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Fei Luo

Publications and source records attributed to Fei Luo.

At least 37 records · Page 2Linked to original sources
PubMed2004

Evidence from brain imaging with fMRI supporting functional specificity of acupoints in humans.

We tested whether the stimulation of acupoints in the same spinal segments could induce different central responses with functional magnetic resonance imaging (fMRI) study. Stimulation of acupoints ST36/SP6 (Zusanli/Sanyinjiao) or GB34/BL57 (Yanglingquan/Chengshan) both activated primary and secondary somatosensory area, insula, ventral thalamus, parietal Brodmann Area 40, temporal lobe, putamen, and cerebellum, while de-activated amygdala. Nevertheless, ST36/SP6 stimulation specifically activated orbital frontal cortex and de-activated hippocampus. Alternatively, stimulation of GB34/BL57 activated dorsal thalamus and inhibited those of primary motor area and premotor cortex. Thus, stimulation of acupoints in the same spinal segments induced distinct though overlapped cerebral response patterns, which indicated the existence of acupoint specificity.

Adult↗
PubMed2004

NMDA receptor in nucleus accumbens is implicated in morphine withdrawal in rats.

The purpose of the present study is to elucidate whether ketamine, a non-competitive antagonist of the NMDA receptor, can suppress the morphine withdrawal syndrome in rats at a dose without affecting motor functions and to identify its site of action in the central nervous system. Rats were made dependent on morphine by multiple injections of morphine hydrochloride for 5 days. They were then given ketamine at the following doses and routes of administration: (a) intraperitoneal (i.p.) injections (2-16 mg/kg), (b) intracerebroventricular (i.c.v.) injections (4-100 microg), and (c) intra-nucleus accumbens (NAc) or intra-amygdalar microinjections (0.4-10 microg). Naloxone HCl (1 mg/kg, i.p.) was administered 3 h after the last ketamine injection to precipitate withdrawal syndrome, which was scored within a period of 30 min. Results showed that some of the precipitated withdrawal signs were dose-dependently suppressed by repeated injections of ketamine at 8 and 16 mg/kg, i.p. or 100 microg, i.c.v. Dose-dependent suppression was observed by repeated microinjections (0.4-10 microg) of ketamine to NAc, but not to amygdala. These results indicate that the NMDA receptor antagonist ketamine has the ability to suppress morphine withdrawal syndrome in experimental settings without motor interference, and NAc could be the critical CNS site mediating such effect.

Amygdala↗
PubMed2004

Suppression of neuropathic pain by peripheral electrical stimulation in rats: mu-opioid receptor and NMDA receptor implicated.

Peripheral electrical stimulation (PES) has been utilized to manage chronic pain associated with nerve injury. However, the data on clinical effectiveness are conflicting and the neurophysiological mechanism is not well known. This study was designed to assess whether PES relieved neuropathic pain and its possible mechanisms. The neuropathic pain model was made with lumbar 5th (L5) and 6th (L6) spinal nerve ligations in rats. Nociceptive responses of the rats were assessed by the cold plate test (the number and duration of paw lifts that occurred in 5 min on a 5 +/- 1 degrees C cold plate). PES with a frequency of 2 Hz and at increasing strengths was given for 30 min via stainless-steel needles inserted into standard acupoints on the leg and back, respectively. Immunochemistry was used to examine the immunoreactivity of the NMDA receptor 1 (NR1) subunit in the spinal cord dorsal horn. The results are as follows: (1) PES relieved neuropathic pain and the effect was blocked by 1.0 mg/kg naloxone. (2) The effect of one session of PES lasted up to 12 h. (3) Repetitive PES showed a cumulative effect and no tolerance was observed. (4) There was a significant increase of NR1 immunoreactivity in the superficial laminae of the spinal cord of neuropathic pain rats as compared with naive rats. This increase could be reversed by repetitive 2 Hz PES. These results suggest that PES can relieve neuropathic pain, and that mu-opioid receptors and NMDA receptors are involved in the effect of PES.

Animals↗
PubMed2004

Nociceptive responses of anterior cingulate cortical ensembles in behaving rats.

