Avicatonin

We show here that osteoclasts possess an abundant level of focal adhesion kinase, a novel cytosolic tyrosine kinase with unique structural features that may play an important role in the action of pp60c-src, cell surface integrins, and hormonal peptides. The presence of focal adhesion kinase in the bone cell osteoclast was determined using monoclonal antibodies to the kinase by employing immunofluorescent staining. The expression of focal adhesion kinase in the osteoclast was markedly suppressed following exposure to calcitonin. However, calcitonin-induced down regulation of the kinase was apparent only following a prolonged exposure. Our hypothesis that focal adhesion kinase is maximally expressed in the osteoclasts was confirmed when the transfection of avian osteoclasts and fibroblasts, with v-src containing plasmid pATV-8, induced increased expression of the kinase in the fibroblasts but did not alter the expression level of FAK in the osteoclasts.

A study on administration of avicatonin, a synthetic derivative of chicken calcitonin, during the period of fetal organogenesis was carried out using Slc: Wistar rats.Avicatonin was administered i.m. at 0(control), 1.6, 8 and 40 U/kg daily from day 7 to day 17 of pregnancy.Twenty three to 25 dams in each group were sacrificed on day 21 of pregnancy to examine their conceptuses teratol.Other 15 dams in each group were allowed to deliver to examine postnatal development of their pups.Transient reduction of body weight and depressions of body weight gain and food intake were observed for F₀ dams in the 8 and 40 U/kg groups.However, there were no lethal or teratogenic effects on the fetuses in any dosage group.No adverse effects on growth, functional development including learning ability, and reproductive performance were observed in the offspring.In the open field test, however, decreased number of ambulations and rearings were observed in the F₁ female of the 40 U/kg group.The slightly high values of spleen and thymus weights were noted in F₁ female offspring from dams treated at 40 U/kg.The relation between these changes in open field test and organ weights and avicatonin-treatment was unclear.It is concluded that the no-observed-adverse-effect levels of avicatonin are 1.6 U/kg for general condition in maternal animals, 40 U/kg for reproductive function of dams and 8 U/kg for development of offspring, resp., under the conditions of this study.