Regulation of anxiety during the postpartum period

Functional significance of hormonal changes in mammalian fathers

In the 5-10% of mammals in which both parents routinely provide infant care, fathers as well as mothers undergo systematic endocrine changes as they transition into parenthood. Although fatherhood-associated changes in such hormones and neuropeptides as prolactin, testosterone, glucocorticoids, vasopressin and oxytocin have been characterised in only a small number of biparental rodents and primates, they appear to be more variable than corresponding changes in mothers, and experimental studies typically have not provided strong or consistent evidence that these endocrine shifts play causal roles in the activation of paternal care. Consequently, their functional significance remains unclear. We propose that endocrine changes in mammalian fathers may enable males to meet the species-specific demands of fatherhood by influencing diverse aspects of their behaviour and physiology, similar to many effects of hormones and neuropeptides in mothers. We review the evidence for such effects, focusing on recent studies investigating whether mammalian fathers in biparental species undergo systematic changes in (i) energetics and body composition; (ii) neural plasticity, cognition and sensory physiology; and (iii) stress responsiveness and emotionality, all of which may be mediated by endocrine changes. The few published studies, based on a small number of rodent and primate species, suggest that hormonal and neuropeptide alterations in mammalian fathers might mediate shifts in paternal energy balance, body composition and neural plasticity, although they do not appear to have major effects on stress responsiveness or emotionality. Further research is needed on a wider variety of biparental mammals, under more naturalistic conditions, to more fully determine the functional significance of hormone and neuropeptide profiles of mammalian fatherhood and to clarify how fatherhood may trade off with (or perhaps enhance) aspects of organismal function in biparental mammals.

Calorie restriction and corticosterone elevation during lactation can each modulate adult male fear and anxiety-like behaviour

Early life events, such as calorie restriction (CR) and elevated glucocorticoids, can calibrate the lifelong behavioural and physiological profile of an individual. Stress reactivity in adulthood is particularly sensitive to early life events; however, the consequence to fear and anxiety-like behaviour is less clear. Consequently, the current study sought to examine the effects of post-natal CR and glucocorticoid elevation, long considered powerful programming stimuli, on the subsequent fear and anxiety behaviour of the adult offspring. Rat dams received either corticosterone (200 μg/ml) supplementation in drinking water (CORT) or a 25% CR from post-natal day (PND) 1 to 11. Responses to the elevated plus maze (EPM), open field and a predator odour (TMT; 2,5-dihydro-2,4,5-trimethylthiazoline) were characterised in the adult male offspring. Both treatment conditions resulted in enhanced fear responses to TMT, characterised by heightened risk assessment and increased avoidance of TMT. CORT nursed offspring further demonstrated an anxiogenic profile in the open field. Basal hypothalamic-pituitary-adrenal function was unchanged in CORT adult offspring, whilst corticosterone concentration was elevated by post-natal CR. CR and CORT treated dams both exhibited greater anxiety-like behaviour in the EPM. A modest and temporary enhancement of maternal care was observed in CR and CORT treated dams, with CR dams further exhibiting rapid pup retrieval latencies. The results indicate enhanced emotionality in the adult male progeny of dams exposed to CR and corticosterone supplementation during the post-natal period. The modest enhancement of maternal care observed by both treatments is unlikely to have influenced the behavioural profile of the offspring.

Oxytocin in the medial prefrontal cortex regulates maternal care, maternal aggression and anxiety during the postpartum period

The neuropeptide oxytocin (OT) acts on a widespread network of brain regions to regulate numerous behavioral adaptations during the postpartum period including maternal care, maternal aggression, and anxiety. In the present study, we examined whether this network also includes the medial prefrontal cortex (mPFC). We found that bilateral infusion of a highly specific oxytocin receptor antagonist (OTR-A) into the prelimbic (PL) region of the mPFC increased anxiety-like behavior in postpartum, but not virgin, females. In addition, OTR blockade in the postpartum mPFC impaired maternal care behaviors and enhanced maternal aggression. Overall, these results suggest that OT in the mPFC modulates maternal care and aggression, as well as anxiety-like behavior, during the postpartum period. Although the relationship among these behaviors is complicated and further investigation is required to refine our understanding of OT actions in the maternal mPFC, these data nonetheless provide new insights into neural circuitry of OT-mediated postpartum behaviors.

