Aberrant expression of neurotrophic factors in the ventricular progenitor cells of infant congenitally hydrocephalic rats

Objects: This study was conducted to investigate the roles of neurotrophic factors in the development of hydrocephalus in HTX rats. Methods: Expressions of brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and fibroblast growth factor (FGF)-1 were examined immunohistochemically in the cerebral cortex and ventricular zone of 6-day-old rats with congenital hydrocephalus (HTX rats). In the ventricular zone of hydrocephalic rats, potent BDNF-like immunoreactivity (-LI) and weak but significant signals for NT-3- and FGF-1-LIs were observed. However, no significant signals were detected in non-HTX rats. A small subpopulation of ventricular cells was positive for microtubule-associated protein 2 in HTX and non-HTX rats. The positive cells in the HTX rats had neurites much longer than those in the non-HTX animals, suggesting that some ventricular cells of the hydrocephalics had ectopically differentiated into mature neurons. Conclusions: This abnormal differentiation may have been responsible for the aberrant expressions of neurotrophic factors. In contrast, the cerebral neuronal layers did not show such prominent alterations in neurotrophic factor expression.