ABSTRACT
Objective To investigate the correlation between orexin A and the serine proteinase inhibitor vaspin in obese rats with insulin resis?tance(IR)induced by high?fat diet and elaborate the possible action mechanism of orexin involvement in fat metabolism in IR pathological process. Methods A total of 75 4?week?old male Sprague?Dawley rats were randomly divided into the normal dietary group(NC group,n=20)and the high?fat dietary group(HF group,n=55)to establish the model of obese rats with IR,the euglycemic insulin clamp technique was used to determine re?lated indicators of insulin resistance and lipid metabolism. The rats were treated with orexin A(1×10-8?1×10-6 mol/L)by hypodermic injection. The serum levels of orexin A and vaspin in rats were detected with enzyme linked immunosorbent assay. Results After 6 weeks of high?fat diet,the se?rum glucose,insulin,TC,TG and LDL?C were increased significantly in HF group than in NC group,while GIR60~120 in obese rats was decreased significantly[(16.31 ± 1.54)vs(30.22 ± 2.76)mg/(kg · min),P<0.05]. The serum vaspin level was increased 177.08%in HF group compared with NC group(P<0.05). With hypodermic injection of orexin A(1×10-8 mol/L,1×10-7 mol/L and 1×10-6 mol/L),the levels of serum vaspin in?creased 25.00%,68.75%,and 120.83%in NC group and increased 7.52%,24.06%,and 40.60%in HF group. There was a positive correlation be?tween vaspin and orexin A,glucose,insulin,TC,TG,and LDL?C(r1=0.482,P1=0.02,r2=0.515,P2=0.02,r3=0.303,P3=0.04,r4=0.388,P4=0.03,r5=0.255,P5=0.04,r6=0.253,P6=0.04)and a negative correlation between vaspin and HDL?C(r=-0.226,P=0.04)in obese rats with IR. Conclusion High?fat diet can induce insulin resistance and obesity in rats,and orexin A is closely correlated to vaspin in obese rats with insu?lin resistance. Orexin A increases serum vaspin expression and thus involves in onset of insulin resistance in obese rats.
ABSTRACT
[Summary] The neuropeptides orexin A and orexin B are involved in numerous central regulation processes such as energy homeostasis,sleeping behaviour,and neuroendocrine activities.Orexin receptors are expressed in a variety of tissues besides the brain,adrenal gland for example.The article reviews the effect of orexin on adrenal gland function.