Involvement of opioid receptors in oxytocin-induced antinociception in the nucleus accumbens of rats.

UNLABELLED Antinociceptive effects of oxytocin have been demonstrated in mice, rats, dogs, and humans. It has been shown that oxytocin receptors and fibers with oxytocin were distributed in the nucleus accumbens (NAc) of rats. The present study was performed to investigate the regulating role of oxytocin in nociception in the NAc of rats. Intra-NAc administration of oxytocin-induced dose-dependent increases in the hindpaw withdrawal latency (HWL) to noxious thermal and mechanical stimulation in rats, indicating that oxytocin has antinociceptive effects in the NAc of rats. Furthermore, the oxytocin-induced antinociceptive effects were attenuated by intra-NAc administration of the opioid-receptor antagonist naloxone, suggesting that the endogenous opioid system is involved in the oxytocin-induced antinociception in the NAc. Moreover, the oxytocin-induced antinociception was attenuated by intra-NAc injection of the kappa-receptor antagonist nor-binaltorphimine (nor-BNI) and the mu-receptor antagonist beta-funaltrexamine, but not by the delta-receptor antagonist naltrindole, demonstrating the involvements of mu- and kappa-receptors, but not delta-receptor, in the oxytocin-induced antinociception in the NAc of rats. PERSPECTIVE This article supplements the evidence that oxytocin regulates nociception in the central nervous system. It presents additional material for clinical application of oxytocin as an analgesia drug.

[1]  B. Taylor,et al.  Stimulation of dopamine D2 receptors in the nucleus accumbens inhibits inflammatory pain , 2003, Brain Research.

[2]  Stanley J. Watson,et al.  Opioid-receptor mRNA expression in the rat CNS: anatomical and functional implications , 1995, Trends in Neurosciences.

[3]  N. Ostrowski.  OXYTOCIN RECEPTOR mRNA EXPRESSION IN RAT BRAIN: IMPLICATIONS FOR BEHAVIORAL INTEGRATION AND REPRODUCTIVE SUCCESS , 1998, Psychoneuroendocrinology.

[4]  J. Streltzer.  Textbook of Pain, 4th ed , 2001 .

[5]  Xiaoping Zhou,et al.  Involvement of neuropeptide Y and Y1 receptor in antinociception in the arcuate nucleus of hypothalamus, an immunohistochemical and pharmacological study in intact rats and rats with inflammation , 2005, Pain.

[6]  A. Benelli,et al.  Influence of oxytocin on nociception and morphine antinociception , 1993, Neuropeptides.

[7]  J. Yang.  Intrathecal administration of oxytocin induces analgesia in low back pain involving the endogenous opiate peptide system. , 1994 .

[8]  Allan I. Basbaum,et al.  Central nervous system mechanisms of pain modulation , 2006 .

[9]  J. Fichna,et al.  Inhibition of trigemino-hypoglossal reflex in rats by oxytocin is mediated by μ and κ opioid receptors , 2005, Brain Research.

[10]  J. Stewart,et al.  Tachykinin NK-1 and NK-3 selective agonists induce analgesia in the formalin test for tonic pain following intra-VTA or intra-accumbens microinfusions , 1997, Behavioural Brain Research.

[11]  Gerardo Rojas-Piloni,et al.  Oxytocin and electrical stimulation of the paraventricular hypothalamic nucleus produce antinociceptive effects that are reversed by an oxytocin antagonist , 2006, PAIN.

[12]  C. Marsden,et al.  γ-aminobutyric acid levels in the intercellular space in the nucleus accumbens of the rat brain during a nociceptive conditioned response , 2006, Neuroscience and Behavioral Physiology.

[13]  Long-chuan Yu,et al.  Involvements of mu- and kappa-opioid receptors in morphine-induced antinociception in the nucleus accumbens of rats , 2006, Neuroscience Letters.

[14]  M. Zimmermann,et al.  Ethical guidelines for investigations of experimental pain in conscious animals , 1983, Pain.

[15]  Long-chuan Yu,et al.  Anti-nociceptive effect of neuropeptide Y in the nucleus accumbens of rats: an involvement of opioid receptors in the effect , 2002, Brain Research.

[16]  Gerardo Rojas-Piloni,et al.  Paraventricular hypothalamic influences on spinal nociceptive processing , 2006, Brain Research.

[17]  T. Lundeberg,et al.  Anti-nociceptive effects of oxytocin in rats and mice , 1994, Neuroscience Letters.

[18]  R. Buijs,et al.  Distribution and synaptic release of oxytocin in the central nervous system , 1985 .

[19]  Long-chuan Yu,et al.  Blockade effect of mu and kappa opioid antagonists on the anti-nociception induced by intra-periaqueductal grey injection of oxytocin in rats , 2002, Brain Research.

[20]  G. Gimpl,et al.  The oxytocin receptor system: structure, function, and regulation. , 2001, Physiological reviews.

[21]  P. Wall,et al.  Textbook of pain , 1989 .

[22]  M. Millan.  Descending control of pain , 2002, Progress in Neurobiology.

[23]  Long-chuan Yu,et al.  Antinociceptive role of oxytocin in the nucleus raphe magnus of rats, an involvement of μ-opioid receptor , 2003, Regulatory Peptides.

[24]  Long-chuan Yu,et al.  Involvement of opioid receptors in the oxytocin-induced antinociception in the central nervous system of rats , 2004, Regulatory Peptides.

[25]  Man-ying Xu,et al.  [Influence of glutamate and NMDA-receptor antagonist MK-801 on the electric activities of pain-excitation neurons in the nucleus accumbens of rats]. , 2005, Sheng li xue bao : [Acta physiologica Sinica].

[26]  G. Paxinos,et al.  The Rat Brain in Stereotaxic Coordinates , 1983 .