Thyroid status and adenosine triphosphataseactivity in experimental Trypanosoma congolense infection in rabbits

The effect of trypanosome infection on the plasma levels and ratios of tri-iodothyronine (T₃) and thyroxine (T₄) as well as the activity of mitochondrial adenosine triphosphatase (ATPase) were investigated. Three groups of sexually mature white New Zealand rabbits were used. Group 1 consisted of the normal non-infected rabbits, group 2 were experimentally infected with Trypanosoma congolense and group 3 were infected but given replacement doses of thyroxine. The infected animals (group 2) showed a rapid decline in both T₃ and T₄ but an increase in the T₃/T₄ ratio indicating differential production or clearance rates between the two hormones. The mitochondrial ATPase activity was found to be depressed in the infected group whereas there was no significant difference in the ATPase activity between the non-infected (group 1) and infected-treated animals (group 2). It is postulated that trypanosome induced hypothyroid status may play a role in the impairment of mitochondrial ATPase activity, a key enzyme in energy metabolism.