Attenuation of pain-related behaviour evoked by carrageenan injection through blockade of neuropeptide Y Y1 and Y2 receptors.
BACKGROUND
It is well known that neuropeptide Y (NPY) participates in the modulation of chronic pain, but its exact role has not yet been fully explained. In this study, we explored whether targeted delivery of NPY and its antagonists into dorsal root ganglion (DRG) modulates pain-related behaviour in rats with experimentally induced inflammatory nociception.


METHODS
Inflammatory nociception was induced by intraplantar carrageenan injection. Immediately after carrageenan injection, NPY or its antagonists were injected directly into DRG. Behavioural testing was performed on the day preceding the carrageenan injection and four times (5 h after, on the first, fifth and eighth days) following the injection. Immunohistochemical analysis was performed 8 days following the surgery.


RESULTS
Our results showed that NPY, applied directly to DRG, induced cold allodynia in carrageenan inflammatory pain model. NPY in carrageenan-injected rats did not additionally exacerbate activation of satellite cells in DRG and astrocytes in dorsal horn caused by intraplantar carrageenan injection. However, application of NPY Y1 and Y2 antagonists directly into DRG reversed carrageenan proalgesic effects and reduced gliosis in DRG and dorsal horn.


CONCLUSIONS
These findings indicate an important link between pain-related behaviour and neuroimmune actions of NPY Y1 and Y2 receptors.
Laboratory for Pain Research, Department of Anatomy, Histology and Embryology, University of Split School of Medicine, Split, Croatia.
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S
Kostić
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Puljak
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D
Sapunar
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D002351:Carrageenan; D005727:Ganglia, Spinal / Q000187:drug effects* / Q000503:physiopathology; D006930:Hyperalgesia / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D007249:Inflammation / Q000139:chemically induced / Q000503:physiopathology; D008297:Male; D009478:Neuropeptide Y / Q000494:pharmacology*; D010147:Pain Measurement; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors*; D018013:Receptors, Neuropeptide / Q000037:antagonists & inhibitors*; D017476:Receptors, Neuropeptide Y / Q000037:antagonists & inhibitors*; D045442:Rotarod Performance Test
D009478:Neuropeptide Y; C066211:Npy1r protein, rat; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; D017476:Receptors, Neuropeptide Y; C095889:neuropeptide Y2 receptor; D002351:Carrageenan