Changes in the adrenal gland and cortisol secretions in experimental acute Trypanosoma brucei brucei infection in Sahel bucks

Abstract

The effects of experimental acute Trypanosoma brucei brucei infection on the function and structure of the adrenal gland of Sahel bucks were studied for forty days. Eight Sahel bucks aged between 8 and 15 months were used. They were divided into two groups of five (infected) and three (uninfected) bucks. Group I were inoculated with 1ml containing about 1×10⁶ trypanosomes (Trypanosoma brucei brucei, Federe strain) via the jugular vein. Group II was uninfected control. Parasitaemia in the infected bucks appeared 3-4 days post-infection. The mean serum cortisol concentrations of the uninfected control and the infected groups at day 0 were 3.33 ± 0.44 μg/dl and 2.4 ± 0.29μg/dl, respectively. By day 4 post-infection, the mean serum cortisol concentration of the infected group increased to its peak value of 21.8 ± 6.25μg/dl compared to 3.0 ± 0.86 μg/dl of the uninfected control on the day all infected bucks became parasitaemic. Grossly, the adrenal glands of the infected group were enlarged. Histopathologically, there was adrenal cortical hypertrophy in the infected group. The results indicate that acute trypanosomosis due to experimental T. brucei brucei infection in Sahel buck caused hypertrophy of the adrenal gland and a significant increase in the circulatory cortisol concentration of the infected bucks at the onset of parasitaemia followed by a decrease to pre-infection cortisol concentration till the end of the 40 days duration of the experiment. Further study on the long-term effect of experimental Trypanosoma brucei brucei infection on the adrenal gland of Sahel bucks is recommended.