Young RF, Bach FW, Van Norman AS, Yaksh TL. Release of beta-endorphin and methionine-enkephalin into cerebrospinal fluid during deep brain stimulation for chronic pain. Effects of stimulation locus and site of sampling.
J Neurosurg 1993;
79:816-25. [PMID:
8246048 DOI:
10.3171/jns.1993.79.6.0816]
[Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The authors systematically studied the release of the endogenous opioid peptides beta-endorphin and methionine (met)-enkephalin into the cerebrospinal fluid (CSF) during deep brain stimulation in patients suffering from otherwise intractable chronic pain. Nine patients were included in the study; six had stimulation electrodes placed in both the periventricular gray matter (PVG) and the thalamic nucleus ventralis posterolateralis (VLP) and three in the PVG only. Immunoreactivity of beta-endorphin and met-enkephalin (beta-EPir and MEir, respectively) was measured by radioimmunoassays in ventricular and lumbar CSF samples obtained before, during, and after stimulation. Prestimulation concentrations of beta-EPir and MEir were lower in ventricular than in lumbar CSF (6.6 +/- 0.5 vs. 13.7 +/- 1.0 pmol/liter, p = 0.0001, for beta-EPir; 33.6 +/- 5.1 vs. 48.3 +/- 3.2 pmol/liter, p < 0.05, for MEir). Ventricular CSF concentrations of both beta-EPir and MEir increased significantly during PVG stimulation, whereas VPL stimulation was without effect. No changes were seen in lumbar CSF levels of the peptides during stimulation in either site. A significant inverse relationship was found between the "during:before stimulation" ratios of visual analog scale ratings and beta-EPir levels during PVG stimulation. The beta-EPir and MEir concentration during:before stimulation ratios were positively correlated, whereas no correlation was present in prestimulation samples from ventricular or lumbar CSF. High-performance liquid chromatography of ventricular CSF pools obtained during PVG stimulation revealed that major portions of beta-EPir and MEir eluted as synthetic beta-endorphin and met-enkephalin, respectively, thus documenting the release of beta-endorphin and met-enkephalin into ventricular CSF during PVG stimulation. The finding of a direct relationship between beta-EPir release and pain alleviation may suggest a role for beta-endorphin in the analgesic mechanism of PVG stimulation.
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