A Mouse Model of Intestinal Partial Obstruction

Summary

Intestinal obstructions are a partial or complete blockage of the intestine that can cause severe abdominal pain, nausea, vomiting, and preventing the passage of stool. This procedure for creating intestinal partial obsructions in mice is reliable in studying the mechanisms underlying pathological cell growth and death in the intestine.

Abstract

Intestinal obstructions, that impede or block peristaltic movement, can be caused by abdominal adhesions and most gastrointestinal (GI) diseases including tumorous growths. However, the cellular remodeling mechanisms involved in, and caused by, intestinal obstructions are poorly understood. Several animal models of intestinal obstructions have been developed, but the mouse model is the most cost/time effective. The mouse model uses the surgical implantation of an intestinal partial obstruction (PO) that has a high mortality rate if it is not performed correctly. In addition, mice receiving PO surgery fail to develop hypertrophy if an appropriate blockade is not used or not properly placed. Here, we describe a detailed protocol for PO surgery which produces reliable and reproducible intestinal obstructions with a very low mortality rate. This protocol utilizes a surgically placed silicone ring that surrounds the ileum which partially blocks digestive movement in the small intestine. The partial blockage makes the intestine become dilated due to the halt of digestive movement. The dilation of the intestine induces smooth muscle hypertrophy on the oral side of the ring that progressively develops over 2 weeks until it causes death. The surgical PO mouse model offers an in vivo model of hypertrophic intestinal tissue useful for studying pathological changes of intestinal cells including smooth muscle cells (SMC), interstitial cells of Cajal (ICC), PDGFRα⁺, and neuronal cells during the development of intestinal obstruction.

Introduction

Intestinal obstructions are a partial or complete blockage in the small or large intestine which prevents digested food, fluids, and gas from moving through the intestines¹. Due to the obstruction, the blockage induces the intestinal walls to become thickened, narrowing the lumen². Intestinal obstruction can occur as a result of abdominal or pelvic surgeries that cause abdominal adhesion tissue formation or from GI disorders such as inflammatory bowel diseases (Crohn's disease), diverticulitis, hernias, volvulus, stricture, intussusception, constipation, fecal impaction, pseudo-obstruction, cancers and tumors

Protocol

The following protocol has been approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Nevada-Reno (UNR) Animal Resources and complies with all institutional ethical guidelines regarding the use of research animals.

1. Animals.

1. Obtain mature (4-6 weeks old) C57BL/6 mice weighing between 20-30 g. House the colony of laboratory mice in a centralized animal facility at UNR Animal Resources.

2. Partial Obstruction Surgery

NOTE: Surgeries are performed in a room dedicated to surgical procedures. All surgical instruments are autoclaved prior....

Results

Partial obstruction (PO) was surgically induced in one month old mice by placing a silicone ring around the ileum close to the ileocecal sphincter. This ring created a partial blockage in the ileum. Sham operations (SO) were also performed without a ring on age/sex matched mice and these mice did not show any symptoms similar to those found in PO mice. Mice quickly recovered from PO surgery within a few hours. They showed no obvious behavioral changes or weakness within the first week, bu.......

Discussion

We demonstrated that mice receiving the intestinal PO surgery consistently and reproducibly develop intestinal smooth muscle hypertrophy, which mimics human intestinal obstruction. Intestinal obstruction surgeries have been developed for different animals including mice⁷, rats¹⁰, guinea pigs¹¹, dog¹² and cats¹³. The mouse model of intestinal obstruction has time, cost, size, and phenotypic advantages ov.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Surgical drape	Medical and veterinary supplies	SMS40	40”X100 yards
Underpad, econ, pro plus	Medical and veterinary supplies	MSC281224	17x24”
Iris scissors	Braintree scientific, Inc	SC-i-130
Iris scissors	Vantage	V95-304
Dumont electronic & jeweler tweezers	Dumont	98-180-3
Braided absorbable suture	Covidien polysorb	SL-5687G	5-0, polyglactin
Nylon non-absorbable mono filament	AD surgical	S-N618R13	6-0, nylon
Surgical blade	Dynarex		No.15
Needle holder	Jacobson microvascular	36-1342TC	8.5 inch
Scalpel handle	Flinn scientific	AB1049
Microsurgical scissor	WPI	503305
Petrolatum ophthalmic ointment	Puralube VET		3.5 g
Fluriso (isoflurane)	Vetone	V1 502017	250 ml
Steri-strip reinforced skin closure	3M	R1547
Surgical gloves	Medline	MSG2270
Ear loop face mask	The safety zone	RS700
Avant gauze non-woven sponges	Caring	PRM25444
Surgical cup	Admiral  craft OYC-2	725-A42	2.5 oz
Swabstick	ChloraPrep	260103	2% w/v Chlorhexidine  Gluconate (CHG) and 70% v/v Isopropyl Alcohol (IPA)
Cotton tipped applicator	Puritan	806-WC
Buprenorphine	Zoo pharm	BZ8069317	1 mg/ml
Gentamycin sulfate	Vetone	G-6336-04	100 mg/ml
Fast acting gel cream remover	Veet	8111002
Syringe	AHS	AH01T2516	1 ml with needle
Silicon ring	VWR	60985-720	6 mm in length, 4 mm exterior diameter, 3.5 mm interior diameter
C57BL/6 mice	The Jackson Laboratory		4-6 weeks old