OBJECTIVE: To confirm the role of anterior cingulated cortices (ACC) in the coding of pain affect by exploring the neural ensemble coding pattern within the anterior cingulate cortex in behaving rats with a multichannel recording technique. METHODS: In five adult male Sprague-Dawley rats, two arrays of eight stainless steel microwires were bilaterally implanted into ACC. Noxious radiant heat stimulation was applied to the tail, bilateral fore-paws and hind-paws of freely moving rats. Neuroelectric signals were obtained from the microwires and sent to a multichannel recording device via cables and connectors. The time stamps of neuronal activities were stored on a personal computer for off-line analysis. RESULTS: Noxious heat stimuli evoked predominantly excitatory and sustained neural activity within ACC, reflecting the processing of pain unpleasantness; pain-related anticipatory responses could be seen near the stimulation start, indicating the behavioral preparation for escape; ACC neurons had broad receptive fields by showing quite similar pain-related responses to stimuli on either side of the hind-paw, suggesting that they are not eligible for the localization of a stimulus. CONCLUSION: ACC has played a major role in processing the affective-motivational aspect of pain.

Animals↗
PubMed2004

[Progress in the study of pain-related somatosensory evoked potentials].

Important progresses has been made in the study of pain-related somatosensory evoked potentials (pain SEP) in the past decades. Pain generating stimulation techniques in humans are used in combination with the methodology of evoked electrical brain potentials. The current review will discuss stimulation techniques, components of evoked potentials, dipole source analysis of evoked potentials with the recent study of pain SEP.

Animals↗
PubMed2004

[Clinical study on effect of acupoint sticking of chuanfuling in dog-days in preventing and treating children asthma in remission stage].

OBJECTIVE: To explore the effect and mechanism of acupoint sticking of Chuanfuling (CFL) in dog-days (the hottest periods of the year) in preventing and treating children asthma in remission stage. METHODS: Ninety patients were divided into three groups, 30 in each. Patients in the CFL group were treated with CFL sticking, in the Western medicine (WM) group treated with Pulmicort inhalation, and in the control group was untreated. The clinical effect and indexes of humoral immunity (IgE, IgA, IgG) and cellular immunity (Eos, IL-4, IFN-gamma) before and after treatment were observed. RESULTS: After treatment in the CFL group all the immune parameters were significantly improved (P<0.05 or P<0.01), all were better than those in the control group (P<0.05 or P<0.01), and the effect on IgA and IgG was better than that in the WM group. In the WM group after treatment, improvement was shown on the IgE and cellular immune parameters with signifian difference (P<0.05 or P<0.01), better than those in the control group (P<0.05 or P<0.01). Besides, significant difference was shown in comparing IL-4 level between the WM group and the CFL group (P<0.05). CONCLUSION: CFL sticking in dog-days could significantly improve the immune function in children with asthma to alleviate and control the attack.

Acupuncture Points↗
PubMed2003

Parallel pain processing in freely moving rats revealed by distributed neuron recording.

The present study was designed to examine the possible differential roles of the medial and lateral pain systems in pain perception. We used a microwire array recording technique to record the pain-evoked neural activity of multiple neurons in freely moving rats. Noxious radiant heat was delivered to either hind-paw in a randomized order. A total of 256 single units were recorded in primary somatosensory cortex (SI), anterior cingulate cortex (ACC), and medial dorsal (MD) and ventral posterior (VP) thalamus during the painful stimulation. The results showed that SI neurons displayed a strong pain-related excitatory response with short duration and significant contralateral bias; VP had very similar functional patterns to that of SI. This suggested that SI, together with VP, participate in the processing of the sensory-discriminative aspect of pain. In contrast, ACC and MD shared common characteristics of moderate and longer-lasting increase of neural activity, bilateral receptive fields without contralateral preference, as well as the anticipatory response at the start of a painful stimulus, corresponding to the specific role of ACC and MD in the affective-motivational aspects of pain. The results provide an initial demonstration of distributed activity patterns within different pain systems in awake and freely moving rats, hence, providing confirmation of the existence of the dual pain pathways.

Action Potentials↗
PubMed2003

High frequency stimulation of the subthalamic nucleus improves treadmill locomotion in unilateral 6-hydroxydopamine lesioned rats.

This study investigated the influence of electrical stimulation of the subthalamic nucleus (STN) on motor impairment induced by unilateral 6-hydroxydopamine (6-OHDA) lesions in the medial forebrain bundle. Rats were trained to walk on a treadmill and then implanted with microelectrode arrays in and near the STN. The neurotoxin 6-OHDA was injected into the medial forebrain bundle (MFB) unilaterally to produce a targeted lesion of the dopaminergic system. Successful lesions produced impaired treadmill walking behavior. High frequency stimulation (HFS) of the STN improved treadmill walking immediately and restored normal walking patterns. The same HFS failed to evoke visible side effects such as stepping, turning, raising of the head or facial muscle contraction in the absence of treadmill movement, or to change rotational behaviors elicited by the dopamine (DA) agonist apomorphine in unilateral lesioned rats. This suggests that the stimulation did not cause movement by an activation of brainstem locomotor regions or an increase attention leading to movement. Apomorphine-induced rotation may represent an imbalance of dopaminergic activation which remains during HFS. This work may provide a rodent model for deep brain stimulation (DBS) in patients with Parkinson's disease, and be suitable for further investigation of the neural mechanisms underlying the therapeutic effects of DBS.

