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A-42 Free Communication/Poster - Endocrinology Wednesday, May 27, 2015, 7: 30 AM - 12: 30 PM Room: Exhibit Hall F

Endocrine-disruption And The Regulation Of Physical Activity And Mammary Gland Development In Mice

312 Board #163 May 27, 11

00 AM - 12

30 PM

Schmitt, Emily E.; Porter, Weston W.; Lightfoot, J. Timothy FACSM

Author Information
Medicine & Science in Sports & Exercise: May 2015 - Volume 47 - Issue 5S - p 76
doi: 10.1249/01.mss.0000476610.52500.ee
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The most potent biological regulators of daily physical activity (PA) known are the sex hormones and that there are multiple environmental endocrine disruptors (ED) that directly affect sex hormone functioning; therefore it is possible that environmental exposure to ED may directly affect PA and play a role in mammary gland development.

PURPOSE: To determine if prenatal exposure to benzyl butyl phthalate (BBP) will decrease PA and disrupt mammary gland development.

METHODS: Two pregnant female C57Bl/6J inbred mice were either endocrine disrupted using BBP or by saline/control on gestation days 9-16 (500 mg/kg/day). Pups (BBP, n=23; control, n=20) were weaned at 3 weeks of age and placed in individual cages with running wheels at 4-10 weeks of age to measure daily distance, duration, and speed or placed on a locked running wheel. Mouse weight and body composition was also measured weekly with an Echo MRI. Mammary glands were analyzed for histological differences, proliferation and hormone receptor status.

RESULTS: There were no significant PA differences observed with endocrine disruption treatment in either male (p=0.94) or female (p=0.72) groups. There was no change in lean mass (p=0.09) or fat mass (p=0.85) in males between the BBP and control group. There was a significant decrease in change in lean mass (p=0.01) and no change in fat mass (p=0.10) in females between the BBP and control group. There was a significant difference in relative percentage of stained glands between the control and BBP treated mice for Ki67 (p=0.00436) but no difference in ER relative percentage (p=0.18).

CONCLUSION: There was no direct relationship between endocrine disruption and physical activity with a slight decrease in lean body mass in the female BBP mice possibly indicating interference in hormone levels. Surprisingly, in the female BBP mice there was increased proliferation and disruption of ductal morphogenesis including ductal filling and cruciform structures and localized invasion in to the surrounding stroma as well as a higher percentage of tumor cells as indicated by Ki67 indicative of cancer cell proliferation. The lack of difference in ER would suggest that the effect is independent of hormone signaling but a hormone dependency analysis (Ovex) needs to be completed.

© 2015 American College of Sports Medicine