Altered mechanosensitive properties of vagal afferent fibers innervating the stomach following gastric surgery in rats.
OBJECTIVE
Several types of gastric surgeries have been associated with early satiety, dyspepsia and food intolerances. We aimed to examine alterations in gastric vagal afferents following gastric surgery-fundus ligation.


METHODS
Six week old, male Sprague-Dawley rats underwent chronic ligation (CL) of the fundus. Sham rats underwent abdominal surgery, but without ligation. Another group of rats underwent acute ligation (AL) of the fundus immediately prior to experiments. CL and sham rats were allowed to grow to age 3-4 months. Food intake and weights were recorded post-operatively. Gastric compliance and gastric wall thickness was measured at baseline and during gastric distension (GD). Extracellular recordings were made to examine response characteristics of vagal afferent fibers to GD and to map the stomach receptive field (RF). The morphological structures of afferent terminals in the stomach were examined with retrograde tracings from the nodose ganglion.


RESULTS
The CL group consumed significantly less food and weighed less than sham control. The mean compliance of the CL group was significantly less than control, but higher than the AL group. The spontaneous firing and responses to GD of afferent fibers from the CL rats were significantly higher than AL rats. There was a marked expansion of the gastric RF in the CL rats with significant reorganization and regeneration of intramuscular array (IMA) terminals. There was no difference in total wall or muscle thickness among the groups.


CONCLUSIONS
CL results in aberrant remodeling of IMAs with expansion of the gastric RF and alters the mechanotransduction properties of vagal afferent fibers. These changes could contribute to altered sensitivity following gastric surgery.
Miranda
A
A
Division of Gastroenterology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA. amiranda@mcw.edu
Mickle
A
A
Medda
B
B
Zhang
Z
Z
Phillips
R J
RJ
Tipnis
N
N
Powley
T L
TL
Shaker
R
R
Sengupta
J N
JN
D000818:Animals; D001835:Body Weight; D003187:Compliance; D004435:Eating; D005748:Gastric Fundus / Q000601:surgery; D008026:Ligation; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology; D040542:Mechanotransduction, Cellular; D009130:Muscle, Smooth / Q000000981:diagnostic imaging / Q000294:innervation / Q000601:surgery; D009412:Nerve Fibers / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012527:Satiation; D013270:Stomach / Q000000981:diagnostic imaging / Q000294:innervation* / Q000601:surgery*; D014463:Ultrasonography; D014630:Vagus Nerve / Q000503:physiopathology*