EFFECT OF GROWTH-HORMONE ON THE INFLAMMATORY ACTIVITY OF EXPERIMENTALCOLITIS IN RATS

The effect of daily treatment with 2.0 mg biosynthetic human growth ho rmone per kilogram body weight or isotonic NaCl (controls) on experime ntal colitis was investigated in rats. Colonic inflammation was induce d by instillation of trinitrobenzene sulfonic acid (TNB) intraluminall y into the left colon. Untreated NaCl-instilled rats were used for com parison with intact colon. Four days after TNB instillation the growth hormone-treated rats had lower macroscopic and microscopic damage sco res and less infiltration of neutrophils, measured as myeloperoxidase activity (MPO), than controls. The biomechanical properties of the col on showed that the breaking strength and energy absorption were reduce d in the control rats with colitis compared with intact colon, whereas the rats treated with growth hormone had unchanged strength and energ y absorption. The differences in MPO activity, damage scores, and biom echanical properties were associated with a higher concentration of in sulin-like growth factor I in serum from growth hormone-treated rats a fter 4 days than controls. Finally, the growth hormone-treated rats re gained their initial body weight after 7 days, in contrast to the body weight of control rats, which remained 11% lower than their initial b ody weight.