Animals↗
PubMed2003

Relations between brain network activation and analgesic effect induced by low vs. high frequency electrical acupoint stimulation in different subjects: a functional magnetic resonance imaging study.

Two- or 100-Hz electrical acupoint stimulation (EAS) can induce analgesia via distinct central mechanisms. It has long been known that the extent of EAS analgesia showed tremendous difference among subjects. Functional MRI (fMRI) studies were performed to allocate the possible mechanisms underlying the frequency specificity as well as individual variability of EAS analgesia. In either frequencies, the averaged fMRI activation levels of bilateral secondary somatosensory area and insula, contralateral anterior cingulate cortex and thalamus were positively correlated with the EAS-induced analgesic effect across the subjects. In 2-Hz EAS group, positive correlations were observed in contralateral primary motor area, supplementary motor area, and ipsilateral superior temporal gyrus, while negative correlations were found in bilateral hippocampus. In 100-Hz EAS group, positive correlations were observed in contralateral inferior parietal lobule, ipsilateral anterior cingulate cortex, nucleus accumbens, and pons, while negative correlation was detected in contralateral amygdala. These results suggest that functional activities of certain brain areas might be correlated with the effect of EAS-induced analgesia, in a frequency-dependent dynamic. EAS-induced analgesia with low and high frequencies seems to be mediated by different, though overlapped, brain networks. The differential activations/de-activations in brain networks across subjects may provide a neurobiological explanation for the mechanisms of the induction and the individual variability of analgesic effect induced by EAS, or that of manual acupuncture as well.

Acupuncture Analgesia↗
PubMed2003

Modulation of cold pain in human brain by electric acupoint stimulation: evidence from fMRI.

The purpose of this study is to investigate the modulation of pain responses in the human brain by electric acupoint stimulation (EAS). Eight healthy subjects were enrolled; each received real or mock EAS treatment in separate sessions. Cool (18 degrees C) and cold (2 degrees C) stimuli were delivered, during which functional magnetic resonance imaging scans were performed, before and after treatment. Real EAS specifically increased the pain-specific activation in bilateral secondary somatosensory area, medial prefrontal cortex, and Brodmann area (BA) 32, while it decreased the activation in contralateral primary somatosensory area, BA7, and BA24. We suggest that EAS may induce an analgesic effect via modulation of both the sensory and the emotional aspect of pain processing.

Adult↗
PubMed2003

Brain opioid-receptors are involved in mediating peripheral electric stimulation-induced inhibition of morphine conditioned place preference in rats.

Conditioned place preference (CPP) paradigm has been suggested as one of the animal models for drug craving. The present study was performed to examine the effect of 100 Hz peripheral electric stimulation (PES) on the expression of morphine-induced CPP. Rats were trained with morphine for 4 days to establish the CPP paradigm in a three-chamber "unbiased" apparatus. Morphine-induced CPP was maintained up to 4 weeks when tests were given once a week. PES of 100 Hz administered 30 min a day for 3 days significantly attenuated morphine-induced CPP (P<0.01). I.c.v. injection of the delta-opioid receptor antagonist naltrindole (NTI) or the kappa-antagonist norbinaltorphimine (nor-BNI) but not the mu-antagonist cyclic D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH(2) (CTAP), completely blocked the inhibitory effect of 100 Hz PES on the expression of morphine-induced CPP (P<0.05-0.01). These results indicate that the anti-craving effects induced by repeated PES of 100 Hz is mediated by the activation of supra-segmental delta- and kappa-opioid receptors in the central nervous system.

Animals↗
PubMed2003

Sliding-window technique for the analysis of cerebral evoked potentials.

OBJECTIVE: To evaluate the efficiency of sliding-window technique in extracting and analyzing somatosensory evoked potentials (SEP) from multichannel electroencephalogram (EEG) data. METHODS: A time window of certain window size was moved along the time dimension of data sets. Values within the window were averaged for each trial, and then compared with a preset control window. The probability of randomly appeared significance resulting from repeated statistical comparison was calculated utilizing simulated EEG data sets. Cluster size (number of successive significant data points with given individual significance threshold) was determined to keep the general alpha value under 0.05. To test this procedure, multichannel EEG signals were recorded and analyzed from fourteen healthy right-handed volunteers, with painful and non-painful electrical stimuli delivered to the right middle fingers. RESULTS: Cluster size increased in parallel with window size and individual statistical threshold. The major SEP components of real EEG data, as well as the difference between pain and non-pain SEPs, were demonstrated to be significant with the sliding-window method. CONCLUSION: Sliding-window method is an effective tool for the analysis of SEP data.

