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Effect of chronic capsaicin treatment on tachykinin NK1 binding sites in the rat
journal contribution
posted on 2023-05-17, 05:41 authored by Dominic GeraghtyDominic Geraghty, Burcher, EBinding sites for [125I]-Bolton-Hunter substance P (BHSP) were investigated in homogenates of rat submandibular gland, colon smooth muscle, and urinary bladder. In vehicle-treated animals, the equilibrium dissociation constant (KD) was similar for both submandibular gland (0.46 +/- 0.03 nM) and colon (0.57 +/- 0.04 nM), although the maximum density of binding sites (Bmax) was about six-fold higher in submandibular gland compared with colon. These binding parameters remained unchanged in capsaicin-pretreated animals (140 mg/kg IP). In contrast, capsaicin pretreatment reduced (p less than 0.05) the Bmax in urinary bladder by twenty-five percent (0.56 fmol/mg wet weight) when compared to vehicle-treated controls (0.73 fmol/mg wet weight), although the KD was unchanged (vehicle, 0.29 +/- 0.08 nM; capsaicin, 0.24 +/- 0.04 nM). These data demonstrate that the NK1 receptors in submandibular gland and colon smooth muscle are not associated with or dependent upon intact primary afferent sensory neurons. However, a minority of NK1 receptors in the urinary bladder were lost after capsaicin, indicating that these receptors are located on sensory terminals, or may be dependent on growth factors or other chemicals released from these nerves.
History
Publication title
PeptidesVolume
13Pagination
409-411ISSN
0196-9781Department/School
School of Health SciencesPublisher
Elsevier Science IncPlace of publication
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