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Sucrose induced analgesia in the brainstem of neonatal rat pups.

SUCROSE INDUCED ANALGESIA IN THE BRAINSTEM OF NEONATAL RAT PUPS. Indre Augustinaite, Matthew Ennis, and Yi-Hong Zhang, Christian Brothers University, Memphis, Tennessee (IA), and University of Tennessee Health Science Center, Memphis, Tennessee (ME, YHZ). Previous studies show that nursing produces analgesia in neonatal humans and rats. Sugars in breast milk stimulate oral cavity sweet-responsive taste buds which triggers opioid release in the brain. The neural circuits mediating this analgesia are unknown. The goal of this study was to inactivate a key brain site involved in opioid analgesia, the rostral ventromedial medulla (RVM), to determine its role in analgesia produced by intraoral sucrose infusion in neonatal rats (ages P10-P13). Intraoral sucrose infusion produced analgesia as measured by hindpaw withdrawal responses to a series of von Frey filaments; i.e., sucrose increased the filament force needed to produce a withdrawal response. Sucrose analgesia was unaffected by microinjection of saline into RVM. By contrast, microinjection of the local anesthetic lidocaine into RVM eliminated sucrose-induced analgesia. As lidocaine suppresses neural activity, these findings indicate that sucrose-induced analgesia is mediated, at least in part, by the RVM.
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Title Annotation:WESTERN REGION
Author:Augustinaite, Indre; Ennis, Matthew; Zhang, Yi-Hong
Publication:Journal of the Tennessee Academy of Science
Article Type:Report
Geographic Code:1USA
Date:Jul 1, 2008
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