Abstract (provisional)
Background
Infectious diseases and inflammation during pregnancy increase the offspring's risk
for behavioral disorders. However, how immune stress affects neural circuitry during
development is not well known. We tested whether a prenatal immune challenge interferes
with the development of social play and with neural circuits implicated in social
behavior.
Methods
Pregnant rats were given intraperitoneal injections of the bacterial endotoxin lipopolysaccharide
(LPS - 100 microgram/kg) or saline on the 15th day of pregnancy. Offspring were tested
for social play behaviors between postnatal days 26-40. Brains were harvested on postnatal
day 45 and processed for arginine vasopressin (AVP) mRNA in situ hybridization.
Results
In males, LPS treatment reduced the frequency of juvenile play behavior and reduced
AVP mRNA expression in the medial amygdala and bed nucleus of the stria terminalis.
These effects were not found in females. LPS treatment did not change AVP mRNA expression
in the suprachiasmatic nucleus, paraventricular nucleus, or supraoptic nucleus of
either sex, nor did it affect the sex difference in the size of the sexually dimorphic
nucleus of the preoptic area.
Conclusions
Given AVP's central role in regulating social behavior, the sexually dimorphic effects
of prenatal LPS treatment on male AVP mRNA expression may contribute to the sexually
dimorphic effect of LPS on male social play and may, therefore, increase understanding
of factors that contribute to sex differences in social psychopathology.