Using animal models to study post-partum psychiatric disorders

The post-partum period represents a time during which all maternal organisms undergo substantial plasticity in a wide variety of systems in order to ensure the well-being of the offspring. Although this time is generally associated with increased calmness and decreased stress responses, for a substantial subset of mothers, this period represents a time of particular risk for the onset of psychiatric disorders. Thus, post-partum anxiety, depression and, to a lesser extent, psychosis may develop, and not only affect the well-being of the mother but also place at risk the long-term health of the infant. Although the risk factors for these disorders, as well as normal peripartum-associated adaptations, are well known, the underlying aetiology of post-partum psychiatric disorders remains poorly understood. However, there have been a number of attempts to model these disorders in basic research, which aim to reveal their underlying mechanisms. In the following review, we first discuss known peripartum adaptations and then describe post-partum mood and anxiety disorders, including their risk factors, prevalence and symptoms. Thereafter, we discuss the animal models that have been designed in order to study them and what they have revealed about their aetiology to date. Overall, these studies show that it is feasible to study such complex disorders in animal models, but that more needs to be done in order to increase our knowledge of these severe and debilitating mood and anxiety disorders.

Effects of sex and reproductive experience on the number of orexin A-immunoreactive cells in the prairie vole brain

Large populations of cells synthesizing the neuropeptide orexin (OX) exist in the caudal hypothalamus of all species examined and are implicated in physiological and behavioral processes including arousal, stress, anxiety and depression, reproduction, and goal-directed behaviors. Hypothalamic OX expression is sexually dimorphic in different directions in laboratory rats (F>M) and mice (M>F), suggesting different roles in male and female physiology and behavior that are species-specific. We here examined if the number of hypothalamic cells immunoreactive for orexin A (OXA) differs between male and female prairie voles (Microtus ochrogaster), a socially monogamous species that pairbonds after mating and in which both sexes care for offspring, and if reproductive experience influences their number of OXA-immunoreactive (OXA-ir) cells. It was found that the total number of OXA-ir cells did not differ between the sexes, but females had more OXA-ir cells than males in anterior levels of the caudal hypothalamus, while males had more OXA-ir cells posteriorly. Sexually experienced females sacrificed 12 days after the birth of their first litter, or one day after birth of a second litter, had more OXA-ir cells in anterior levels but not posterior levels of the caudal hypothalamus compared to females housed with a brother (incest avoidance prevents sibling mating). Male prairie voles showed no effect of reproductive experience but showed an unexpected effect of cohabitation duration regardless of mating. The sex difference in the distribution of OXA-ir cells, and their increased number in anterior levels of the caudal hypothalamus of reproductively experienced female prairie voles, may reflect a sex-specific mechanism involved in pairbonding, parenting, or lactation in this species.

Impairments in the initiation of maternal behavior in oxytocin receptor knockout mice

