The Effects of Calcitonin on Serum Calcium Levels in Immature Brown Trout, Salmo trutta

Salmon calcitonin was administered intraperitoneally (0.1, 10, 1000 ng/100 g of fish) to freshwater-adapted, immature, female brown trout, Salmo trutta, and changes in serum calcium levels were determined. The lowest dose (0.1 ng) had an effect similar to injection of saline (control), but the higher doses produced hypercalcemia. These latter effects were associated with increased serum levels of calcitonin. Maintaining immature brown trout in waters containing 20 and 50 m M calcium chloride resulted in a significant lowering of serum calcitonin with time although serum calcium levels remained stable. The extent of the decrease in serum calcitonin increased with the higher levels of environmental calcium.