Patterns of global gene expression in rat skeletal muscle during unloading and low-intensity ambulatory activity

• DOI: 10.1152/physiolgenomics.00001.2002
• Publication Date: 2015-03-03T15:53:24Z
• Authors: Lionel Bey; Nagabhavani Akunuri; Po Zhao; Eric P. Hoffman; Deborah G. Hamilton; Marc T. Hamilton
• Keywords: 0303 health sciences; Gene Expression Profiling; Hindlimb; Rats; Rats, Sprague-Dawley; Weight-Bearing; 03 medical and health sciences; Gene Expression Regulation; Hindlimb Suspension; Physical Conditioning, Animal; Animals; Cluster Analysis; Female; Muscle, Skeletal; Muscle Contraction; Oligonucleotide Array Sequence Analysis

Physical inactivity and unloading lead to diverse skeletal muscle alterations. Our goal was identify the genes in whose expression is most sensitive periods of unloading/reduced physical activity that may be involved triggering initial responses before phenotypic changes are evident. The ability short activity/loading as an effective countermeasure against gene mediated by also tested. Affymetrix microarrays were used compare mRNA levels soleus under three experimental treatments ( n = 20–29 rats each): 12-h hindlimb (HU), HU followed 4 h intermittent low-intensity ambulatory postural (4-h reloading), control (with activity). Using a combination criteria, we identified small set (∼1% 8,738 on array or 4% significant expressed genes) with reproducible largest altered activity. Analysis revealed coordinated regulation transcription for large number key signaling proteins factors protein synthesis/degradation energy metabolism. Most (21 25) downregulated during returned at least reloading. In surprising contrast, 27 38 upregulated remained significantly above control, but showed trends toward reversal. This introduces new concept that, general, unloading/inactivity will more resistant periodic reloading than those downregulated. study reveals loading/activity rat indicates targets initiate alterations inactivity.