Intrathecal lemnalol, a natural marine compound obtained from Formosan soft coral, attenuates nociceptive responses and the activity of spinal glial cells in neuropathic rats

The investigators previously found that the administration of lemnalol, a natural marine compound isolated from the Formosan soft coral Lemnalia cervicorni, produced anti-inflammatory and analgesic effects in carrageenan-injected rats. Recently, several studies have demonstrated that the development and maintenance of neuropathic pain are accompanied by releasing of proinflammatory mediators from activated glial cells in the spinal cord. In this study, we investigated the antinociceptive properties of lemnalol, a potential anti-inflammatory compound, on chronic constriction injury (CCI) in a well-established rat model of neuropathic pain. Our results demonstrated that a single intrathecal administration of lemnalol (0.05-10 μg) significantly attenuated CCI-induced thermal hyperalgesia and mechanical allodynia, 14 days postsurgery. Furthermore, immunohistofluorescence analyses showed that lemnalol (10 μg) also significantly inhibits CCI-induced upregulation of microglial and astrocytic immunohistochemical activation markers in the dorsal horn of the lumbar spinal cord. Double immunofluorescent staining demonstrated that intrathecal injection of lemnalol (10 μg) markedly inhibited spinal proinflammatory mediator tumor necrosis factor-α expression in microglial cells and astrocytes in neuropathic rats. Collectively, our results indicate that lemnalol is a potential therapeutic agent for neuropathic pain, and that further exploration of the effects of lemnalol on glial proinflammatory responses is warranted.     

黄芪建中汤对脾胃虚寒型胃溃疡大鼠作用机制研究

目的 研究黄芪建中汤对脾胃虚寒型胃溃疡(GU)模型大鼠胃组织炎性因子以及缺氧诱导因子-1α(HIF-1α)、环氧化酶-2(COX-2)、诱导型一氧化氮合酶(iNOS)和内皮型一氧化氮合酶(eNOS)蛋白表达水平的影响.方法 Wistar大鼠用综合造模法复建脾胃虚寒型GU模型.按随机数字表法将模型大鼠分为5组:模型组、阳...     

Gender-specific vascular effects elicited by chronic ethanol consumption in rats: a role for inducible nitric oxide synthase

BACKGROUND AND PURPOSE: Epidemiological data suggest that the risk of ethanol-associated cardiovascular disease is greater in men than in women. This study investigates the mechanisms underlying gender-specific vascular effects elicited by chronic ethanol consumption in rats. EXPERIMENTAL APPROACH: Vascular reactivity experiments using standard muscle bath procedures were performed on isolated thoracic aortae from rats. mRNA and protein for inducible NO synthase (iNOS) and for endothelial NOS (eNOS) was assessed by RT-PCR or western blotting, respectively. KEY RESULTS: In male rats, chronic ethanol consumption enhanced phenylephrine-induced contraction in both endothelium-intact and denuded aortic rings. However, in female rats, chronic ethanol consumption enhanced phenylephrine-induced contraction only in endothelium denuded aortic rings. After pre-incubation of endothelium-intact rings with L-NAME, both male and female ethanol-treated rats showed larger phenylephrine-induced contractions in aortic rings, compared to the control group. Acetylcholine-induced relaxation was not affected by ethanol consumption. The effects of ethanol on responses to phenylephrine were similar in ovariectomized (OVX) and intact (non-OVX) female rats. In the presence of aminoguanidine, but not 7-nitroindazole, the contractions to phenylephrine in rings from ethanol-treated female rats were greater than that found in control tissues in the presence of the inhibitors. mRNA levels for eNOS and iNOS were not altered by ethanol consumption. Ethanol intake reduced eNOS protein levels and increased iNOS protein levels in aorta from female rats. CONCLUSIONS AND IMPLICATIONS: Gender differences in the vascular effects elicited by chronic ethanol consumption were not related to ovarian hormones but seemed to involve the upregulation of iNOS.     

