Fig. 4

Effects of naloxone on anti-hypertensive effects by acupuncture or rVLM neuronal activity.a–c Effects of intra-rVLM administration of naloxone on anti-hypertensive effects by EA + MA at Neuro-Sps. Representative pulse signals measured on the time points of 120 min after stimulation (b) and injection sites verified by toluidine blue stain (c). Either naloxone (n = 5) or saline (n = 5) was injected into rVLM 10 min before EA + MA treatment. *P < 0.05 vs. Saline. Although naloxone group slightly decrease blood pressure up to 40 min after naloxone administration, there are no differences in the blood pressure during the time points between naloxone and saline groups. d–f in vivo extracellular recordings of neurons in the rVLM. EA at Neuro-Sps increased the firing rate of rVLM neurons (n = 7, d, f), while pretreatment of naloxone prior to acupuncture prevented acupuncture-induced activation of rVLM neurons (n = 7, e, f). *P < 0.05