Effects of Tyr-MIF's family of peptides on immobilization stress-induced antinociception in rats
Bocheva, A.I.; Dzambazova-Maximova, E.B.
Folia Medica 46(2): 42-46
2004
ISSN/ISBN: 0204-8043 PMID: 15506550 Document Number: 568030
The Tyr-MIF-1 family of peptides includes MIF-1, Tyr-MIF-1, Tyr-W-MIF-1 and Tyr-K-MIF-1, which have been isolated from bovine hypothalamus and cortex of human brain. Data in the literature suggest that peptides of Tyr-MIF-1's family have opioid-like and anti-opioid actions. All these peptides interact with opioid receptors and in addition bind to non-opiate sites specific for each of the peptides and able to inhibit the expression of some forms of stress-induced analgesia (SIA) in various species. To examined the effects of the Tyr-MIF-1's peptides on immobilization stress-induced antinociception. Tyr-MIF-1's peptides were given to male Wistar rats intraperitoneally before or after 1 hour of restraint. The changes in the mechanical nociceptive threshold of the animals were measured by the Randall-Selitto paw pressure test. Immobilization of the rats increased the pain threshold at least 1 h. Tyr-MIF-1's peptides have contrasting effects on immobilization stress-induced antinociception in paw-pressure test in rats. When administered before immobilization procedure they potentiated the immobilization stress-induced antinociception, while if given after immobilization, they reduced it. Antinociceptive effects of Tyr-MIF-1, Tyr-W-MIF-1 and Tyr-K-MIF-1 were reduced in condition of stress. Tyr-MIF-1's peptides exerted antiopioide effects under condition of stress in paw-pressure test. These antiopioide effects were more pronounced when peptides were injected after stress exposure.