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Chicken, human(alpha) CGRPs and their analogues were synthesized to investigate the relationship between structure and serum calcium and phosphate lowering effects. The native hormones contain 37 amino acid residues with only four positions (3, 14, 15 and 23) that differ. Chicken CGRP exhibits stronger and longer lasting activities than the human hormone. A chicken CGRP analogue with replacement of Asp at position 14 by Gly (as in human CGRP) showed great reduction of activity. The converse replacement of Gly at position 14 by Asp in human CGRP enhanced this analogue activity. Among the synthetic analogues, des-1-Ala-des-alpha-amino chicken CGRP, exhibited the most potent and long lasting biological activity.

Teriparatide significantly increases bone mineral density (BMD) of the lumbar vertebrae and femur and has a strong effect in reducing the risk of bone fractures. However, few detailed investigations with dual-energy X-ray absorptiometry (DXA) of the effects of teriparatide on the radius have been reported; specifically, there are no reports of the use of once-weekly teriparatide. In this study, the effect of once-weekly teriparatide in increasing BMD was examined in the distal 1/10 of the radius and the distal 1/3 of the radius using a DXA system for the radius. In addition, the effect of radius positioning, especially accurate correction of rotation and inclination before and after administration of teriparatide, was evaluated in an assessment of its efficacy. It was found that when positioning was corrected, a significant increase in BMD in the distal 1/10 of the radius was observed after 6 months of once-weekly teriparatide. In the distal 1/3 of the radius, no significant increase of BMD was observed. This suggests that when DXA scans of the radius are analyzed with appropriate positioning, weekly teriparatide significantly increases BMD in the distal 1/10 of the radius, which is rich in cancellous bone.

Calcitonin (CT) plays an important role in calcium homeostasis, and its precursor, proCT, is positively associated with the body mass index in the general human population. However, the physiological role of endogenous CT in the regulation of metabolism remains unclear. Knockout mice with gene-targeted deletion of exon 4 of Calca (CT KO) were generated by targeted modification in embryonic stem cells. Male mice were used in all experiments and were fed a slightly higher fat diet than the standard diet. The CT KO mice did not exhibit any abnormal findings in appearance, but exhibited weight loss from 15 months old, i.e., significantly decreased liver, adipose tissue, and kidney weights, compared with wild-type control mice. Furthermore, CT KO mice exhibited significantly decreased fat contents in the liver, lipid droplets in adipose tissues, serum glucose, and lipid levels, and significantly increased insulin sensitivity and serum adiponectin levels. CT significantly promoted 3T3-L1 adipocyte differentiation and suppressed adiponectin release. These results suggested that CT gene deletion prevents obesity, hyperglycemia, and hyperlipidemia in aged male mice. This is the first definitive evidence that CT may contribute to glucose and lipid metabolism in aged male mice, possibly via decreased adiponectin secretion from adipocytes.