Electrical stimulation of cervical vagal afferents. II. Central relays for behavioral antinociception and arterial blood pressure decreases

摘要: 1. Supraspinal substrates mediating vagal afferent stimulation (VAS)-induced inhibition of the nociceptive tail-flick reflex were examined by use soma-selective neurotoxin ibotenic acid and nonselective local anesthetic lidocaine. Fifty rats studied in lightly anesthetized state maintained with pentobarbital sodium. 2. The threshold intensity VAS required to inhibit a cut-off latency 10 s was established all rats. Ibotenic (5 or micrograms, 0.5 microliter) lidocaine (4%, then microinjected into various regions brain stem followed reestablishment produce reflex. 3. Microinjections ipsilateral nucleus tractus solitarius (NTS), medial rostroventral medulla (principally raphe magnus; NRM), bilaterally dorsolateral pons locus coeruleus/subcoeruleus; LC/SC), significantly increased either rostral caudal ventrolateral (RVLM CVLM, respectively) vagus nerve stimulated LC/SC did not affect produced VAS. Arterial blood pressure decreases attenuated eliminated after microinjections NTS, RVLM, NRM. Lidocaine CVLM also 4. These outcomes obtained behavioral measures are consistent preceding study using electrophysiological establishing that cells LC/SC, NRM fibers passage important inhibitory effects present studies confirm previous reports importance RVLM VAS-produced depressor responses but demonstrate is critical for this cardiovascular response.