Effects of hyperprolactinemia and ovariectomy on the tibial epiphyseal growth plate and bone formation in mice.

Roberta Bastos Wolff

doi:10.1590/so100-720320140005065

Abstract

To evaluate the effects of ovariectomy and the hyperprolactinemia procedure in the tibial epiphyseal growth plate of female mice. In this study, the epiphyseal growth plate of ovariectomized (OVX) and/or rendered hyperprolactinemic female mice by 50 days of treatment with 200 μg metoclopramide (M) was evaluated morphologically, morphometrically and immuno-histochemically. Forty female and adult mice were divided into four groups according to treatment: V group--animals treated with saline solution; H group--hyperprolactinemic animals; Ovx/V group--ovariectomized animals and treated with saline solution; Ovx/H group--hyperprolactinemic and ovariectomized animals. After the treatment period, the animals were sacrificed, tibia was removed and fixed in 10% buffered formalin and decalcified in 10% formic acid. The material was immersed in paraffin and subjected to histological processing in paraffin. The sections were stained with Masson's trichrome and immunohistochemistry was carried out for the pro-apoptotic protein BCL-2. The images for the morphological and morphometric study were analyzed with the imaging program AxioVision 4.8 (Carl-Zeiss(r), Germany). The combination of hyperprolactinemia and the ovariectomy procedure decreased the number of resting chondrocytes 1.5-fold, the number of proliferative chondrocytes 1.8-fold; the percentage of resting cartilage 2.4-fold and the percentage of trabecular bone 2.1-fold, compared with respective control animals. The procedure of ovariectomy combined with the metoclopramide-induced hyperprolactinemia in female mice has showed marked bone degeneration due to significant decrease of cell proliferation in the epiphyseal growth plate and bone formation.

Highlights

The bone formation through endochondral ossification is a process initiated by mesenchymal cell condensation, and it leads to the formation of a cartilaginous scaffold that will later be replaced by bone[1]
In the group treated with metoclopramide (H; Figure 1B), the resting and proliferative cartilages have fewer and less organized chondrocytes with more spaces between them, and the hypertrophic cartilage has a larger number of chondrocytes, which are much more rounded and less arranged, in comparison with the control group
The growth plate is responsible for the growth of long bones via the process of endochondral ossification, and it goes through a series of events called “bone turnover”[6]

Summary

Introduction

The bone formation through endochondral ossification is a process initiated by mesenchymal cell condensation, and it leads to the formation of a cartilaginous scaffold that will later be replaced by bone[1]. The growth plate is an epiphyseal hyaline cartilage located between the epiphysis and diaphysis of long bones, and it is responsible for the growth of these bones through an endochondral ossification process. This cartilage is divided into five distinct zones: resting, proliferative, hypertrophic, calcified, and ossified[1,2]

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Results

Conclusion