Pancreatic enzyme activity in passer domesticus exposed to corticosterone

Abstract

In animals, it is well documented that stress produces metabolic alterations and an allostatic response (activation of the hypothalamicpituitary-adrenal axis and increase of corticosterone levels in blood) to maintain homeostasis in organisms. The objective of this work was to study the long-term corticosterone (CORT) effects on the digestive function in Passer domesticus. We focus especially on modifications in the activity of pancreatic enzymes, trypsin and chymotrypsin. To achieve our goal, 32 sparrows were exposed to different concentrations of CORT in drinking water (0, 20, 40 and 80 mg/l) for 72 hours emulating a long-term stress situation. After treatment, body weight was measured, blood extraction and subsequent removal of digestive organs (intestine, liver and pancreas) were performed at the same time (8:00 am), to avoid disturb by circadian/daily variation. The Heterophil/Lymphocyte (H/L) ratio was used as an indicator of stress in birds. The mass of pancreas was measured and homogenized. The enzymatic activity of trypsin and chymotrypsin were determined. Previously, chymotrypsinogen was activated by enterokinase for 60 min to measure chymotrypsin activity. We analyzed the mass-specific enzyme activities (μmol min−1 g wet tissue−1) using one-way ANOVA with Tukey post-hoc test (p < 0.05). We found a proportional increased inthe H/L index in concordance with CORT treatments. It was not found differences in the mass of pancreas and activity of enzymes (p > 0.05). Studies in chickens show a variation in digestive enzymes by corticosterone. However, our case in wild birds, we didn´t found effect of CORT on pancreatic enzyme activities. Previously, we found similar results with intestinal enzymes (carbohydrases and proteases). So, future research will be in direction to comparative studies in poultry and wild birds, under the same experimental design, to dilucidated mechanism involved in enzyme modulation by CORT. Supported by CyT-UNSL PROICO 02-0820 and FONCYT PICT-201-0595.