二苯乙烯苷预防性干预大鼠动脉硬化对其一氧化氮合酶表达的影响

目的探讨二苯乙烯苷(TSG)对动脉粥样硬化(AS)大鼠一氧化氮(NO)含量及主动脉一氧化氮合酶(NOS)表达的影响。方法SD大鼠60只,♂,随机分为6组:①正常对照组;②模型组;③TSG低剂量组;④TSG中剂量组;⑤TSG高剂量组;⑥辛伐他汀阳性对照组。造模12wk后,颈动脉取血,检测血清NO含量。取血后分离主动脉,保存于-70℃,检测主动脉组织中NOS含量,RT-PCR检测大鼠主动脉eNOS和iNOS mRNA表达。实验数据采用STATA8.0软件进行统计分析。结果与模型组相比,辛伐他汀组和TSG各剂量组均能增加血清及主动脉组织NO的含量、主动脉组织NOS的水平、主动脉组织eNOS mRNA的表达及降低主动脉组织iNOS mRNA的表达,并呈剂量依赖性。结论TSG能上调AS大鼠动脉壁eNOS mRNA的表达,抑制AS大鼠动脉壁iNOS mRNA的表达,这可能是TSG抗AS的机制之一。     

Effect of a nitric oxide releasing derivative of paracetamol in a rat model of endotoxaemia

BACKGROUND AND PURPOSE: Nitroparacetamol is a nitric oxide-releasing paracetamol with novel anti-inflammatory properties compared to the parent compound. This study has investigated the anti-inflammatory activity of nitroparacetamol in a model of endotoxaemia in rats to probe the mechanisms underlying this effect. EXPERIMENTAL APPROACH: Nitroparacetamol (92 mg kg(-1)), paracetamol (50 mg kg(-1)) or vehicle were administered to male, Wistar rats 15 min prior to or 3 h after lipopolysaccharide (0.5 mg kg(-1), serotype 0127:B8). Mean arterial pressure and heart rate were measured for 5 h and plasma and organs were then obtained to determine organ dysfunction, inducible nitric oxide synthase and cyclooxygenase-2 expression (lung, liver and kidney tissue) and plasma nitrate/nitrite. In separate experiments, nitroparacetamol, paracetamol or vehicle was administered 1 h before acetylcholine (0.1 microg kg(-1)) or sodium nitroprusside (0.25 microg kg(-1)) to determine if nitroparacetamol desensitizes responses to exogenous/endogenous nitric oxide. KEY RESULTS: Nitroparacetamol prevented but did not reverse the lipopolysaccharide-induced hypotension. There was no effect on heart rate or plasma markers of organ dysfunction. Nitroparacetamol prevented the increased plasma nitrate/nitrite and expression of COX-2 and iNOS, whereas paracetamol exerted partial inhibition of COX-2 in lung alone. Nitroparacetamol also reduced responses to acetylcholine and sodium nitroprusside. CONCLUSIONS AND IMPLICATIONS: NO is the active component of nitroparacetamol in this model of endotoxaemia. Pro-inflammatory processes targeted by nitroparacetamol have been shown to include iNOS/COX-2 induction and possibly vascular soluble guanylyl cyclase. Precise mechanisms underlying the NO effect are unclear but inhibition of cytokine formation may be important.     

Inhibition of inducible nitric oxide synthase attenuates acute endotoxin-induced lung injury in rats

1. In the present study, we investigated the effects of the inducible nitric oxide (iNOS) inhibitors S-methylisothiourea (SMT) and l-N(6)-(1-iminoethyl)-lysine (l-Nil) on endotoxin-induced acute lung injury (ALI), as well as the associated physiological, biomedical and pathological changes, in anaesthetized Sprague-Dawley rats and in rat isolated perfused lungs. 2. Endotoxaemia was induced by an intravenous (i.v.) infusion of lipopolysaccharide (LPS; Escherichia coli 10 mg/kg). Lipopolysaccharide produced systemic hypotension and tachycardia. It also increased the lung weight/bodyweight ratio, lung weight gain, exhaled nitric oxide (NO), the protein concentration in bronchoalveolar lavage and microvascular permeability. 3. Following infusion of LPS, plasma nitrate/nitrite, methyl guanidine, pro-inflammatory cytokines (tumour necrosis factor-alpha and interleukin-1beta) were markedly elevated. Pathological examination revealed severe pulmonary oedema and inflammatory cell infiltration. Pretreatment with SMT (3 mg/kg, i.v.) or l-Nil (3 mg/kg, i.v.) significantly attenuated the LPS-induced changes and ALI. 4. The results suggest that the inflammatory responses and ALI following infusion of LPS are due to the production of NO, free radicals and pro-inflammatory cytokines through the iNOS system. Inhibition of iNOS is effective in mitigating the endotoxaemic changes and lung pathology. Inhibitors of iNOS may be potential therapeutic agents for clinical application in patients with acute respiratory distress syndrome.     

