Search

Background: Aquaporin 4 (AQP4), usually expressed at astrocytes end-feet, is a main component of the lymph-lymphatic system and promotes paravascular cerebrospinal fluid-interstitial fluid exchange. Moreover, angiotensin II type 1 (AT 1 ) receptor affects amyloid β (Aβ) levels. This study aimed to detect the effect of AT 1 receptor deficiency on the blood-brain barrier (BBB) of traumatic brain injury (TBI) mice and the effect on Aβ level and glial lymphatic circulation., Methods: TBI model was built using AT 1 receptor knockout mice (AT 1 -KO) and C57BL/6 mice (wild type, WT). BBB integrity was detected by Evans blue extravasation. The expression of the astrocytic water channel AQP4 and astrocyte activation were evaluated with immunofluorescence. The expressions of amyloid precursor protein (APP), junction protein zonula occludens protein-1 (ZO-1) and occludin in mice brain were detected by Western blot (WB). Aβ levels were assayed by enzyme-linked immunosorbent assay (ELISA)., Results: AT 1 receptor deficiency defended BBB integrity and rescued occludin and ZO-1 decrease in mice brain induced by TBI. AT 1 -KO mice had less increase of APP expression and Aβ 1-42, Aβ 1-40 levels compared to WT mice under TBI. Moreover, AT 1 receptor deficiency was found to significantly inhibit AQP4 depolarization after TBI., Conclusion: T 1 receptor deficiency attenuated TBI-induced impairments of BBB by rescuing tight junction proteins and inhibited AQP4 polarization, thus improving the function of glymphatic system to enhance interstitial Aβ clearance in TBI mice brain.

Background: The glymphatic pathway has been shown to be impaired in traumatic brain injury (TBI). Omega-3 polysaturated fatty acids (Omega-3, PUFAs) are involved in the clearance of amyloid-ß through the glymphatic system and this effect is Aquaporin-4 (AQP4) dependent. We hypothesize that Omega-3 PUFAs can alleviate neurological impairment in TBI by protecting the glymphatic pathway. Methods: We pretreated mice with Omega-3 PUFAs rich fish oil and introduced TBI in the mice. Neurological functions were assessed through the modified neurological severity score (mNSS) system and Rota-rod test. Aß42 levels and radioisotope clearance were examined to determine the function of glymphatic system. AQP4 protein and mRNA expressions and its polarity were examined in fish oil treated TBI mice or control mice. Finally, the integrity of blood-brain barrier was determined by Evans blue extravasation and measurement of tight junction proteins (ZO-1 and Occludin) levels. Results: TBI surgery induced significant neurological functional impairment, Omega-3 PUFAs attenuated TBI-induced neurological impairment, as evidenced by reduced mNSS, improved performance in the Rota-rod test. Furthermore, Omega-3 PUFAs improved glymphatic clearance after induction of TBI in mice, reduced Aß42 accumulation, partially restored the clearance of both 3H-mannitol and 14C-Inulin. Omega-3 PUFAs also suppressed AQP4 expression and partially prevented loss of AQP4 polarity in mice undergoing TBI. Finally, Omega-3 PUFAs protected mice from TBI induced blood-brain barrier disruption. Conclusion: Omaga-3 PUFAs attenuate neurological function by partially restoring the AQP4 dependent glymphatic system in mice with TBI. [ABSTRACT FROM AUTHOR]

Intracranial hemorrhage (ICH) is a common subtype of stroke with high morbidity and mortality. However, few studies have examined the effects of diabetes on the recovery from ICH-induced brain injury. Therefore, we examined the effects of diabetes on protein levels of aquaporins, neuronal loss, angiogenesis, blood brain barrier (BBB) integrity, and neurological deficits following intra-DH collagenase-induced ICH in the hippocampus. We found that diabetic rats exhibited enhanced AQP9 expression in the hippocampus relative to non-diabetic rats, which was associated with increased behavioral deficits. Additionally, ICH induced neovascularization, proliferation of brain microvascular endothelial cells, and hippocampal neuronal loss. However, ICH-induced neovascularization and proliferation of brain microvascular endothelial cells was severely impaired in diabetic rats. Furthermore, ICH-induced hippocampal neuronal loss was exaggerated in diabetic rats. Finally, ICH impaired BBB integrity in the ipsilateral hemisphere, which was increased in diabetic rats. Taken together, the attenuated brain angiogenesis, increased hippocampal neuronal loss, and impaired BBB integrity in diabetic rats after ICH were associated with enhanced AQP9 expression. This may suggest that AQP9 is one of the underlying mechanisms that can mitigate the recovery from ICH in diabetic populations. [ABSTRACT FROM AUTHOR]

Subarachnoid hemorrhage (SAH) is a life-threatening disease that causes high morbidity and mortality. Pirfenidone is a SAH drug that prevents secondary bleeding and cerebral infarction. To improve its therapeutic efficacy, this study aimed to employ a functionalized graphene oxide nanosheet (FGO) as a drug carrier loading pirfenidone to treat SAH. The graphene oxide nanosheet was introduced with transcription activator peptide (Tat), followed by functionalization with methoxy polyethylene glycol (mPEG) and loading with pirfenidone. The pirfenidone-loaded FGO (pirfenidone-FGO) exhibits better treatment efficacy than the single pirfenidone due to more effective loading and controlled release of the drug in tissue. The introduction of Tat and mPEG onto GO nanosheet contributes to the ability to cross the blood–brain barrier and the stability in blood circulation of the drug. At lower pH values, the highly efficient release of the drug from the pirfenidone-FGO exerts effective treatment to acidic inflammatory lesion after severe SAH. Besides its treatment function, FGO is also shown as a strong near infrared absorbing material which can be applied in photoacoustic imaging, allowing rapid real-time monitoring with deep resolution of brain tissues after SAH. The treatment efficacy of pirfenidone-FGO for central nervous system injuries is further demonstrated by hematoxylin and eosin staining of coronal brain slices, as well as measurements of brain water content and blood–brain barrier permeability. Our study supports the potential of FGO in clinical application in treatment of SAH. [ABSTRACT FROM AUTHOR]