Hyaluronic acid and proliferation/cellular death amount in the female rats mammary gland after estroprogestative therapy

Abstract

Aims

To evaluate the concentration of hyaluronan acid and proliferation/cellular death in mammary gland of ovariectomized female rat after estroprogestative therapy.

Materials and methods

Forty ovariectomized female rats were divided into four groups with 10 animals/each: OG (vehicle); EG: (Estradiol, 7 days of treatment), PG (Progesterone acetate, 23 days of treatment), and EPG: (Estradiol, 7 days of treatment, and next Progesterone acetate, 23 days of treatment). Twenty-four hours after the last treatment, all animals were euthanized, the mammary gland removed, then, a fragment was immersed in acetone to quantifying of the hyaluronan acid biochemical method (ELISA-Like fluorometric assay), and a fragment fixed for 24 h in 10% formaldehyde in phosphate-buffered saline (PBS) processed for immunohistochemistry method for detection of the cell marker proliferation (Ki67) and cellular marker death by DNA fragmentation the TUNEL method.

Results

The estradiol-treatment alone (EG) or associated with progesterone (EPG) affected the concentration of hyaluronan acid, increased cell proliferation, and decreased cell death compared to OG and PG (p < .05) in the mammary tissue.

Conclusions

Our results suggest that the excessive reduction of HA in mammary tissue, as occurred with progesterone treatment, can lead to a breakdown of the extracellular matrix. These changes may be indicative of mammary pathology such as the development of tumor.

雌激素治疗后雌性大鼠乳腺中透明质酸含量及细胞增殖/死亡情况摘要

目的：评估雌激素治疗后卵巢切除雌性大鼠乳腺中透明质酸的浓度和增殖/细胞死亡情况。

材料与方法：40只去势雌性大鼠分为4组, 每组10只：OG（载体）；例如：（雌二醇, 治疗7天）、PG（醋酸孕酮, 治疗23天）和EPG（雌二醇, 治疗7天, 接着醋酸孕酮, 治疗23天）。最后一次治疗24小时后, 对所有动物实施安乐死, 切除乳腺, 然后将一片组织浸入丙酮中, 用透明质酸生化法（类似ELISA的荧光测定法）进行定量, 将一片组织固定在10%甲醛缓冲液（PBS）中24小时, 用免疫组织化学方法检测细胞标记物增殖（Ki67）和细胞标记物死亡（DNA片段化TUNEL法）情况。

结果：与OG和PG相比, 单独应用雌二醇（EG）或联合应用孕酮（EPG）可影响乳腺组织中透明质酸的浓度, 增加细胞增殖, 减少细胞死亡（p<0.05）。

结论：研究结果表明, 与孕酮治疗一样, 乳腺组织中透明质酸（HA）的过度减少可导致细胞外基质的破坏。这些变化可能提示乳腺病理情况, 如肿瘤的发展。

Keywords:

• Mammary gland
• hyaluronan acid
• proliferation
• cellular death
• estradiol
• progesterone

Acknowledgements

The authors thank the Esmeralda Miristeni Eher and Sandra de Moares Fernezlian from the Laboratory of Immunohistochemistry, Department of Pathology, Faculty of Medicine, University of São Paulo, for carrying out immunohistochemistry.

Disclosure statement

The authors report no conflict of interest. The authors alone are responsible for the content and writing of this paper.