Omentin-1 levels are reduced by pharmacologic doses of leptin, but remain unaffected by energy deprivation and display no day-night variation

Abstract

Objective: To study the day-night variation of omentin-1 levels and assess whether leptin and/or short- and long-term energy deprivation alter circulating omentin-1 levels via cytokines.

Design and methods: Omentin-1 levels were measured hourly in serum samples from six healthy men to evaluate for day-night variation. To study effects of acute energy deprivation and of leptin administration, eight healthy subjects were studied in the fasting state for 72 h with administration of either placebo or metreleptin (recombinant human leptin) in physiologic replacement doses. We evaluated the effect of leptin in pharmacologic doses on serum omentin-1 and cytokine levels, as well as on omentin-1 levels in ex vivo omental adipose tissue, in 15 healthy volunteers. To study the effect of chronic energy deprivation and weight loss on omentin-1 levels, we followed 18 obese subjects for 12 months who underwent bariatric surgery.

Results: There is no day-night variation in omentin-1 levels. Short-term and chronic energy deprivation, as well as ex vivo leptin administration and physiologic replacement doses of leptin, do not alter omentin-1 levels; pharmacologic doses of metreleptin reduce omentin-1 levels, whereas levels of tumor necrosis factor-α receptor II and interleukin-6 tend to increase.

Conclusions: Omentin-1 levels are reduced by pharmacologic doses of metreleptin independent of effects on cytokine levels.

Figure 1. Study 1: Study in the isocaloric fed state

Circadian variation of omentin-1 levels on day 3 of baseline fed state (95% confidence band in solid line, 95% prediction band in dashed line, bars are standard errors)

Figure 2. Study 4:Study in the fasting state with pharmacologic doses of metreleptin

Levels of leptin (Panel A), omentin-1 (Panel B), sTNFRII (Panel C) and IL-6 (Panel D) after administration of pharmacologic dose metreleptin (0.1mg/kg). Bars indicate standard errors; stars indicate significant change when compared with baseline, p <0.05.