Sham Feeding in Rats with Chronic, Reversible Gastric Fistulas

Gerard P. Smith1

1 Cornell University Medical College and New York Hospital–Cornell Medical Center, White Plains, New York
Publication Name:  Current Protocols in Neuroscience
Unit Number:  Unit 8.6D
DOI:  10.1002/0471142301.ns0806ds04
Online Posting Date:  May, 2001
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Sham feeding occurs when ingested food is prevented from accumulating in the stomach and small intestine by surgical intervention. Sham feeding permits the investigation of the orosensory controls of meal size in the absence of postingestive controls. This unit details preoperative preparation, surgery, postoperative care and maintenance, and test procedures for the simplest and most widely used method, which involves implantation of a gastric cannula in a rat to provide a chronic, reversible gastric fistula.

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Table of Contents

  • Reagents and Solutions
  • Commentary
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Basic Protocol 1:

  • 200‐ to 400‐g rat
  • Appropriate anesthetic (see step ): e.g., chloropent (a chloral hydrate/pentobarbital mixture; see recipe) or ketamine and xylazine
  • Isotonic saline (0.9% NaCl), 37°C
  • Anesthetic jelly
  • Liquid food (see reciperecipes)
  • General surgery instruments (including scalpel with no. 10 blades, spreader, toothed forceps, hemostats, iris scissors, and wound clips), sterilized by autoclaving
  • Custom‐made surgical materials (see ), sterilized by autoclaving: gastric cannula with screw‐cap, cannula bullet, cannula pliers, collecting‐tube connector, and Marlex mesh ∼20‐mm‐diameter circles
  • Size 3‐0 and 4‐0 silk
  • 20‐ml syringe
  • Test cage with metal wire floor, with slot cut through middle of floor from front to back
NOTE: All right and left directions in the protocol refer to the visual field of the operator, not the anatomical side of the rat.NOTE: Use standard aseptic technique throughout the procedure.
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Literature Cited

Literature Cited
   Davis, J.D. and Campbell, C.S. 1973. Peripheral control of meal size in the rat: Effect of sham feeding on meal size and drinking rate. J. Comp. Physiol. Psychol. 83:379‐387.
   Davis, J.D. and Levine, M. 1977. A model for the control of ingestion. Psychol. Rev. 84:379‐412.
   Davis, J.D. and Smith, G.P. 1990. Learning to sham feed: Behavioral adjustments to loss of physiological postingestional stimuli. Am.J.Physiol. 259:R1228‐R1235.
   Janowitz, H.D. and Grossman, M.I. 1949. Some factors affecting the food intake of normal dogs and dogs with esophagostomy and gastric fistula. Am. J. Physiol. 159:143‐148.
   Mook, D.G. 1963. Oral and postingestional determinants of the intake of various solutions in rats with esophageal fistulas. J. Comp. Physiol. Psychol. 56:645‐659.
   Nissenbaum, J.W. and Sclafani, A. 1987. Sham‐feeding response of rats to polycose and sucrose. Neurosci. Biobehav. Rev. 11:215‐222.
   Paré, W.P. 1972. Conditioning and avoidance responding effects on gastric secretion in the rat with chronic fistula. J.Comp. Physiol. Psychol. 80:150‐162.
   Pavlov, I.P. 1910. The Work of the Digestive Glands. Charles Griffin & Company, London.
   Phifer, C.B., Browde, J.A., Jr., and Hall, W.G. 1986. Ontogeny of glucose inhibition of independent ingestion in preweanling rats. Brain Res. Bull. 17:673‐679.
   Sclafani, A. and Nissenbaum, J.W. 1985. Is gastric sham‐feeding really sham‐feeding? Am. J. Physiol. 248:R387‐R390.
   Smith, G.P. 1996. The direct and indirect controls of meal size. Neurosci. Biobehav. Rev. 20:41‐46.
   Weingarten, H.P. and Kulikovsky, O.T. 1989. Taste‐to‐postingestive consequence conditioning: Is the rise in sham feeding with repeated experience a learning phenomenon? Physiol. Behav. 45:471‐476.
   Wellman, P.J. 1994. Laboratory Exercises in Physiology and Psychology. Allyn and Bacon, Boston.
   Young, R.C., Gibbs, J., Antin, J., Holt, J., and Smith, G.P. 1974. Absence of satiety during sham feeding in the rat. J. Comp.Physiol. Psychol. 87:795‐800.
Key Reference
   Smith, 1996. See above.
  Review summarizing evidence and current ideas about the control of meal size, emphasizing how the potency of preabsorptive positive and negative feedbacks are modulated by other factors that affect food intake. Includes a number of the references relevant to sham feeding.
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