Effects of aqueous extract of <i>Syzygium aromaticum</i> (<i>clove</i>) on mercury chloride-induced toxicity in the hippocampus of adult Wistar rats

Mercury is a neurotoxic substance that crosses the blood-brain barrier and disrupts neuronal functions by inducing oxidative stress (OS), impairment of neurotransmission, and neuronal damage, resulting in cognitive and motor dysfunction. Since OS is one of the mechanisms of actions of mercury, reports suggest that antioxidant-rich plants can attenuate its effects. Accordingly, this study investigated the effect of aqueous extract of Syzygium aromaticum (AESA) on mercury chloride - induced hippocampal toxicity in adult Wistar rats. Thirty-six (36) rats were randomized into six groups of six rats each. Group A (Control), B [4 mg/kg mercury chloride (HgCl2)], C (250 mg/kg AESA), D (500 mg/kg AESA), E (4 mg/kg HgCl2 and 250 mg/kg AESA) and F (4 mg/kg H g C l 2 a n d 5 0 0 m g / k g A E S A ) . A l l administration was via oral route and lasted for 28 days. At the end of the experimental period, rats were weighed, euthanized via cervical dislocation, brain harvested, weighed and analyzed for biochemical and histological changes. Findings from the study revealed that Syzygium aromaticum is a nutrient-rich plant as indicated by its high content of bioactive compounds like glycosides, phenols, flavonoids, alkaloids and eugenols. There was a significant decrease (p<0.05) in body weight, SOD, CAT, GPx activity, as well as a significant increase (p<0.05) in MDA concentration in rats treated with HgCl2 only when compared to control. A significant increase (p<0.05) in body weight, SOD, CAT, GPx activity as well as a significant decrease (p<0.05) in MDA concentration was observed in rats treated with AESA when compared to HgCl2 only group. Histological findings revealed atrophy and vacuolation of the pyramidal cells and astrocytes in the hippocampus of rats treated with HgCl2 only when compared to control. However, normal pyramidal cells of the hippocampus (CA1) were observed in HgCl2-exposed rats pretreated with AESA comparable to the rats treated with HgCl2 only. Conclusively, S. aromaticum possesses significant neuroprotective effects, suggesting its potential as a therapeutic agent in the prevention and management of neurodegenerative disorders.