Peak B endorphin concentration in cerebrospinal fluid: reduced in chronic pain patients and increased during the placebo response

• Published in: Psychopharmacology 1990-09, Vol.102 (1), p.112-116
• Main Authors: Lipman, J J, Miller, B E, Mays, K S, Miller, M N, North, W C, Byrne, W L
• Format: Article
• Language: English
• Subjects: beta-Endorphin - cerebrospinal fluid; Chronic Disease; Humans; Injections, Intraventricular; Pain - cerebrospinal fluid; Placebos
• ISSN: 0033-3158; 1432-2072
• DOI: 10.1007/bf02245754

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 greater than 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 less than 0.001, t-test). Peak B levels measured from CSF of the NR group undergoing this procedure did not change (P greater than 0.4, paired t-test). In contrast, a significant 2.3-fold increase was measured in the CSF peak B level of the PR group (P less than 0.05, paired t-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.