Paternal deprivation prior to adolescence and vulnerability to pituitary adenomas

Preweaning Paternal Deprivation Impacts Parental Responses to Pups and Alters the Serum Oxytocin and Corticosterone Levels and Oxytocin Receptor, Vasopressin 1A Receptor, Oestrogen Receptor, Dopamine Type I Receptor, Dopamine Type II Receptor Levels in Relevant Brain Regions in Adult Mandarin Voles

Although maternal separation and neonatal paternal deprivation (PD) have been found to exert a profound and persistent effects on the physiological and behavioural development of offspring, whether preweaning PD (PPD; from PND 10 to 21) affects maternal and parental responses to pups and the underlying neuroendocrine mechanism are under-investigated. Using monogamous mandarin voles (Microtus mandarinus), the present study found that PPD increased the latency to approach a pup-containing ball, decreased the total durations of sniffing and contacting a pup-containing ball and walking and increased the total duration of inactivity in both sexes. Moreover, PPD decreased serum oxytocin levels and increased corticosterone levels, but only in females. Furthermore, in both males and females, PPD decreased the expression of oxytocin receptor mRNA and protein in the medial preoptic area (MPOA), nucleus accumbens (NAcc) and medial prefrontal cortex (mPFC), but increased it in the medial amygdala (MeA) and decreased the expression of oestrogen receptor mRNA and protein in the MPOA. PPD increased the expression of dopamine type I receptor in the NAcc, but decreased it in the mPFC. PPD decreased dopamine type II receptor (D2R) in the NAcc both in males and females, but increased D2R in the mPFC in females and decreased D2R protein expression in males. Moreover, PPD decreased vasopressin 1A receptor (V1AR) in the MPOA, MeA and mPFC, but only in males. Our results suggest that the reduction of parental responses to pups induced by PPD may be associated with the sex-specific alteration of several neuroendocrine parameters in relevant brain regions.

Prolactin and human weight disturbances: A puzzling and neglected association

Weight gain at the outset of prolactinomas in many women is well documented. Yet, this symptom is absent from the clinical descriptions of the disease in textbooks and reviews. This omission is almost certainly due to the absence of a physiological explanation for the phenomenon, as prolactin is not a recognized fat promoting hormone. In this review we present the clinical evidence for a relationship between prolactin and fat accumulation and address some possible mechanisms involved. We put forward the hypothesis that prolactin is a component of a neuroendocrine program - maternal subroutine - aimed at optimizing the care of the young through the production of milk, promotion of maternal behavior and increase in the metabolic efficiency of the mother. These adaptations can enable her to face the extraordinary metabolic expenses of pregnancy and nursing, especially during times of suboptimal environmental conditions. We emphasize the uniqueness of prolactin in that it is a hormone that is tonically inhibited and which has its major effects on the regulation of an inter-individual (the mother - offspring dyad), rather than an intra-individual, system. This approach opens a window to consider the possibility of external events as regulators of this system. It also allows addressing a variety of hitherto unexplained findings reported in the literature. Examples include: association of prolactinomas with paternal deprivation and with stressful life events; pseudocyesis; acute life event-driven episodes of galactorrhea; episodes of rapid weight gain following a life event; prolactin surges (without associated cortisol surges) following some psychological stresses.

Increased anxiety and decreased sociability induced by paternal deprivation involve the PVN-PrL OTergic pathway

Early adverse experiences often have devastating consequences. However, whether preweaning paternal deprivation (PD) affects emotional and social behaviors and their underlying neural mechanisms remain unexplored. Using monogamous mandarin voles, we found that PD increased anxiety-like behavior and attenuated social preference in adulthood. PD also decreased the number of oxytocin (OT)-positive neurons projecting from the paraventricular nucleus (PVN) and reduced the levels of the medial prefrontal cortex OT receptor protein in females and of the OT receptor and V1a receptor proteins in males. Intra-prelimbic cortical OT injections reversed the PD-induced changes in anxiety-like behavior and social preferences. Optogenetic activation of the prelimbic cortex OT terminals from PVN OT neurons reversed the PD-induced changes in emotion and social preference behaviors, whereas optogenetic inhibition was anxiogenic and impaired social preference in naive voles. These findings demonstrate that PD increases anxiety-like behavior and attenuates social preferences through the involvement of PVN OT neuron projections to the prelimbic cortex.

Parental care early in life is essential for normal development of the brain in humans and some other animals. It also lays the ground work for healthy behaviors later in life. Many studies have looked at the importance of a mother’s care, but less attention has been paid to the role played by fathers. Research shows that children who grow up without a father are at risk of emotional and behavioral problems later in life. But it is not clear how missing a father’s care affects brain development.

Oxytocin, a chemical produced by a part of the brain called the paraventricular nucleus, plays a key role in parental bonding. Another part of the brain called the prelimbic cortex regulates many emotions and many complex behaviors. Studying animals, like the mandarin vole, that form strong bonds with both parents is one way to learn more about how the loss of paternal care affects oxytocin or emotional and behavioral health.

Now, He et al. show that mandarin voles raised without a father are more anxious and socialize less with other voles than those raised with a father. The voles deprived of paternal care also have fewer oxytocin-producing cells in the paraventricular nucleus and fewer receptors for oxytocin in the prelimbic cortex. Injecting oxytocin into the prelimbic cortex eliminated the anxious and antisocial behavior seen in the voles lacking paternal care. Using a technique called optogenetics to restore the release of oxytocin in the prelimbic cortex reduced anxious behavior and restored normal social interactions. Using the same approach to interfere with communication between the paraventricular nucleus and prelimbic cortex in voles raised with a father also triggered anxious and antisocial behavior.

The experiments reveal that fathers play an important role in brain and behavioral development in mandarin voles. He et al. show that a lack of paternal care leads to deficits in oxytocin and a poor communication between the paraventricular nucleus and prelimbic cortex that contribute to emotional and social abnormalities in the voles. More studies are needed to determine father’s care has similar effects in humans. But if this relationship is confirmed, it might lead scientists to develop new strategies for treating psychiatric disorders in people deprived of paternal care.

Neighborhood and Family Environment of Expectant Mothers May Influence Prenatal Programming of Adult Cancer Risk: Discussion and an Illustrative DNA Methylation Example

Childhood stressors including physical abuse predict adult cancer risk. Prior research portrays this finding as an indirect mechanism that operates through coping behaviors, including adult smoking, or through increased toxic exposures during childhood. Little is known about potential direct causal mechanisms between early-life stressors and adult cancer. Because prenatal conditions can affect gene expression by altering DNA methylation, with implications for adult health, we hypothesize that maternal stress may program methylation of cancer-linked genes during gametogenesis. To illustrate this hypothesis, we related maternal social resources to methylation at the imprinted MEG3 differentially methylated regulatory region, which has been linked to multiple cancer types. Mothers (n = 489) from a diverse birth cohort (Durham, North Carolina) provided newborns' cord blood and completed a questionnaire. Newborns of currently married mothers showed lower (-0.321 SD, p < .05) methylation compared to newborns of never-married mothers, who did not differ from newborns whose mothers were cohabiting and others (adjusted for demographics). MEG3 DNA methylation levels were also lower when maternal grandmothers co-resided before pregnancy (-0.314 SD, p < .05). A 1-SD increase in prenatal neighborhood disadvantage also predicted higher methylation (-0.137 SD, p < .05). In conclusion, we found that maternal social resources may result in differential methylation of MEG3, which demonstrates a potential partial mechanism priming socially disadvantaged newborns for later risk of some cancers.