Treatment of diabetic autonomic neuropathy with an aldose reductase inhibitor

To evaluate the effects of the aldose reductase inhibitor Ponalrestat (Statil) on diabetic autonomic neuropathy, a double-blind placebo controlled trial was carried out on a group of 34 diabetic patients with documented cardiac autonomic neuropathy. After a 4-week, placebo run-in period, patients were randomised for treatment with 600 mg Statil or placebo for another 24 weeks. Moreover, the reliability of the autonomic nerve function tests was investigated by comparing the results at onset and at week 4. Fifteen patients treated with Statil and 12 with placebo completed the study. Neither symptom scores nor cardiovascular reflexes, pupil reflexes and skin vasomotor reflexes improved after Statil therapy, which led us to conclude that Statil is not effective in the treatment of diabetic autonomic neuropathy. Reliability coefficients for cardiovascular reflexes and pupil reflex showed high values, ranging from 60% to 80%. Therefore these methods are recommended in future therapy trials.     

Axonal transport and tissue contents of substance P in rats with long-term streptozotocin-diabetes. Effects of the aldose reductase inhibitor ‘statil’

This study examined the axonal transport of substance P-like immunoreactivity (SPLI) and its content in dorsal root ganglion, trigeminal ganglion, stomach and ileum of non-diabetic rats and two groups of rats with streptozotocin-induced diabetes of 9 months duration. One diabetic group received the aldose reductase inhibitor ‘Statil’ throughout the period of study. To reduce morbidity all diabetic animals were given twice-weekly injections of a long-acting insulin which restricted weight loss but did not prevent regular and severe hyperglycaemia. Axonal transport of SPLI was studied by measurement of accumulation at 12 h ligatures on the left sciatic nerve. There were no differences between the 3 groups either in the calculated anterograde and retrograde mean rates of accumulation (ranges 6.0 to 7.6 and 0.38 to 0.72 mm/h respectively) or mobile fractions of SPLI (means from 0.54 to 0.58). There were, however, marked reductions in anterograde and retrograde accumulations of SPLI in the constricted nerves of the ‘untreated’ diabetics (respectively 57 and 33% of controls;P < 0.01 for both). In the ‘Statil’-treated rats these deficits were attenuated (80 and 75% of controls). Diabetes also reduced the SPLI content of unligated sciatic nerve and trigeminal ganglion (65 and 75% of controls). ‘Statil’ prevented the deficit in the ganglion, but not in the nerve. ‘Statil’ treatment prevented themyo-inositol depletion and attenuated the sorbitol and fructose accumulation seen in the sciatic nerves of the untreated diabetic animals suggesting effective inhibition of aldose reductase in this tissue. The total SPLI content of the stomach and 1-cm segments of ileum were unaltered in the diabetic animals but due to the increased weights of these tissues the SPLI content per unit weight was reduced. These changes were unaffected by ‘Statil’.     

Stimulation of nerve growth factor and substance P expression in the iris–trigeminal axis of diabetic rats—involvement of oxidative stress and effects of aldose reductase inhibition

In rats with streptozotocin-induced diabetes, we measured increased (by 61%; P<0.05) mRNA for nerve growth factor (NGF) in the iris together with increased (by 82%; P<0.05) mRNA for preprotachykinin (the substance P precursor) in the trigeminal ganglion, suggesting that increased NGF was driving increased substance P gene expression. In other diabetic rats, these changes were prevented by treatment with either an antioxidant (butylated hydroxytoluene; 1% by diet) or an aldose reductase inhibitor (ARI) (sorbinil; 25 mg/kg/day p.o.) and the sorbinil treatment was associated with significant inhibition of polyol pathway intermediates in both lens and sciatic nerve. This suggests that polyol pathway activity in the lens may translate to oxidative stress-driving stimulation of NGF gene expression in the iris. The change is selective for NGF, because expression of the analogous neurotrophin, neurotrophin-3 (NT-3), was unaltered in the same irises. These changes suggest that oxidative stress and/or inflammation can drive up NGF expression in diabetes—a mechanism that might participate in iritis.     

