The analgesic effect of calcitonin in humans: Studies on the role of opioid peptides

The possibility that the analgesic action of calcitonin could be due to variations in β-endorphin levels in both peripheral blood and cerebrospinal fluid was studied. A total of 40 μg of synthetic salmon calcitonin was injected i.v. in four male volunteers undergoing minor operations under rachianesthesia. β-Endorphin was determined in blood and cerebrospinal fluid samples that were collected before and at regular intervals after calcitonin injection. No statistically significant variation in β-endorphin levels was observed either in peripheral blood or cerebrospinal fluid. Since the injected calcitonin was free of contaminants (demonstrated by both high pressure liquid chromatography and radioimmunoassay of endorphins made on the injected preparation) and since an increase was observed in the immunoreactive calcitonin in cerebrospinal fluid following calcitonin i.v., a self-analgesic action may be hypothesized, even though action through prostaglandins or other systems cannot be excluded.