Referenced in: none

Automatically associated channels: TRP , TRPV , TRPV1

Title: Diabetic rats show reduced cardiac-somatic reflex evoked by intrapericardial capsaicin.

Authors: Xiao-Hua Liu, Chao Qin, Jian-Qing Du, Yan Xu, Na Sun, Jing-Shi Tang, Qiang Li, Robert D Foreman

Journal, date & volume: Eur. J. Pharmacol., 2011 Jan 25 , 651, 83-8

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/21114980

Abstract
Painless myocardial infarction is a serious complication of diabetes. The present study examined whether cardiac nociception was altered in the streptozotocin-induced diabetic rat model by assessing intrapericardial capsaicin-evoked electromyography (EMG) responses in the spinotrapezius muscle. Somatic sensitivities to mechanical and thermal stimulation of the skin were also determined. Intrapericardial administration of capsaicin evoked a concentration-dependent EMG response, which was reproducible with repeated administration. However, the capsaicin-induced EMG responses were different in streptozotocin-induced diabetic rats and controls. Intrapericardial capsaicin produced fewer EMG responses, which were delayed and reduced in streptozotocin-treated rats compared to controls. Pretreatment with capsazepine, a TRPV1 antagonist, significantly decreased capsaicin-evoked EMG activity in both streptozotocin-treated and control rats. In addition, streptozotocin-treated rats showed a decreased paw withdrawal threshold in response to mechanical stimulation but no change in response to radiant heat stimulation. These results suggest that streptozotocin-induced diabetic rats develop somatic mechanical hypersensitivity (allodynia), but reduced cardiac nociception. Decreased TRPV1 function may contribute to the reduction of cardiac nociception in the diabetic rat.