高压氧对神经病理性痛大鼠疼痛行为学及脊髓背角NOS 表达的影响

目的：观察高压氧对神经病理性痛大鼠疼痛行为学及脊髓背角 NOS 表达的影响。方法成年雄性 SD大鼠32只,随机分成4组,每组8只,包括：假手术组（S 组）、坐骨神经结扎组（CCI 组）、HBO 预处理组（pre－HBO 组）和 HBO 后处理组（post－HBO 组）。所有大鼠 CCI 术前1 d 测量机械痛阈值基线（MWT）。 CCI 术后第1、2、3、7、14、21和第28天观察疼痛反应行为,测量 MWT。 CCI 术后第28天,对脊髓背角中 nNOS、 eNOS 及 iNOS 阳性神经元进行计数。结果CCI 术前4组 MWT 值无明显差异（ P ＞0．05）。每个时间点,与 S 组比较,pre－HBO、post－HBO 和 CCI 组MWT 值明显降低（ P ＜0．05）,且 CCI 组下降幅度最大。每个时间点,与 CCI 组比较,pre－HBO 组和 post－HBO 组 MWT值明显高于 CCI 组（ P ＜0．05）。与 S 组比较,CCI 后第28天 CCI 组、pre－HBO 组和 post－HBO 组大鼠脊髓 nNOS 和iNOS 阳性神经元数量明显增多（ P ＜0．05）。 CCI 组大鼠脊髓 nNOS 和 iNOS 阳性神经元数量明显高于 pre－HBO 组和post－HBO 组（ P ＜0．05）。4组大鼠脊髓 eNOS 阳性神经元数量未见明显差异（ P ＞0．05）。结论高压氧对神经痛的发生有预防和治疗作用,可能通过降低 NOS 的表达缓解疼痛。     

Therapeutic administration of 3,4,5-trimethoxy-4'-fluorochalcone,a selective inhibitor of iNOS expression,attenuates the development of adjuvant-induced arthritis in rats

We have previously investigated the effects of a series of dimethoxy- and trimethoxychalcone derivatives, with various patterns of fluorination, on nitric oxide production in LPS-stimulated murine RAW 264.7. The present study was designed to determine if 3,4,5-trimethoxy-4'-fluorochalcone (CH 17) could modulate the production of NO and/or prostaglandins in vivo. On the mouse macrophage cell line RAW 264.7 CH 17 inhibited dose-dependently NO production, with an IC₅₀ value in the nanomolar range, and reduced PGE₂ levels by a 58% at 10 M. This compound had no direct inhibitory effect on iNOS and COX-2 activities. NO reduction was the consequence of inhibition of the expression of iNOS. In vitro experiments indicated that CH 17 is an inhibitor of the nuclear factor-B (NF-B) pathway of cellular activation in macrophages. This compound exhibited in vivo an inhibitory behaviour correlated with its in vitro results on nitrite and PGE₂ accumulation. In the rat adjuvant-induced arthritis, oral administration of CH 17 (25 mg/kg) on days 17–24 after adjuvant injection, significantly inhibited paw oedema, protected from weight loss and reduced the levels of inflammatory mediators (nitrites and PGE₂) in paw homogenates, without affecting PGE₂ levels in stomach homogenates. The profile and potency of this compound, a selective inhibitor of iNOS expression that interferes with NF-B activation, may have relevance for the inhibition of the inflammatory response, representing a new approach to the modulation of different inflammatory pathologies.     

慢性神经痛大鼠鞘内联合应用吗啡和氯胺酮在脊髓上水平的抗伤害性作用及对吗啡耐受的影响

目的研究鞘内联合应用吗啡和氯胺酮对慢性神经痛大鼠的抗伤害作用机制及对吗啡耐受的影响。方法 40只Wistar大鼠,体质量220～260 g,制备坐骨神经结扎模型并进行鞘内置管,随机分为5组(n=8):B组为空白对照组;C组鞘内注射0.9%盐水10μL;K组鞘内注射氯胺酮50μg;M组鞘内注射吗啡20μg;KM组鞘内注射吗啡10μg和氯胺酮25μg。坐骨神经结扎术后第4天开始鞘内给药,每日1次,连续7 d。用药7d后处死大鼠,取大脑皮质、海马、脑干组织,硝酸还原酶法测定NO浓度和NOS活性。结果与B组比较,C和K组脑干NO浓度升高,M组皮质、海马、脑干中NO浓度均升高;与C组比较,M组皮质、海马NO浓度升高,KM组海马、脑干中NO浓度降低;与M组比较,KM组皮质、海马、脑干NO浓度均降低(P<0.05或0.01)。与B组比较,C、K和M组皮质、海马、脑干中NOS活性均升高;与C和M组比较,KM组皮质、海马、脑干中NOS活性均降低(P<0.05或0.01)。结论神经病理性痛大鼠鞘内联合应用吗啡和氯胺酮可在脊髓上水平产生抗伤害性作用,并可抑制吗啡耐受的形成,这可能与大脑皮质、海马、脑干的NO水平和NOS活性有关。     

