Lr. Morgan et al., EXPOSURE TO MALE SIBLINGS FACILITATES THE RESPONSE TO ESTRADIOL IN SEXUALLY NAIVE FEMALE PRAIRIE VOLES, Physiology & behavior, 61(6), 1997, pp. 955-956
Female prairie voles undergo induced estrus, and require both physical
contact with males and exposure to male urine to become reproductivel
y active. This study attempted to determine if physical contact with m
ales enhanced female response to estradiol. Two groups of sexually nai
ve females were tested. One was reared without any exposure to males a
fter weaning, and the other was reared with sibling males to 60 days o
f age. Sibling males were used because females avoid direct contact wi
th the urine of related males, allowing for the establishment of a gro
up of females that experienced physical contact in the relative absenc
e of exposure to male pheromones associated with urine. Females were t
hen subcutaneously injected with 0.5 mu g estradiol benzoate once a da
y for 7 days. Sexual receptivity was tested with novel adult males 48
h and 168 h after the first injection. There was a significant differe
nce between the treatment groups, with 10% of sexually naive females r
eared without sibling males displaying lordosis compared to 70% of fem
ales raised with sibling males. The results indicate that exposure to
sibling males significantly increased a female's behavioral response t
o estradiol. (C) 1997 Elsevier Science Inc.