Shoji Takakura

Ipragliflozin, an SGLT2 inhibitor, exhibits a prophylactic effect on hepatic steatosis and fibrosis induced by choline-deficient l-amino acid-defined diet in rats

Ipragliflozin is a selective sodium glucose cotransporter 2 (SGLT2) inhibitor that increases urinary glucose excretion by inhibiting renal glucose reabsorption and thereby causes a subsequent antihyperglycemic effect. As nonalcoholic fatty liver disease (NAFLD), including nonalcoholic steatohepatitis (NASH), is closely linked to metabolic diseases such as obesity and diabetes, we investigated the effect of ipragliflozin on NAFLD in rats fed a choline-deficient l-amino acid-defined (CDAA) diet. Five weeks after starting the CDAA diet, rats exhibited hepatic triglyceride (TG) accumulation, fibrosis, and mild inflammation. Repeated oral administration of ipragliflozin (3mg/g, once daily for 5 weeks) prevented both hepatic TG accumulation (188 vs.290 mg/g tissue vehicle-treated group; P<0.001) and large lipid droplet formation. Further, ipragliflozin exerted a prophylactic effect on liver fibrosis, as indicated by a marked decrease in hydroxyproline content and fibrosis score. Pioglitazone, which is known to be effective on hepatic fibrosis in CDAA diet-fed rats as well as NASH patients with type 2 diabetes mellitus (T2DM), also exerted a mild prophylactic effect on fibrosis, but not on hepatic TG accumulation or inflammation. In conclusion, ipragliflozin prevented hepatic TG accumulation and fibrosis in CDAA-diet rats. These findings suggest the therapeutic potential of ipragliflozin for patients with NAFLD.

Prevention of renal interstitial fibrosis via histone deacetylase inhibition in rats with unilateral ureteral obstruction.

Acute rejection following renal transplantation has become manageable with the introduction of calcineurin inhibitors, FK506 and cyclosporine A. However, chronic allograft dysfunction accompanied by renal interstitial fibrosis, which induces graft loss, remains unresolved. Here, we evaluated the effect of FR276457, a pan-histone deacetylase (HDAC) inhibitor, on interstitial fibrosis in the injured kidneys of a rat model of unilateral ureteral obstruction. The injured kidneys, harvested on Day 14 following the operation, showed progression of interstitial fibrosis, increases of hydroxyproline contents, and mRNA expression of collagen type Ialpha1 and monocyte chemotactic protein 1 (MCP-1). However, these changes were found to be prevented with daily oral administration of FR276457. In addition, given that MCP-1 is believed to contribute to progressive fibrosis, we investigated the direct effect of FR276457 on MCP-1 production by activated THP-1 cells in vitro. Results showed that FR276457 administration decreased MCP-1 production in these cells in a concentration-dependent manner. Findings from the present study suggested that a pan-HDAC inhibitor may exert a prophylactic effect against renal interstitial fibrosis by inhibiting MCP-1 production.

Characterization of a 2,4-Dinitrochlorobenzene-Induced Chronic Dermatitis Model in Rats

Although many mouse models of atopic dermatitis have been reported, few rat models have been studied. In this study, a rat chronic allergic dermatitis model was developed and evaluated as a pharmacological model of atopic dermatitis. Prominent ear thickening and scratching were induced after the application of 2,4-dinitrochlorobenzene to the right ear of Brown Norway rats 3 times per week for 3 weeks. Histopathologically, infiltration of T cells in the ear was observed on day 7, and eosinophils and mast cells were found in addition to T cells on day 21. The expression of interferon-γ and interleukin-4 was increased on day 7 when compared with normal rats. However, interferon-γ expression had disappeared by day 21. Tacrolimus ointment applied after ear tissue thickening fully developed, suppressed chronic dermatitis in a dose-dependent manner. This model has some symptomatic and histopathological similarities to atopic dermatitis and might be useful in pharmacological studies.

