To investigate the effect and mechanism of gastrodin regulating synaptopodin 2 (SYNPO2) on hypoxic-ischemic brain damage (HIBD) in neonatal rats.

The left common carotid artery of neonatal rats was ligated, and the rats were placed in a hypoxic chamber for 40 minutes to establish the HIBD model. Rats were randomly divided into sham operation group (no common carotid artery ligation or hypoxia treatment), model group (HIBD model established), gastrodin group (intraperitoneal injection of gastrodin 100 mg·kg^-1 1 hour before common carotid artery ligation, 1 hour after hypoxia, and 12 hours after hypoxia), gastrodin+oe-NC group (3 days before modeling, 3 microliters oe-NC was transplanted intracerebroventricularly in rats, subsequent treatment same as the gastrodin group) and gastrodin+oe-SYNPO2 group (3 days before modeling, 3 microliters oe-SYNPO2 was transplanted intracerebroventricularly in rats, subsequent treatment same as the gastrodin group), with 10 rats in each group. Western blot was used to detect the levels of SYNPO2 and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mechanistic target of rapamycin (mTOR) signaling pathway-related proteins; short-term behavioral tests were used to detect neurological function in each group; the dry-wet weight method was used to detect brain water content; TdT-mediated dUTP nick end labeling was used to detect the apoptosis rate of brain tissue cells in each group; immunofluorescence was used to detect the levels of lysosomal associated membrane protein 1 (LAMP1) and microtubule associated protein 1 light chain 3 beta (LC3B) proteins in brain tissue of each group.

The relative expression levels of SYNPO2 protein in the sham operation group, model group, gastrodin group, gastrodin+oe-NC group and gastrodin+oe-SYNPO2 group were 1.00±0.16, 2.05±0.34, 1.38±0.18, 1.35±0.17 and 1.68±0.22, respectively; the relative expression levels of phosphorylated PI3K (p-PI3K)/PI3K protein were 1.00±0.19, 0.25±0.04, 0.65±0.08, 0.68±0.07 and 0.35±0.05, respectively; the relative expression levels of phosphorylated Akt (p-Akt)/Akt protein were 1.00±0.13, 0.28±0.04, 0.49±0.06, 0.51±0.07 and 0.31±0.04, respectively; the relative levels of phosphorylated mTOR (p-mTOR)/mTOR protein were 1.00±0.16, 0.22±0.04, 0.52±0.06, 0.54±0.07 and 0.29±0.05, respectively; the righting reflex latency periods were (2.56±0.33), (14.86±2.12), (5.66±0.75), (5.23±0.79) and (10.33±1.56) s, respectively; the negative geotaxis latency periods were (17.86±2.44), (56.33±8.22), (22.12±3.56), (23.05±3.22) and (40.22±5.66) s, respectively; the cliff avoidance reflex latency periods were (7.11±0.85), (16.55±2.32), (7.22±0.85), (7.83±0.96) and (13.55±2.45) s, respectively; the water contents were (51.56±6.47)%, (62.16±6.22)%, (55.02±6.25)%, (54.63±7.22)% and (61.98±5.17)%, respectively; the apoptosis rates were (5.17±0.65)%, (75.32±9.65)%, (25.65±3.89)%, (23.85±2.98)% and (50.56±6.89)%, respectively; the relative fluorescence intensity of LAMP1 were 1.00±0.15, 3.85±0.44, 1.14±0.15, 1.18±0.19 and 3.22±0.39, respectively; the relative fluorescence intensity of LC3B were 1.00±0.18, 3.45±0.52, 1.25±0.16, 1.21±0.15 and 1.68±0.19, respectively; the above indicators of the model group were statistically significant compared with the sham operation group, the above indicators of the gastrodin group were statistically significant compared with the model group, and the above indicators of the gastrodin+oe-SYNPO2 group were statistically significant compared with the gastrodin+oe-NC group (P<0.05, P<0.01, P<0.001).

Gastrodin inhibits SYNPO2, alleviates brain edema and neurological dysfunction in HIBD rats, protects neuronal structural integrity, reduces neuronal apoptosis, and alleviates excessive autophagy, which may be achieved by activating the PI3K/Akt/mTOR pathway.