Protective effects of mercaptoethylguanidine,a selective inhibitor of inducible nitric oxide synthase,in ligature-induced periodontitis in the rat

1. Excessive production of nitric oxide (NO), and the generation of peroxynitrite have been implicated in various proinflammatory conditions. In the present study, using mercaptoethylguanidine (MEG), a selective inhibitor of iNOS and a peroxynitrite scavenger, we investigated the role of iNOS and peroxynitrite in a rat model of periodontitis.
2. Periodontitis was produced in rat by a ligature of 2/0 braided silk placed around the cervix of the lower left 1st molar. Animals were then divided into two groups: one group of rats was treated with MEG (30 mg kg⁻¹, i.p., 4 times per day for 8 days), animals in the other group received vehicle. At day 8, the gingivomucosal tissue encircling the mandibular 1st molars was removed on both sides from ligated and sham operated animals for inducible nitric oxide synthase (iNOS) activity assay and for immunocytochemistry with anti-iNOS serum. Plasma extravasation was measured with the Evans blue technique. Alveolar bone loss was measured with a videomicroscopy.
3. Ligation caused a significant, more than 3 fold increase in the gingival iNOS activity, whereas it did not affect iNOS activity on the contralateral side, when compared to sham-operated animals. Immunohistochemical analysis revealed iNOS-positive macrophages, lymphocytes and PMNs in the connective tissue and immunoreactive basal layers of epithelium on side of the ligature, and only a few iNOS-reactive connective tissue cells on the contralateral side. Ligation significantly increased Evans blue extravasation in gingivomucosal tissue and alveolar bone destruction compared to the contralateral side. MEG treatment significantly reduced the plasma extravasation and bone destruction.
4. The present results demonstrated that ligature-induced periodontitis increases local NO production and that MEG treatment protects against the associated extravasation and bone destruction. Based on the present data, we propose that enhanced formation of NO and peroxynitrite plays a significant role in the pathogenesis of periodontitis.

     

Altered expression of cyclooxygenase-2, 12-lipoxygenase,inducible nitric oxide synthase-2 and surfactant protein D in lungs of patients with pulmonary injury caused by sulfur mustard

Context: Sulfur mustard (SM) is a strong alkylating toxicant that targets different organs, particularly human lung tissue. Change in genes expression is one of the molecular mechanisms of SM toxicity in damaged tissue.

Objective: The purpose of this investigation is to characterize the expression of cyclooxygenase-2 (COX-2), 12-lipoxygenase (12-LO), inducible nitric oxide synthase 2 (iNOS2), and surfactant protein D (SFTPD) in lungs of patients who exposed to SM.

Methods: Lung biopsies were provided from SM-exposed patients (n?=?6) and controls (n?=?5). Total RNA were extracted from all specimens and then cDNA was synthesized for each sample. Changes in gene expression were measured using RT² Profiler ?PCR Array.

Results: Pulmonary function tests revealed more obstructive and restrictive spirometric patterns among patients compared to the control group. Expression of COX-2 and 12-LO in the lung of patients was increased by 6.2555 (p?=?0.004) and 6.2379-folds (p?=?0.002), respectively. In contrast, expression of SF-D and iNOS genes was reduced by 8.5869-fold (p?=?0.005) and 2.4466-folds (p?=?0.011), respectively.

Conclusions: Mustard lungs were associated with overexpression of COX-2 and 12-LO, which are responsible for inflammation, overproduction of free radicals and oxidative stress. Downregulation of iNOS2 and SF-D are probably the reason for lung disease and dysfunction among these patients. Therefore, the expression of these genes could be an important, routine part of the management of such patients.     