Pharmacokinetics and Pharmacodynamics of ASP2151, a Helicase-Primase Inhibitor, in a Murine Model of Herpes Simplex Virus Infection

ABSTRACT ASP2151 (amenamevir) is a helicase-primase inhibitor against herpes simplex virus 1 (HSV-1), HSV-2, and varicella zoster virus. Here, to determine and analyze the correlation between the pharmacodynamic (PD) and pharmacokinetic (PK) parameters of ASP2151, we examined the PD profile of ASP2151 using in vitro plaque reduction assay and a murine model of HSV-1 infection. ASP2151 inhibited the in vitro replication of HSV-1 with a mean 50% effective concentration (EC50) of 14 ng/ml. In the cutaneously HSV-1-infected mouse model, ASP2151 dose dependently suppressed intradermal HSV-1 growth, with the effect reaching a plateau at a dose of 30 mg/kg of body weight/day. The dose fractionation study showed that intradermal HSV-1 titers were below the detection limit in mice treated with ASP2151 at 100 mg/kg/day divided into two daily doses and at 30 or 100 mg/kg/day divided into three daily doses. The intradermal HSV-1 titer correlated with the maximum concentration of drug in serum (Cmax), the area under the concentration-time curve over 24 h (AUC24h), and the time during which the concentration of ASP2151 in plasma was above 100 ng/ml (T>100). The continuous infusion of ASP2151 effectively decreased intradermal HSV-1 titers below the limit of detection in mice in which the ASP2151 concentration in plasma reached 79 to 145 ng/ml. Our findings suggest that the antiviral efficacy of ASP2151 is most closely associated with the PK parameter T>100 in HSV-1-infected mice. Based on these results, we propose that a plasma ASP2151 concentration exceeding 100 ng/ml for 21 to 24 h per day provides the maximum efficacy in HSV-1-infected mice.

Effect of zenarestat, an aldose reductase inhibitor, on endoneurial blood flow in experimental diabetic neuropathy of rat

The effects of zenarestat, an aldose reductase inhibitor, on endoneurial blood flow (NBF) were explored in streptozotocin-induced diabetic rats. Rats were maintained on a diet of containing 0.09% zenarestat for 8 weeks, then NBF in the sciatic nerve was measured using microelectrode hydrogen polarography. NBF in the diabetic control rats was significantly lower than values in age-matched control rats, however, NBF was not significantly altered in diabetic rats treated with zenarestat. Direct application of nitric oxide synthase inhibitor, NG-nitro-L-arginine, did not affect NBF in diabetic control rats, whereas this application significantly reduced NBF both in age-matched control and zenarestat treated diabetic rats. Considerable levels of zenarestat were confirmed in the sciatic nerve in the drug treated rats. These data suggest that aldose reductase, such as zenarestat, might restore or prevent the alteration of endoneurial blood flow resulting from an impairment of nitric oxide function.

Effect of ipragliflozin, an SGLT2 inhibitor, on progression of diabetic microvascular complications in spontaneously diabetic Torii fatty rats ☆

AIMS We investigated the effect of the selective sodium-dependent glucose cotransporter 2 inhibitor ipragliflozin on the simultaneous progression of diabetic microvascular complications of retinopathy, nephropathy and neuropathy in individual Spontaneously Diabetic Torii (SDT) fatty rats. MAIN METHODS Ipragliflozin was administered to male SDT fatty rats for 12weeks. Male Sprague-Dawley rats of the same age were used as non-diabetic controls. Non-fasting plasma glucose and glycated hemoglobin levels were measured every 4weeks. Cataract formation was monitored once a week, and the electroretinogram was measured after 6weeks of treatment. After the treatment period, motor nerve conduction velocity was measured and urinalysis was conducted. Tissue samples were then dissected for histopathological examination. KEY FINDINGS Treatment with ipragliflozin reduced glycated hemoglobin levels, inhibited the progression of cataract formation, prevented the prolongation of oscillatory potential peaks in the electroretinogram, ameliorated the slowing of motor nerve conduction velocity, and reduced the severity of glomerulosclerosis in SDT fatty rats. SIGNIFICANCE These results suggest that the control of hyperglycemia with ipragliflozin slows the progression of the diabetic complications of retinopathy, nephropathy, and neuropathy.

