Alterations in brain metabolism, CNS morphology and CSF dynamics in adult rats with kaolin-induced hydrocephalus.

The present study describes the biochemical changes, morphological development and the cerebrospinal fluid dynamics of the kaolin-induced hydrocephalus in the adult rat. Two, 4 and 6 weeks after microsurgical kaolin instillation into the rat cisterna magna the basal intracranial pressure and the cerebrospinal fluid outflow resistance were measured. To determine possible biochemical changes in the rat cerebrum, brain stem and cerebellum the concentrations of glutamine, glutamate, glutathione, aspartate, GABA, alanine and taurine were measured by high pressure liquid chromatography. In addition, ventriculomegaly and syringomyelia were assessed, measuring the lateral ventricles and central canals by means of an image-processing computer program. It could be shown that the acute phase of kaolin-induced hydrocephalus in the first 4 weeks is characterised by a high basal intracranial pressure, a considerably increased CSF outflow resistance and a rise in brain water content in the fourth week. The changes in the concentrations of amino acids were moderate. Glutamine was increased and taurine was decreased in the cerebrum and alanine was increased in the brain stem. The chronic phase, however, is defined by normal basal pressure, declining outflow resistance, progression of ventriculomegaly and distinct changes in the biochemical parameters such as a remarkable decrease of glutamate, glutamine and taurine in the cerebellum, a decrease of taurine and alanine plus an increase in glutamine in the cerebrum and an increase of alanine in the brain stem. Moreover, cerebral metabolism in the adult rat seems to be more resistant to the effects of hydrocephalus than metabolism in neonatal and infantile rats.