Effects of aqueous seed extract of soybeans (glycine max) on mercury chloride-induced toxicity on the cerebrum of adult Wistar rats.

Abstract

Mercury chloride (HgCl₂) is a heavy metal known to cause adverse effects on biological systems, particularly the central nervous system. The cerebrum, which is responsible for cognitive functions, has been reported to be vulnerable to mercury toxicity. Numerous studies have demonstrated that plants and their phytochemicals possess therapeutic potentials. Hence, there is increased attention towards the therapeutic potential of herbal extracts. Soybean (Glycine max), a legume known for its high protein content and rich source of bioactive phytochemicals has been reported to possess antioxidant, anti-inflammatory, estrogenic, anti-diabetic, and neuroprotective properties. Accordingly, this study investigated the neuroprotective effects of aqueous seed extract of soybeans on mercury chloride-induced toxicity in adult Wistar rats. Twenty-four rats were divided into four groups (n=6): Group A (control) received 1ml distilled water, Group B received 4 mg/kg body weight of HgCl₂, Group C received 1000 mg/kg body weight of aqueous seed extract of soybeans, and Group D received 1000 mg/kg body weight of aqueous seed extract of soybeans 1 hour before 4 mg/kg HgCl₂. All administration via orogastric tube lasted for 28 days. At the end of the experimental period, the rats were weighed and Y-maze test was used to evaluate spontaneous alternation of the experimental rats. Following sacrifice, the cerebrum was harvested for histological assessment. Results obtained shows a significant decrease (p<0.05) in the body weight change of experimental animals in Group B when compared to group A (control) while Groups C and D showed significant increases (p<0.05) in the body weight change when compared to Group B. No significant differences were observed in relative brain and cerebral weights across experimental groups. In the Y-maze test, Group B exhibited a significant decrease (p<0.05) in spontaneous alternation when compared to group A whereas Groups C and D showed significant increase (p<0.05) in spontaneous alternation when compared to Group B. Photomicrographs obtained revealed shrunken neuronal cells with pyknotic nuclei and irregular pia mater in group B when compared to group A. Group C showed fewer dark, shrunken neuronal cells while Group D, several normal pyramidal cells were observed when compared to group B. These findings suggest that aqueous seed extract of soybean possess the potential to mitigate mercury chloride-induced neurotoxicity. Further research is needed to understanding the mechanism of action involved in the neuroprotective potentials exhibited by aqueous seed extract of soybeans.