Although stress during the perinatal period may influence a number of
enzymes in the gastrointestinal tract, the resulting effects on digestive processes are not completely understood. In suckling rats,
corticosteroid administration increases levels of
proteases in gastric mucosa and pancreas, but previous studies of unstimulated
luminal fluid proteolytic activity suggest no effect. To re-evaluate this phenomenon, we injected suckling rats with
cortisone acetate (5 mg/100 g
body weight) subcutaneously daily on days 9-11 followed by sacrifice on day 12; littermates served as controls.
Luminal fluid from stomach and small intestine was analyzed for proteolytic activity by a sensitive assay in which incubation in vitro with 125I-bovine
casein was followed by measurement of radioactivity soluble in
trichloroacetic acid.
Cortisone acetate produced significant increases in
luminal proteolytic activity in all gastrointestinal segments with the most dramatic effect observed in the ileum; this segment showed a more than 10-fold enhancement of proteolysis with
steroid treatment. Analysis of
acid-precipitable reaction products by electrophoresis in
polyacrylamide gels containing
sodium dodecyl sulfate also revealed enhancement of
casein degradation by
luminal fluid in all segments from
steroid-treated animals. We conclude that
corticosteroid increases
luminal proteolysis in the gastrointestinal tract of the suckling rat. This phenomenon may have implications for
steroid-induced premature closure to macromolecular absorption and
protein digestive capacity during the perinatal period.