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Spinal nociceptin mediates electroacupuncture‐related modulation of visceral sympathoexcitatory reflex response in rats
Author(s) -
Zhou Wei,
Mahajan Aman,
Longhurst John
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.739.10
Subject(s) - nociceptin receptor , electroacupuncture , reflex , spinal cord , (+) naloxone , endocrinology , medicine , efferent , opioid receptor , withdrawal reflex , opioid peptide , antagonist , receptor antagonist , opioid , anesthesia , chemistry , receptor , acupuncture , afferent , alternative medicine , psychiatry , pathology
This study investigated the importance of nociceptin in the visceral reflex modulation during electroacupuncture (EA). Cardiovascular pressor reflex responses were induced by gastric distension (GD) in anesthetized Sprague‐Dawley rats. Intrathecal injection of nociceptin (10 nM) at T2‐3 attenuated the GD‐induced pressor responses by 37 ± 5% similar to the influence of EA at P 5–6 acupoints for 30 minutes (42 ± 7% decrease). Intrathecal injection of the nociceptin antagonist, [N‐Phe1]‐nociceptin (1–13) NH2, partially reversed the EA response by 67%. Pretreatment with the opioid receptor antagonist naloxone did not alter the EA‐like inhibitory effect of nociceptin on the pressor reflex, while a combination of nociceptin receptor antagonist with naloxone completely abolished the EA effect. Intrathecal injection of nociceptin attenuated the pressor responses to electrical stimulation of the rostral ventrolateral medulla by 46% suggesting that nociceptin acts in efferent pathways. Immunoreactivity for nociceptin was observed in neurons in the superficial laminae of the dorsal horn, ventral horn and intermediolateral column (IML) of the spinal cord. Furthermore, EA at P 5–6 activated nociceptinergic neurons in the IML and the dorsal horn. These results suggest that nociceptin in the spinal cord mediates the visceral reflex responses, likely through its effect on both afferent and efferent pathways.