ABSTRACT
Mercury is a global environmental pollutant, which can accumulate in the different organ system of the body inducing tissue damage and oxidative stress especially in the nervous system. Due to its widespread exposure, it has proven to be a serious health hazard. Neurodegenerative disorders as well as different pathological diseases has been said to induce oxidative stress. Mercury chloride toxicity has been shown to induce oxidative stress through the generation of free radicals and alteration of the cellular antioxidant defense system. Humans are equipped with a defense system that controls free radicals and reduces oxidative stress. The intake of exogenous is able to mop up these excess free radicals which are produced due to mercury chloride exposure. Rooibos tea which is well known for its rich antioxidant contents, has been reported to have a high potency in enhancing intracellular antioxidant defenses thereby leading to reduced oxidative stress. Studies have shown its anti-inflammatory, anti-diabetic and anti-oxidative effects. For these forty-four days of study, thirty adult Wistar rats, which weighed between 127g to 179g, were used for this study. The rats were grouped into five groups (A, B, C, D and E), and these groups contained a total of six rats each. They were bred at the Animal House, Department of Anatomy, School of Basic Medical Science, College of Medical Sciences, University of Benin, Benin City, Edo State, Nigeria and kept in polypropylene cages under normal room temperature. At this stage, the administration began. Group A acted as the control and were given 1ml of sterile water, Group B was given 4mg/kg bodyweight of Mercury chloride only, Group C was administered with 250mg/kg bodyweight aqueous leaf extract of Aspalathus linearis and 4mg/kg bodyweight of Mercury chloride, Group D were administered with 500mg/kg bodyweight aqueous leaf extract of Aspalathus linearis and 4mg/kg bodyweight of Mercury chloride, Group E were administered with 500mg/kg bodyweight aqueous leaf extract of Aspalathus linearis only. All administrations were given orally, through an orogastric tube. At the end of the study period, the rats were weighed and neurobehavioral activities such as novel object recognition test and y-maze test were evaluated. The rats were euthanized through cervical dislocation and their brains dissected out. Findings from this study showed that RI was significantly lowered in Mercury Chloride only treated rats when compared with controls. Conversely, when compared to rats exposed to BPA only, a significant increase in RI was observed in the RB group thus suggesting a neuroprotective role by rooibos tea against possible BPA-induced short-term memory loss. Histological findings from the control showed the normal histology of the hippocampus. However, mercury chloride treated group of Wistar rats showed depletion, reduction, degeneration of cells. However, administration of the extract, Rooibos Tea, was actually able to mitigate the depletion and degeneration of cells in the hippocampus of adult Wistar rats. In conclusion, aqueous extract of Aspalathus linearis had no effect in the histopathological damage of the hippocampus caused by the action of the mercury chloride.