Adult↗
PubMed2003

Modulation of pain signal processing by electric acupoint stimulation: an electroencephalogram study.

OBJECTIVE: To investigate the analgesia-related modulation of electroencephalographic activities by transcutaneous electric acupoint stimulation (EAS). METHODS: In 15 healthy human beings, 64-channel electroencephalogram was recorded and power spectrum analysis was employed before, during and after EAS. Non-acupoint electric stimulation was used as control. All subjects were asked to rate their sensation to painful stimulations before and after treatment. RESULTS: The relative theta power near contra-lateral centro-parietal area during EAS was negatively correlated with the pain score after EAS. Similarly, the beta activity during EAS near contra-lateral prefrontal cortex, ipsi-lateral inferior frontal and temporal lobe, and ipsi-lateral occipito-parietal cortex, were all negatively correlated with pain score after EAS. CONCLUSION: These changes might reflect a modulation of brain activity by EAS in specific areas, which were in turn involved in modulation of certain aspects of pain-signal processing.

Acupuncture Points↗
PubMed2003

Inhibition by peripheral electric stimulation of the reinstatement of morphine-induced place preference in rats and drug-craving in heroin addicts.

OBJECTIVE: To test the hypothesis that peripheral electric stimulation (PES) may suppress the reinstatement of morphine-induced conditioned place preference (CPP) in rats as well as the drug craving of detoxified heroin addicts in a frequency-dependent manner. METHODS: CPP model of the rat was constructed with two compartment automatic CPP apparatus, and the craving of the heroin addicts was assessed with a visual analogue scale (VAS). RESULTS: (1) PES of low frequency could prevent the drug priming- or foot shock-induced reinstatement of morphine CPP; (2) this effect was naloxone-reversible, suggesting a possible involvement of endogenous opioid mechanisms; and (3) PES of low frequency could also accelerate the rate of natural decay of drug craving in heroin addicts after successful abstinence. CONCLUSION: PES might serve as a therapeutic measure for the treatment of heroin addiction.

Adolescent↗
PubMed2003

[Electroacupuncture suppresses morphine--induced conditioned place preference (CPP) in rats].

OBJECTIVE: To examine the effects produced by electroacupuncture (EA) of different frequencies on the expression of morphine conditioned place preference (CPP) in rats. METHODS: SD rats were given 4 days consecutive trials in a computerized three-chamber "unbiased" CPP apparatus. Twenty-four hours later, the time spent on drug-pairing compartment of the rat was examined. Rats trained with CPP paradigms were then given EA of 2 Hz or 100 Hz once a day for 3 days. Twenty-four hours after the final EA session, they were again put to the CPP chamber, and the time spent on drug-pairing compartment was measured. RESULTS: Rats receiving morphine at a dose of 4 mg.kg-1 (i.p.) showed significantly enhanced preference scores in drug-pairing side than that of the control group. In other words, rats preferred the drug-pairing environment to the nondrug-pairing place. In addition, rats that received treatment with EA of 2 Hz or 100 Hz spent significantly less time on the drug pairing side than that of the CPP control group. CONCLUSION: Morphine-induced CPP paradigms were stably established in rats using a computer-controlled 3-chamber CPP experimental system. The expression of CPP could be significantly inhibited by multiple treatments with EA of either 2 Hz or 100 Hz.

Animals↗
PubMed2003

Effect of 6-OHDA lesions of the dopaminergic mesolimbic system on drug priming induced reinstatement of extinguished morphine CPP in rats.

OBJECTIVE: To evaluate the role played by mesolimbic dopaminergic system in the reinstatement of drug-seeking behavior induced by priming injections of morphine. METHODS: After the extinguishment of morphine conditioned place preference (CPP), low-dose catecholaminergic neurotoxin 6-hydroxydopamine (6-OHDA) was bilaterally injected into ventral tegmental area (VTA, 1 g.L-1) and nucleus accumbens (NAc, 5 g.L-1) before being primed with low-dose morphine. RESULTS: The effects of drug-priming to induce reinstatement of morphine CPP could be completely abolished by 6-OHDA microinjected into VTA to damage the perikaryon of dopaminergic neurons, or into NAc to lesion the terminal field of the dopaminergic pathway. CONCLUSION: The functional integrality of the mesolimbic dopaminergic system is indispensable for drug priming-induced reinstatement of conditioned place preference.

Animals↗