Sex differences in oxytocin receptor binding in forebrain regions: correlations with social interest in brain region- and sex- specific ways.
Social interest reflects the motivation to approach a conspecific for the assessment of social cues and is measured in rats by the amount of time spent investigating conspecifics. Virgin female rats show lower social interest towards unfamiliar juvenile conspecifics than virgin male rats. We hypothesized that the neuropeptide oxytocin (OT) may modulate sex differences in social interest because of the involvement of OT in pro-social behaviors. We determined whether there are sex differences in OT system parameters in the brain and whether these parameters would correlate with social interest. We also determined whether estrus phase or maternal experience would alter low social interest and whether this would correlate with changes in OT system parameters. Our results show that regardless of estrus phase, females have significantly lower OT receptor (OTR) binding densities than males in the majority of forebrain regions analyzed, including the nucleus accumbens, caudate putamen, lateral septum, bed nucleus of the stria terminalis, medial amygdala, and ventromedial hypothalamus. Interestingly, male social interest correlated positively with OTR binding densities in the medial amygdala, while female social interest correlated negatively with OTR binding densities in the central amygdala. Proestrus/estrus females showed similar social interest to non-estrus females despite increased OTR binding densities in several forebrain areas. Maternal experience had no immediate or long-lasting effects on social interest or OT brain parameters except for higher OTR binding in the medial amygdala in primiparous females. Together, these findings demonstrate that there are robust sex differences in OTR binding densities in multiple forebrain regions of rats and that OTR binding densities correlate with social interest in brain region- and sex-specific ways.
Neurobiology of Social Behavior Laboratory, Department of Psychology, Boston College, Chestnut Hill, MA, USA. Electronic address: kelly.dumais@bc.edu.
Kelly M
KM
Dumais
Remco
R
Bredewold
Thomas E
TE
Mayer
Alexa H
AH
Veenema
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001931:Brain Mapping; D005260:Female; D008297:Male; D009042:Motivation / Q000502:physiology; D016548:Prosencephalon / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D018045:Receptors, Oxytocin / Q000378:metabolism*; D012727:Sex Characteristics; D012919:Social Behavior
D018045:Receptors, Oxytocin
AIP; Amygdala; BNSTdl; BNSTp; CA1; CA1 of the hippocampus; CPUd; CPUm; CeA; Estrogen; Estrus; Female; LSi; LSv; MPOA; Male; MeA; NACC; NACCa; NACCp; OT; OTR; Oxytocin; Oxytocin receptor; PVN; Rats; SON; Sex differences; Social interest; VMH; agranular insular cortex; anterior nucleus accumbens; central amygdala; dorsal caudate putamen; dorsolateral bed nucleus of the stria terminalis; intermediate lateral septum; medial amygdala; medial caudate putamen; medial preoptic area; nucleus accumbens; oxytocin; oxytocin receptor; paraventricular nucleus of the hypothalamus; posterior bed nucleus of the stria terminalis; posterior nucleus accumbens; supraoptic nucleus of the hypothalamus; ventral lateral septum; ventromedial hypothalamus