A three-way interaction between gender, genotype and sciatic neurectomy was only detected for medullary area. The post-hoc analysis showed that female Lrp5HBM+ mice experienced less endocortical expansion than female WTHBM− mice (medullary area:
6.3 ± 3.8% vs. 16.4 ± 2.2% respectively, p < 0.05), no other differences were detected between male Lrp5HBM+ and their WTHBM− littermates or between male and female Lrp5−/− mice and their WT+/+ littermates. In cancellous bone, gender had a significant effect on the magnitude of sciatic neurectomy-induced change in Tb.Th and Tb.N, but not BV/TV or Tb.Sp, with male mice losing slightly more Tb.Th (− 20.2% vs. − 16.7%, respectively, p < 0.05, data not shown) and females losing more Tb.N (− 24.9% vs. − 22.9%, respectively, p < 0.05, data not shown). Genotype also had a significant effect on see more the magnitude of loss on all parameters of cancellous bone. Lrp5HBM+ mice experienced less loss in BV/TV than their WTHBM− littermates (− 17.2% vs. − 43.3%, respectively, p < 0.05, data not shown). This could be attributed to a reduced loss in Tb.Th and Tb.N. In contrast, Lrp5−/− mice showed a greater loss in BV/TV than their WT+/+ littermates (− 52.4% vs. − 41.3% respectively, p < 0.05, data not shown) due to a greater reduction in Tb.N and increase in Tb.Sp. A three-way interaction between gender, genotype and selleck products sciatic neurectomy was not detected for any of the cancellous
bone parameters; therefore bone loss was similar in male and female mice within each genotype. The trabecular architecture in the control and sciatic neurectomised limbs of the eight groups of mice are illustrated in Fig. 2. In summary these findings show that the degree of cortical and cancellous bone loss associated with sciatic neurectomy is affected by Lrp5 status.
The presence of the Lrp5 HBM mutation is associated with less loss in cortical and cancellous bone than in their WTHBM− controls. The lack of difference in cortical bone loss with disuse between Lrp5−/− mice and their WT+/+ controls indicates that normal Lrp5 function has no effect on this process. However, in cancellous bone absence of Lrp5 is associated with a greater decrease in Tb.N and increase in Tb.Sp than in WT+/+ controls. Mechanical loading significantly and dose-responsively second increased the cortical bone parameters, % cortical bone area and % total area in WT+/+ males, but Lrp5−/− males showed a complete absence of cortical bone responses ( Table 2, Fig. 3). Female WT+/+ mice failed to respond dose-responsively to loading for cortical bone parameters ( Table 3), but some of the individual load groups produced significant side-to-side loading effects for cortical variables ( Table 2). Like their WT counterparts, Lrp5−/− females showed no dose–response to loading in cortical parameters, but significant side-to-side loading effects for some cortical bone parameters were found ( Table 2 Fig. 3).