Modulation of immunoreactive epidermal growth factor levels in the submandibular gland, pancreas, liver, kidney and gastrointestinal tract of suckling rats by cortisone and tri-iodothyronine.

Suckling rats exhibit age-dependent differences in epidermal growth factor (EGF) levels in several organs. The present studies evaluated the effects of two hormones known for their maturative effect on suckling rats, cortisone and tri-iodothyronine (T3), on immunoreactive EGF levels in specific organs. Suckling rats were administered cortisone (5 mg/100 g body weight per day) or T3 (50 micrograms/100 g body weight per day) on days 8, 9, 10 and 11 after birth, and killed on day 12. Submandibular glands, kidneys, pancreas, liver and gastrointestinal tract mucosa and lumen were assayed for immunoreactive EGF by a species-specific radioimmunoassay. Low levels of EGF in the submandibular glands were increased slightly by both T3 and cortisone treatment. Cortisone evoked a tenfold increase in EGF in the pancreas, but had no effect on levels in the kidney or liver. In contrast, T3 evoked a sixfold increase in the EGF level in the kidney, but had no effect on levels in the pancreas or liver. Hormonal administration had no effect on EGF levels in the stomach. Within the intestinal tract, cortisone had no effect on the luminal EGF content of the duodenum, jejunum or ileum, but caused a decrease in the midjejunum. T3 evoked a decrease in the luminal EGF content of the ileum. The effect of cortisone on mucosal EGF content varied between regions; an increase was seen in the duodenum with a decrease in the midjejunum and ileum. T3 administration resulted in a significant decrease in EGF only in the mucosa of the ileum.(ABSTRACT TRUNCATED AT 250 WORDS)