The neuroprotective effect of pyrroloquinoline quinone on traumatic brain injury.

Pyrroloquinoline quinone (PQQ) is a water-soluble, anionic, quinonoid substance that has been established as an essential nutrient in animals. Owing to the inherent properties of PQQ as an antioxidant and redox modulator in various systems, PQQ is expected to be used in pharmacological applications in the near future. Although many recent studies have investigated its neuroprotective effects, the effect of PQQ on traumatic brain injury (TBI) has not been examined. In this study we employed Morris water maze (MWM) training, the results of which showed that PQQ led to improved behavioral performance in post-TBI animals. Considering that many experiments have suggested that β-1,4-galactosyltransferase I (β-1,4-GalT-I) and -V play significant roles in inflammation and the nervous system, in the present study we used Western blot analysis to study the effect of PQQ on the expression of β-1,4-GalT-I and -V. We found apparent expression upregulation of β-1,4-GalT-I and -V after PQQ was systemically administered. Lectin-fluorescent staining with RCA-I also revealed that PQQ contributed to expression upregulation of the galactosidase β-1 (Gal β-1), 4-galactosyltransferase N-acylsphingosine (4-GlcNAc) group in microglia and neurons of the cortex and hippocampal CA2 region. In summary, our experiment established that PQQ may play an important role in recovery post-TBI.