Dragon's blood inhibits chronic inflammatory and neuropathic pain responses by blocking the synthesis and release of substance P in rats

As a traditional Chinese medicine, dragon's blood (DB) is widely used in treating various pains for thousands of years due to its potent anti-inflammatory and analgesic effects. In the present study, we observed that intragastric administration of DB at dosages of 0.14, 0.56, and 1.12 g/kg potently inhibited paw edema, hyperalgesia, cyclooxygenase-2 (COX-2) protein expression, or preprotachykinin-A mRNA expression in carrageenan-inflamed or sciatic nerve-injured (chronic constriction injury) rats, respectively. A short-term (15 s or 10 min) pre-exposure of cultured rat dorsal root ganglion (DRG) neurons to DB (0.3, 3, and 30 μg/ml) or its component cochinchinenin B (CB; 0.1, 1, and 10 μM) blocked capsaicin-evoked increases in both the intracellular calcium ion concentration and the substance P release. Moreover, a long-term (180 min) exposure of cultured rat DRG neurons to DB or CB significantly attenuated bradykinin-induced substance P release. These findings indicate that DB exerts anti-inflammatory and analgesic effects by blocking the synthesis and release of substance P through inhibition of COX-2 protein induction and intracellular calcium ion concentration. Therefore, DB may serve as a promising potent therapeutic agent for treatment of chronic pain, and its effective component CB might partly contribute to anti-inflammatory and analgesic effects.     

Protective effect of curcumin,a Curcuma longa constituent,in early colonic inflammation in rats

Curcumin, a polyphenol derived from the plant, Curcuma longa, has a variety of pharmacological effects, including chemotherapeutic, anti‐inflammatory, antiangiogenic, and antioxidant activities. To gain a better understanding of the effects and mechanisms of action of curcumin on the acute injury caused by intra‐colonic administration of acetic acid (AA) in rats, inflammation was assessed by histology and myeloperoxidase activity (MPO; an index of neutrophil infiltration in the mucosa); Th1 and Th2 cytokine production; histological and histochemical analysis of the lesions; nitrite production in colon mucosa; and the expression of iNOS, COX‐1 and ‐2 using Western blotting and inmmunohistochemistry. We also studied the involvement of the p38 MAPK/JNK signalling pathway in the protective effect of curcumin in acute colonic inflammation. Curcumin (50–100 mg/kg/day) reduced the degree of colonic injury, the index of neutrophil infiltration and Th1 cytokine secretion, and increased IL‐10 production, reduced colonic levels of nitrites, and reduced COX‐2 and iNOS overexpression. A reduction in the activation of p38 and JNK MAPKs was also observed. Thus, we show that the widely used food additive, curcumin reduced the development of AA‐induced colitis and alleviated the inflammatory response. Inhibition of MAPK signalling by curcumin could explain the changes on the cytokine Th1/Th2 profile, the reduction of COX‐2 and iNOS signaling, as well as the decreased nitrite production in colonic mucosa, suggesting that curcumin may be useful in the treatment of ulcerative colitis. Drug Dev Res, 2009. © 2009 Wiley‐Liss, Inc.     

HYP-1, a novel diamide compound, relieves inflammatory and neuropathic pain in rats

In the present study, we investigated whether a novel compound, 2-(2-(4-((4-chlorophenyl)(phenyl)methyl)piperazin-1-yl)-2-oxoethylamino)-N-(3,4,5-trimethoxybenzyl)acetamide (HYP-1), is capable of binding to voltage-gated sodium channels (VGSCs) and evaluated both its inhibitory effect on Na⁺ currents of the rat dorsal root ganglia (DRG) sensory neuron and its in vivo analgesic activity using rat models of inflammatory and neuropathic pain. HYP-1 showed not only high affinity for rat sodium channel (site 2), but also potent inhibitory activity against the TTX-R Na⁺ currents of the rat DRG sensory neuron. HYP-1 co-injected with formalin (5%, 50 μl) under the plantar surface of rat hind paw dose-dependently reduced spontaneous pain behaviors during both the early and late phases. This result was confirmed by c-Fos immunofluorescence in the L4-5 spinal segments. A large number of c-Fos-positive neurons were observed in rat injected with a mixture of formalin and vehicle, but not in rat treated with a mixture of formalin and HYP-1. In addition, the effectiveness of HYP-1 (6 and 60 mg/kg, i.p.) in suppression of neuropathic pain, such as mechanical, cold and warm allodynia, induced by rat tail nerve injury was investigated. HYP-1 showed limited selectivity over hERG, N-type and T-type channels. Our present results indicate that HYP-1, as a VGSC blocker, has potential analgesic activities against nociceptive, inflammatory and neuropathic pain.     

