STROKE-PRONE SHR (SHRSP) AS A MODEL FOR OSTEOPOROSIS

Since previous studies on SHRSP showed various abnormalities in Ca metabolism, aged SHRSP together with age-matched Wistar-Kyoto (WKY) were examined for bone mineral density and contents as well as bone histomorphometry and mechanical properties. SHRSP and WKY, 10 rats of each group at the age of 7 to 8 months were sacrificed with or without tetracycline and calcein labellings for the estimation of mineral appositional rate. Both femurs, tibia and the 1st lumbar vertebra were extirpated from each rat; one femur was used for mineral density and content analyses and the other was used for analyzing mechanical properties by three point-bending and torque methods (Maruto, MZ500D). Mineral density and cortical thickness index were decreased significantly in SHRSP compared with WKY, and Ca contents were decreased as well. Correspondingly femurs from SHRSP were proven to be fragile in the maximum bending stress. Undecalcified histological sections of tibial proximal epiphysis histomorphometrically indicated bone volume and trabecular thickness were significantly decreased in SHRSP. These findings together with others indicate SHRSP can be a good model for spontaneous osteoporosis in man.