Alcohol alters skeletal muscle heat shock protein gene expression in rats: these effects are moderated by sex, raised endogenous acetaldehyde, and starvation.
Alcoholic myopathy is a common pathology characterized by wasting due to reduced protein synthesis, although the mechanisms involved remain unclear. Women are particularly sensitive and malnutrition exacerbates the myopathy. This study aimed to address (i) whether long-term alcohol feeding alters expression of heat shock proteins (HSPs) in male and female rats; (ii) the effect of immediate alcohol dosing with or without raised levels of endogenous acetaldehyde; and (iii) the effect of starvation. To address this, (i) male and female rats were fed alcohol in the long-term (6-7 weeks as 35% of energy in a liquid diet) and compared to controls fed the same diet with isoenergetic glucose; (ii) male rats given an immediate bolus (75 mmol ethanol per kilogram body weight intraperitoneally) 2.5 hours before sacrifice and compared to controls given a dose of saline (with or without pretreatment with cyanamide-an acetaldehyde dehydrogenase inhibitor which raises endogenous acetaldehyde); (iii) male rats starved for 1 or 2 days then immediately dosed with alcohol. Protein levels of HSP 27, HSP 60, and HSP 70 were measured in muscles of male rats fed alcohol and pair-fed control rats by SDS-PAGE and Western blotting in study I. Levels of HSP 27, HSP 60, HSP 70, and HSP 90 mRNA were analyzed in hind limb skeletal muscle by reverse transcription-polymerase chain reaction with an endogenous internal standard, glyceraldehyde-3-phosphate-dehydrogenase. (i) Long-term alcohol dosage reduced HSP 27 in male rats but not in females, whereas HSP 90 mRNA increased in long-term alcohol-fed female rats but not in male rats. These changes were reflected by a similar trend in HSP protein content, although statistical significance was not achieved. (ii) There was no effect on any of the HSP mRNAs in rats dosed immediately with alcohol or in combination with cyanamide. (iii) Starvation per se for 2 days was associated with an increase in HSP 27 mRNA. Alcohol administration after 2 days starvation caused a blunting of the increased HSP 27 mRNA in starvation alone. This suggests that long-term alcohol exposure affects HSP gene expression and that this effect is moderated by sex and starvation. This may contribute to, or reflect, the biochemical lesion in alcoholic myopathy.
Nakahara
Tatsuo
T
Department of Chemistry, Faculty of Science, Kyushu University Ropponmatsu, Chuo-ku, Fukuoka 810-8560, Japan.
Hunter
Ross
R
Hirano
Makoto
M
Uchimura
Hideyuki
H
McArdle
Ann
A
Broome
Caroline S
CS
Koll
Michael
M
Martin
Colin R
CR
Preedy
Victor R
VR
D000079:Acetaldehyde / Q000378:metabolism*; D000818:Animals; D003484:Cyanamide / Q000494:pharmacology; D000431:Ethanol / Q000633:toxicity*; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D006360:Heat-Shock Proteins / Q000032:analysis / Q000235:genetics*; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D012737:Sex Factors; D013217:Starvation / Q000378:metabolism*
D006360:Heat-Shock Proteins; D012333:RNA, Messenger; D000431:Ethanol; D003484:Cyanamide; D000079:Acetaldehyde