The modifying effects of fish oil on fasting ghrelin mRNA expression in weaned rats

Ghrelin expression and secretion seem to be influenced by the fat content of the diet. However, data on the probable adverse effect of high fat diet (HFD) with different dietary fats and saturation level of fatty acids is inconclusive. This study aimed at investigating the effects of HFDs on fasting total and acyl-ghrelin plasma levels, gastric fundus and duodenum ghrelin mRNA expressions. Weaned Wistar rats (n = 50) were randomly divided to five groups of HFDs with fish oil (HF-F), olive oil (HF-O), soy oil (HF-S), butter (HF-B) and the controls. After 8 weeks, blood samples were collected. While the animals were fasting for 24 h, their blood and tissue samples were obtained. Plasma parameters of total and acyl ghrelin and ghrelin mRNA expression level in stomach and duodenum were measured.The HF-B fed group had lower fasting plasma acyl ghrelin level than the control, HF-F and HF-O groups (P < 0.05); furthermore, the HF-F group had significantly higher acyl ghrelin level than the HF-S one (P < 0.05). After feeding, all the groups, except for the HF-B one, had a significantly lower plasma acyl ghrelin levels (P < 0.05), compared with the fasting state. Ghrelin mRNA expression levels in the gastric fundus and duodenum were significantly lower in the HF-B as compared to the control group. Furthermore, the HF-F group had significantly higher mRNA level in the duodenum, in comparison with the HF-B and HF-S groups. As HF-F and HF-O diets had the highest stimulatory effect on fasting ghrelin expression and plasma level, consumption of these dietary oils can play an important role in ghrelin regulation, which might affect feeding behavior and energy intake.

► HF-S and HF-B did not increase fasting acyl-ghrelin concentration.
► Food intake and weight gain in HF-S and HF-B groups were higher than other ones.
► Fasting mRNA expression in duodenum was only modified by the HF-F.
► HF-F and HF-O had the highest stimulatory effect on fasting ghrelin expression and plasma level.