| Objective: To study the effect of berberine(BBR)on ameliorating neurovascular dysfunction in early diabetic rats.Methods: Streptozotocin(STZ,55 mg·kg-1)was used by intraperitoneal injection to induce the diabetic rats model.The animals were randomly divided into control group,diabetic group and BBR treated group.After 72 hours of injection STZ,blood glucose taken from tail vein was measured.Diabetic rats model was considered successful if the glucose value was over16.7 mmol·L-1.After 2 weeks of diabete success,BBR(200 mg·kg-1)was administered once a day for another 2 weeks.HE staining was used to observe the morphologic changes in mesenteric blood vessel.Electric field stimulation(EFS)was used to induce neurogenic response in vascular smooth muscle,to observe the damage of nitrergic and adrenergic nerve in superior mesenteric artery and iliac artery on diabetic rats,and investigate the effects of BBR on that.Otherwise,neurotransmitters release of nitric oxide(NO)and norepinephrine(NA)from nitrergic and adrenergic nerves were measured on superior mesenteric and iliac arteries in rats.Results:1 The changes of body weight,blood glucose and features of mesenteric vessels of rats1.1 Changes of the body weight and the blood glucose levelCompared with the contemporaneous control group,the body weight was significantly decrease,but the blood glucose level was significantly increased in both diabetic and BBR treated group rats(P<0.01).Simultaneously,there were no significant difference on the body weight and blood glucose level between the diabetic and BBR treated group rats(P>0.05).1.2 Changes of the appearance of mesenteric vesselsFresh mesenteric vessels: control group had less blood stasis in intravascular,and there had plump adipose tissue around perivascular;diabetic group had severe blood stasis,and the adipose tissue appeared atrophy;BBR treated group were improved on deformation and blood stasis,compared with the diabetic group.2 Observations of neurogenic contraction of isolated superior mesenteric artery and iliac artery in rats2.1 Methodological study of EFS-induced contractile responses in isolated arteries of ratsThe repeatable,stable and frequency-dependent contractile responses of superior mesenteric artery and iliac artery were induced by EFS,and the contractile responses of arteries were abolished by 0.1 ?mol·L-1 TTX.2.2 The difference of vasoconstriction induced by EFS in different groups of ratsIn superior mesenteric artery,there was no significant difference on vasoconstrictions among control group,diabetic group and BBR treated group rats(P>0.05).In iliac artery,vasoconstriction was significantly increased in diabetic group rats,compared with the control group(P<0.05);but there was no significant difference on vasoconstriction between the diabetic and BBR treated group rats(P>0.05).2.3 Effects of ?-receptor blocker on vasoconstriction induced by EFSAfter 1 ?mol·L-1 phentolamine administrated,the vasoconstrictions induced by EFS were decreased,and the changes of contractile responses(i.e.difference values: the values of before phentolamine minus the values of after phentolamine)in superior mesenteric artery had no significant difference among control group,diabetic group and BBR treated group rats(P>0.05).In iliac artery,the vasoconstrictions induced by EFS were decreased by 1?mol·L-1 phentolamine,and the changes of contractile responses were significantly increased in diabetic group rats,compared with the control group(P<0.01);but there was no significant difference on changes between diabetic and BBR treated group rats(P>0.05).2.4 Effects of nitric oxide synthase inhibitors on vasoconstriction induced by EFSAfter 1 mmol·L-1 L-NAME or 7-NI administrated,the vasoconstrictions induced by EFS were increased,and the changes of contractile responses in superior mesenteric artery were significantly decreased in diabetic group rats,compared with the control group(P<0.01,P<0.05);but the changes of contractile responses in BBR treated group were significantly increased,compared with the diabetic group(P<0.05,P<0.05).In iliac artery,there were no significant differences on the changes of contractile responses after L-NAME or 7-NI administrated among control group,diabetic group and BBR treated group rats(P>0.05,P>0.05).2.5 Effects of nitric oxide synthase inhibitors on vasoconstriction to NAIn superior mesenteric arteries and iliac arteries of each group,L-NAME had no significant effects on concentration-response curve of NA(P>0.05);but 7-NI had light inhibited effects on concentration-response curve of NA(P<0.01).3 Measurement of neurotransmitter release induced by EFS on isolated arteries in rats3.1 Effects of berberine on NO release from isolated arteries in diabetic ratsIn superior mesenteric artery,NO releases were significantly decreased in diabetic rats,compared with control rats(P<0.01);treatedwith BBR improved NO release(P<0.01).NO releases were decreased significantly by 7-NI or TTX in superior mesenteric arteries of all three groups(P<0.01).In iliac artery,NO releases had no significant difference among control group,diabetic group and BBR treated group rats(P>0.05).NO releases were decreased by 7-NI in diabetic and BBR treated groups rats(P<0.05);but NO releases were decreased by TTX in control and BBR treated groups rats(P<0.05).3.2 Effects of BBR on NA releases from isolated arteries in diabetic ratsIn superior mesenteric artery,NA release had no significant difference among control group,diabetic group and BBR treated group rats(P>0.05).In iliac artery,NA releases were significantly increased in diabetic rats,compared with control rats(P<0.05);but there was no significant difference on NA releases between diabetic and BBR treated rats(P>0.05).4 HE and immunohistochemistry staining in superior mesenteric arteries of ratsIn the arteries of three groups rats,elastic membranes were clearly stratified;muscular coloring was clear and uniform.In control group rats,fat cells were full,and the ganglions were normal.Compared with control rats,the fat cells were shrinked,and the ganglions were swelling in diabetic rats.After BBR treated,adipocytes morphology and ganglions morphology were improved to a certain extent.Immunohistochemistry staining showed that in superior mesenteric artery,the expression of n NOS was reduced in diabetic rats,compared with control group;after BBR treated,the expression of n NOS was improved to a certain extent.Conclusions: In the STZ-induced early diabetic rats,the nitrergic nerve on superior mesenteric artery is damaged,and the release of NO transmitter is decreased;the excitability of adrenergic nerve on iliac artery is increased.BBR significantly improves the dysfunction of nitrergic nerves,but has less affection on adrenergic nerves. |
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