Protective Effects of Nigranoic Acid on Cerebral Ischemia–Reperfusion Injury and its Mechanism Involving Apoptotic Signaling Pathway

The goal of this study was to assess the expression of poly ADP-ribose polymerase (PARP) and apoptosis-inducing factor (AIF) in the hippocampal CA1 region, and to find out whether nigranoic acid treatment exhibits protective effects on brain through PARP/AIF signaling pathway in cerebral ischemia–reperfusion animal model. Rats were randomly divided into three groups: Sham-surgery, ischemia–reperfusion, and nigranoic acid-treated. Rat models of middle cerebral artery occlusion were prepared using a way of thread occlusion. Rats in the nigranoic acid group were administered with 1 mg/kg intragastric nigranoic acid 6 and 2 h before brain ischemia, respectively. Following reperfusion, samples were collected at different time-points (6, 24, and 72 h) and each group was further divided into three subgroups. Apoptosis was measured using the terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling method. The protein expression levels of AIF and PARP were detected using Western blot and AIF mRNA quantity was evaluated using the reverse transcription-polymerase chain reaction. Apoptosis, levels of AIF and PARP protein expression, and levels of AIF mRNA expression were significantly increased in the ischemia–reperfusion group compared with the sham-surgery group. However, apoptosis and the expression levels of AIF protein, PARP protein, and AIF mRNA at different time-points were significantly decreased in the nigranoic acid-treated group compared with the model group. We can judge that nigranoic acid has a strong protective effect on rat cerebral ischemia–reperfusion injury, and acts by downregulating nerve cell apoptosis by preventing the overactivation of PARP and AIF nuclear translocation.