Hypophysectomy enhances interleukin-1β, tumor necrosis factor-α, and interleukin-10 mRNA expression in the rat brain

Although the effects of various cytokines as regulators of hormone synthesis and production are well documented, the role for pituitary hormones as modulators of cytokine synthesis is not fully understood. In this study, we investigated the effect of pituitary hormones' depletion on cytokine synthesis after short- (21 days) and long- (35 days) term hypophysectomy (ST- HX and LT-HX, respectively). The expression of the proinflammatory cytokine interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) and the anti- inflammatory cytokines IL-10 and transforming growth factor-β (TNF-β) in the rat brain was studied using in situ hybridization. Our results indicate that IL-1β mRNA-expressing cells were significantly upregulated at day 21 in hypophysectomized rats compared to sham-operated controls. This enhanced expression was also detected later at day 35 post hypophysectomy. However, TNF-α mRNA expression was significantly increased only at the later sampling interval. IL-10 mRNA-expressing cells were increased after long-term hypophysectomy compared to controls. TGF-β mRNA-expressing cells were not increased after hypophysectomy. In conclusion, these results suggest a role for pituitary hormones in IL-1β, TNF-α, and IL-10 synthesis.