Effect of changes in food consistency on NADH-ubiquinone oxidoreductase activity and levels of mRNA for ND1, 51kDa, 75kDa and myosin heavy chain isoforms in two different portions of rat masseter muscle.
We investigated the effect of a change in food consistency on properties of the masseter muscle in 3-week-old rats fed a soft diet for 9 weeks (Group S) and fed a soft diet for 5 weeks followed by a hard diet for 4 weeks (Group S-H). The NADH-O2 oxidoreductase activity, levels of mRNAs transcribed from genes encoding NADH-ubiquinone oxidoreductase (Complex I: ND1, 51kDa, and 75kDa) and myosin heavy chain (MyHC) isoforms and the phenotype of the muscle fibers were measured in the superficial and deep portions of the muscle. In the period from 8 weeks to 12 weeks of age, NADH-O2 oxidoreductase enzyme activity in both the superficial and deep portions of the muscle showed similar patterns in Group S and Group S-H. In contrast, the ND1, 51kDa and 75kDa mRNA levels in the superficial and deep portions of the masseter muscle in the Group S-H were higher than those of Group S in the 12-week-old rats, except for the 51kDa mRNA in the superficial portion of the masseter muscle. MyHC-IIa and MyHC-IId/x mRNA levels in the superficial portion of the masseter muscle were higher in the Group S-H than in the Group S. These observations suggest that short-term feeding stress such as the transition from a soft diet to a hard diet causes changes in oxidative metabolism, in mRNA levels for the Complex I components ND1 and 75kDa, and the mRNA levels for the MyHC isoforms IIa and IId/x in the superficial portion of rat masseter muscle, but no changes in the composition of muscle fiber types.
Ide
Yoshiaki
Y
Department of Anatomy, School of Life Dentistry at Tokyo, the Nippon Dental University, 1-9-20 Fujimi, Chiyoda-Ku, Tokyo 102-8159, Japan.
Sato
Iwao
I
D000818:Animals; D004032:Diet; D042967:Electron Transport Complex I / Q000378:metabolism*; D008297:Male; D008406:Masseter Muscle / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D008931:Mitochondria, Muscle / Q000378:metabolism; D018485:Muscle Fibers, Skeletal / Q000166:cytology*; D018995:Myosin Heavy Chains / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D020033:Protein Isoforms; D012333:RNA, Messenger; D018995:Myosin Heavy Chains; D042967:Electron Transport Complex I