Characterization of a refinement of the "pylorus ligation" model of rat gastric ulceration resulting in "no pain" and a more specific pharmacological response.

INTRODUCTION: The pharmacological assessment of the factors for gastric protection of a test substance should involve experimental models that can determine the involvement of cytoprotective factors, as well as their influence on the secretion of hydrochloric acid. The original protocol of pylorus ligation in rats proposed by Shay et al. in 1945, still in use today, provides a latency time of 240 min without considering the effect of postoperative pain in the mechanisms of peptic ulcer. This paper proposes a modification of this experimental protocol by eliminating the pain throughout the postoperative period, as a refinement of the test with consequent improvement of the pharmacological response.

METHODS: Adult male Wistar/Uni rats underwent surgical ligation of the pylorus and were kept anesthetized throughout the experimental period (4h) in contrast to the other experimental groups that followed the original protocol proposed by Shay et al., 1945.

RESULTS: We were able to determine effective doses for a positive control, as well as of a variety of secretagogues in the new experimental protocol proposed.

DISCUSSION: The suppression of post-surgical pain, through the use of anesthesia throughout the experimental period, brought several benefits for the study of gastric acid secretion, rendering a more homogeneous pharmacologic response in non-inbred animals, thus being an effective experimental procedure.