Effects of various durations of post-treatment with trimetazidine against ischemia-reperfusion : early and long-term effects in a rat kidney model

Abstract

Acute kidney injury (AKI) is a well-known risk factor for poor prognosis in hospitalized patients and believed to be often the consequence of ischemia-reperfusion (I/R) injury. The rats were euthanized 5 days or 8 weeks after I/R injury. The effect of post I/R treatment with TMZ was determined using different variables: renal function (serum blood urea nitrogen [BUN] and creatinine), renal histologic change including apoptotic cell death and fibrosis, and related signaling proteins including hypoxia inducible factor (HIF)-1α, vascular endothelial growth factor (VEGF), phosphorylated-Akt (P-Akt), endothelial nitric oxide synthase (eNOS), Bcl-2, matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). Post I/R treatment with TMZ significantly reduced serum levels of BUN and creatinine, apoptotic cell death through up-regulation of HIF-1α-VEGF and P-Akt/eNOS, and Bcl-2 related apoptotic signaling pathways 24 hr after renal I/R injury. Although serum levels of BUN and creatinine recovered to baseline values, post I/R treatment with TMZ reduced renal tubular cell necrosis and apoptosis via up-regulation of HIF-1α-VEGF, P-Akt/eNOS, and TIMPs, attenuation of MMPs activities, and alteration of the ratio of Bax for Bcl-2 at 5 days after renal I/R injury regardless of the treatment protocol. Post I/R treatment with TMZ, however, did not suppress the progression of renal fibrosis and expression of related signal pathways, 8 weeks after renal I/R injury. These results indicate that post I/R treatment with TMZ has beneficial effect on renal protection against I/R injury at early and intermediate period, while it failed to inhibit the longterm renal fibrotic change. Trimetazidine (TMZ, 1 - [2, 3, 4 - trimethoxybenzyl] piperazine, dihydrochloride), an antiischemic agent used for decades, has a theoretical potential to reduce I/R injury through modulations of various cell survival pathways. Yet, the majority of studies including clinical studies have concentrated on the early effects of TMZ pre-treated before I/R injury, limiting its clinical applicability. The aim of this study was to elucidate the effects of various durations of TMZ administered after renal I/R injury on renal recovery in long-term as well as short-term aspects with the evaluation of relevant signaling pathways in rats. In short-term study, Sprague-Dawley (SD) rats were randomly assigned to four groups: Sham, untreated control I/R (IRC), TMZ treatment before I/R (TMZ-pre), TMZ treatment after I/R (TMZ-post). TMZ (3 mg/kg, intraperitoneally) was administered 1 hr before ischemia (pre) or upon reperfusion (post). All rats except in the Sham group underwent left side nephrectomy and the right renal pedicle was clamped for 45 min and then reperfused for 24 hr when the rats were euthanized for analysis. In intermediate and long-term studies, rats were randomly assigned to four groups: Sham, IRC, TMZ post-treatment after I/R (TMZ-single), daily TMZ post-treatment after I/R (TMZ-daily). TMZ (3 mg/kg, intraperitoneally) was administered once immediately upon reperfusion (TMZ-single), or administered once a day for a scheduled period (TMZ-daily).