Relationships between hypocalcaemic and anorectic effect of calcitonin in the rat

Salmon calcitonin (sCT, 2 and 20 U/kg), porcine calcitonin (pCT, 20 and 40 U/kg) and human calcitonin (hCT, 20 and 40 U/kg) were injected subcutaneously to rats trained to eat their food during two hours each day. Food intake and serum Ca++ concentrations were determined at the end of 2h-feeding period. A long lasting anorectic effect was observed for 20 U/kg of sCT with a parallelism between hypocalcaemia and anorexia in the first 8 hours after treatment; on the contrary, rats continued to eat less than controls in the following hours when their serum Ca++ concentrations had risen to normal or even higher levels. As regards pCT and hCT, it was shown that these peptides reduced significantly meal size only for 1-2 hours when serum Ca++ levels were at their lowest levels for these peptides.