INTRODUCTION. Calcitonin is a
natural peptide hormone produced by parafollicular cells (C-cells) in
the thyroid gland. Binding of low concentrations of calcitonin to the
calcitonin receptor on osteoclasts induces a rapid change in the
cytoskeletal structure of the osteoclasts in vitro, which in turn leads
to a reduction in bone resorption. Furthermore, calcitonin has been
recently shown to possess regulatory actions on cartilage and
subchondral bone, which may cause long-term clinical benefits. The
expression of calcitonin receptors in muscles has not been adequately
investigated. The aim of this study is to investigate the expression of
calcitonin receptor in the rat quadriceps femoris muscle.MATERIALS/METHODS.
Twelve 21-day-old male Wistar rats were housed in well-ventilated
stainless cages with 12-hour light-dark cycle and a maximum of 3 rats
per cage. Six of them were provided food and water ad libitum and the
rest only water for two days, after which all the animals were
sacrificed. The right quadriceps femoris muscles were dissected, fixed
(10% neutral formalin for 24 h), embedded in paraffin
(4-μm thick sections) and processed for immunohistochemical
staining of the calcitonin receptors. The protocols were approved by
the appropriate University committee.RESULTS.
Immunoexpression of calcitonin receptors was evident in the connective
tissue around the muscle fibers.CONCLUSIONS. Calcitonin
receptors are expressed in the connective tissue around the muscle
fibers of the quadriceps femoris muscle. The physiologic importance of
calcitonin receptor expression for the development of the region
remains to be clarified. KEY WORDS: calcitonin,
calcitonin receptor,
rat, quadriceps femoris.