examined in all groups. Result shows, in the neurobehavoural activity, for rearing and ambulation a decrease (P < 0.05) was observed in group B when compared with control, however in rearing and ambulation an increase (P > 0.05) was observed in group C, D and F when compared with group B. For grooming and immobility an increase (P > 0.05) was observed in group B when compared with control, however in grooming and immobility a decrease (P < 0.05) was observed in group C, D and F when compared with group B. Result for antioxidant activity showed oxidative stress ( low antioxidant activity) in group B whereas the Control, RBT and Vit. E groups increase in antioxidant activity. Result from histology showed degeneration of the purkinje cells in the purkinje cell layer of the cerebellum in group B when compared with control, however treatment with RBT and Vit. E reversed the effect. In conclusion the findings showed Aspalathus linearis (rooibos) help to attenuate the neurotoxic effect of mercury-chloride on the cerebellum of adult Wistar rat
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