[Abstract Title]. - Society for Neuroscience

ats have much smaller mean colony size and significantly less reproductive skew (8% of
Damaraland mole-rats mate while less than 1% of naked mole-rats mate). We are examining
motoneuron number in Onuf‟s nucleus and size of the UM, LA, and IC muscles in subordinate
and breeding Damaraland mole-rats. Similar to naked mole-rats, preliminary findings indicate a
lack of sex difference in the number of motoneurons in Onuf‟s nucleus of subordinate
Damaraland mole-rats (p > 0.5). The size of the LA also was not different in male and female
subordinates (p > 0.3), and like naked mole-rats, there was no bulb of the penis. However, male
subordinates had larger UMs than female subordinates (p < 0.04). We are currently examining
breeding Damaraland mole-rats to test the hypothesis that sex differences in perineal muscles
and motoneurons develop when animals become breeders.
Disclosures: M.L. Seney , None; L. Bengston, None; N.G. Forger, None; B. Goldman, None.
Poster
278. Sex Differences I
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 278.6/LL27
Topic: E.01.e. Sexual differences
Support: NIH PO1 HD044232
Title: Estrogen receptor immunoreactivity in late-gestation fetal lambs: effects of sex and
prenatal steroids
Authors: *R. I. WOOD 1 , L. M. GORTON 1 , M. M. MAHONEY 2 , J. M. MAGORIAN 1 , T. M.
LEE 2 ;
1 Dept Cell & Neurobiol, Keck Sch. Med. USC, Los Angeles, CA; 2 Dept. of Psychology, Univ. of
Michigan, Ann Arbor, MI
Abstract: In sheep, prenatal exposure to androgens has profound organizational effects on
reproductive function and behavior. Male sheep experience an earlier pubertal onset of tonic
pulsatile secretion of luteinizing hormone (LH), but the preovulatory LH surge is abolished.
Likewise, rams demonstrate aggression and masculine sexual behavior, while ewes show
receptive behaviors during estrus. The critical period for sexual differentiation in sheep occurs
during the middle of gestation: treatment of pregnant ewes with testosterone masculinizes sexual
behavior and patterns of LH in female lambs. Reproductive neuroendocrine function and
behavior are sensitive to gonadal steroid hormone action in the brain, principally via binding to
estrogen receptors (ER). Considering the substantial sex differences in steroid-dependent
physiology and behavior, we hypothesized that male and female sheep differ in the number and