红细胞醛糖还原酶测定荧光法的建立及临床应用

红细胞醛糖还原酶测定荧光法的实验探讨。方法利用ＮＡＤＰＨ、ＤＬ－甘油醛 ,磷酸缓冲液和适量红细胞溶血液组成的反应体系,建立了一种红细胞醛糖还原酶的荧光测定法,并对酶反应最适条件进行了实验探讨。     

Cyclocarya paliurus extract alleviates diabetic nephropathy by inhibiting oxidative stress and aldose reductase

Diabetes is the leading cause of end-stage renal disease because diabetic nephropathy (DN) develops in 30–40% of the patients. This study investigated the protective effect of the aqueous extract from leaves of Cyclocarya paliurus (Batal.) Iljinsk (ACP) on DN by inhibiting oxidative stress and aldose reductase (AR) activity. ACP was obtained by hot water extraction. The in vitro antioxidant capability and AR inhibition of ACP were investigated by employing various established systems. DN rats were used to assess the reno-protective effect of ACP. Results showed that the polysaccharide and total polyphenol contents of ACP were (479.3?±?19.8) mg/g and (38.3?±?2.3) mg/g, respectively. ACP exhibited strong antioxidant ability and AR inhibition in vitro and in vivo; furthermore, the inhibition mechanism of ACP in AR takes the form of uncompetitive inhibition. In addition, the animals treated with ACP showed significant amelioration of blood glucose, serum biomarkers related to renal function, urinary protein excretion, and histopathological changes in the kidney. The results suggest that ACP has a potential role in ameliorating renal damage involved in DN.     

糖尿病视网膜病变的药物治疗进展

糖尿病视网膜病变是最常见的糖尿病微血管病变。目前有很多致力于延缓糖尿病视网膜病变的药物研究,包括对肾素-血管紧张素系统阻滞剂、蛋白激酶C抑制剂、血管内皮生长因子抑制剂、生长抑素类似物、抗炎药物、晚期糖基化终末产物抑制剂及醛糖还原酶抑制剂等的研究。本文就近几年在这些方面的研究工作作一综述。     

Vicenin 2 isolated from Artemisia capillaris exhibited potent anti-glycation properties

Vicenin 2, isolated from a traditionally used medicinal plant Artemisia capillaris, is a 6,8-di-C-glucoside of apigenin which has been previously reported to possess a wide variety of pharmacological activities including antioxidant, anti-inflammatory, anti-cancer, and hepatoprotective. However, there have not been any reports concerning its anti-diabetic potential until now. Therefore, in the present study, we evaluated the anti-diabetic potential of vicenin 2 via α-glucosidase, protein tyrosine phosphatase 1B (PTP1B), rat lens aldose reductase (RLAR), and advanced glycation end products (AGE) formation inhibitory assays. Vicenin 2 strongly inhibited α-glucosidase, PTP1B, and RLAR in the corresponding assays. In addition, vicenin 2 inhibited the formation of both fluorescent AGE and nonfluorescent AGE, e.g., CML, as well as the level of fructosamine in glucose–fructose-induced bovine serum albumin (BSA) glycation. In the test system, vicenin 2 suppressed glycation-induced protein oxidation by attenuating the formation of protein carbonyl groups as well as by inhibiting the modification of protein thiol groups. Moreover, vicenin 2 was found to be a potent inhibitor of glycation-induced formation of amyloid cross-β structures in BSA. Taken together, vicenin 2 might be a useful lead for the development of multiple target-oriented therapeutic modalities for the treatment of diabetes and diabetes-associated complications.     

Comparison of the effects of inhibitors of aldose reductase and sorbitol dehydrogenase on neurovascular function, nerve conduction and tissue polyol pathway metabolites in streptozotocin-diabetic rats

