Metabolic effects of pancreatectomy and hypophysectomy in the yellow American eel, Anguilla rostrata LeSueur

Abstract

Metabolic effects of pancreatectomy and hypophysectomy were compared in the yellow American eel, Anguilla rostrata. It is reconfirmed that in the yellow eel pancreatectomy does not cause the classical symptoms of diabetes mellitus. In the present experiment, the operation was followed by a strong, stress-related hyperglycemic tendency. Liver glycogen was restored after an initial drop. Neither breakdown of adipose tissue nor an increase in serum free fatty acids or cholesterol was observed. Serum amino acid nitrogen was temporarily increased. Hypophysectomized eels showed a tendency to lower levels of serum glucose. Liver and muscle glycogen were statistically significantly lowered. Contrary to observations in the teleost Fundulus heteroclitus and the rat, the hypophysectomized eels showed a hypocholesteremia. No hyperuremia was seen, which again is in contrast to observations in F. heteroclitus. Both pancreatectomy and hypophysectomy were followed by a drop of the hematocrit and an increase in tissue hydration which persisted in the hypophysectomized eels 20 days after surgery. When both operations were combined, the eels survived only in 1:3 seawater, but not in fresh water or 2:3 seawater. The question of an osmoregulatory role of the islet organ is briefly discussed. Surgical stress affected probably all parameters with the possible exception of the abdominal fat stores. When the data of this study are integrated in an overall phylogenetic scale, it appears that in the intermediary metabolism the role of the pituitary is more conservative, while the importance of islet hormones increases in the tetrapodes.