Chronic Alcohol Dysregulates Skeletal Muscle Myogenic Gene Expression after Hind Limb Immobilization in Female Rats

Abstract

Alcohol use and aging are risk factors for falls requiring immobilization and leading to skeletal muscle atrophy. Skeletal muscle regeneration is integral to post-immobilization recovery. This study aimed to elucidate the effects of alcohol and ovarian hormone loss on the expression of genes implicated in muscle regeneration. Three-month-old female rats received an ovariectomy or a sham surgery, consumed an alcohol-containing or control diet for 10 weeks, were subjected to unilateral hind limb immobilization for seven days, and finally were allowed a three (3d)- or 14 (14d)-day recovery. Immobilization decreased the quadriceps weight at 3d and 14d, and alcohol decreased the quadriceps weight at 14d in the nonimmobilized hind limb (NI). At 3d, alcohol decreased gene expression of myoblast determination protein (MyoD) in the immobilized hind limb (IMM) and myocyte enhancer factor (Mef)2C and tumor necrosis factor (TNF)α in NI, and ovariectomy increased MyoD and decreased TNFα expression in NI. At 14d, alcohol increased the gene expression of Mef2C, MyoD, TNFα, and transforming growth factor (TFG)β in IMM and decreased monocyte chemoattractant protein (MCP)1 expression in NI; ovariectomy increased TNFα expression in NI, and alcohol and ovariectomy together increased Mef2C expression in NI. Despite increased TGFβ expression, there was no concomitant alcohol-mediated increase in collagen in IMM at 14d. Overall, these data indicate that alcohol dysregulated the post-immobilization alteration in the expression of genes implicated in regeneration. Whether alcohol-mediated molecular changes correspond with post-immobilization functional alterations remains to be determined.

IL-1β and TNF-α Modulation of Proliferated and Committed Myoblasts: IL-6 and COX-2-Derived Prostaglandins as Key Actors in the Mechanisms Involved

“…TNF-α levels in injured muscle have been shown to rise dramatically due to a strong increase in its synthesis by injured myofibrils and its release by infiltrating inflammatory cells [ 12 , 13 , 14 , 15 ]. While a transient increase in intramuscular TNF-α levels after injury is required for muscle regeneration and repair, a persistent high concentration of this mediator inhibits myogenesis and limits recovery, leading to muscle wasting [ 8 , 16 , 17 ]. Increased synthesis of TNF-α, observed in the early phase of differentiation of C2C12 myoblasts in culture, is positively associated with regeneration, since its inhibition prevents the process of muscle repair [ 16 , 18 ].…”

“…While a transient increase in intramuscular TNF-α levels after injury is required for muscle regeneration and repair, a persistent high concentration of this mediator inhibits myogenesis and limits recovery, leading to muscle wasting [ 8 , 16 , 17 ]. Increased synthesis of TNF-α, observed in the early phase of differentiation of C2C12 myoblasts in culture, is positively associated with regeneration, since its inhibition prevents the process of muscle repair [ 16 , 18 ]. In parallel to TNF-α release, an increased expression of TNF-α receptors is found in injured muscle fibres [ 13 , 14 ], which has been shown to regulate the exiting of the cell cycle and the initiation of myogenic differentiation [ 19 ].…”

Pathophysiological mechanisms of alcoholic myopathy - Lessons from rodent models

“…Skeletal muscle recovery may be complicated by alcohol use and altered hormonal status among older individuals (Lukaszyk et al, 2016). To examine this question, we utilized Lieber-DeCarli feeding in rats for 10 weeks culminating in 1 week of unilateral hind limb immobilization followed by 3 or 14 days of remobilization (Levitt et al, 2020c). Our data indicated that alcohol dysregulates the expression of markers of muscle regeneration following unilateral hind limb immobilization.…”

“…The most common diet used is the Lieber-DeCarli diet (Lieber and DeCarli,1989) and the control diet is isocalorically matched to the alcohol calories. This strategy is widely used to study end-organ injury, including chronic alcohol-induced skeletal muscle pathology (Levitt et al, 2020c;Crowel et al, 2016;Lang, 2018).…”

Ethanol‐Impaired Myogenic Differentiation is Associated With Decreased Myoblast Glycolytic Function

“…We previously observed that in vivo chronic binge alcohol administration decreases the in vitro differentiation potential of myoblasts isolated from simian immunodeficiency virus (SIV)‐infected (Simon et al, 2017) or SIV‐naïve male rhesus macaques (Simon et al, 2014) and that in vitro ethanol (EtOH) treatment (50mM) decreases the differentiation potential of myoblasts from male macaques assessed at 5 days of differentiation (Adler et al, 2019). Furthermore, our studies in a rodent model of hindlimb immobilization demonstrated that chronic alcohol feeding suppressed SKM expression of myogenic genes at 3 days after remobilization following 1 week of immobilization (Levitt et al, 2020). However, whether alcohol similarly impairs in vitro myoblast differentiation potential in females is unknown.…”