Oxytocin (Oxt) acting through its single receptor subtype, the Oxtr, is important for the coordination of physiology and behavior associated with parturition and maternal care. Knockout mouse models have been helpful in exploring the contributions of Oxt to maternal behavior, including total body Oxt knockout (Oxt −/−) mice, forebrain conditional Oxtr knockout (Oxtr FB/FB) mice, and total body Oxtr knockout (Oxtr −/−) mice. Since Oxtr −/− mice are unable to lactate, maternal behavior has only been examined in virgin females, or in dams within a few hours of parturition, and there have been no studies that have examined their anxiety-like and depression-like behavior following parturition. To improve our understanding of how the absence of Oxt signaling affects maternal behavior, mood and anxiety, we designed a study using Oxtr −/− mice that separated nursing behavior from other aspects of maternal care, such as licking and grooming by thelectomizing (i.e. removing the nipples) of Oxtr +/+ mice and sham-thelectomizing Oxtr −/− mice, and pairing both genotypes with a wet nurse. We then measured pup abandonment, maternal behavior, and postpartum anxiety-like and depression-like behaviors. We hypothesized that genetic disruption of the Oxtr would impact maternal care, mood and anxiety. Specifically, we predicted that Oxtr −/− dams would have impaired maternal care and increased anxiety-like and depression-like behaviors in the postpartum period. We found that Oxtr −/− dams had significantly higher levels of pup abandonment compared to controls, which is consistent with previous work in Oxtr FB/FB mice. Interestingly, Oxtr −/− dams that initiated maternal care did not differ from wildtype controls in measures of maternal behavior. We also did not find any evidence of altered anxiety-like or depressive-like behavior in the postpartum period of Oxtr −/− dams. Thus, our data suggest that Oxt lowers the threshold for the initiation of maternal behavior.

The effects of bromocriptine treatment during early pregnancy on postpartum maternal behaviors in rats

Prolactin, a hormone of the anterior pituitary, is involved in initiating maternal behavior, alleviating postpartum anxiety, and stimulating lactogenesis. Bromocriptine, a dopamine D2 receptor agonist, inhibits prolactin secretion. Bromocriptine administration represses postpartum maternal behaviors (pup retrieval) in mice, and causes elevated anxiety in the elevated plus maze [Larsen & Grattan (2010). Endocrinology 151(8): 3805-3814]. Whether similar effects exist in other species is unknown. The present study examined the possible involvement of prolactin during early gestation on maternal behavior and anxiety in rats. Bromocriptine given on days 2-4 of pregnancy resulted in impaired postpartum maternal behaviors in a novel environment during early lactation. However, compared to controls, bromocriptine-treated subjects did not exhibit increased postpartum anxiety in the elevated plus maze. These findings support work in mice that bromocriptine treatment during early gestation impedes postpartum maternal care, and indicate that early gestational hormonal status affects postpartum behavior more broadly in other mammals.

Maternal and affective behaviors of lactating rats reared in overlapping litters

Postpartum mating in rats gives rise to complex family units consisting of the mother and two overlapping litters. As a consequence, newborn pups of the second litter, since the moment they are born, acquire experience not only from interaction with the mother and age-matched littermates but also from interaction with older siblings. Newborn pups reared in overlapping litters (OLs) receive a different pattern of maternal stimulation compared to those reared in single litters (SL: one litter of same aged pups), as the mothers reduce some maternal behavior components and juvenile pups from the first litter develop maternal behavior. Since there is strong evidence showing that variations in maternal behavior are transmitted throughout generations, we hypothesized that the altered pattern of maternal stimulation received by OL reared females would modify their behavior during motherhood. To test this hypothesis maternal behavior, maternal aggression and experimental anxiety of dams reared under OL and SL conditions during the first postpartum week were compared. No differences were found between the groups in their maternal behavior and aggression. This result may be explained by the maternal behavior of the juveniles that could compensate for the deficits in the caregiving behaviors received by OL litters. However, a subtle temporal reorganization of the licking behavior was found in OL reared mothers, together with an increased anxiety-related behavior in the plus maze test. These results suggest dissociation in the effects provoked by early environmental alterations on different behavioral systems, and more importantly, that independently of their early family composition, both groups can cope effectively with the changing demands of the pups.

