Electrical Stimulation of Deep Peroneal Nerve Mimicking Acupuncture Inhibits the Pressor Response via Capsaicin-lnsensitive Afferents in Anesthetized Rats

Objective:To assess the inhibitory modulation of blood pressure by stimulation of the deep peroneal nerve(DPN) and to determine the involvement of nociceptive fibers in the modulation.Methods:All the animals were divided into six groups(A-F).The rats in groups A and B received no pretreatment.The rats in groups C and D received subcutaneous injection of capsaicin or control vehicle,respectively,near the DPN for 2 days.Those in groups E and F had the DPN exposed to capsaicin or control vehicle,respectively,for 20 min.Subsequently,pressor responses were induced by stimulation of paraventricular nucleus(PVN) either electrically(groups A and C-F) or chemically via injection of glutamate(group B).After two stable pressor responses(baseline),all groups were subject to 5-min DPN stimulation followed by PVN stimulation for 10 s. Arterial blood pressure,heart rate,and electrocardiogram were recorded.The pressor response was calculated as the difference in the mean arterial pressure(MAP) before and after PVN stimulation,and changes from baseline in pressor response after DPN stimulation were compared between the groups.Results:Increases of MAP of 22.88±2.18 mm Hg and 20.32±5.25 mm Hg were induced by electrical(group A) or chemical(group B) stimulation of the PVN,respectively.These pressor responses were inhibited by stimulation of the DPN,and the MAP was reduced to 12.00±2.10 mm Hg in group A(n=6,P