Circulating ghrelin and ghrelin to obestatin ratio are low in patients with untreated mild-to-moderate hypertension

Obestatin, encoded by the same gene as ghrelin, was first described as a physiological opponent of ghrelin. We investigated fasting plasma ghrelin and obestatin levels and ratio of ghrelin to obestatin in humans with untreated mild-to-moderate hypertension and humans with normal blood pressure. We found that the plasma concentration of ghrelin and the ratio of ghrelin to obestatin were significantly lower in hypertension group compared with control group (236.3 ± 12.3 pg/ml vs 381.4 ± 25.6 pg/ml, P < 0.01; 0.89 ± 0.06 vs 1.2 ± 0.06, P < 0.01). The plasma concentration of obestatin was lower in hypertension group compared with control group, but the difference between the two groups was not significant (276.2 ± 15.1 pg/ml vs 325.4 ± 25.8 pg/ml, P > 0.05). In a multiple regression model, systolic blood pressure, triglyceride and obestatin were independent predictors of ghrelin (standardized coefficient = − 0.332; P = 0.019; standardized coefficient = − 0.302; P = 0.030; standardized coefficient = 0.630; P < 0.0005, respectively). In another multiple regression model, only ghrelin was an independent predictor of obestatin (standardized coefficient = 0.861; P < 0.0005). Both systolic blood pressure and triglyceride were independent predictors of ratio of ghrelin to obestatin (standardized coefficient = − 0.385; P = 0.033; standardized coefficient = − 0.430; P = 0.018, respectively). Our data suggests that there are disturbances of ghrelin and obestatin in the circulating plasma of humans and the ghrelin/obestatin system might play a role in blood pressure regulation.

Research Highlights
► Our study showed that both fasting plasma ghrelin level and the ratio of ghrelin to obestatin were significantly lower in hypertension group compared with control group and that SBP and DBP were negatively correlated with them in humans. To our knowledge, this is the first study reporting that there are disturbances of plasma ghrelin and obestatin levels in the patients with untreated mild-to-moderate hypertension.