Is peak bone mass achieved following recovery from reduced energy availability?
Abstract
We previously demonstrated focal bone loss and disrupted metabolic hormone levels in sedentary (SED) and exercising (EX) rats after 12 wks of reduced energy availability (EA; energy intake minus exercise energy expenditure). We hypothesized that peak bone mass (total bone mineral content, totBMC) at 12 mo of age would be diminished by 12 wks reduced EA, even after 12 wks of recovery (REC). After acclimation to AIN‐93M purified diet, 5‐ mo‐old female rats (n=72) were randomized into SED and EX groups; half of each group was designated −25% EA. During REC, all rats were fed ad lib and exercise volume was halved. After 12 wks REC, fat mass was 30% lower in −25EA SED vs. ADLIB SED; however, there were no differences in lean mass. After 4 wks REC, totBMC (by DXA) in −25EA SED was 15% lower vs. ADLIB SED; after 12 wks REC it matched ADLIB SED values. TotBMC for −25EA EX was higher than −25EA SED rats at all time points. Serum IGF‐1 and leptin, reduced after 12 wks of − 25EA, rebounded quickly with regain of fat mass, except for lower leptin in −25EA SED. After 12 wks REC, mineralizing surface on mid‐shaft tibia (by histomorphometry) was low only in ADLIB EX. These data suggest that cortical bone integrity and metabolic hormones recover from stringent reductions in EA when energy balance is re‐established in both SED and EX conditions. Whether the same recovery potential exists for cancellous bone compartments after reduced EA has yet to be determined.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Apr 01, 2012
- Source ID
- 10.1096/fasebj.26.1_supplement.820.22
Entities
People
- Elizabeth S. Greene
- Florence Lima
- Kaleigh Ann Camp
- Mary Jane De Souza
- Sibyl N. Swift
- Susan A. Bloomfield
Organizations
- Pennsylvania State University
- United States Department of Defense