Cavernous sinus ganglia are sources for parasympathetic innervation of cerebral arteries in rat

Retrograde tracing and immunohistochemistry was used in rats to investigate whether the ganglia in the cavernous sinus contribute to cerebrovascular innervation. The cavernous sinus ganglia in rat include the cavernous part of the pterygopalatine ganglion (PGC) and small cavernous ganglia (CG). The tracers, fluorogold and fast blue, were applied to the middle cerebral artery in eight rats. After 1 to 4 days, the cavernous sinuses were dissected out and studied as whole mount preparations and sections. A moderate number of labeled neurons were visible in the ipsilateral PGC and CG. Furthermore, fibers in the cavernous nerve plexus and abducens nerve were labeled, suggesting that the pathway from the cavernous sinus ganglia to the cerebral arteries runs through the cavernous plexus and then retrogradely along the abducens nerve to the internal carotid artery. Selected sections were immunohistochemically stained for the cholinergic marker, vesicular acetylcholine transporter (VAChT). Most cells in the PGC and CG were VAChT-immunoreactive, some of which also contained tracer. Tt is concluded that in rat. the cavernous sinus ganglia, consisting of the PGC and small CG, contribute to parasympathetic cerebrovascular innervation and that the cavernous nerve plexus and abducens nerve are involved in the pathway from these ganglia to the cerebral arteries.