Mechanisms Of Teriparatide Promoting Vascular Regeneration And Improving Nerve Injury In Rat MCAO/R Model

Background:Teriparatide is a recombinant parathyroid hormone analogue that is widely used to treat bone defects,bone nonunion,and osteoporosis in postmenopausal women.In addition to its stimulation of osteoblastic activity,teriparatide can induce Ang-1 synthesis through the adenylate cyclase/protein kinase(AC/PKA)signaling pathway to promote angiogenesis.There is no research on whether teriparatide can treat cerebral infarction.Therefore,we ask whether teriparatide can improve the prognosis of MCAO/R model by promoting angiogenesis and reducing ischemia-reperfusion injury while resisting osteoporosis.Methods:1.In order to verify whether teriparatide can reduce the size of cerebral infarction and alleviate the symptoms of nerve injury,we used small animal magnetic resonance imaging(MRI)to dynamically observe the changes of cerebral infarction area in the rat MCAO/R model after treatment with teriparatide and compared with the normal saline group.In addition,we used the open field test(Open field)and Garcia scores to observe the total motor distance and the changes of motor and sensory scores in the two groups and to evaluate the autonomic and exploratory behavior and the recovery of motor and sensory function in the two groups.At the same time,we also used H&E staining to further observe the changes of cerebral infarction area and cell injury.2.To explore whether teriparatide can reduce the area of cerebral infarction by inducing the expression of Ang-1 and promoting angiogenesis,we detected the content of Ang-1 in the tissue around the cerebral infarction by Western Blot and the expression of CD31+and the amount of neovascularization by immunohistochemical staining.At the same time,we used laser speckle to observe the improvement of cerebral blood perfusion on the infarcted side.In addition,in order to explore whether teriparatide promotes the expression of Ang-1 through AC/PKA pathway,we gave Forskolin,an activator of AC,and H-89,an inhibitor of PKA,respectively,and ELISA was used to detect the content of Ang-1 around the infarcted focus of rats in each group.3.To investigate whether teriparatide improves neurologic recovery by inhibiting oxidative stress and interfering with neuroinflammation,we tested the standard of Nrf2,HO1,SOD2,IL-1β,and IL-6 in the peri-infarct area.In addition,we used Nissl staining to observe the improvement of nerve injury.4.Furthermore,to explore whether teriparatide alleviates neurological dysfunction by reducing blood-brain barrier disruption and brain edema,we examined the level of MMP9,Ang-2,and AQP-4 in the peri-infarct area.In addition,we also examined the leakage of Evans Blue and measured the brain water content to evaluate the protection of the blood-brain barrier and the relief of brain edema.Results:Teriparatide can promote angiogenesis,reduce cerebral infarct size,and increase cerebral perfusion by upregulating Ang-1 expression.Additionally,teriparatide can promote the expression of HO1,SOD2,and inhibit the production of pro-inflammatory cytokines IL-1β,IL-6 by upregulating Nrf2 expression.we further found that teriparatide can mitigate blood-brain barrier disruption and brain edema by downregulating the expressions of MMP9,Ang-2,and AQP-4.Conclusions:Our results indicate that teriparatide is neuroprotective through multiple mechanisms of action that include promoting angiogenesis,inhibiting oxidative stress and neuroinflammation,protecting the blood-brain barrier,and reducing brain edema.