Effects of salmon calcitonin and anti-salmon calcitonin antibody on plasmacalcium concentrations in the goldfish, Carassius auratus

The role of calcitonin (CT) in plasma calcium regulation was studied by the administration of exogenous CT and anti-salmon(s) CT antibody using goldfi sh, Carassius auratus, loaded or otherwise with calcium. CT elicited a decr ease in plasma calcium concentrations at a dose of 10 ng/g body weight 1 h after administration. However, no effects were observed following doses of 30 ng and 50 ng/g 1 h, nor for the three doses 3 h after administration. In calcium-loaded fish, the effect of CT was different depending on the dosag e of CT. Ten ng and 50 ng/g induced a decrease and an increase in plasma ca lcium concentrations, respectively, 3 h after administration. Anti-sCT anti body (0.02 mu g or 0.1 mu g/g) did not affect plasma calcium concentrations . In calcium-loaded fish, neither dose of anti-sCT antibody changed plasma calcium concentrations I h after administration. However, following a dose of 0.1 mu g/g, plasma calcium concentrations decreased after 3 h. A positiv e correlation between plasma calcium concentrations and the gonad somatic i ndex (GSI) in females was no longer apparent after administration of anti-s CT antibody. There was no relationship between plasma calcium concentration s and GSI in control and anti-sCT antibody-treated males. These results sug gested that CT regulates plasma calcium concentrations in different ways de pending on the dosage with CT having a role in calcium physiology during vi tellogenesis.