Suppression by dexamethasone of interrenal activity in adult sockeye salmon (Oncorhynchus nerka)

Abstract Dexamethasone injected intraperitoneally as a single dose of 1 mg/kg of body weight suppressed cortisol secretion in response to stress in sexually maturing sockeye salmon. The full effect of a single dose was still evident after 5 and 6 days in most fish and in many fish after 12 days. Sexually maturing sockeye salmon which had received either four doses of dexamethasone during a period of 47 days or six doses during 75 days, were compared with controls which had received similar regimens of peanut oil. The progressive increase in interrenal hypertrophy during the treatment period seen in the peanut oil controls was abolished in the fish receiving dexamethasone.