title: Antiopioid properties of the TYR-MIF-1 family.
abstract: 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 human brain cortex. All these peptides interact with opioid receptors and in addition bind to non-opiate sites specific for each of the peptides. Data in the literature suggest that peptides of the Tyr-MIF-1 family (Tyr-MIF-1s) have antiopioid and opioid- like effects. It is known that some anti-opioid peptides (AOP) could reverse morphine-induced analgesia in rodents and men and able to inhibit the expression of some forms of stress-induced analgesia (SIA) in various species. We examined the effects of the Tyr-MIF-1 peptides (all in dose 1 mg/kg i.p.) in the male Wistar rats on morphine-induced analgesia in acute pain using the paw-pressure (PP) and the tail-flick (TF) tests and on immobilization stress-induced antinociception using the PP test. Our results showed that the Tyr-MIF-1 peptides significantly decreased the analgesic effect of morphine (1 mg/kg i.p.) in both tests used. Immobilization of the rats increased the pain threshold for at least 1 h. The Tyr-MIF-1 peptides reduced stress-induced antinociception in PP test. In conclusion, our findings indicate that Tyr-MIF-1s modulate the analgesic effects of morphine and SIA, which corresponds with the hypothesis about AOP mentioned above.
authors.affiliation: Institute of Physiology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., bl. 23, 1113 Sofia, Bulgaria. bocheva@bio.bas.bg
authors.forename: A
authors.initials: A
authors.lastname: Bocheva
authors.forename: E
authors.initials: E
authors.lastname: Dzambazova-Maximova
mesh_terms: D000818:Animals; D006614:Hindlimb / Q000502:physiology; D007103:Immobilization / Q000379:methods; D009075:MSH Release-Inhibiting Hormone / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*; D009020:Morphine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000737:chemistry / Q000494:pharmacology*; D010146:Pain / Q000188:drug therapy / Q000503:physiopathology / Q000517:prevention & control; D010147:Pain Measurement / Q000295:instrumentation / Q000379:methods; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology; D011312:Pressure / Q000009:adverse effects; D051381:Rats; D017208:Rats, Wistar; D013623:Tail / Q000502:physiology; D013997:Time Factors
chemical_list: D009292:Narcotic Antagonists; C090826:tyrosyl-prolyl-lysyl-glycinamide; C077532:tyrosyl-prolyl-tryptophyl-glycinamide; D009020:Morphine; C036930:tyrosyl-prolyl-leucyl-glycinamide; D009075:MSH Release-Inhibiting Hormone