Effect of Huanglian Jiedutang in Improving Brain Iron Metabolism Disorders， Myelin Damage， and Aggressive Behavior in VaD Mice via Regulation of FBXL5/IRP2

Abstract:

Objective This study aims to investigate the effect of Huanglian Jiedutang on brain iron metabolism disorders， myelin damage， and aggressive behavior in vascular dementia （VaD） mice by regulating the F-box leucine-rich repeat protein 5 （FBXL5）/iron regulatory protein 2 （IRP2） pathway.Method Sixty C57BL/6J mice were randomly divided into six groups： sham operation group， model group， risperidone group （2 mg·kg^-1·d^-1）， and low-dose， medium-dose， and high-dose groups of Huanglian Jiedutang （0.25， 0.5， 1 g·kg^-1·d^-1）， with 10 mice in each group. The VaD model was established by bilateral carotid artery stenosis （BCAS）. Drug intervention was administered for two weeks starting from the seventh week. Behavioral assessments， including the touch escape and resident-intruder tests， were conducted in the ninth week. After the behavioral tests， ventromedial hypothalamus ventrolateral （VMHvl） tissue samples were collected. Western blot was used to detect the expression of myelin-associated glycoprotein （MAG）， myelin oligodendrocyte glycoprotein （MOG）， myelin basic protein （MBP）， 4-hydroxynonenal （4-HNE）， glutathione peroxidase 4 （GPX4）， transferrin receptor 1 （TFR1）， ferritin light chain （Ft-L）， ferroportin 1 （FPN1）， FBXL5， and IRP2. Immunofluorescence was used to measure MBP fluorescence intensity. Transmission electron microscopy was employed to observe ultrastructural changes in the myelin sheath. Perl's staining was used to detect tissue iron deposition. Malondialdehyde （MDA） and superoxide dismutase （SOD） levels were measured by enzyme linked immunosorbent assay （ELISA）.Result Compared to the sham operation group， the model group exhibited a significant increase in biting， aggression， and irritability scores， along with a reduced latency of the attack （P<0.01）. The expression levels of MAG， MOG， and MBP， as well as the fluorescent density of MBP， were significantly decreased （P<0.01）. Disordered myelin ultrastructure， increased Ft-L and TFR1 expression， decreased FPN1 expression， and elevated iron deposition were observed （P<0.01）. Antioxidants GPX4 and SOD were reduced， while 4-HNE and lipid peroxidation product MDA were increased （P<0.01）. FBXL5 protein expression decreased， and IRP2 protein expression increased （P<0.01）. Compared with the model group， in the middle-dose and high-dose groups of Huanglian Jiedutang and the risperidone group， the number of bites， aggressive behaviors， and irritability scores were reduced （P<0.05， P<0.01）， while the latency of the attack increased （P<0.01）. In the middle-dose and high-dose groups of Huanglian Jiedutang， the expression levels of MAG， MOG， and MBP， as well as MBP immunofluorescence increased （P<0.01）. The ultrastructure was orderly arranged. Ft-L and TFR1 expression decreased； FPN1 expression increased， and iron deposition was reduced （P<0.01）. GPX4 and SOD expression levels increased， and 4-HNE and MDA expression levels decreased （P<0.01）. FBXL5 protein expression increased， and IRP2 protein expression decreased （P<0.01）.Conclusion Huanglian Jiedutang may alleviate brain iron metabolism disorders， myelin damage， and aggressive behavior in VaD mice by regulating FBXL5/IRP2 expression in the VMHvl region.