Moxibustion promotes hematoma clearance in rats with intracerebral hemorrhage by up-regulating the expressions of PPARγ/CD36 and M2 phenotype polarization of microglia

To observe the effects of moxibustion on hematoma clearance and neurological functional recovery after intracerebral hemorrhage (ICH) in rats, and to explore the potential mechanisms by which moxibustion mitigates secondary brain injury after ICH.

SD rats were randomly divided into control, model, acupuncture, and moxibustion groups, with 15 rats in each group. The ICH model was established by collagenase injection into the caudate nucleus of rats. The rats in the acupuncture group and moxibustion group received treatments at “Baihui” (GV20) for 20 min, once daily for 5 consecutive days from the 3^rd day after modeling. The modified neurological severity score (mNSS) and the open field test were used to evaluate the neurological deficits and motor function of ICH rats. Hematoma volume was observed in serial coronal brain sections. Myelin integrity and demyelination around the hematoma were evaluated by luxol fast blue myelin staining. The expression levels of hematoma clearancerelated proteins, peroxisome proliferator-activated receptor γ (PPARγ) and CD36, in perilesional brain tissue were measured by Western blot. Immunofluorescence was used to detect M1 (iNOS⁺CD68⁺) and M2 (CD206⁺CD68⁺) microglia around the hematoma to assess microglial polarization in ICH rats.

Compared with the control group, the mNSS and immobility time in the open field of the model group were increased significantly (P<0.01), whereas the total moving distance and the number of grid crossings in the open field were decreased significantly (P<0.01), volume of the hematoma was increased (P<0.05), the myelin staining was sparse, there were many vacuoles, and there were obvious demyelination changes, the proportions of M1 and M2 types of microglia in the model group were significantly increased (P<0.01, P<0.05). After treatment, compared with the model group, the mNSS and immobility time in the open field of the rats in the acupuncture group and moxibustion group were significantly decreased (P<0.05, P<0.01), the total moving distance and the number of grid crossings were significantly increased (P<0.01, P<0.05), and the hematoma volume was significantly decreased (P<0.05); the expression levels of PPARγ and CD36 in brain tissue were significantly increased (P<0.05, P<0.01); the ratio of M1 microglia decreased (P<0.05), while M2 microglia ratio increased significantly (P<0.05) around the hematoma.

Moxibustion can effectively reduce the neurological injury and promote the clearance of hematoma in ICH rats. The mechanisms may involve up-regulation of PPARγ and CD36 expression, and modulation of microglial polarization.