Placentophagia in weanling female laboratory rats

Placentophagia is common in parturient mammals and offers physiological and behavioral advantages for mothers. In natural environments, weanlings are often present during the birth of younger siblings, but it is unknown if weanling rats are placentophagic or prefer placenta over other substances. To examine this, primiparous rats were remated during the postpartum estrus and their weanling daughters remained in the natal nest during their mother's next parturition. Continuous observation revealed that 58% of weanlings were placentophagic. To determine if this placentophagia occurs away from parturient mothers, weanling females still living in their natal nest were offered placenta, liver, or cake frosting in a novel chamber. They ingested more placenta and liver than frosting. Thus, many weanling female laboratory rats are placentophagic during the birth of younger siblings but do not selectively prefer placenta when tested outside their natal nest. Consequences of placentophagia by weanling female rats are unknown, but it may promote their alloparenting or later postpartum mothering.

Maternal anxiety and breastfeeding: findings from the MAVAN (Maternal Adversity, Vulnerability and Neurodevelopment) Study

BACKGROUND

Maternal anxiety and depression may impair maternal intention, motivation, and self-efficacy in multiple domains associated with child health including breastfeeding.

OBJECTIVE

We tested the hypothesis that mothers who experience substantial anxiety during pregnancy or the postpartum period are at increased risk for reduced initiation, exclusivity, and continuation of breastfeeding.

METHODS

We obtained data on 255 Canadian pregnant women from the Maternal Adversity, Vulnerability and Neurodevelopment (MAVAN) study recruited between June 2004 and February 2009. We utilized data collected from 18 to 23 weeks gestation through 12 months postpartum. Multivariate logistic regression was used to assess whether scores on the Hamilton Anxiety Scale (HAM-A) and State-Trait Anxiety Inventory (STAI) were associated with initiation, exclusivity, and continuation of breastfeeding.

RESULTS

Prenatal anxiety was not associated with breastfeeding outcomes. In adjusted models, a single point increase in HAM-A scores at 3 months postpartum was associated with an 11% reduction in the odds of exclusive breastfeeding at 6 months (adjusted odds ratio [aOR] = 0.89; 95% CI, 0.80-0.99). A single point increase in STAI State and STAI Trait scores at 3 months postpartum was associated with a 4% (aOR = 0.96; 95% CI, 0.92-0.99) and 7% (aOR = 0.93; 95% CI, 0.86-1.00) reduction, respectively, in the odds of any breastfeeding at 12 months.

CONCLUSION

Our findings suggest a relationship between maternal anxiety and reduced exclusivity and continuation of breastfeeding. Maternal anxiety should be actively monitored and managed appropriately in the postpartum period to support optimal breastfeeding practices.

Differential postpartum sensitivity to the anxiety-modulating effects of offspring contact is associated with innate anxiety and brainstem levels of dopamine beta-hydroxylase in female laboratory rats

In female mammals, the postpartum period involves dramatic shifts in many socioemotional behaviors. This includes a suppression of anxiety-related behaviors that requires recent physical contact with offspring. Factors contributing to differences among females in their susceptibility to the anxiety-modulating effect of offspring contact are unknown, but could include their innate anxiety and brain monoaminergic activity. Anxiety behavior was assessed in a large group of nulliparous female rats and the least-anxious and most-anxious tertiles were mated. Anxiety was assessed again postpartum after females were permitted or prevented from contacting their offspring 4 h before testing. Levels of dopamine β-hydroxylase (DBH, norepinephrine synthesizing enzyme) and tryptophan hydroxylase-2 (TPH2, serotonin synthesizing enzyme) were measured in the brainstem and dorsal raphe, respectively. It was found that anxiety-related behavior in the two groups did not differ when dams were permitted contact with offspring before testing. Removal of the offspring before testing, however, differentially affected anxiety based on dams' innate anxiety. Specifically, dams reverted back to their pre-mating levels of anxiety such that offspring removal slightly increased anxiety in the most-anxious females but greatly lowered anxiety in the least-anxious females. This reduction in anxiety in the least-anxious females after litter removal was associated with lower brainstem DBH. There was no relationship between females' anxiety and dorsal raphe TPH2. Thus, a primary effect of recent contact with offspring on anxiety-related behavior in postpartum rats is to shift females away from their innate anxiety to a more moderate level of responding. This effect is particularly true for females with the lowest anxiety, may be mediated by central noradrenergic systems, and has implications for their ability to attend to their offspring.

