Effect of electrical stimulation of the mamillary nuclei of the hypothalamus on skin vessel permeability in intact and capsaicin-treated rats.

Stimulation of the mamillary nuclei of the rat hypothalamus induced increases in the permeability of forelimb skin microvessels. This effect was not seen in rats stimulated after administration of capsaicin at a dose (150 mg/kg) sufficient to deplete vasoactive neuropeptides from the peripheral nerve terminals of capsaicin-sensitive neurons. These data indicate a role for the mamillary nuclei in central mechanisms modulating the effector functions of primary capsaicin-sensitive neurons.