Thyrotoxic Evaluation and Lipid Peroxidation in Wistar Albino Rats Exposed to Vitellaria paradoxa Stem Bark

Background: Vitellaria paradoxa stem bark is used by villagers because of its antimicrobial activity for treating skin diseases and wound infections in some parts of Nigeria without considering its safety.

Aim: The aim of the study was to determine the effect of ingestion of Vitellaria paradoxa stem bark on thyroid hormones and lipid peroxidation in Wistar albino rats.

Place and Duration of Study: The study was undertaken at the Department of Chemical Pathology, Faculty of Medical Laboratory Sciences, Usmanu Danfodiyo University, Sokoto.

Methods: The oral acute toxicity of the extract (LD50) was determined in 30 Wistar rats divided into 6 groups of 5 rats per group. Group 1 was the control and received normal saline. Different doses of 5, 50, 300, 2000, and 5000 mg/kg were administered once to the study groups (2, 3, 4, 5 and 6) respectively. A sub-chronic toxicity study was then carried out in 30 Wistar rats, divided into six groups of 5 rats per group. Group 1 served as control and was given normal saline and standard rat pellets. The remaining 5 groups were administered different doses of 50, 100, 200, 300 and 400 mg/kg Vitellaria paradoxa stem bark extract daily respectively for 30 days. Thyroid function test (T3, T4 and TSH) was carried out by the use of enzyme linked immunosorbent assay (ELISA), malondialdehyde (MDA) and total antioxidant status (TAS) determined by spectrophotometric techniques.

Results: No mortality was recorded in the rats after 24 hours and up to 14 days post-oral treatment, an indication that LD50 of the extract is greater than 5000 mg/kg. In the sub-chronic toxicity study, T3, T4 and TSH values of animals that received higher doses were significantly decreased (p<0.05) than the control groups. MDA values were significantly lower (p<0.05) in treated animals than the control group but there was no significant difference (p>0.05) in the values of TAS.

Conclusion: T3 and T4 play important roles in metabolism, growth and development among others, consumption of Vitellaria paradoxa may have harmful effect in the long term users. Hence, T3 and T4 should be monitored in Vitellaria paradoxa consumers so as to prevent induction of hypothyroidism. However, it may still be of clinical benefit in the treatment of hyperthyroidism. Consumers may not develop oxidative stress induced diseases because of reduced values of MDA in the treated animals.