Serum biochemistry (ALP, Ca, PO4, Mg) was determined at the Rodent Diagnostics Lab (McGill University, Montréal, Quebec, Canada) using routine automated techniques. Commercial assays were used to determine serum levels of CTX (RatLaps ELISA, Nordic Bioscience), 17β estradiol (IBL Immuno-Biological, Hamburg, Germany), leptin (R & D Systems, Minneapolis, Minnesota, United States), and interleukin-6 (R & D Systems).