Interplay between the Thioredoxin System and the ASK‐1 Signaling Pathway in Testicular Ischemia Reperfusion Injury

Abstract

Testicular ischemia reperfusion injury (tIRI) has been suggested through several studies as the underlying mechanism for testicular torsion and detorsion (TTD) due to the excessive generation of reactive oxygen species (ROS) leading to germ cell apoptosis (GCA). The aim of the study is to explore the mechanism of the apoptosis signal‐regulating kinase 1 (ASK1) signaling pathway during tIRI by using its specific inhibitor, NQDI‐1. We also investigated the effect of NQDI‐1 on the expression of the thioredoxin (Trx) system, a major source of ROS. Male Sprague‐Dawley rats (n=36, 250–300 g) were divided equally into three experimental groups: sham, tIRI and tIRI + NQDI‐1 (10 mg/kg). During tIRI, the testicular artery was occluded for 1 hour followed by 4 hours reperfusion. The NQDI1 was injected intraperitoneally 30 minutes post ischemia. Histological analyses were used to evaluate testicular morphological changes as well as spermatogenesis. Gene expression, protein immunoexpression and enzyme activities were assessed by real‐time PCR, ELISA, IHC and colorimetric assays. Following tIRI, histological examination revealed impairment in spermatogenesis represented by a significant decrease in the Johnsen score. Real‐time PCR confirmed the upregulation of the pro‐apoptosis genes BAD and BAX and the downregulation of anti‐apoptosis gene Bcl2, which were accompanied by activation of the executioner caspase‐3 in the tIRI group. The levels of the antioxidants GSH, SOD, as well as thioredoxin reductase (TrxR) enzyme were also reduced upon tIRI induction. Immunoexpression of ph‐p38 and ph‐ASK1 were increased significantly after tIRI indicating the activation of ASK1 signalling pathway, while a remarkable decrease in Trx was simultaneously observed. The above damaging consequences of tIRI were attenuated after NQDI1 treatment obtaining normalized values similar to sham. Our findings suggest that the redox status of the cell is cooperatively regulated with ASK1 signaling to maintain cellular homeostasis during testicular oxidative stress. Additionally, the interplay between the Trx system and ASK1 suggests their potential role in the pathogenesis of tIRI.Support or Funding InformationThe project was supported by the College of Graduate studies and Research Administration, Kuwait University through grant # YM 09/17 and OMICSRU/RCF project grant # SRUL02/13.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.