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Analgesia stimulation of the hypothalamic arcuate nucleus: Tolerance and its cross-tolerance to 2 HZ- or 100 HZ-electroacupuncture analgesia
S63 BLOOD ENDOGENOUS OPIOID PEPTIDES LEVEL CHANGES FOLLOWED BY ACUPUNCTURE TREATMENT IN SUBACUTE PAIN. Q.S. Li, G.F. Xi*, Z.Y. Liu*, et al, Dept. of Neurobiology and Institute of Acupuncture Research, Shanghai Medical University, Shanghai 200032, People's Republic of China.
Poster 77 GREEN Mon-Tues Exhibit Hall
Abs No 120 AIM OF INVESTIGATION: Endogenous opioid peptides (EOP) including -1 morphine like substance (MLS) and leucine enkephalin (LEK) was known to inhibit pain. However, blood EOP were rarely reported. This study observed the venous EOP level in 44 patients with subacute pain and 35 healthy volunteers (HV), moreover, the changes of venous EOP followed by acupuncture treatment in them. METHODS: A prospective, double blind and randomized design was employed, different acupoints were chosen depended on site of pain. 30 min. of acupuncture induction operated at 8:00 am. Blood samples were taken prior to and 30 min. after acupuncture. Serum MLS, isolated by XAD-2, was detected by RRA. Plasma LEK was measured by RIA. Response of acupuncture was evaluated by VAS (pain), VRS, improvement of tenderness and function, and being graded into I (good), II (fair), and III (poor). (1) Blood level of MLS and LEK were significantly lowerin patients with su~~$xspain than in HV. (2) Good response was found in 21 patients (47.7%), fair response in 18 (40.9%), and poor response in 5 (11.4%). (3) Serum MLS was significantly increased from 25.5k4.3 to 35.5+4.6% (competitive rate) after treatment, while no obvious changes in other groups. (4) It was found that the better the analgesic efficacy, the higher the level of serum MLS, until it's level reached to normal. CONCLUSION: Blood EOP level was adversely related to degree of pain. Acupuncture could increase blood EOP, particularly in patients with good response, the better the response, the higher the EOP level. It might be a parameter to reflect the pain and analgesia effect in subacute pain.
ANALGESIA
STIMULATION OF THE HYPOTHALAMIC ARCUATE NUCLEUS: TOLERANCE AND ITS CROSS-TOLERANCE TO 2 HZ- OR 100 HZ-ELECTROACUPUNCTURE ANALGESIA. .Q.~~i~~~~~~~;le:;~~~~~h~~~:. of Physiology, Beijing Medica
GREEN Mon-Tues
Ex;i;;tiii:'
AIM OF INVESTIGATION: In the current study, characterization of tolerance to repeated hypoalgesic stimulation of the arcuate nucleus of hypothalamus (ARH) was examined and a particular attention was focused on its cross-tolerance to 2 Hz- or 100 Hz-electroacupuncture (EA) analgesia. METHODS: In the lightly pentobarbital-anesthetized rat, latency of the tail flick (TFL) to noxious heating on the tail was taken as the measure of pain. Effects on the TFL were assessed following electrical stimulation in the ARH (cl50 uA, 0.3 ms and 32 Hz) for 5 min or EA stimulation (1-2-3 mA, 0.3 ms and 2 or 100 Hz) in the acupoints of S36 and Sp6 for 30 min. RESULTS: Stimulation of the ARH produced a marked elevation of the TFL. Repwstimulation'of the ARH for a total of 11 sessions resulted in a gradual decline in producing analgesia, indicating the development of tolerance to the stimulation. This tolerance could essentially dissipate 7 days after non-stimulation. Tolerance to the ARH analgesic stimulation reduced the hypoalgesic effect of 2 Hz EA by 76% while leaving 100 Hz EA analgesia unaffected. In rats tolerant to low frequency EA analgesia induced by administration of continuous 6 sessions, the ARH stimulation-produced analgesia was attenuated by 62% whereas 100 Hz EA effect ghowed no significant change. Alternatively, rats tolerant to high frequency EA analgesia were found to be still effective to either the ARH or low frequency EA stimulation. CONCLUSION: #- The results suggest that the ARH- and 2 Hz-stimulation produted analgesia via a connnomneural mechanism, supporting the hypothesis that the ARH plays an important role in mediating low frequency EA analgesia.
