Study On The Effect Of Pinacidil On The Postponement Of Osteoporosis In Rats Through Activation Of TLR4 Receptors

Objective: To investigate whether the osteoporosis of castrated female rats was improved after the administration of pinadil,and to explore whether pinadil could activate certain signaling pathways in target cells by binding TLR4 receptors on rat BM-MSC to promote osteogenic differentiation,so as to provide a new theoretical basis for the diagnosis and treatment of osteoporosis.Methods:(1)Osteoporosis modeling: 48 12-week-old SPF-grade female rats were randomly divided into 4 groups of 12 rats each: Ovariectomized+Pinacidil(OVX+PINA),Normal control group(NCP),Sham-operated group(SHAM),and Ovariectomized+Pinacidil(OVX+PINA).-operated group(SHAM),and the de-ovalized group(Ovariectomized,OVX).After anesthesia and resuscitation,each group was housed in a single cage,and penicillin was injected into the tail vein 3 days after surgery to prevent infection.After 3 months,micro-CT tomography was performed to determine whether the modeling was successful.After successful modeling,PINA was injected intraperitoneally at a dose of 1 mg/kg/dose for 6weeks in the OVX+PINA group,and saline was injected intraperitoneally at the same dose in the other groups for control.After the administration of PINA,the rats were executed,and the bone mineral density(BMD)and the number of trabeculae were measured by Micro-CT in each group.differentiation,and immunohistochemistry was used to determine TLR4 expression levels in bone marrow tissue.Results:(1)The effects of PINA administration on bone volume in osteoporotic rats were determined by Micro-CT for the OVX+PINA group with bone microstructural parameters such as bone volume fraction(BV/TV,%),bone trabecular number(Tb.N,1/mm),degree of trabecular separation(Tb.Sp,mm),trabecular junction density(Conn.D,1/mm3),and BMD(mg/cc)were higher than those of the OVX group;the HE staining results further showed that the number of trabeculae in the OVX+PINA group was higher than that of the OVX group.(2)Immunohistochemical determination and analysis of the percentage of TLR4 positive cells and optical density showed that the expression of TLR4 in bone marrow tissues was significantly higher in the OVX+PINA group compared with other groups.Conclusions:(1)The use of PINA can effectively delay the progression of osteoporosis in desiccated rats(2)PINA may achieve its anti-osteoporotic effect by activating TLR4 receptors on their BM-MSC in the OVX group rats,thereby activating some of their signaling pathways.