Summary Aldose reductase inhibitors (ARIs) attenuate diabetic complications in several tissues, including lens, retina, kidney, blood vessels, striated muscle and peripheral nerve. However, it is unclear whether their action in diabetes mellitus depends directly on inhibiting the conversion of glucose to sorbitol by aldose reductase or indirectly by reducing the sorbitol available for subsequent metabolism to fructose by sorbitol dehydrogenase. To identify the polyol pathway step most relevant to complications, particularly neuropathy, we compared the biochemical effects of a sorbitol dehydrogenase inhibitor, WAY-135 706, (250 mg · kg⁻¹· day⁻¹) and an ARI, WAY-121 509, (10 mg · kg⁻¹· day⁻¹) on a variety of tissues, and their effects on nerve perfusion and conduction velocity. After 6 weeks of untreated streptozotocin diabetes, rats were treated for 2 weeks. Sorbitol was elevated 2.1–32.6-fold by diabetes in lens, retina, kidney, aorta, diaphragm, erythrocytes and sciatic nerve; this was further increased (1.6–8.2-fold) by WAY-135 706 whereas WAY-121 509 caused a marked reduction. Fructose 1.6–8.0-fold elevated by diabetes in tissues other than diaphragm, was reduced by WAY-135 706 and WAY-121 509, except in the kidney. Motor and sensory nerve conduction velocities were decreased by 20.2 and 13.9 %, respectively with diabetes. These deficits were corrected by WAY-121 509, but WAY-135 706 was completely ineffective. A 48.6 % diabetes-induced deficit in sciatic nutritive endoneurial blood flow was corrected by WAY-121 509, but was unaltered by WAY-135 706. Thus, despite profound sorbitol dehydrogenase inhibition, WAY-135 706 had no beneficial effect on nerve function. The data demonstrate that aldose reductase activity, the first step in the polyol pathway, makes a markedly greater contribution to the aetiology of diabetic neurovascular and neurological dysfunction than does the second step involving sorbitol dehydrogenase. [Diabetologia (1997) 40: 271–281] Received: 13 August 1996 and in final revised form: 6 December 1996     

A 12-month randomized controlled study of the aldose reductase inhibitor ponalrestat in patients with chronic symptomatic diabetic neuropathy.

The effects of the aldose reductase inhibitor ponalrestat (600 mg day-1) on sensory, electrophysiological, and autonomic function were examined in 50 patients with chronic symptomatic, distal symmetrical diabetic neuropathy in a 52-week randomized, double-blind, parallel-group, placebo-controlled, single-centre study. In an endeavour to identify patients with a degree of neuropathy potentially amenable to pharmacological intervention, a minimum conduction velocity of 30 m s-1 was set for the peroneal motor nerve. At 52 weeks, no significant differences were observed between the ponalrestat and placebo groups in motor (ulnar, median, and peroneal) or sensory (ulnar and radial) nerve conduction velocities, vibration perception thresholds, adjectival symptom scores or tests of autonomic function (mean electrocardiographic R-R interval variability on deep breathing and orthostatic blood pressure response). Ponalrestat was clinically well tolerated and had no significant effect on glycaemic control. The lack of beneficial effects of ponalrestat may in part reflect the advanced stage of the neuropathic process in patients with established symptomatic disease, and the poor reproducibility of current neurophysiological techniques. Firmer knowledge of clinico-pathological correlates allied to improved non-invasive neurophysiological measurement techniques should facilitate the selection of patients for future therapeutic trials in diabetic neuropathy.     

醛糖还原酶拮抗剂治疗大鼠血管再狭窄

背景醛糖还原酶增强氧化应激,促进细胞分裂增殖,激活转录因子、核因子кB(NF-кB),但在血管再狭窄中起的作用报告不多。目的研究醛糖还原酶(AR)在大鼠再狭窄血管中的表达,探讨AR表达与内膜增生的关系,AR拮抗剂依帕司他对再狭窄血管中AR的表达及AR的抑制作用。方法健康雄性SD大鼠24只,随机分成对照组(A组)、手术未干预组(B组)及手术+依帕司他组(C组),每组8只。用通气-干燥法损伤B组及C组大鼠右侧颈总动脉,左侧颈总动脉作为对照。分别于7d及14d后处死大鼠,HE染色以观察内膜及中膜增生情况,并计算内膜、中膜面积及其比值,FISH原位杂交及免疫组化检测AR及NF-кB的表达。结果1)术后第7天损伤侧血管内膜增生明显,第14天后内膜增生进一步加重,对照血管无明显增生。2)依帕司他明显抑制血管内皮损伤后血管内膜增生、血管内膜面积、血管内膜与中膜面积比值明显低于未干预组(P<0.05或P<0.01)。3)AR及NF-кB在损伤侧血管中的表达明显强于对侧。依帕司他明显抑制AR及NF-кB的表达量(P<0.05或P<0.01)。结论依帕司他对血管内膜的增生及再狭窄的形成有抑制作用,伴有AR及NF-кB的表达受抑。