Susceptibility of Herpes Simplex Virus Isolated from Genital Herpes Lesions to ASP2151, a Novel Helicase-Primase Inhibitor

ABSTRACT ASP2151 (amenamevir) is a helicase-primase inhibitor against herpes simplex virus type 1 (HSV-1), HSV-2, and varicella-zoster virus. To evaluate the anti-HSV activity of ASP2151, susceptibility testing was performed on viruses isolated from patients participating in a placebo- and valacyclovir-controlled proof-of-concept phase II study for recurrent genital herpes. A total of 156 HSV strains were isolated prior to the dosing of patients, and no preexisting variants with less susceptibility to ASP2151 or acyclovir (ACV) were detected. ASP2151 inhibited HSV-1 and HSV-2 replication with mean 50% effective concentrations (EC50s) of 0.043 and 0.069 μM, whereas ACV exhibited mean EC50s of 2.1 and 3.2 μM, respectively. Notably, the susceptibilities of HSV isolates to ASP2151 and ACV were not altered after dosing with the antiviral agents. Taken together, these results demonstrate that ASP2151 inhibits the replication of HSV clinical isolates more potently than ACV, and HSV resistant to this novel helicase-primase inhibitor as well as ACV may not easily emerge in short-term treatment for recurrent genital herpes patients.

The effects of zenarestat, an aldose reductase inhibitor, on minimal F-wave latency and nerve blood flow in streptozotocin-induced diabetic rats

The effects of zenarestat, 3-(4-bromo-2-fluorobenzyl)-7-chloro-3,4-dihydro-2,4-dioxo-1(2H)-quinazolineacetic acid, an aldose reductase inhibitor (ARI), on F-wave conduction abnormalities, nerve blood flow (NBF) reduction and sorbitol accumulation were studied in streptozotocin-induced diabetic rats. Two weeks after the induction of diabetes, zenarestat was given once a day for two weeks. In diabetic control rats, marked accumulation of sorbitol, reduction of NBF and prolongation of minimal F-wave latency (FWL) were observed as compared to normal rats. Zenarestat, at a dose of 32 mg/kg, inhibited sorbitol concentration to nearly the normal rat level and significantly improved not only NBF but also minimal FWL. At a dose of 3.2 mg/kg, sorbitol accumulation was inhibited by approximately 40% and there was a tendency to increase in NBF; however, minimal FWL was not improved at all. These data suggest that a highly inhibition of the nerve sorbitol accumulation is requisite for the treatment of diabetic peripheral neuropathy.

Thirteen-month inhibition of aldose reductase by zenarestat prevents morphological abnormalities in the dorsal root ganglia of streptozotocin-induced diabetic rats

The dorsal root ganglia (DRG) have been identified as the target tissue in diabetic somatosensory neuropathy. It has been reported that, in the chronically diabetic state, DRG sensory neurons may undergo morphological changes. In this study, we examined the effect of zenarestat, an aldose reductase inhibitor, on the morphological derangement of the DRG and the sural nerve of streptozotocin-induced diabetic rats (STZ rats) over a 13-month period. The cell area of the DRG in STZ rats was smaller than that in normal rats. A decrease in fiber size was apparent in the sural nerve of the STZ rats, and the fiber density was greater. These morphological changes were reversed in zenarestat-treated STZ rats. The data suggest that, in peripheral sensory diabetic neuropathy, hyperactivation of the polyol pathway induces abnormalities not only in peripheral nerve fiber, but also in the DRG, which is an aggregate of primary sensory afferent cell bodies.

FR177391, a new anti-hyperlipidemic agent from Serratia. II. Pharmacological activity of FR177391.

The pharmacological effect of FR177391, isolated from Serratia liquefaciens No. 1821, was studied in normal animals and various types of animal models of hypertriglyceridemia. Treatment of normal mice with FR177391 resulted in an increase in heparin-releasable lipoprotein lipase (LPL) activity in the blood and epididymal fat tissue. FR177391 treatment decreased triglyceride (TG) and increased high-density lipoprotein cholesterol in the blood in normal rats following 7 days treatment, suggesting potent LPL activating properties of FR177391. Both Triton WR1339-induced severe and fructose-induced mild hypertriglyceridemia in rats were attenuated by FR177391 treatment. Severely elevated levels of TG in db/db mice, an insulin resistant diabetic animal model, also significantly decreased from 14 days of treatment with FR177391. FR177391 treatment for 9 days caused a decrease in the elevated levels of TG in mice induced by intraperitoneal inoculation of murine lymphoma EL-4. Overall, this study demonstrated that FR177391 can be possibly a LPL activating agent and that FR177391 treatment improved hypertriglyceridemia in various rat and mouse animal models. These results suggest that FR177391 is a promising candidate compound for the management of hypertriglyceridemia.