Effects of Low-Intensity Ultrasound on Osteoblasts and Osteoclasts in Goldfish Scale

Abstract

Teleost scales are calcified tissue that contains osteoblasts, osteoclasts, and bone matrix, all of which are similar to those found in human bone. Recently, a new culture system has been developed for the evaluation of bone metabolism using goldfish scales with alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) as markers of osteoblasts and osteoclasts, respe ctively. Using this system, the activities of ALP and TRAP in ontogenic scales were measured after removal of almost all scales on one side of the body. On both days 7 and 10 after removal, the remaining ontogenic scales showed significantly higher TRAP and ALP activity than normal ontogenic scales (p<0.01). Using the remaining ontogenic scales, the effects of low-intensity ultrasound on ALP and TRAP activity were investigated. Alkaline phosphatase activity was significantly increased (p<0.05) 18 and 24 h after ultrasound treatment. In contrast, the TRAP activity in the ultrasound-treated scales was significantly suppressed (p<0.01) after incubation for 24 or 48 h. The results of the present study reveal that low-intensity ultrasound inhibits osteoclast activity in a native calcified tissue environment in which osteoblasts and osteoclasts with increased activity coexist.