Objective: To explore the exact role of ghrelin in glyco- and lipo-metabolism.
Methods: We compared the levels of ghrelin mRNA in gastric tissue, ghrelin in gastric tissue and plasma among LETO rats( non diabetes, n=10), OLETF rats( type 2 diabetes, n=10), OLETF/M rats( OLETF rats managed with Metformin at the dose of 100 mg/kg weight, n=10) and OLETF/F rats( OLETF rats managed with Fenofibrate at the dose of 20 mg/kg weight, n=10). The levels of ghrelin mRNA were tested by Northern blotting, and the ghrelin content in gastric tissue and plasma detected by RIA.
Results: At the age of 30 weeks, the ghrelin fasting plasma levels of OLETF rats were lower than those of LETO rats(37.49+/-6.42 vs 58.52+/-5.85, P<0.05). The fasting blood plasma ghrelin levels of OLETF/M groups showed an increased tendency, but the difference of the fasting blood plasma ghrelin levels to those of the untreated OLETF rats were not noticeable(49.65+/-6.76 vs 37.49+/-6.42,P>0.05). However, the fasting blood plasma ghrelin levels of OLETF/F group were more than those that of the untreated OLETF rats (62.02+/-7.35 vs 37.49+/- 6.42,P<0.05). The mRNA and polypeptide levels of ghrelin in stomach tissue had no marked difference in the 4 groups at the age of 17 weeks. At the age of 30 weeks, the difference of mRNA(1.18+/-0.06 vs 1.27+/-0.05,P<0.05) and polypeptide (114.77+/- 31.65 vs 152.87+/-18.24, P<0.05) between OLETF group and LETO group had been observed. Metformin didn't influence the mRNA and polypeptide levels of ghrelin in stomach tissue markedly. Howere, the polypeptide (161.75+/-23.61 vs 114.77+/-31.65, P<0.05) and mRNA(1.36+/-0.09 vs 1.18+/-0.06,P<0.05) levels of ghrelin in stomach tissue of OLETF/F group were markedly higher than those of stomach tissue ghrelin in the untreated OLETF group.
Conclusion: Our data demonstrate that ghrelin may play a role in protective, compensative and negative-feedback regulation in the disorder of glucose and lipid metabolism.