The comparison of changes of growth patterns and bone mineral densities of ovariectomized female rats treated with estrogen receptor alpha or beta agonist

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 596-621-Pediatric Endocrinology /Steroids and Puberty
Clinical
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-612
Kye Shik Shim*, Kyung A Jeong, Shin-Hee Kim, Byung Ho Kang, Mun Suk Park, Hyunju Chung, You-Jung Yang and Sung-Jig Lim
Kyung Hee University Hospital, Seoul, South Korea
Purpose

It was to compare the effects of estrogen receptor α and β on the pubertal growth, bone mineral density, and epiphyseal closure of long bones in ovariectomized rats.

Method

1. Thirty female wild rats (4-week-old) were ovariectomized and randomly divided into 3 groups (Each group has 10 rats). The group 1 were injected subcutaneously with sesame oil, as a control, group 2 were with propyl pyrazole triol (PPT) 10mg/kg/day as estrogen receptor alpha agonist, group 3 were with diaryl-propionitrile (DPN) 10mg/kg/day as  estrogen receptor beta agonist for 5 weeks.

2. Their crown-lump length, body weight, and bone mineral density of spine and long bones were checked weekly from 2 weeks before through 6 weeks after injections.

3. Blood sampling was done from their tail before and after injections, and serum levels of growth hormone (GH) and estradiol were checked with ELISA.

4. After 6 weeks of injections, they were euthanized, pituitary glands were dissected, and mRNAs were extracted.

5. Their pituitary GH1 mRNA levels were checked with quantitative RT-PCR.

6. Their proximal femurs were dissected and stained with hematoxylin-eosin.

7. The thickness of epiphyseal plate including proliferative and hypertrophic zone of the proximal femurs were measured in 20 evenly divided sites with microscope.

8. Statistical analyses were done among 3 groups before and after injections using ANOVA with multiple comparisons for auxological data, and Kruskall Wallis test for seum levels of GH and estradiol, and pituitary GH1mRNA levels with SPSS ver.13.0.

Results:

1. There was no significant difference in body length among 3 groups.

2. The body weights of rats in group 2 were significant lower than those in other two groups after 5 weeks of injections.

3. Serum GH levels and pituitary GH1 expressions were significantly increased in group 2.

4. The bone mineral densities of spine and long bones were significantly increased in group 2 and 3.

5. There was no significant difference in the thickness of total epiphyseal plate, proliferative zone and hypertrophic zone of the epiphyses among 3 groups.

Conclusion

1. Estrogen receptor alpha is more involved in pituitary GH secretion.

2. The excessive weight gain or subcutaneous fat deposition may be prevented with estrogen receptor alpha agonist.

3. Both Estrogen receptor alpha and beta can be involved in bone mineral deposition.

Nothing to Disclose: KSS, KAJ, SHK, BHK, MSP, HC, YJY, SJL

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: The research grant of Korean Society of Pediatric Endocrinology 2011.