Feeble bronchomotor responses in diabetic rats in association with decreased sensory neuropeptide release. Szilvássy, Judith, István Sziklai, Peter Horvath, Maria Szilasi, József Németh, Péter Kovács, and Zoltán Szilvássy. Departments of 1Oto-rhino-laryngology, 3Pulmonology, 5Clinical Pharmacology, and 2Pharmacology, Medical University of Debrecen, H-4032 Debrecen; and 4Neuroscience Research Group, University Medical School of Pécs, H-7643 Pécs, Hungary
APStracts 9:0027L, 2002.
Type I diabetes is associated with a low incidence of asthma. We tested whether a decrease in sensory neuropeptide release is associated with an attenuated bronchoconstrictive response to field stimulation (FS; 100 stimuli, 20 V, 0.1 ms, 20 Hz) in streptozotocin (STZ)- induced diabetes. The organ fluid of the preparations were also tested for substance P, calcitonin gene-related peptide (CGRP), and somatostatin concentrations by RIA. Preparations were from either normal rats or those pretreated with 50 mg/kg STZ iv 8 wk before experiment. A group of STZ-treated animals was supplied with insulin delivery (4 IU/day sc) implants between 4 and 8 wk. A subgroup was formed to study the effect of capsaicin desensitization. The atropine-resistant contraction was attenuated by diabetes without capsaicin-sensitive relaxation response. Exogenous CGRP and substance P potentiated, whereas somatostatin inhibited (1 nM-10 µM) the FS-induced contractions in rings from either group. FS released somatostatin, CGRP, and substance P from 0.17 ± 0.024, 0.15 ± 0.022, and 1.65 ± 0.093 to 0.58 ± 0.032, 0.74 ± 0.122, and 5.34 ± 0.295 in preparations from normal, and from 0.19 ± 0.016, 0.11 ± 0.019, and 0.98 ± 0.116 to 0.22 ± 0.076, 0.34 ± 0.099, and 1.84 ± 0.316 fmol/mg wet wt in preparations from diabetic rats. Insulin supplementation restored neuropeptide release in rings from STZ-treated rats. The results show that the decreased FS-induced contractions occurred with a decrease in sensory neuropeptide release in STZ-diabetic rats.

Received 4 December 2000; accepted in final form 29 October 2001
APS Manuscript Number L409-0.
Article publication pending Am J Physiol Lung Cell Mol Physiol
ISSN 1080-4757 Copyright 2002 The American Physiological Society.
Published in APStracts on 28 February 2002