Progesterone and IL-17 levels vary on a circadian basis in the mouse liver. Effect of the TNFRp55 deficiency.

RAGUSA JAV; ARIAS JL; DE LA VEGA M; DELGADO SM; DI GENARO MS; CASAIS M; ANZULOVICH AC

POTRERO DE LOS FUNES, SAN LUIS

Congreso; XXX REUNION ANUAL DE LA SOC. DE BIOLOGIA DE CUYO; 2012

Circadian rhythms in peripheral clocks, are regulated by neuroimmunendocrine signals coming, directly or indirectly, from the master clock in the suprachiasmatic nucleus. TNF is a pleiotropic cytokine which exerts its biological function upon binding to its cognate membrane receptors TNFRp55 and TNFRp75. Many key metabolizing enzymes e.g steroidogenics ones, exhibit a circadian tissue-dependent expression profile. Our objective was to analyze the circadian variation of progesterone (Pg) and IL-17 levels as well as the temporal expression of three main enzymes of Pg metabolism (3β-HSD, 20α-HSD and Star), in the liver of C57BL/6, wild type and TNFRp55-/-, mice. Pg and IL-17 levels were measured by RIA and ELISA, respectively. Expression of hepatic 3β-HSD, 20α-HSD and Star was determined by RT-PCR. Levels of Pg and IL-17 oscillate circadianly in the mouse serum and liver. TNFRp55 deficiency affected the phase and the amplitude of Pg curves, however it did not modify those parameters of IL-17 rhythms. Unexpectedly, transcript levels of 3β-HSD, 20α-HSD and Star did not show circadian profiles along a 24 h period. Thus, we suggest the circadian variation of Pg levels could be the result of a circadian post-transcriptional and/or translational regulation of its metabolizing enzymes.