Tartrate resistant acid phosphatase as a marker for scale resorption in rainbow trout, Oncorhynchus mykiss: effects of estradiol-17? treatment and refeeding

Abstract

In teleosts, a considerable part of the body calcium is found in the scales. Associated with the scales are osteoblasts and osteoclasts, and during periods of high calcium demand such as during sexual maturation or starvation, the scales can be resorbed and thereby act as an internal calcium reservoir. In mammalian bone tissue, the activity of an acid phosphatase (ACP) isoenzyme, tartrate resistant acid phosphatase (TRACP), can be used as a marker for osteoclastic activity. In the present study, an evaluation of TRACP as a marker for osteoclastic activity in teleost scales has been performed. ACP and TRACP was histologically localized at resorption sites around the edge of the scales as well as at resorption holes in the scales. The optimal conditions for biochemical measurements of ACP and TRACP activity were found to be pH 5.3, 10 mM paranitrophenylphosphate, incubated for 30 min at room temperature, and 10 mM tartrate added when required. Using TRACP as a marker, estradiol-17β (E2) was found to increase the proportion of scales being resorbed, as well as the number and size of resorption sites per scale. Also, the scales of E2-treated fish showed weaker staining for calcium. Together, the obtained data indicate that estradiol-17β induces osteoclastic activity in teleost scales, resulting in increased resorption of the scales. A period of refeeding following a period of starvation did not have detectable effects on the scale osteoclastic activity and scale resorption.

Calcium balance in sea bream (Sparus aurata): the effect of oestradiol-17beta

“…It was not determined whether the tenfold increase in plasma calcium in the E 2 -treated fish was exclusively associated with higher levels of circulating vitellogenin or whether there may have been additional calcium-binding proteins in the plasma. However, previous reports suggest that virtually all of the calcium in oestrogen-treated freshwater trout is bound to vitellogenin (Persson et al 1994(Persson et al , 1995.…”

“…Para-nitro phenol (pNP; Sigma-Aldrich) was used as the standard. Enzyme activity measurements were performed according to the optimal assay conditions for TRAP measurements for fish scales (Persson et al 1995) and shown to be similar to those reported for mammalian bone tissue (Lau et al 1985).…”

“…Oestrogen treatment, administered usually in the form of oestradiol-17 (E 2 ), is known to induce an increase in circulating levels of vitellogenin in fish (Bradley & Grizzle 1989, Burzawa-Gerard & Dumas-Vidal 1991, Mosconi et al 1998, which is paralleled by an increase in blood plasma calcium (Persson et al 1994(Persson et al , 1995(Persson et al , 1997. This increase in calcium demand during the reproductive period in freshwater fish is met not only from external sources but also by mobilisation of internal calcium stores, such as bone and scales which, in tilapia, account for up to 95% of the total body calcium (Flik et al 1986).…”

The Presence of High-Affinity, Low-Capacity Estradiol-17β Binding in Rainbow Trout Scale Indicates a Possible Endocrine Route for the Regulation of Scale Resorption

“…There is ample evidence that scale resorption increases during sexual maturation of several salmonid species (Crichton, 1935;Järvi and Menzies, 1936;van Someren, 1937;Takagi, 1990;Persson et al, 1998) and that E 2 treatment induces calcium mobilization from scales in goldfish (Carassius auratus), killifish (Fundulus heteroclitus), and rainbow trout (Oncorhynchus mykiss) (Mugiya and Watabe, 1977;Carragher and Sumpter, 1991;Persson et al, 1994). The E 2 -induced calcium mobilization from rainbow trout scales is due to an increased scale osteoclast activity (Persson et al, 1995, and an increased scale osteoclast activity has been observed during sexual maturation of Atlantic salmon, Salmo salar (Persson et al, 1998).…”

Effects of Inorganic Mercury and Methylmercury on Osteoclasts and Osteoblasts in the Scales of the Marine Teleost as a Model System of Bone

“…* and ** indicate statistically significant differences at P < 0.05 and P < 0.01, respectively, from the values of the control scales (n = 8 samples; one sample from one fish). estrogen in the scale osteoclasts of freshwater teleosts was higher than that in those of marine teleosts (Persson et al, 1994;Persson et al, 1995;Guerreiro et al, 2002). We believe that osteoclasts in freshwater teleosts have some important roles in calcium metabolism as compared with those in marine teleosts.…”