Plasma ghrelin and obestatin levels are altered in a pre-diabetic rat model exhibiting established obesity and hypertension

Aims: Altered blood levels of ghrelin and obestatin are associated with appetite, body weight and diabetes, as well as the development of hypertension. Several studies have linked changes in these hormones to the development of metabolic syndrome although this remains controversial. This study examined whether alterations in plasma obestatin and ghrelin levels are associated with the onset of diabetes.
Methods: A pre-diabetic rat model exhibiting established obesity and hypertension was employed. Rats (5 weeks) were fed a standard or high-fat (HF; 36.0%) diet for a periods of 8 weeks. Metabolic measurements were measured twice weekly and blood was sampled for hormone analysis of plasma ghrelin and obestatin levels over 8 weeks. The ghrelin/obestatin ratios were also examined.
Results: Plasma obestatin levels were significantly lower in HF fed rats at week 0 and week 2 (27.7% and 24.8%, respectively; p < 0.05; n = 8), however were unchanged from week 4–8. Plasma ghrelin levels were significantly decreased in HF fed rats compared with those consuming a standard diet over the 8 weeks (19.4–41.0%; p < 0.05–0.01, n = 8). A reduction in the ghrelin/obestatin ratio was observed in HF fed rats at week 4 until week 8 (33.0–42.4% decrease; p < 0.05-0.01). Interestingly, there was no association between hormone levels and blood glucose levels; however ghrelin levels were negatively correlated with hypertension and body weight.
Conclusion: Plasma obestatin and ghrelin levels are significantly reduced in a pre-diabetic rat model which exhibits obesity and hypertension. This suggests that these hormones are associated with the development of metabolic syndrome.