Abstract
Previous work has demonstrated that poly (ADP-ribose) polymerase (PARP) inhibition confers protection on skeletal muscle ischemia–reperfusion (IR) injury in diabetic mice. Published reports, including a model of renal IR injury in normal nondiabetic mice, have shown that poly (ADP-ribosylation) of the critical glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) results in reduced enzyme activity, thereby reducing energy metabolites. This study aims to determine whether PARP inhibition modulates the activity and level of poly (ADP-ribosylation) of GAPDH, along with energy substrates within diabetic skeletal muscle after IR. Two groups of db/db mice underwent 1.5 hours of unilateral hind limb ischemia, followed by 24 hours reperfusion. The treatment group (PJ) received 6× dosages of 30 mg/kg of PJ34, a PARP inhibitor, at 5 minutes before reperfusion, at 15 minutes, and at 2, 6, 12, and 18 hours after reperfusion. The untreated group received equivalent volumes of lactated Ringer's (LR) vehicle at the same time points. Uninjured sham mice were used as the control. Hind limb skeletal muscle tissue was harvested at 24 hours reperfusion to evaluate PARP and GAPDH activity, total GAPDH expression and poly (ADP-ribosylated) GAPDH, in addition to skeletal muscle ATP and lactate. PJ34 treatment significantly reduced PARP activity and increased GAPDH activity relative to LR at 24 hours' reperfusion (Table) . GAPDH expression was significantly lower in the PJ group. Poly (ADP-ribosylation) of GAPDH was significantly reduced in the PJ group. PJ34 treatment significantly increased skeletal muscle ATP and lactate compared with LR.TableLRPJP(n = 6-16)(n = 6-10)PARP activity (% control)300 ± 48221 ± 20.0043GAPDH activity (U/2-mg protein)0.31 ± 0.040.5 ± 0.04.0005GAPDH expression (% control)122.5 ± 894 ± 6.0008GAPDH poly (ADP-ribosylation) (AU)1.5 ± 0.230.41 ± 0.13.0002Muscle ATP (nmol/g tissue)0.3 ± 0.10.84 ± 0.3.0046Muscle lactate (μg/g tissue)229 ± 10375.6 ± 48.00004 Open table in a new tab These data indicate that PARP inhibition by PJ34 increased GAPDH activity, tissue lactate, and ATP, and decreased poly (ADP-ribosylation) of GAPDH after IR. The resulting increase in tissue ATP and lactate may provide mechanistic insight into how PARP inhibition mediates protection against skeletal muscle IR injury.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
