Behavioral and epigenetic consequences of oxytocin treatment at birth.

Oxytocin is used in approximately half of all births in the United States during labor induction and/or augmentation. However, the effects of maternal oxytocin administration on offspring development have not been fully characterized. Here, we used the socially monogamous prairie vole to examine the hypothesis that oxytocin exposure at birth can have long-term developmental consequences. Maternally administered oxytocin increased methylation of the oxytocin receptor (Oxtr) in the fetal brain. As adults, oxytocin-exposed voles were more gregarious, with increased alloparental caregiving toward pups and increased close social contact with other adults. Cross-fostering indicated that these effects were the result of direct action on the offspring, rather than indirect effects via postnatal changes in maternal behavior. Male oxytocin-exposed offspring had increased oxytocin receptor density and expression in the brain as adults. These results show that long-term effects of perinatal oxytocin may be mediated by an epigenetic mechanism

Early postnatal gene expression in the developing neocortex of prairie voles ( Microtus ochrogaster

The earliest and most prevalent sensory experience includes tactile, thermal, and olfactory stimulation delivered to the young via contact with the mother, and in some mammals, the father. Prairie voles (Microtus ochrogaster), like humans, are biparental and serve as a model for understanding the impact of parent/offspring interactions on the developing brain. Prairie voles also exhibit natural variation in the level of tactile stimulation delivered by the parents to the offspring, and this has been well documented and quantified. Previous studies revealed that adult prairie vole offspring who received either high (HC) or low (LC) tactile contact from their parents have differences in the size of cortical fields and the connections of somatosensory cortex. In the current investigation we examined gene expression, intraneocortical connectivity, and cortical thickness in newborn voles to appreciate when differences in HC and LC offspring begin to emerge. We observed differences in developmentally-regulated genes, as well as variation in prelimbic and anterior cingulate cortical thickness at postnatal day 1 (P1) in HC and LC voles. Results from this study suggest that parenting styles, such as those involving high or low physical contact, impact the developing neocortex via very early sensory experience as well as differences in epigenetic modifications that may emerge in HC and LC voles

Anti-Inflammatory Influences on Behavioral, But Not Cortisol, Responses During Maternal Separation

The present study examined the effect of anti-inflammatory agents on the behavioral and plasma cortisol responses of guinea pig pups during isolation in a novel environment. In Experiment 1, intracerebroventricular (ICV) administration of interleukin-10 (IL-10), across a range of doses, significantly reduced passive behaviors of isolated pups. In Experiment 2, neither ICV IL-10 nor alpha-melanocyte stimulating hormone affected the plasma cortisol response to the separation procedure. These results provide further evidence that the passive behaviors of isolated guinea pig pups are mediated by proinflammatory cytokines and indicate that cytokines do not affect behavior indirectly by means of an action on hypothalamic-pituitary-adrenal activity

Anti-Inflammatory Influences on Behavioral, But Not Cortisol, Responses During Maternal Separation

The present study examined the effect of anti-inflammatory agents on the behavioral and plasma cortisol responses of guinea pig pups during isolation in a novel environment. In Experiment 1, intracerebroventricular (ICV) administration of interleukin-10 (IL-10), across a range of doses, significantly reduced passive behaviors of isolated pups. In Experiment 2, neither ICV IL-10 nor alpha-melanocyte stimulating hormone affected the plasma cortisol response to the separation procedure. These results provide further evidence that the passive behaviors of isolated guinea pig pups are mediated by proinflammatory cytokines and indicate that cytokines do not affect behavior indirectly by means of an action on hypothalamic-pituitary-adrenal activity

Anti-Inflammatory Influences on Behavioral, But Not Cortisol, Responses During Maternal Separation

The present study examined the effect of anti-inflammatory agents on the behavioral and plasma cortisol responses of guinea pig pups during isolation in a novel environment. In Experiment 1, intracerebroventricular (ICV) administration of interleukin-10 (IL-10), across a range of doses, significantly reduced passive behaviors of isolated pups. In Experiment 2, neither ICV IL-10 nor alpha-melanocyte stimulating hormone affected the plasma cortisol response to the separation procedure. These results provide further evidence that the passive behaviors of isolated guinea pig pups are mediated by proinflammatory cytokines and indicate that cytokines do not affect behavior indirectly by means of an action on hypothalamic-pituitary-adrenal activity

Individual differences in cortical connections of somatosensory cortex are associated with parental rearing style in prairie voles (Microtus ochrogaster).

Early-life sensory experiences have a profound effect on brain organization, connectivity, and subsequent behavior. In most mammals, the earliest sensory inputs are delivered to the developing brain through tactile contact with the parents, especially the mother. Prairie voles (Microtus ochrogaster) are monogamous and, like humans, are biparental. Within the normal prairie vole population, both the type and the amount of interactions, particularly tactile contact, that parents have with their offspring vary. The question is whether these early and pervasive differences in tactile stimulation and social experience between parent and offspring are manifest in differences in cortical organization and connectivity. To address this question, we examined the cortical and callosal connections of the primary somatosensory area (S1) in high-contact (HC) and low-contact (LC) offspring using neuroanatomical tracing techniques. Injection sites within S1 were matched so that direct comparisons between these two groups could be made. We observed several important differences between these groups. The first was that HC offspring had a greater density of intrinsic connections within S1 compared with LC offspring. Additionally, HC offspring had a more restricted pattern of ipsilateral connections, whereas LC offspring had dense connections with areas of parietal and frontal cortex that were more widespread. Finally, LC offspring had a broader distribution of callosal connections than HC offspring and a significantly higher percentage of labeled callosal neurons. This study is the first to examine individual differences in cortical connections and suggests that individual differences in cortical connections may be related to natural differences in parental rearing styles associated with tactile contact