1000 Section - Exercise ameliorates microglial activation and cognitive impairment induced by GFAT1 knockdown after traumatic brain injury

Numerous studies have reported that the activation status of microglia plays an important role in reducing neuroinflammation and promoting neurological function recovery after exercise training. Glutamine-fructose-6-phosphate transaminase 1 (GFAT1) is the main enzyme that regulates the hexosamine biosynthesis pathway (HBP) and is also important in the neuroinflammatory process. However, the molecular mechanism by which GFAT1 promotes neurological function recovery after brain injury by regulating microglia activation remains unclear.

Design:

A needle puncture method was used to establish a mouse TBI model. TBI mice were randomly divided into sedentary groups and exercise training groups. Mice in the exercise training groups had free access to a running wheel for 14 days. Western blot and immunofluorescence assays were used to detect the expression and localization of GFAT1 following TBI. The behavioral tests and electrophysiological recordings were performed to evaluate microglial activation and neurological function after GFAT1 knockdown with GFAT1 shRNA lentivirus. A cell model was established using irisin and lipopolysaccharide. Western blot was conducted to quantify inflammation-related proteins. TUNEL staining was used to assess neuronal apoptosis in the presence of conditioned medium.

Results:

The TBI group exhibited high GFAT1 expression level than sham group. Following TBI, GFAT1 shRNA lentivirus significantly increased Interleukin-6 (IL-6) expression and accelerated cognitive impairment progression. In the TBI + LV-shGFAT1 group, exercise training promoted cognitive function recovery, reduced IL-6 expression, and upregulated the expressions of heme oxygenase-1 (HO-1) and nuclear factor E2-related factor 2 (Nrf2). In the cell model, lipopolysaccharide stimulation induced the expression of GFAT1, IL-6, and inducible nitric oxide synthase (iNOS). However, GFAT1 knockdown further exacerbated the expression of IL-6 and iNOS. Additionally, irisin pretreatment reduced neuronal apoptosis and the expression of IL-6 and iNOS, while increasing the expression of Nrf2 and HO-1.

Conclusion:

Exercise ameliorates microglial activation and cognitive impairment induced by GFAT1 knockdown after traumatic brain injury.