Growth Hormone Did Not Enhance Mucosal Hyperplasia after Small-Bowel Resection

Abstract

Background: Insulin-like growth factor (IGF)-I enhances the mucosal hyperplasia that normally occurs after massive small-bowel resection. The present studies examined whether growth hormone (GH) infusion increases serum IGF-I levels and, thereby, enhances mucosal hyperplasia after small-bowel resection. Methods: Male Sprague-Dawley rats weighing approximately 140 g were subjected to 80% jejunoileal resection or sham operation (ileal transection). A mini-osmotic pump was then inserted under the skin immediately after surgery to deliver either vehicle or 3 mg/kg/day GH. All animals were killed 7 days postoperatively, and the remaining intestine was removed and divided at the anastomotic site. Results: Food intake did not differ between control and GH-infused groups. Resected rats infused with GH grew faster than resected rats infused with vehicle. However, GH did not stimulate the weight gain of sham-operated rats. In both duodenojejunum and ileum, GH infusion did not stimulate hyperplasia beyond that which normally occurs after small-bowel resection, nor did it increase mucosal mass in sham-operated rats. GH infusion did not alter serum IGF-I or IGF-binding protein (IGFBP) levels in either resected or sham-operated rats. GH infusion resulted in increased sucrase and maltase activities in the ileal mucosa of resected rats. Conclusions: The present results suggest that a pharmacologic dose of GH directly stimulates growth of resected animals and ileal sucrase and maltase activities without increasing serum IGF-I levels or increasing absorptive surface area in the small intestine.

Key Words:

• Insulin-like growth factor-I
• insulin-like growth factor binding proteins