Anti-angiogenic activity of resveratrol, a natural compound from medicinal plants

Resveratrol (3,4',5-trihydroxy-trans-stilbene), a naturally occurring phytoalexin found in grapes and wine, possesses cancer-preventive activity. Angiogenesis is a crucial step in the growth and metastasis of cancers. We have investigated the effect of resveratrol on angiogenesis in vitro and ex vivo, and found that resveratrol directly inhibited human umbilical vein endothelial cell growth and decreased the gelatinolytic activities of matrix metalloproteinase-2. Tube formation was inhibited by treatment with resveratrol after plating endothelial cells on Matrigel. Resveratrol treatment also inhibited endothelial cell attachment to basement membrane components fibronectin and laminin, and displays similar behavior on cell chemotaxis. In addition, resveratrol has been found to be an angiogenesis inhibitor in the rat aorta matrix culture model. Therefore, inhibition of angiogenesis associated with cancer may be a novel mechanism for the anticancer activity of resveratrol.     

Induction of nitric oxide synthase in vivo and cell injury in rat duodenal epithelium by a water soluble extract of Helicobacter pylori

1. Helicobacter pylori (Hp) infection, which involves the gastric antrum and duodenal mucosa, may be involved in peptic ulceration by stimulating the local release of cytoxic or pro-inflammatory factors.
2. Nitric oxide (NO) is known to be cytotoxic at high concentration. The aim of the present study was therefore to investigate the ability of a water soluble extract of Hp to induce NO synthase in duodenal mucosa and epithelial cells following its administration in vivo in rats and determine its association with cell damage.
3. Administration of Hp water extract (4 ml kg⁻¹) led to the expression of the calcium-independent inducible nitric oxide synthase (iNOS) after 4 h in the duodenum, determined as [¹⁴C]-arginine conversion to citrulline.
4. This iNOS activity was not reduced by pretreatment with anti-neutrophil serum (0.4 ml kg⁻¹, i.p., 3 h before challenge). However, dexamethasone pretreatment (1 mg kg⁻¹, i.v., 2 h before the extract), or administration of the NO synthase inhibitor N^G-nitro-L-arginine methyl ester (L-NAME, 5 mg kg⁻¹, i.v., 2.5 h after the extract) reduced this activity.
5. Furthermore, iNOS was expressed in duodenal isolated epithelial cells 4 h after the i.v. challenge with the extract, at a time when the cellular viability was also reduced, as assessed by trypan blue exclusion.
6. Dexamethasone pretreatment, administration of L-NAME, or pretreatment with polymyxin B (1 mg kg⁻¹, i.v.) which binds endotoxin, reduced both the iNOS activity and epithelial cell damage.
7. The induction of NO synthase by the Hp extract thus results in duodenal epithelial cell injury and such actions could play a role in pathogenesis of peptic ulcer disease.

     

Sildenafil, a phosphodiesterase type 5 inhibitor, attenuates diabetic nephropathy in non-insulin-dependent Otsuka Long-Evans Tokushima Fatty rats

BACKGROUND

It is well established that the pathogenesis of diabetic nephropathy is associated with abnormalities of renal nitric oxide (NO) generation. Many of the biological actions of NO are mediated by cGMP, which is rapidly degraded by phosphodiesterases. In this study, we evaluated the renoprotective effects of sildenafil (SIL), an inhibitor of phosphodiesterase-5, in type 2 diabetic rats.

METHODS

Male Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a non-insulin-dependent diabetes model, and Long-Evans Tokushima Otsuka rats, a non-diabetic control, were treated with either SIL (2.5 mg·kg⁻¹ in drinking water) or undosed water for 28 weeks, starting at 30 weeks of age.

RESULTS

Sildenafil treatment significantly decreased albuminuria, attenuated glomerular hyperfiltration and resulted in a decrease in glomerular hypertrophy, in addition to a reduced glomerulosclerosis score and a dramatic decrease in the number of glomerular and tubulointerstitial proliferating cell nuclear antigen-positive cells in OLETF rats. This was accompanied by a significant reduction in renal cortical mRNA levels of collagen types I and III. The increased mRNA levels of matrix metalloproteinase (MMP)-2, MMP-9, tissue inhibitors of MMPs (TIMP)-1 and TIMP-2 in the OLETF rats were significantly or partially attenuated by SIL treatment.

CONCLUSIONS

This study suggests that SIL attenuated diabetic nephropathy due to its potent antiproliferative effects and its regulatory effects on extracellular matrix. This latter effect is thought to be a result of its ability to affect the balance between MMPs and their inhibitors.