The role of glucocorticoids in the growth of the digestive tract in mink (Mustela vison)

The effect of glucocorticoids on the growth of digestive organs was investigated in the postnatal period of mink. A total of 110 mink kits from 20 litters were either not injected or injected intramuscularly for seven days with saline, adrenocorticotropic hormone (ACTH, 50 mu g/kg/day) or hydrocortisone-acetate (synthetic glucocorticoid, 50 mg/kg/day). The kits were killed at 2-10 weeks of age. Plasma cortisol levels did not change significantly with age in the control animals. In the ACTH group, plasma cortisol was minimum at 4 weeks of age, whereas in the hydrocortisone-acetate group, plasma cortisol was maximum at this age. The mink appears to have a period of reduced adrenal responsiveness to ACTH and a low metabolic clearance rate of cortisol around 4 weeks of age. The weight of the ventricle, pancreas and intestine per body weight reached a maximum at 6-8 weeks of age. Hydrocortisone-acetate treated kits showed reduced body growth at 2-6 weeks and increased weight of the pancreas and intestine at 6-10 weeks. The postnatal growth of digestive organs was relatively slow in mink kits and the effects of exogenous cortisol administration occurred relatively late in mink compared with some other species (rats, pigs). Cortisol may play a regulatory role in the growth of digestive organs in the postnatal period of mink kits.