PubMed · 10741321
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L Sher. 2000. The placebo effect and endogenous opioids.. https://doi.org/10.1177/014107680009300315
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The placebo response is commonly invoked as a factor in the therapeutic relationship between the family physician and the patient, but important recent literature can be difficult for family physicians to access. Coordinated interdisciplinary research into the placebo response as it occurs in primary care settings is lacking. Although there is controversy about the nature and scope of the placebo response, important suggestions are emerging about its psychological mechanisms (expectancy and conditioning) and the biochemical pathways that act as psychosomatic linkages (endorphins, catecholamines and cortisol, psychoneuroimmumunology). The available research justifies interventions by family physicians that maximize the placebo response in everyday patient encounters. These include the sustained partnership approach, working with patients on the narratives they construct to explain illness, listening to patients, providing them with satisfactory explanations, expressing care and concern, and enhancing their sense of control. Notable opportunities exist for family medicine investigators to expand the understanding of this phenomenon.
At the beginning of the 70-ties various studies showed the existence of endogenous opiates in central nervous system. The chemical structure of first endogenous pentapeptides called enkephalins (met-enkephalin and leu-enkephalin) and their receptor was already known in 1975. Further investigations confirmed the existence of opiates (endorphins) in brain, pituitary gland, spinal cord and other tissues. Endorphins may exert various effects: analgesic (especially dynorphin and b-endorphin), antidiuretic, depressive on respiratory center, constipative, they also cause physical and mental dependence. These peptides, which are not known thoroughly may play a big part in the regulation of many biochemical and hemodynamic processes. Many of these mechanisms are already described and changes in concentrations of endorphins, for example in patients with silent myocardial ischaemia, are basic in the pathogenesis of this disease. Many of these mechanisms are controversial, the role of endogenous opiates in pathogenesis of hypertension or congestive heart failure is still unknown. This study summerizes the present knowledge endorphins and tries to answer whether changes in the concentration of endorphins are primary or secondary to the biochemical and hemodynamic disturbances in 2 diseases.
A microbore electrospray (ESI) injection system has been adapted to our 9.4-tesla ESI FT-ICR mass spectrometer, greatly enhancing the stability and sensitivity of the system. Spray was generated from micro-ESI needles made from sharply tapered, polished fused silica capillaries of 25 to 50 microns inner diameter. Micro-ESI permits low-level sample analysis by constant infusion at sub-microL/min flow rate over a wide range of solvent conditions in both positive- and negative-ion mode. The system is flexible and allows rapid conversion to allow routine LC/MS analysis on low-level mixtures presented in biological media. LC/MS analyses were accomplished by replacing micro-ESI needles with capillaries packed with reverse phase retention media to permit analyte concentration and purification prior to analysis (micro-ESI/LC). A unique nano-flow LC pumping system was developed, capable of producing a true unsplit solvent gradient at flow rates below 1 microL/min. The micro-ESI/LC FT-ICR system produces mass spectra from a mixture of three neuroactive peptides at a concentration of 500 amol/microL (5 fmol each total loaded) in biological salts with baseline separation, signal-to-noise ratio of > 10:1 and mass resolving power > 5000. These results represent a reduction in detection limit by a factor of approximately 2 x 10(6) over the best previously published LC/FT-ICR MS data.