Endotoxin-induced interleukin 1 expression in testicular macrophages is accompanied by downregulation of the constitutive expression in Sertoli cells.

Interleukin-1alpha (IL-1alpha) is constitutively produced by Sertoli cells in adult rat testes. We demonstrate here that adult rats initiate expression of IL-1alpha and IL-1beta in testicular macrophages and decrease plasma testosterone by 60%, 2 h after administration of endotoxin. The macrophage activation was accompanied by downregulation of IL-1alpha mRNA expression in Sertoli cells. Despite increased tissue concentrations of IL-1alpha and IL-1beta immunoreactive protein, the level of bioactive IL-1 in the testis remained unchanged. Testes from prepubertal rats responded similarly to endotoxin, but lacked constitutive expression of IL-1alpha. We conclude that endotoxin-induced inflammation involves the testis by local macrophage activation and cytokine secretion. The paracrine mechanisms regulating IL-1 bioactivity in the testis are unknown but may represent a means to protect germ cells from noxious effects of inflammation. Copyright 2001 Academic Press.