Maternal aggression in rodents: brain oxytocin and vasopressin mediate pup defence

The most significant social behaviour of the lactating mother is maternal behaviour, which comprises maternal care and maternal aggression (MA). The latter is a protective behaviour of the mother serving to defend the offspring against a potentially dangerous intruder. The extent to which the mother shows aggressive behaviour depends on extrinsic and intrinsic factors, as we have learned from studies in laboratory rodents. Among the extrinsic factors are the pups' presence and age, as well as the intruders' sex and age. With respect to intrinsic factors, the mothers' innate anxiety and the prosocial brain neuropeptides oxytocin (OXT) and arginine vasopressin (AVP) play important roles. While OXT is well known as a maternal neuropeptide, AVP has only recently been described in this context. The increased activities of these neuropeptides in lactation are the result of remarkable brain adaptations peripartum and are a prerequisite for the mother to become maternal. Consequently, OXT and AVP are significantly involved in mediating the fine-tuned regulation of MA depending on the brain regions. Importantly, both neuropeptides are also modulators of anxiety, which determines the extent of MA. This review provides a detailed overview of the role of OXT and AVP in MA and the link to anxiety.

Genetic variation in oxytocin rs2740210 and early adversity associated with postpartum depression and breastfeeding duration

Mothers vary in duration of breastfeeding. These individual differences are related to a variety of demographic and individual maternal factors including maternal hormones, mood and early experiences. However, little is known about the role of genetic factors. We studied single-nucleotide polymorphisms (SNPs) in the OXT peptide gene (rs2740210; rs4813627) and the OXT receptor gene (OXTR rs237885) in two samples of mothers from the Maternal adversity, Vulnerability and Neurodevelopment study (MAVAN), a multicenter (Hamilton and Montreal, Canada) study following mothers and their children from pregnancy until 7 years of age. Data from the Hamilton site was the primary sample (n = 201) and data from Montreal was the replication sample (n = 151). Breastfeeding duration, maternal mood (measured by the CES-D scale) and early life adversity (measured by the CTQ scale) were established during 12 months postpartum. In our primary sample, polymorphisms in OXT rs2740210, but not the other SNPs, interacted with early life adversity to predict variation in breastfeeding duration (overall F8,125  = 2.361, P = 0.021; interaction effect b = -8.12, t = -2.3, P = 0.023) and depression (overall F8,118  = 5.751, P ≤ 0.001; interaction effect b = 6.06, t = 3.13, P = 0.002). A moderated mediation model showed that higher levels of depression mediated the inverse relation of high levels of early life adversity to breastfeeding duration, but only in women possessing the CC genotype [effect a' = -3.3401, 95% confidence interval (CI) = -7.9466 to -0.0015] of the OXT SNP and not in women with the AA/AC genotype (a' = -1.2942, ns). The latter findings (moderated mediation model) were replicated in our Montreal sample (a' = -0.277, 95% CI = -0.7987 to -0.0348 for CC; a' = -0.1820, ns for AA/AC).

Characterization of GABAergic neurons in the mouse lateral septum: a double fluorescence in situ hybridization and immunohistochemical study using tyramide signal amplification

