| The Female Athlete Triad is a syndrome occurring in physically active females of reproductive years, and results from the combined effect of disordered eating, oligo/amenorrhea, and osteoporosis. Currently, there is no animal model of the Female Athlete Triad. The goal of this investigation was to develop a rat model representing the interrelated components of the Female Athlete Triad.; Twelve female Sprague Dawley rats (age = 34 days) were fed ad libitum (AIN-93) and allowed access to running wheels during an initial 14-week period, providing Baseline and age-related data. Daily collection of data included dietary intake, body weight, estrous cycling (vaginal smears), and voluntary running distance. At the age of 4.5 months, rats were randomized into two groups, 6 restrict-fed (70% of ad lib intake) and 6 continued as ad libitum-fed controls. Total weight loss throughout the Treatment Phase (12 weeks) was set at a maximum of 30%. Energy intake, expenditure, and availability (kcal/gm BW) was calculated for each animal. Onset of anestrus was determined by vaginal smears, and concentrations of serum estradiol and leptin were measured in all rats. At the end of the study, femurs, tibias, and ovaries were excised and analyzed. Femoral and tibial bone mineral density (BMD) and bone mineral content (BMC) were determined by dual energy x-ray absorptiometry (DXA).; Acyclic vaginal smears occurred in all restrict-fed animals with a total weight loss between 19–28% (mean = 24%). As a result of continued wheel running, coupled with reduced diet intake, the restrict-fed rats exhibited a negative shift in energy availability during both the weight loss (−0.01 kcal/gm BW) and anestrus phase (−0.006 kcal/gm BW; p = 0.002) of Treatment. After 12 weeks, restrict-fed rats showed reduced concentrations of serum estradiol (11.5 ± 2.7 vs 30.3 ± 20.3 pg/ml; p = 0.002) and serum leptin (0.55 ± 0.08 vs 3.35 ± 2.35 ng/ml; p = 0.002), lower ovarian weight 17.3 ± 6.08 vs 40.7 ± 9.5 mg; p = 0.002), and decreased BMC of the femur (0.306 ± 0.03 vs 0.360 ± 0.03 gm/cm; p = 0.041) and tibia (0.221 ± 0.03 vs 0.260 ± 0.02 gm/cm p = 0.05). Based on the findings from this investigation, specific objectives in developing the animal model were obtained. As a result, the restrict-fed rats exhibited criteria that were similar to the Female Athlete Triad, i.e., energy restriction, persistent anestrus, and lower bone mass. |
