Effects of hydrocephalus on the sympathetic nerves of cerebral arteries, investigated with WGA-HRP anterograde tracing in the rat.

The effects of hydrocephalus on the plexus of sympathetic nerves of the intracranial vessels were investigated using wheat germ agglutinin combined with horseradish peroxidase (WGA-HRP). Hydrocephalus was induced by injection of kaolin into the cisterna magna of rats. Three weeks later the superior cervical ganglion (SCG) of one side received WGA-HRP. Three days later the circle of Willis and the contralateral superior cervical ganglion were dissected out. The intensity of labelling and density on the cerebral vessels and the number of labelled neurons on the contralateral superior cervical ganglion were calculated. The intensity of labelled nerves and thick bundles were significantly decreased, although tracing the nerve fibers throughout the length of the vessels was possible. The number of labelled neurons in the contralateral superior cervical ganglion indicated that the injection technique of WGA-HRP into the ganglion was correct in all rats. These results are in favour of the assumption, that the hydrocephalus related incomplete adrenergic denervation of the sympathetic perivascular nerve plexus was mainly due to neuropraxia of the nerve fibers rather than anatomical interruption of the axons.