Kappa-Opioid Receptors in the Caudal Nucleus Tractus Solitarius Mediate 100 Hz Electroacupuncture-Induced Sleep Activities in Rats

Abstract

Previous results demonstrated that 10 Hz electroacupuncture (EA) of Anmian acupoints in rats during the dark period enhances slow wave sleep (SWS), which involves the induction of cholinergic activity in the caudal nucleus tractus solitarius (NTS) and subsequent activation of opioidergic neurons and μ-receptors. Studies have shown that different kinds of endogenous opiate peptides and receptors may mediate the consequences of EA with different frequencies. Herein, we further elucidated that high-frequency (100 Hz)-EA of Anmian enhanced SWS during the dark period but exhibited no direct effect on rapid eye movement (REM) sleep. High-frequency EA-induced SWS enhancement was dose-dependently blocked by microinjection of naloxone or κ-receptor antagonist (nor-binaltorphimine) into the caudal NTS, but was affected neither by μ- (naloxonazine) nor δ-receptor antagonists (natatrindole), suggesting the role of NTS κ-receptors in the high-frequency EA-induced SWS enhancement. Current and previous results depict the opioid mechanisms of EA-induced sleep.

Amygdala opioid receptors mediate the electroacupuncture-induced deterioration of sleep disruptions in epilepsy rats

“…Nevertheless, REM sleep during the following light period was decreased from 15.3 ± 1.3% obtained from the undisturbed baseline to 11.5 ± 1.1% acquired from rats treated with 100 Hz EA stimuli (p < 0.05, Figure 2F). There was no change, except that the sleep suppression caused by ketamine during the first 4-h postadministration, in the sleep-wake activity when rats received the sham EA stimulation (the sham group, Figure 1A & 1B), which is consistent with our previous results [11,30]. This observation indicated that high-frequency EA stimulation of bilateral Feng-Chi acupoints did not alter NREM sleep, but decreased REM sleep during the light period in normal rats.…”

“…Our results indicated that 100 Hz stimulation of bilateral Feng-Chi acupoints elicited no significant effect in the physiological sleep in normal rats, whereas EA stimuli further deteriorated pilocarpineinduced decreases of NREM sleep and REM sleep. Referring to our previous finding that 100 Hz EA stimulation of Anmian acupoints, which locate near by the FengChi acupoints, enhances physiological sleep in normal rats [11], suggesting the effect of high-frequency EA of Feng-Chi acupints involves a specific mechanism. These observations, since they subvert the functions of FengChi acupoints documented in the Lingshu Jing, surprise us.…”

“…Furthermore, we also found that 100 Hz EA stimulation of FengChi acupoints per se induces epileptiform EEGs. The effects of high-frequency EA stimulation of Feng-Chi acupoints on epileptic induction is a specific action, because 100 Hz EA stimulation of Anmian acupoints, which are located near by the Feng-Chi acupoints, did not exhibit epileptic activity [11]. In present study, we further investigated the role of EA stimulation of bilateral Feng-Chi acupoints in normal rats and in rats with pilocarpine-induced sleep disruptions.…”

“…While μ-and δ-opioid receptors in the spinal cord are dominant in the low-frequency EA-induced analgesia, κ-opioid receptors contribute to the high-frequency EA effect [22,23]. Our previous results also delineated that 10 Hz EA stimulation of Anmian acupoints enhances NREM sleep through activation of μ-opioid receptors in the caudal NTS [10], whereas κ-receptors contribute to the 100 Hz EAinduced sleep enhancement [11]. This study further elucidated the involvement of CeA opioid receptors in sleep alterations induced by high-frequency (100 Hz) EA stimulation of bilateral Feng-Chi acupoints in rats with amygdaloid focal epilepsy.…”

Preventive Effects of Ellagic Acid on Nucleus Tractus Solitarius Electrical Activity and Oxidative Stress Altered by Cerebral Global Ischemia/Reperfusion in Rat

“…A teflon coated stainless steel bipolar metal wire electrode (0.005" bare, 0.008" coated, A-M systems, Inc. WA) was implanted into the brain NTS with stereotaxic coordination according to rat brain stereotaxic atlas of Paxinos' and Watsons' [28]: AP:-14.04 mm to bregma; ML:0.4 mm, and DV:8 mm from the dura respectively. All implants were fixed to the skull by dental acrylic cement and two stainless steel glass anchor small screws [29,30]. Establishment of microelectrodes at the right site was confirmed by passing the DC through the active wire in order to making lesion at electrode tip point and histological section performed at the end of experiments.…”