Expression of HCA2 Receptors in Femoral Epiphysis and Metaphysis of Rats with Dexamethasone-Induced Osteoporosis

The present study describes the changes in expression of hydroxy- carboxylic acid receptor 2 (HCA2 receptor) in
femoral epiphysis and metaphysis of rats with glucocorticoid-induced osteoporosis (GIO). 16 growing male
Sprauge dawley rats were randomly divided into two equal groups consisting of normal control and rats that
were rendered osteoporotic by receiving 0.1 mg/kg/day dexamethasone subcutaneously. After 4 weeks, all rats
were sacrificed and immediately right and left femoral bones were removed for RT-qPCR and histological
examination, respectively. Immunohistochemical parameters using a primary rabbit polyclonal GPR109A
antibody in hematoxylin and eosin- counter stained slides were determined. HCA2 receptor expression was
evaluated using RT- qPCR. Qualitative and histomorphometric evaluation of slides revealed the establishment of
glucocorticoid- induced osteoporosis (GIO) in rats treated with dexamethasone. In immunohistochemical study,
dexamethasone administration appreciably reduced receptor density in all evaluated cell types and in total slides
as compared to control. mRNA level of HCA2 receptor gene was reduced in dexamethasone- treated group. GIO
may be associated with down regulation of HCA2 receptors in proximal femoral bone of rats at mRNA as well
as protein level in no- cell type-specific manner, although reduction in protein expression needs to be further
confirmed by western blotting.