Effect And Mechanism Of Penehyclidine Hydrochloride Pretreatment On Rhabdomyolysis-induced Acute Kidney Injury In Rats

Background High intensity military training and war trauma can result in rhabdomyolysis (RM), which sometimes induces acute kidney injury (AKI) with high fatality. However, their pathogenesis and control measures remain unclear. Our previous studies suggested that an anticholinergic agent called anisodamine alleviated RM-induced AKI in rats by improving minicirculation, reducing oxidative stress and inhibiting apoptosis. Penehyclidine hydrochloride (PHC) is an analogous selective anticholinergic agent with both antimuscarinic and antinicotinic activities. It has been widely used as an anesthetic premedication in China. Previous studies in animals have shown that PHC reduces oxidative stress and apoptosis. More recently, PHC has been shown to ameliorate renal ischemia-reperfusion injury in rats. However, whether and how can PHC alleviate RM-induced AKI are still remain unknown.Objective To establish a rat model of RM-induced AKI, evaluate whether PHC pretreatment could ameliorate AKI induced by RM in rats and elucidate the underlying mechanisms.Methods Ninety adult male Sprague-Dawley rats weighing 200-220 g were randomly assigned into five groups (n=18):control group (C), in which 10 ml/kg of normal saline were injected intramuscularly (i.m.) in equally divided dosages into each hind limb; group AKI, in which 10 ml/kg of 50% glycerol were injected i.m. in equally divided dosages into each hind limb; group PHC, which received 0.2 mg/kg of PHC intraperitoneally (i.p.) 30 min before glycerol injection; group ZnPP, in which 10 mg/kg ZnPP was injected i.p.24 h before glycerol injection; and group PHC+ZnPP, in which PHC and ZnPP were separately administered as described above. All groups except group C achieved RM-induced AKI. At 1,6 and 24 h after glycerol injection, six rats from each group were randomly selected and sacrificed. Venous blood samples were collected, and serum was isolated by coagulation and centrifugation. The left kidney was harvested and preserved at -80℃ for HO-1 enzymatic activity, real-time quantitative PCR (RT-qPCR) and Western blotting analysis, while the right kidney was harvested and fixed in 4% paraformaldehyde for pathology and immunohistochemistry examination.Results 1) Compared with group C, serum BUN, Cr and CK and tubular injury scores were significantly higher in group AKI at any time point (P<0.01). Compared with group AKI, serum BUN and Cr and tubular injury scores were significantly lower in group PHC at any time point (P<0.01 or 0.05). Compared with group PHC, the indexs above were significantly higher in groups ZnPP and PHC+ZnPP at any time point (P<0.01 or 0.05).2) In group AKI, levels of myoglobin in serum and renal tissues, HO-1 activity, expression of Nrf2 in nuclear protein and HO-1 mRNA and protein in renal tissues were significantly higher us. group C. In group PHC, levels of myoglobin in serum and renal tissues were significantly lower, and HO-1 activity, expression of Nrf2 and HO-1 both at gene and protein levels in renal tissues were significantly higher vs. group AKI. In groups ZnPP and PHC+ZnPP, levels of myoglobin in serum and renal tissues were significantly higher, and HO-1 activity, expression of Nrf2 and HO-1 both at gene and protein levels in renal tissues were significantly lower at some time points vs. group PHC.3) Compared with group C, renal cell apoptosis rate and expression of GRP78 and caspase-12 both at gene and protein levels in renal tissues were significantly higher in group AKI at any time point (P<0.01). Compared with group AKI, the indexs above were significantly lower in group PHC at some time points (P<0.01 or 0.05).Conclusion 1) Severe RM resulted in AKI in rats. PHC pretreatment ameliorated the pathological renal injury and renal dysfunction in RM-induced AKI in rats.2) Nrf2/HO-1 pathway played a renoprotective role in RM-induced AKI in rats. PHC pretreatment ameliorated RM-induced AKI by promoting the Nrf2/HO-1 pathway in renal tissues, which decreased the accumulation of myoglobin and heme in the kidney. 3) Endoplasmic reticulum stress (ERS)-mediated apoptosis involved in the patho-physiologic process of RM-induced AKI in rats. PHC pretreatment alleviated RM-induced AKI and decreased the renal cell apoptosis rate by inhibiting ERS in renal tissues in rats.