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Morphometric analysis of the pelvis in mice treated neonatally with tamoxifen
Abstract:
The pelves of male and female C57BL/Tw mice given five daily injection of 100 micrograms tamoxifen, 50 micrograms dihydrotestosterone (DHT), or 2 micrograms diethylstilbestrol (DES) from the day of birth were examined morphometrically and histomorphometrically. Total areas of the pelvis, ilium, ischium, and pubis were significantly smaller in neonatally tamoxifen-treated mice than in the controls. There was no significant difference in length of the ischium between tamoxifen-treated and control mice of both sexes. However, lengths of ilium and pubis, and widths of ilium, pubis, and ischium in tamoxifen-treated male and female mice were significantly smaller than in the respective controls. In contrast, neonatal treatment with DHT or DES did not affect the shape of the pelvis of either sex. In the neonatally tamoxifen-treated females, the number of osteoblasts and osteoclasts per 200 microns trabecular surface length and per 10,000 microns2 subperiosteal area of pubic bone section was smaller than in the controls. Inhibition of ossification persisted in the junction of the pubis and ischium of pelves treated with tamoxifen in vitro. These results suggest that neonatally administered tamoxifen mainly retards the growth of the ilium and pubis in mice by changing the activities of osteoclasts and osteoblasts, and that tamoxifen acts directly on the neonatal mouse pubis to inhibit its ossification.
Insights
Neonatal tamoxifen exposure in mice significantly reduced pelvic bone growth, impacting ilium and pubis development. This tamoxifen effect appears to directly inhibit bone ossification by altering osteoblast and osteoclast activity.
Area of Science:
- Endocrinology
- Developmental Biology
- Orthopedics
Background:
- Neonatal exposure to certain endocrine-disrupting chemicals can impact skeletal development.
- Tamoxifen is a selective estrogen receptor modulator with known effects on bone metabolism.
Purpose of the Study:
- To investigate the effects of neonatal tamoxifen, dihydrotestosterone (DHT), and diethylstilbestrol (DES) exposure on mouse pelvic morphology and bone formation.
- To determine if tamoxifen directly affects neonatal bone ossification.
Main Methods:
- Morphometric and histomorphometric analysis of pelves from male and female C57BL/Tw mice.
- Neonatal daily injections of tamoxifen, DHT, or DES from birth.
- In vitro assessment of tamoxifen's effect on pubic bone ossification.
Main Results:
- Neonatal tamoxifen treatment significantly reduced total pelvic area, ilium, and pubis dimensions in both sexes.
- DHT and DES did not alter pelvic shape in neonatally treated mice.
- Tamoxifen reduced osteoblast and osteoclast numbers and inhibited ossification in the pubic bone.
Conclusions:
- Neonatal tamoxifen administration retards mouse ilium and pubis growth by altering osteoblast and osteoclast activity.
- Tamoxifen exhibits a direct inhibitory effect on neonatal mouse pubic bone ossification.
