dynorphins and Arthritis--Rheumatoid

To observe the analgesic effect of electroacupuncture (EA) on collagen-induced arthritis (CIA) rats and its regulating effect on inflammation reaction and the endogenous opioid system of synovial tissues. Methods A total of 30 healthy male Wistar rats were randomly divided into a control group, a model group and an EA group, 10 rats in each one. The chronic pain model of CIA rats was made by cattle type-II collagen in the model group and EA group. Rats in the EA group were treated with EA at "Zusanli" (ST 36) and "Kunlun" (BL 60) for 30 min from 16th day after model establishment, once a day for consecutive 10 days. Rats in the control group did not receive any treatment. Rats in the model group were treated with fixation as the EA group. Threshold of pain, arthritis index, paw swelling were measured before model establishment and 16 d, 20 d, 23 d and 25 d after model establishment. The levels of beta-endorphin (β-END), met-enkephalin (met-ENK), dynorphin A (Dyn A) were measured by radioimmunoassay; the mRNA expressions of mu opioid receptor (MOR), kappa opioid receptor (KOR) and delta opioid receptor (DOR) in synovial tissues of CIA rats were detected by I quantitative polymerase chain reaction (qPCR).. Compared with the control group, threshold of pain was reduced (all P<0. 01), arthritis index was increased (all P<0. 01) and paw swelling was increased (all P<0. 01) in the model group on the 16th day, 20th day, 23rd day, 25th day after model establishment. Compared with the model group, the threshold of pain was increased in the EA group (all P<0. 01), arthritis index and paw swelling were reduced (all P<0. 01) on the 23rd day and 25th day after model establishment. Compared with the control group, the level of Dyn A in synovial tissues of CIA rats was increased in the model group (P<0. 01); the mRNA expressions of MOR, KOR and DOR were down-regulated lower than 0. 5 fold of normal level. Compared with the model group, the level of β-END in synovial tissues of the knee joint was increased in the EA group (P<0. 05), and the mRNA expressions of MOR, KOR and DOR in synovial tissues of CIA rats were up-regulated more than 2 folds of normal level.. The intervention of EA on chronic pain of CIA rats is superior, which is likely to be related with effects of EA on anti-inflammation and up-regulation of synovial tissue β-END and MOR, KOR, DOR.

Topics: Acupuncture Analgesia; Acupuncture Points; Analgesics, Opioid; Animals; Arthritis, Rheumatoid; beta-Endorphin; Cattle; Chronic Pain; Dynorphins; Electroacupuncture; Enkephalin, Methionine; Humans; Male; Rats; Rats, Wistar; Receptors, Opioid, mu; Synovial Fluid

By the use of highly selective antisera and an immunohistochemical technique the possible coexistence of proenkephalin- (PRO-ENK)- and prodynorphin (PRO-DYN)-derived peptides was examined in 4- to 6-micron thick serial sections of the L4-L5 segments of the spinal cord of non-colchicine-treated polyarthritic rats. In control, non-colchicine treated animals, virtually no cell bodies stained for the PRO-ENK-derived peptides, heptapeptide (MRF) and octapeptide (MRGL), nor for the PRO-DYN-derived peptides, dynorphin A (DYN) and alpha-neoendorphin (NEO). In contrast, in polyarthritic rats, numerous large (15-30 micron) multipolar neurons could be visualized with each antiserum in laminae IV/V. Alternate staining of adjacent sections with either anti-MRF or anti-MRGL antisera, followed by either anti-DYN or anti-NEO antisera, revealed a clear coexistence of PRO-ENK and PRO-DYN peptides. It was possible to demonstrate co-localization of all 4 opioids in a single cell. It appeared that all cells staining for PRO-ENK peptides in laminae IV/V also stained for PRO-DYN peptides.

Topics: Animals; Arthritis, Rheumatoid; Dynorphins; Endorphins; Enkephalins; Male; Oligopeptides; Protein Precursors; Rats; Rats, Inbred Strains; Spinal Cord