Intracerebral stimulation of the seventh cranial nerve in the rat. Effects on cerebrospinal fluid pressure

The effect of the intracerebral stimulation of the seventh cranial nerve was studied in anesthetized, artificially ventilated rats. The stimulation was carried out at the genu level by inserting a micropipette according to known stereotaxic coordinates. In 9 experiments, the cerebrospinal fluids pressure increased significantly 0.92 to 1.05 cm H2O above basal level after the stimulation of the same point on the left and right sides of the brain, without changes in mean arterial blood pressure. This response was interpreted as a sudden increase in cerebral blood volume produced by the dilatation of cerebral blood vessels. The section of the right greater superficial petrosal nerve abolished the increase in cerebrospinal fluid pressure after stimulation of the right side, while the response to stimulation of the left side was similar to the one observed in control animals. Consequently, the neurogenic vasodilation produced by intracerebral stimulation of the seventh cranial nerve in the rat seems to be mediated by a functional Chorobski-Penfield pathway running with the greater superficial petrosal nerve.