Changes in the Hypothalamic and Brain Stem Catecholaminergic Systems in Experimental Hydrocephalus: A Histochemical Observation

Abstract

Fluorescence histochemical analysis combined with a sensitive assay method using high performance liquid chromatography (HPLC) revealed definite changes in the central catecholaminergic systems in experimental hydrocephalus. Hydrocephalus was induced in rats by injection of kaolin into the cisterna magna. Rats were placed into three groups: control, paired feeding, and hydrocephalic. Then hydrocephalic group was divided into mild and severe subgroups according to the degree of neurological symptoms. Brain norepinephrine (NE) levels were decreased in the frontal cortex, in the hippocampus, and in the cerebellum. NE levels in the hypothalamus were decreased only in the severe hydrocephalic group. There were no significant differences between the control and the paired feeding groups in brain NE levels. Brain dopamine (DA) concentration was the same in the hydrocephalic and the control groups. Fluorescent histochemistry revealed the accumulation of NE in the cell body of the locus coeruleus and the subcoeruleus neurons. In contrast, the NE fluorescence of the nerve terminals was reduced in the frontal cortex and the periventricular area of the hypothalamus. Catecholamine histofluorescence was not changed in the striatum and the lower brain stem. The coerulo-cortical and periventricular pathways of the ascending NE systems were selectively impaired in experimental hydrocephalus.