Hypophysectomy inhibits the synthesis of tumor necrosis factor α by rat macrophages : partial restoration by exogenous growth hormone or interferon γ

We recently demonstrated that GH and interferon-γ (IFNγ) act in a similar manner to prime macrophages in vitro and in vivo for enhanced superoxide anion release. In this report we investigated the physiological role of the pituitary gland and GH in in vivo priming of resident peritoneal macrophages for the synthesis of tumor necrosis factor-α (TNFα) in vitro. Compared to normal rats, hypophysectomized animals had an 83% reduction in macrophage production of TNFα after in vitro stimulation with lipopolysaccharide. Sham operation had no significant effect on the ability of macrophages to secrete TNFα in response to lipopolysaccharide. Both native pituitaryderived porcine GH (48 μg/rat · 9 days) and native pituitaryderived rat GH (96 μg/rat · 9 days) more than tripled the in vitro production of TNFα by macrophages from hypophysectomized rats (342 and 358 vs. 112 U/mg protein for placebo-treated rats, respectively). Each of these preparations of GH also increased growth more than 6-fold in hypophysectomized r...