Expression of acetylcholine receptor mRNAs in atrophying and nonatrophying skeletal muscles of old rats.
We examined the age-related association in skeletal muscle between atrophy and expression of mRNAs encoding both the gamma-subunit of the nicotinic acetylcholine receptor (AChR), and myogenin, a transcription factor that upregulates expression of the gamma-subunit promoter. Gastrocnemius and biceps brachii muscles were collected from young (2-mo-old), adult (18-mo-old), and old (31-mo-old) Fischer 344/Brown Norway F1 generation cross male rats. In the gastrocnemius muscles of old vs. young and adult rats, lower muscle mass was accompanied by significantly elevated AChR gamma-subunit and myogenin mRNA levels. In contrast, the biceps brachii muscle exhibited neither atrophy nor as drastic a change in AChR gamma-subunit and myogenin mRNA levels with age. Expression of the AChR epsilon-subunit mRNA did not change with age in either gastrocnemius or biceps brachii muscles. Thus changes in skeletal muscle AChR gamma-subunit and myogenin mRNA levels may be more related to atrophy than to chronological age in old rats.
Gomes
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Department of Integrative Biology, Pharmacology, and Physiology, University of Texas-Houston Medical School, Houston, Texas 77030, USA.
Booth
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FW
D000818:Animals; D001284:Atrophy; D015152:Blotting, Northern; D001835:Body Weight / Q000502:physiology; D006614:Hindlimb / Q000502:physiology; D008297:Male; D024510:Muscle Development; D018482:Muscle, Skeletal / Q000254:growth & development / Q000378:metabolism* / Q000473:pathology; D018008:Myogenin / Q000096:biosynthesis / Q000235:genetics; D009929:Organ Size / Q000502:physiology; D015347:RNA Probes; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D011914:Rats, Inbred BN; D011916:Rats, Inbred F344; D011950:Receptors, Cholinergic / Q000096:biosynthesis*
C503803:Myog protein, rat; D018008:Myogenin; D015347:RNA Probes; D012333:RNA, Messenger; D011950:Receptors, Cholinergic