Effects of testosterone on fever and vasopressin mRNA in wether sheep given endotoxin.

This study investigated the effects of testosterone on the febrile response of castrated rams to immunological challenge. Core temperature was recorded by radiotelemetry in wethers (n = 6) injected with lipopolysaccharide endotoxin or saline before and after androgen treatment. The number of cells expressing vasopressin mRNA in the brain region implicated in the anti-pyretic response, the bed nucleus of the stria terminalis, was determined by in situ hybridisation histochemistry. Endotoxin, but not androgen, increased vasopressin message (P < 0.05), and androgen also did not alter basal or febrile temperatures. Hence, these preliminary findings question whether the androgen-dependent anti-pyretic mechanism described in the male rat is of physiological significance in the ram.