Gamma-aminobutyric acid (GABA) neurotransmission in the lateral septum (LS) is implicated in modulating various behavioral processes, including emotional reactivity and maternal behavior. However, identifying the phenotype of GABAergic neurons in the CNS has been hampered by the longstanding inability to reliably detect somal immunoreactivity for GABA or glutamic acid decarboxylase (GAD), the enzyme that produces GABA. In this study, we designed unique probes for both GAD65 (GAD2) and GAD67 (GAD1), and used fluorescence in Situ hybridization (FISH) with tyramide signal amplification (TSA) to achieve unequivocal detection of cell bodies of GABAergic neurons by GAD mRNAs. We quantitatively characterized the expression and chemical phenotype of GABAergic neurons across each subdivision of LS and in cingulate cortex (Cg) and medial preoptic area (MPOA) in female mice. Across LS, almost all GAD65 mRNA-expressing neurons were found to contain GAD67 mRNA (approximately 95-98%), while a small proportion of GAD67 mRNA-containing neurons did not express GAD65 mRNA (5-14%). Using the neuronal marker NeuN, almost every neuron in LS (> 90%) was also found to be GABA-positive. Interneuron markers using calcium-binding proteins showed that LS GABAergic neurons displayed immunoreactivity for calbindin (CB) or calretinin (CR), but not parvalbumin (PV); almost all CB- or CR-immunoreactive neurons (98-100%) were GABAergic. The proportion of GABAergic neurons immunoreactive for CB or CR varied depending on the subdivisions examined, with the highest percentage of colocalization in the caudal intermediate LS (LSI) (approximately 58% for CB and 35% for CR). These findings suggest that the vast majority of GABAergic neurons within the LS have the potential for synthesizing GABA via the dual enzyme systems GAD65 and GAD67, and each subtype of GABAergic neurons identified by distinct calcium-binding proteins may exert unique roles in the physiological function and neuronal circuitry of the LS.

Noradrenergic alpha-2 receptor modulators in the ventral bed nucleus of the stria terminalis: effects on anxiety behavior in postpartum and virgin female rats

Emotional hyperreactivity can inhibit maternal responsiveness in female rats and other animals. Maternal behavior in postpartum rats is disrupted by increasing norepinephrine release in the ventral bed nucleus of the stria terminalis (BSTv) with the α2-autoreceptor antagonist, yohimbine, or the more selective α2-autoreceptor antagonist, idazoxan (Smith et al., 2012). Because high noradrenergic activity in the BSTv can also increase anxiety-related behaviors, increased anxiety may underlie the disrupted mothering of dams given yohimbine or idazoxan. To assess this possibility, anxiety-related behaviors in an elevated plus maze were assessed in postpartum rats after administration of yohimbine or idazoxan. It was further assessed if the α2-autoreceptor agonist clonidine (which decreases norepinephrine release) would, conversely, reduce dams' anxiety. Groups of diestrous virgins were also examined. It was found that peripheral or intra-BSTv yohimbine did increase anxiety-related behavior in postpartum females. However, BSTv infusion of idazoxan did not reproduce yohimbine's anxiogenic effects and anxiety was not reduced by peripheral or intra-BSTv clonidine. Because yohimbine is a weak 5HT1A receptor agonist, other groups of females received BSTv infusion of the 5HT1A receptor agonist 8OH-DPAT, but it did not alter their anxiety-related behavior. Lastly, levels of norepinephrine and serotonin in tissue punches from the BSTv did not differ between postpartum and diestrous rats, but serotonin turnover was lower in mothers. These results suggest that the impaired maternal behavior after BSTv infusion of yohimbine or idazoxan cannot both be readily explained by an increase in dams' anxiety, and that BSTv α2-autoreceptor modulation alone has little influence on anxiety-related behaviors in postpartum or diestrous rats.

Fatherhood reduces the survival of adult-generated cells and affects various types of behavior in the prairie vole (Microtus ochrogaster )

