Coenzyme Q10 supplementation modulates NF[kappa]B and Nrf2 pathways in exercise training.

Author:Pala, Ragip
Position:Research article - Report
 
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Introduction

Coenzyme Q10 (or 1,4-benzoquinone) is a component of the electron transport chain in mitochondria which is linked to the generation of energy in the cell (Bentinger et al., 2010). The deficiency of Q10 has been reported to result in poor athletic performance and/or disease pathogenesis including encephalomyopathy, cerebellar ataxia, Leigh syndrome and myopathy (Garrido-Maraver et al., 2014). The Q10 deficiency in skeletal muscle has been shown to show a spectrum of clinical manifestations and suggested to lead to a secondary impairment of mitochondrial fatty acid oxidation (Schaefer et al., 2009). In a study, Q10 has been reported to protect skeletal muscles against exercise-induced injury in rats (Kon et al., 2007). In its reduced form, Q10 holds electrons rather loosely and inhibits the peroxidation of lipids, thus acting as an antioxidant (Mellors and Tappel, 1966; Sarter, 2002), and protects against oxidative injury.

Interventions including nutrition, pharmacology and exercise may induce the expression of Nuclear Factor Kappa-light-chain-enhancer of activated B cells (NF[kappa]B) and cellular antioxidant systems via the Nuclear Factor (erythroid-derived 2)-Like 2 (Nrf2)-Kelch-like ECH-associated protein 1 (Keap-1) signaling pathway and play a role in preventing inflammatory processes (Lee et al., 2011). The inducible hemeoxygenase (HO-1) is an antioxidant stress protein, mainly induced by reactive oxygen species (ROS), cytokines and hyperthermia that has been reported to be upregulated in endurance-trained male subjects after a half marathon run (Niess et al., 1999).

Despite a need of adequate antioxidant levels to attenuate exercise-induced oxidative damage, a debate exists whether antioxidant supplementations potentiate health outcomes of physical exercise. In contrast supraphysiological dosages of antioxidant supplementations may interfere with ROS-mediated cell signaling and blunt the positive effects of exercise (Atalay et al., 2006).

We postulate that Q10 supplementation and exercise-induced protection can be a safe tool to control oxidative stress and inflammation. This study reports that Q10 can modulate the expression of NF[kappa]B, I[kappa]B, Nrf2 and HO-1 after exercise training, supporting the role of Q10 in antioxidant defense and inflammation.

Methods

Animals

Twenty-eight male Wistar rats (age: 8 week, weight: 180 [+ or -] 20 g) were housed in a controlled environment with a 12:12-h light-dark cycle at 22[degrees]C and were provided with rat chow and water ad libitum. All experiments were conducted under the National Institute of Health's Guidelines for the Care and Use of Laboratory Animals and approved by the Ethics Committee of the Firat University. Animals were randomly divided into the following four groups: (i) Control [Sedentary, Group I], (ii) Q10 control [Control diet + Q10, that is, sedentary, but administered with Q10, Group II] (iii) Exercise training [Control diet + subjected to chronic exercise training for six weeks, Group III], and (iv) Q10 supplemented [Control diet + subjected to physical exercise and Q10 treatment, Group IV]. Q10 was administered daily for six weeks as an oral supplement by gastric tube at a dose level of 300 mg/kg body weight. The selection of the dose (300 mg/kg b. wt.) was based on previous studies where this dosage demonstrated a significant antioxidant effect in rat (Kon et al., 2007). Composition of diet fed to animals is shown in Table 1.

Exercise protocol

The rats were subjected to treadmill exercise on a motorized rodent treadmill purchased from Commat Limited, Ankara, Turkey. The treadmill included a stimulus grid at the back end of the treadmill which provided an electric shock if the animal placed its paw on the grid. The apparatus consisted of a 5-lane animal exerciser utilizing single belt construction with dividing walls suspended over the tread surface. All exercise tests were performed during the same time period of the day to minimize diurnal effects. All rats were pre-trained in order for the animals to be exposed to the treadmill equipment and handling for 1 week. For this purpose, animals in the exercise training groups were habituated by treadmill exercise over a 5-day period such that: (i) 1st day, 10 m/min, 10 min, (ii) 2nd day, 20 m/min, 10 min, (iii) 3rd day, 25 m/min, 10 min, (iv) 4th day, 25 m/min, 20 min and (v) 5th day, 25 m/min, 30 min. After 1 week treadmill familiarization to eliminate novel and stress effects, animals in treadmill exercise groups ran on the treadmill 25 m/min, 45 min/day and five days per week for 6 weeks according to the protocol published earlier (Liu et al., 2008).

Sample collection

Sedentary and exercise rats were sacrificed via cardiac puncture under ether anesthesia. Exercise groups were sacrificed 48 h after the last exercise. To minimize diurnal effects, animals were killed at the same hour. Within 1 min, the blood sample was transferred into EDTA-coated tube and plasma was separated by centrifugation at 1,750 x g for 10 min. The plasma was stored at -80[degrees]C until the time of analysis. Heart, liver and muscle tissues were rapidly collected and frozen at -80[degrees]C for further analyses.

Laboratory analyses

Plasma was used for the determination of urea, glucose and lipid profile, using an automatic analyzer (Samsung LAbGeO PT10, Samsung Electronics Co, Suwon, Korea). Repeatability and device/method precision of [LABGEO.sup.PT10] was established according to the IVR-PT06 guideline.

All proteins (NF[kappa]B, I[kappa]B, Nrf2 and HO-1) in the signal transduction pathway were analyzed by Western blot methods in heart, liver and slow-twitch muscles (soleus and gastronemius deep portion). Proteins were extracted from heart, liver and muscle tissues for Western blots (Sahin et al., 2013). For protein analyses an accurately weighed heart, liver or muscle tissues were homogenized in 1:10 (w/v) in 10 mM Tris-HCl buffer at pH 7.4, containing 0.1 mM NaCl, 0.1 mM phenylmethylsulfonyl fluoride and 5 [micro]M soybean (soluble powder; Sigma, St. Louis, MO, USA) as trypsin inhibitor. After centrifugation at 15,000 g at 4[degrees]C for 30 min supernatant was...

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