Evaluation of the Therapeutic Potential of Anthocleista djalonensis Stem Bark Aqueous Extract against Mercury (II) Chloride-Induced Splenic Toxicity in Adult Wistar Rats

Mercury is a potent environmental toxin and a major global health concern, posing serious risks to humans and animals. This study examined the possible protective effects of Anthocleista djalonensis extract on the spleens of adult Wistar rats exposed to mercuric chloride. Anthocleista djalonensis, which is traditionally used in medicine, may contain compounds that prevent damage caused by mercuric chloride to vital organs such as the spleen. Following a two-week acclimatisation period, thirty-six (36) adult male rats were divided into six groups (six rats per group) and administered 2 mg/kg of mercuric chloride and varying doses of Anthocleista djalonensis extract, either separately or in combination, for 28 days. On day 29, the rats were sacrificed, and their spleens were carefully harvested, weighed and fixed in 10% formal saline for histological examination. The experiment evaluated changes in body weight, relative spleen weight and splenic cytoarchitectural integrity. The results showed that rats exposed to mercuric chloride alone (Group B) experienced significant weight loss, whereas administration of Anthocleista djalonensis extract at different doses prevented considerable changes in body weight. No appreciable differences in spleen weight were observed among the groups. Histopathological analysis revealed dose-dependent alterations in splenic tissue. The control group exhibited normal splenic architecture, with clearly defined red pulp, white pulp and sinuses, indicating a healthy immune microenvironment. Rats treated with HgCl₂ alone demonstrated follicular activation and reduced red cell sequestration. However, rats treated with Anthocleista djalonensis extract alone demonstrated enhanced red cell sequestration, follicular activation and sinus histiocyte activation, whereas varying levels of protection were observed when Anthocleista djalonensis extract and mercury(II) chloride were administered together. The study suggests that, whereas HgCl₂ exposure induces immunotoxicity and alters splenic function, Anthocleista djalonensis extract may exert protective effects by modulating immune responses and enhancing red cell sequestration.