In VivoÊCalcium Imaging Visualizes Incision-Induced Primary Afferent Sensitization and Its Amelioration by Capsaicin Pretreatment

Authors
H Ishida, Y Zhang, R Gomez et al

Lab
University of Texas Health Science Center at San Antonio, San Antonio, TX, U.S.A.

Journal
Journal of Neuroscience

Abstract
Previous studies have shown that infiltration of capsaicin into the surgical site can prevent incision-induced spontaneous pain like behaviors and heat hyperalgesia. In the present study, we aimed to monitor primary sensory neuron Ca2+Êactivity in the intact dorsal root ganglia (DRG) using Pirt-GCaMP3 male and female mice pretreated with capsaicin or vehicle before the plantar incision. Intraplantar injection of capsaicin (0.05%) significantly attenuated spontaneous pain, mechanical, and heat hypersensitivity after plantar incision. The Ca2+Êresponse inÊin vivoÊDRG and inÊin situÊspinal cord was significantly enhanced in the ipsilateral side compared with contralateral side or naive control. Primary sensory nerve fiber length was significantly decreased in the incision skin area in capsaicin-pretreated animals detected by immunohistochemistry and placental alkaline phosphatase (PLAP) staining. Thus, capsaicin pretreatment attenuates incisional pain by suppressing Ca2+Êresponse because of degeneration of primary sensory nerve fibers in the skin.

BIOSEB Instruments Used:
Rodent pincher - analgesia meter (BIO-RP-M)