Substance P N-terminal fragment SP(1-7) attenuates chronic morphine tolerance and affects dynorphin B and nociceptin in rats
2011 (English)In: Peptides, ISSN 0196-9781, E-ISSN 1873-5169, Vol. 32, no 8, 1661-1665 p.Article in journal (Refereed) Published
The N-terminal substance P fragment SP(1-7) is known to modulate hyperalgesia and opioid withdrawal in animal models. This study examined the effects of intraperitoneal (i.p.) injections of SP(1-7) on chronic morphine tolerance and on the levels of dynorphin B (DYN B) and nociceptin/orphanin FQ(N/OFQ) in various brain areas of male Sprague Dawley rats. Morphine tolerance was induced by subcutaneous injections of the opioid (10 mg/kg) twice daily for 7 days. SP(1-7) injected i.p. (185 nmol/kg) 30 min prior to morphine reduced the development of morphine tolerance. Immunoreactive (it) DYN B and N/OFQ peptide levels were measured in several areas of the central nervous system. Levels of ir DYN B in rats treated with SP(1-7) and morphine were decreased in the nucleus accumbens. substantia nigra and ventral tegmental area and increased in the frontal cortex. The ir N/OFQ levels were increased in the periaqueductal gray and decreased in the nucleus accumbens. Since the concentration profiles of the two peptides were altered by SP(1-7) in the areas that are implicated in the modulation of opioid tolerance and analgesia, it is suggested that DYN B and N/OFQ systems may be involved in the effects of SP(1-7) on opioid tolerance.
Place, publisher, year, edition, pages
2011. Vol. 32, no 8, 1661-1665 p.
Dynorphin B (DYN B), Morphine, Nociceptin/orphanin FQ (N/OFQ), Opioid tolerance, Rat brain, Substance P (SP), SP(1-7)
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-159258DOI: 10.1016/j.peptides.2011.06.030ISI: 000294572800014OAI: oai:DiVA.org:uu-159258DiVA: diva2:443524