Plasma adrenocorticosteroid levels in adult Fundulus heteroclitus (killifish) following hypophysectomy and pectoral fin amputation

Adult male and female Fundulus heteroclitus (killifish) were used in experiments designed to measure the plasma corticosteroid levels in control regenerate, sham hypophysectomized, hypophysectomized and intact fish ten days after pectoral fin amputation. Our data provide evidence for an anterior pituitary—adrenocortical axis in this fish since hypophysectomy was followed by a significant decrease in the plasma adrenocorticosteroid levels. The data also indicate that plasma adrenocorticosteroids are not abolished ten days after hypophysectomy. Cortisol is the major adrenocorticosteroid in this species although lesser amounts of corticosterone were also detected. The use of metopirone failed to reduce adrenocorticosteroid levels further in the hypophysectomised fish. In the presence of only low titres of adrenocorticosteroids our hypophysectomized fish survived and fin regeneration ensued for the ten days duration of the experiments.