Peak B endorphin concentration in cerebrospinal fluid: reduced in chronic pain patients and increased during the placebo response
The level of an endogenous opioid (peak B endorphin) was measured in chromatographically fractionated cerebrospinal fluid (CSF) sampled from two groups of chronic pain patients before and after intrathecal saline (placebo) injection. As assessed by a verbal rating scale, one group reported no change in their level of pain (non-responders, NR;n=6) while the other group reported complete or >50% pain relief (placebo responders, PR;n=14). We find, as has been reported previously, that initial peak B levels were lower (by 50%) in these chronic pain patients' CSF than in CSF from pain-free (PF) normal controls (P<0.001,t-test). Peak B levels measured from CSF of the NR group undergoing this procedure did not change (P>0.4, pairedt-test). In contrast, a significant 2.3-fold increase was measured in the CSF peak B level of the PR group (P<0.05, pairedt-test). This is the first direct evidence that a CSF opioid is correlated with placebo pain relief in chronic pain patients. Peak B is a potent analgesic substance when administered by the intracerebroventricular route in mice and its level is related to the patients' pain status in a presumably causal manner.
Key wordsChronic pain Peak B Endogenous opioid Endorphin Analgesia Placebo Cerebrospinal fluid
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- Beecher HK (1955) The powerful placebo. JAMA 159:1602–1606Google Scholar
- Evans FJ (1974) The power of the sugar pill. Psychol Today 7:55–59Google Scholar
- Levine JD, Gordon NC, Fields HL (1978a) The mechanism of placebo analgesia. Lancet II:657–754Google Scholar
- Levine JD, Gordon NC, Fields HL (1978b) Naloxone dose dependently produces analgesia and hyperalgesia in postoperative pain. Nature 278:741–742Google Scholar
- Lipman JJ, Miller BE, Mays KS, North WC, Karara S, Byrne WL (1981) CSF Endorphin levels in chronic pain patients before and after a placebo pain relief. Endogenous and exogenous opiate agonists and antagonists. Kodansha Press, Tokyo, Japan, pp 315–317Google Scholar
- Sarnoff SJ, Arrowood JG (1946) Differential spinal block. Surgery 20:150–165Google Scholar
- Stimmell B (1983) Neuroregulators and pain. Pain, analgesia and addiction. Raven Press, New York, pp 18–38Google Scholar
- Terenius L (1978) The implications of endorphins in pathological states. In: Van Ree JM, Terenius L (eds) Characteristics and functions of opioids. Elsevier, Amsterdam, pp 143–157Google Scholar