AGEs-TRPM2 Signaling Pathway Is Involved In Postmenopausal Diabetic Osteoporosis

Objective:To investigate the role of AGEs(advanced glycation end products,AGEs)-TRPM2(transient receptor potential melastatin 2)signaling pathway in postmenopausal diabetic osteoporosis.Methods:Part 1: 12-week-old SPF female SD rats were randomly divided into four groups,10 in each group,named control group(control group),ovariectomy group(ED group),diabetes group(DM group),ovariectomy with diabetes group(ED + DM group).The control group did not do any treatment.The ED group underwent resection of bilateral ovaries under sterile conditions to establish a rat model of postmenopausal osteoporosis.The DM group received intraperitoneal injection of streptozotocin(60 mg/kg)to establish diabetic osteoporosis.In the rat model of loosening,the ED+DM group underwent resection of bilateral ovaries under sterile conditions.Ten days later,a rat model of postmenopausal diabetic osteoporosis was established by intraperitoneal injection of streptozotocin(60 mg/kg).After 12 weeks,the serum levels of advanced glycation end products(AGEs)and transient receptor potential M2(TRPM2)were determined by enzyme-linked immunosorbent assay(ELISA).The left and right femurs and lumbar vertebrae(L2-L5)Bone mineral density detection and analysis with dual-energy X-ray absorptiometry;Bone strength test using the machine for the left femur and L5;HE staining morphological analysis and immunohistochemical staining for the right femur.Part 2: 12-week-old SPF female SD rats were randomly divided into four groups,10 in each group,named control group(control group),ovariectomy with diabetes group(ED+DM group),AGEs inhibitor group,and TRPM2 inhibitor group.The first two groups of animals were treated as the first part,the AGEs inhibitor group and the TRPM2 inhibitor group were established in the postmenopausal diabetic osteoporosis rat model,and then given aminoguanidine(intraperitoneal injection,75 mg/kg,twice a week).TRPM2 inhibitor group was treated with clotrimazole(intraperitoneal injection,50 mg/kg,twice a week).After 12 weeks,the serum levels of advanced glycation end products(AGEs)and transient receptor potential M2(TRPM2)were determined by enzyme-linked immunosorbent assay(ELISA).The left and right femurs and lumbar vertebrae(L2-L5)Bone mineral density detection and analysis with dual-energy X-ray absorptiometry;Bone strength test using the machine for the left femur and L5;HE staining morphological analysis and immunohistochemical staining for the right femur.Results:1.ED group,DM group,ED + DM group have obvious osteoporosis performance,the bone density decreased,and the biomechanical properties of bone decreased.HE staining of the femur and lumbar vertebra showed that the number of trabecular bone decreased,the thickness decreased,accompanied by trabecular bone fracture,disordered arrangement,complete destruction,increased trabecular space,and increased medullary cavity width.Among them,the ED+DM group was the most obvious.2.The expression levels of AGEs and TRPM2 in serum of each group were detected by Elisa.The results showed that the expression levels of AGEs and TRPM2 in ED+DM group were significantly increased.3.By using AGEs inhibitors or TRPM2 inhibitors in ED+DM rats,it was found that both inhibitors can increase bone mineral density and biomechanical strength,and increase the number and thickness of trabecular bone.4.After using AGEs inhibitors in ED+DM rats,the expression levels of AGEs and TRPM2 decreased.When the TRPM2 inhibitor was used in the ED+DM group,the expression level of TRPM2 was significantly decreased,while the expression level of AGEs remained unchanged.conclusions:1.The expression of AGEs and TRPM2 is significantly increased in postmenopausal diabetic osteoporosis rat models.Inhibition of AGEs or TRPM2 can increase bone mineral density,biomechanical strength and increase bone mass in postmenopausal diabetic osteoporosis rats.Those suggest that AGEs and TRPM2 may be involved in the pathogenesis of postmenopausal diabetic osteoporosis and may play an important role in this process.2.Inhibition of AGEs can reduce the expression of TRPM2 protein,while inhibition of TRPM2 can not reduce the expression of AGEs,suggesting that AGEs may regulate TRPM2 upstream,inhibit calcium influx,and then exert effects,and participate in the pathogenesis of postmenopausal diabetic osteoporosis.3.The AGEs-TRPM2 signaling pathway may be an important signaling pathway for the development and progression of postmenopausal diabetic osteoporosis.Interventions in this pathway may be important for the treatment of this disease.