Neuro-protective effects of increased <i>O</i>-GlcNAcylation by glucosamine in an optic tectum traumatic brain injury model of adult zebrafish

This study investigated the behavioral and molecular changes in the telencephalon following needle stab-induced injury in the optic tectum of adult zebrafish. At 3 days post-injury (dpi), there was noticeable structural damage to brain tissue and reduced neuronal proliferation in the telencephalon that persisted until 30 dpi. Neurobehavioral deficits observed at 3 dpi included decreased exploratory and social activities and impaired learning and memory (L/M) functions; all of these resolved by 7 dpi. The injury led to a reduction in telencephalic phosphorylated cAMP response element-binding protein and O-GlcNAcylation, both of which were restored by 30 dpi. There was an increase in GFAP expression and nuclear translocation of NF-κB p65 at 3 dpi, which were not restored by 30 dpi. The injury caused decreased O-GlcNAc transferase and increased O-GlcNAcase levels at 3 dpi, normalizing by 30 dpi. Glucosamine (GlcN) treatment at 3 dpi significantly restored O-GlcNAcylation levels and L/M function, also reducing GFAP activation. Glucose treatment recovered L/M function by 7 dpi, but inhibition of the hexosamine biosynthetic pathway by 6-diazo-5-oxo-L-norleucine blocked this recovery. These findings suggest that the O-GlcNAc pathway is a potential therapeutic target for addressing L/M impairment following traumatic brain injury in zebrafish.