# Presentation: 121015

## Assessing the Impact of Body Weight on Male and Female Pubertal Development

**EPA Special Study**
**Tammy Stoker, PhD.**
**Gamete and Early Embryo Biology Branch**
**Reproductive Toxicology Division**
**NHEERL, U.S. EPA**

## Overview

**Present data from food restriction study**
**Discuss results of previous studies using male and female pubertal protocols. **
**Discuss examples of published data and conclusions evaluating the**** ****role of body weight and growth on pubertal events. **

## Study Objectives

**Assess the relationship between growth rate and pubertal development**
**Determine whether or not reduced body weights over a range of 2 – 20% confound the endpoints in the Female and Male Pubertal Protocols**

## Methods

**Four groups of male and female Wistar rats (n=13) were fed 90%, 80%, 70% and 60% of *****ad libitum***** controls **
**Pecentages were based on 24 h food intake of controls.**

## Female Pubertal Protocol

**Female Pubertal Protocol**

## Body Weight: Female Wistar Rats 

## Body Weight at NecropsyFemale Pubertal Study

**Percent reduction in BW as compared with control **
**Group 90 (2.0%)**
**Group 80 (4.6%)**
**Group 70 (12.1%)**
**Group 60 (18.8%)**

- *

- *

- Mean +/- SEM (n=13):  *  P<0.05

## 15.2% *

**8.2%**** ***
**15.2%**** *******

**Reduction in BW on PND 33**

## Age at VO

| Con | 90% | 80% | 70% | 60% |
| --- | --- | --- | --- | --- |
| 33
0.56 | 33.3
0.67 | 32.7
0.70 | 34.0
0.97 | 34.5
0.97 |

**Mean**

**SEM**

**Group**

**Age at VO**

## Ovary Weight

- *

- *

*****

*****

- * = p< .05 for absolute weight.
- r = p< .05 for relative weight.

## Uterus Weight

## Thyroid Hormones: Female

**Thyroid Hormones: Female**

**TSH**

**T3**

**T4**

## Summary of Female 

**Reduced body weight gains from 2.0 to 18.8% (at necropsy)**
**no effect on VO, uterine weights or thyroid hormones**
**Body weight decreases of 12.1 and 18.8% **
**decreased ovarian weight**
**Importantly, there were no significant differences in any of the female reproductive endpoints at less than 12.1% decreased body weight.**

## Male Pubertal Protocol

**Male Pubertal Protocol**

## Body Weight: Male Wistar Rats

## Body Weight at Necropsy:Male Wistar Rats

**Percent reduction in BW as compared with control **
**Group 90 (2.2%)**
**Group 80 (4.4%)**
**Group 70 (12.5%)**
**Group 60 (20.7%)**

## Reduction in BW on PND 44

**Reduction in BW on PND 44**

**8.5%**** ***

**19.0%**** *******

## Age at Preputial Separation

## Ventral Prostate Weight

- *

- * = p< .05 for absolute weight.
- r = p< .05 for relative weight.

## Seminal Vesicle Weight

- *

## Epididymis Weight

- *

- r

## Testes Weight 

- r

- r

## Thyroid Hormones-Male

- *

- *

- *

**T4**

**TSH**

**Thyroid Hormones-Male**

**T3**

- *

- *

## Male Summary

**Reductions in body weight gain from 2.2 to 20.7% had **
**no effect on PPS or testes weight**
**Decreases in body weight from 12.5 to 20.7%**
-  **decreased T3 and T4**
**Decreases in body weight of 20.7% **
**decreased ventral prostate, seminal vesicle and epididymal weights**
**Importantly, there were no significant alterations of the male reproductive endpoints at decreases of less than 12.5%. **

## Adrenal Weights 

- *

- *

- *

- * = p< .05 for absolute weight.
- r = p< .05 for relative weight.

- Male

- Female

*****

*****

## Anterior Pituitary Weight

- *

- *

- *

- Male

-  Female

*****

*****

## Kidney Weights

- *

- *

- *

- r

- Males

- Females

*****

*****

## Liver Weight

- *

- *

- *

- *

- r

- r

- r

- Males

- Females

*****

*****

- r

## Study Conclusions

**A 10% reduction in body weight has no effect on pubertal development**
**Pubertal protocols detect a wide variety of EDCs apart from modest decreases in BW**

## Background Literature

**Studies were designed to retard  reproductive senescence and prolong lifespan:**
**Litter alterations during early postnatal days resulted in 30 - 65% bw difference.  **
**Other studies severely restricted food intake at weaning.  **
**Indeed, these studies found that puberty was delayed. **
**The first week of life is critical for nourishment and setting of adult bw.**

## Continued:

**“****attainment of critical bw” hypothesis**
**“****critical body fat” hypothesis **
**“****growth rate” hypothesis**
**All have been questioned by more recent investigations which were unable to repeat earlier studies(Aguilar et al.,1984; Glass et al., 1984,  Ronnekleiv, Ojeda & McCann, 1978;Bronson, 2001;  Crawford and Osler, 1975).**

## General agreement in literature 

**A 10% decrease in body weight gain in the pubertal assays does not appear to confound the selected endpoints (Connor et al., 2000).**
**The reproductive systems in the adult male and female rat are relatively resistant to body weight reductions down to 70% of control (Chapin et al., 1993).**

## Relationship between reduction in body weight versus  change in age at PPS

**Relationship between reduction in**
** ****body weight versus age at PPS**

## Relationship Between Body Weight and Age at Vaginal Opening 

## Does the estrogen mediated suppression of appetite confound the detection of VO? 

**Methoxychlor (0, 25, 50, 100, 200 mg/kg) **

## Acknowledgments

**Collaborators**
**Susan Laws, Ph.D.**
**Ralph Cooper, Ph.D.**
**Earl Gray, Ph.D.**
**Jerome Goldman, Ph.D.**
**Robert Kavlock, Ph.D.**

**Technical Assistance**
**Janet Ferrell**
**Keith McElroy**
**Kate Bremser**
**Korin Elliott**

**Reproductive Toxicology Division**
**NHEERL, ORD, U.S. EPA**