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Octreotide inhibits capsaicin‐induced activation of C and Aδ afferent fibres in rat hairy skin in vivo
Author(s) -
Wang Jun,
Cao DongYuan,
Guo Yuan,
Ma ShaoJie,
Luo Rong,
Pickar Joel G,
Zhao Yan
Publication year - 2011
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.2011.05542.x
Subject(s) - capsaicin , octreotide , chemistry , agonist , subcutaneous injection , somatostatin , somatostatin receptor , endocrinology , medicine , antagonist , pharmacology , receptor
Summary 1. The present study investigated whether the somatostatin receptor (SSTR) agonist, octreotide, could inhibit the activation of dorsal skin afferent fibres induced by local injection of capsaicin in the rat. 2. Single unit activity from Aδ mechano‐heat sensitive (AMH; n = 41) and C mechano‐heat sensitive (CMH; n = 30) afferents was recorded after their isolation in thin filaments from the dorsal cutaneous nerve branches. The effect of subcutaneous octreotide injection on the change in discharge rate and mechanical threshold induced by capsaicin was determined. 3. Capsaicin (0.05%) injection into the edge of the receptive field of both AMH and CMH units increased their discharge rate and decreased their mechanical threshold. Pre‐injection of octreotide inhibited these responses, and co‐application of SSTR antagonist, cyclosomatostatin, reversed the inhibitory effect of octreotide. 4. The present study provides electrophysiological evidence that the signal evoked by the somatostatin receptor inhibits the activation and mechanical sensitization evoked by capsaicin in the terminals in small‐diameter sensory neurons.