Effects of stimulation of the trigeminal caudal nucleus on microvascular permeability in the eye in normal and capsaicin-treated rats.

Electrical stimulation of the trigeminal caudal nucleus in rats evoked increases in the permeability of eye microvessels. The microvascular effect did not appear when the nucleus was stimulated after administration of capsaicin 10 days before surgery (total dose 150 mg/kg, s.c., on two sequential days, given as 20, 30, 50, and 50 mg/kg). It is suggested that capsaicin-sensitive neurons in the trigeminal ganglion mediate the microvascular effect of stimulation of the trigeminal caudal nucleus.