Poster 77 GREEN Mon-Tues Exhibit Hall
Abs No 120 AIM OF INVESTIGATION: Endogenous opioid peptides (EOP) including -1 morphine like substance (MLS) and leucine enkephalin (LEK) was known to inhibit pain. However, blood EOP were rarely reported. This study observed the venous EOP level in 44 patients with subacute pain and 35 healthy volunteers (HV), moreover, the changes of venous EOP followed by acupuncture treatment in them. METHODS: A prospective, double blind and randomized design was employed, different acupoints were chosen depended on site of pain. 30 min. of acupuncture induction operated at 8:00 am. Blood samples were taken prior to and 30 min. after acupuncture. Serum MLS, isolated by XAD-2, was detected by RRA. Plasma LEK was measured by RIA. Response of acupuncture was evaluated by VAS (pain), VRS, improvement of tenderness and function, and being graded into I (good), II (fair), and III (poor). (1) Blood level of MLS and LEK were significantly lowerin patients with su~~$xspain than in HV. (2) Good response was found in 21 patients (47.7%), fair response in 18 (40.9%), and poor response in 5 (11.4%). (3) Serum MLS was significantly increased from 25.5k4.3 to 35.5+4.6% (competitive rate) after treatment, while no obvious changes in other groups. (4) It was found that the better the analgesic efficacy, the higher the level of serum MLS, until it's level reached to normal. CONCLUSION: Blood EOP level was adversely related to degree of pain. Acupuncture could increase blood EOP, particularly in patients with good response, the better the response, the higher the EOP level. It might be a parameter to reflect the pain and analgesia effect in subacute pain.
ANALGESIA
STIMULATION OF THE HYPOTHALAMIC ARCUATE NUCLEUS: TOLERANCE AND ITS CROSS-TOLERANCE TO 2 HZ- OR 100 HZ-ELECTROACUPUNCTURE ANALGESIA. .Q.~~i~~~~~~~;le:;~~~~~h~~~:. of Physiology, Beijing Medica
GREEN Mon-Tues
Ex;i;;tiii:'
AIM OF INVESTIGATION: In the current study, characterization of tolerance to repeated hypoalgesic stimulation of the arcuate nucleus of hypothalamus (ARH) was examined and a particular attention was focused on its cross-tolerance to 2 Hz- or 100 Hz-electroacupuncture (EA) analgesia. METHODS: In the lightly pentobarbital-anesthetized rat, latency of the tail flick (TFL) to noxious heating on the tail was taken as the measure of pain. Effects on the TFL were assessed following electrical stimulation in the ARH (cl50 uA, 0.3 ms and 32 Hz) for 5 min or EA stimulation (1-2-3 mA, 0.3 ms and 2 or 100 Hz) in the acupoints of S36 and Sp6 for 30 min. RESULTS: Stimulation of the ARH produced a marked elevation of the TFL. Repwstimulation'of the ARH for a total of 11 sessions resulted in a gradual decline in producing analgesia, indicating the development of tolerance to the stimulation. This tolerance could essentially dissipate 7 days after non-stimulation. Tolerance to the ARH analgesic stimulation reduced the hypoalgesic effect of 2 Hz EA by 76% while leaving 100 Hz EA analgesia unaffected. In rats tolerant to low frequency EA analgesia induced by administration of continuous 6 sessions, the ARH stimulation-produced analgesia was attenuated by 62% whereas 100 Hz EA effect ghowed no significant change. Alternatively, rats tolerant to high frequency EA analgesia were found to be still effective to either the ARH or low frequency EA stimulation. CONCLUSION: #- The results suggest that the ARH- and 2 Hz-stimulation produted analgesia via a connnomneural mechanism, supporting the hypothesis that the ARH plays an important role in mediating low frequency EA analgesia.