Characterization of noradrenergic transmission at the dorsal motor nucleus of the vagus involved in reflex control of fundus tone

• DOI: 10.1152/ajpregu.00630.2007
• Publication Date: 2008-01-16T20:25:43Z
• Authors: Melissa A. Herman; Mark Niedringhaus; Alisa Alayan; Joseph G. Verbalis; Niaz Sahibzada; Richard A. Gillis
• Keywords: Dorsal motor nucleus; Fundus (uterus)

Quantitative analysis of innervation to dorsal motor nucleus the vagus (DMV) fundus-projecting neurons indicates that approximately 17% input are noradrenergic. To determine whether this small percentage innervating DMV output stomach is physiologically relevant, we evaluated role norepinephrine at in mediating a vagovagal reflex controlling fundus. A strain gauge was sutured onto fundus isoflurane-anesthetized rats monitor changes tone evoked by esophageal distension (ED). ED produced decrease 0.31 +/- 0.02 g (P < 0.05), which could be reproduced after 30-min interval between distensions. Bilateral cervical vagotomy and/or pretreatment with intravenous atropine methylbromide prevented reflex-induced relaxation. In contrast, N(G)-nitro-L-arginine methyl ester had no effect. microinjection alpha2-adrenoreceptor antagonists (yohimbine and RS-79948) into also response. Before antagonists, decreased 0.33 0.05 0.05). After antagonist microinjection, only 0.06 > prazosin effect on Microinjection mimicked prior an antagonist. Our results indicate noradrenergic important suggest released acts alpha2-adrenoreceptors inhibit activity cholinergic-cholinergic excitatory pathway