To evaluate the effects of the hydromethanol extract of Helianthus annuus on leucocyte profile and spleen histology after prolonged exposure to Wistar rats. This study involved the incorporation of varied concentrations (2.50, 5.00 and 10.00 mg/10 g) of hydromethanol extract of H. annuus in feed and feeding same to Wistar rats for 90 consecutive days. Blood samples were collected from the retro-orbital plexus of the rats on days 30, 60 and 90, for leucocyte count. Histopathological examination of the spleen was also conducted. The extract treatment did not cause a significant (p >0.05) change in the leucocyte profile and the spleen histology in the treated rats when compared to the normal control rats. On day 90, the total leucocyte counts of 15.24 ± 1.47, 12.69 ± 0.84 and 16.29 ± 3.36 for the groups that were treated with extract 2.50, 5.00 and 10.00 mg/10 g feed respectively, were not significantly (p > 0.05) different when compared with the total leucocyte count (12.01 ± 0.77) of the control group. The findings suggest that hydromethanol extract of H. annuus do not have a significant effect on the leucocyte profile and the histology of spleen.