Motherhood has profound effects on physiology, neuronal plasticity, and behavior. We conducted a series of experiments to test the hypothesis that fatherhood, similarly to motherhood, affects brain plasticity (such as cell proliferation and survival) and various behaviors in the highly social prairie vole (Microtus ochrogaster). In Experiment 1, adult males were housed with their same-sex cage mate (control), single-housed (isolation), or housed with a receptive female to mate and produce offspring (father) for 6 weeks. Fatherhood significantly reduced cell survival (assessed by bromodeoxyuridine labeling), but not cell proliferation (assessed by Ki67-labeling), in the amygdala, dentate gyrus of the hippocampus, and ventromedial hypothalamus, suggesting that fatherhood affects brain plasticity. In Experiment 2, neither acute (20 min) nor chronic (20 min daily for 10 consecutive days) pup exposure altered cell proliferation or survival in the brain, but chronic pup exposure increased circulating corticosterone levels. These data suggest that reduced cell survival in the brain of prairie vole fathers was unlikely to be due to the level of pup exposure and display of paternal behavior, and may not be mediated by circulating corticosterone. The effects of fatherhood on various behaviors (including anxiety-like, depression-like, and social behaviors) were examined in Experiment 3. The data indicated that fatherhood increased anxiety- and depression-like behaviors as well as altered aggression and social recognition memory in male prairie voles. These results warrant further investigation of a possible link between brain plasticity and behavioral changes observed due to fatherhood.

Effects of noradrenergic alpha-2 receptor antagonism or noradrenergic lesions in the ventral bed nucleus of the stria terminalis and medial preoptic area on maternal care in female rats

RATIONALE

Maternal behavior in laboratory rats requires a network of brain structures including the ventral bed nucleus of the stria terminalis (BSTv) and medial preoptic area (mPOA). Neurotransmitter systems in the BSTv and mPOA influencing maternal behaviors are not well understood, although norepinephrine is an excellent candidate because the BSTv contains the densest noradrenergic fiber plexus in the forebrain and norepinephrine in the mPOA is known to influence other female reproductive functions.

OBJECTIVES

We hypothesized that downregulated noradrenergic activity in the BSTv and mPOA is necessary for mothering.

METHODS

Postpartum mother-litter interactions were observed after BSTv infusion of yohimbine (an α2 autoreceptor antagonist that increases norepinephrine release), and after BSTv or mPOA infusion of the more selective α2 autoreceptor antagonist idazoxan. Lastly, noradrenergic input to the BSTv/mPOA was selectively lesioned in nulliparous rats with anti-DBH-saporin to determine if this would facilitate mothering.

RESULTS

BSTv yohimbine almost abolished retrieval of pups but did not significantly affect dams' ability to initiate contact, lick, or nurse them. BSTv idazoxan disrupted retrieval somewhat less than yohimbine, but significantly reduced nursing. mPOA idazoxan impaired retrieval more severely than that found after BSTv infusion. Anti-DBH-saporin almost eliminated noradrenergic terminals in the BSTv and reduced them by over 60% in the mPOA, but did not promote maternal responding. It also did not affect females' anxiety-related behavior.

CONCLUSIONS

Downregulated noradrenergic activity in the BSTv and mPOA is necessary for postpartum maternal behavior in rats, but eliminating this system alone is insufficient to promote maternal behaviors in nulliparous females.

Lactation deficit in OFA hr/hr rats may be caused by differential sensitivity to stress compared with Wistar and Sprague Dawley rats

OFA hr/hr (OFA) rats present a major lactation deficit that impairs offspring survival. To explore whether abnormal stress responsiveness causes this deficit, we compared their hormonal (prolactin, progesterone, and corticosterone) responses to stress (room change and 2-min ether exposure) with those of Wistar and Sprague Dawley (SD) rats. We tested responses during the estrous cycle, pregnancy, lactation, after ovariectomy, and ovarian steroid hormone priming, and responses to suckling. We evaluated hypothalamic expression of receptors for prolactin (PRLRlong) and the isoforms of receptors for progesterone (PRA and B) and estrogen (ERα and β) in late pregnancy. We tested whether administration of an anxiolytic (diazepam) improved lactation. Ether exposure increased circulating levels of the three hormones in the three strains of rats, cycling and ovariectomized, but was less effective in pregnancy and lactation. Elevated estrogen level (estrus and estradiol-treated ovariectomized rats) potentiated the prolactin response more in SD and OFA rats than in Wistar rats. Elevated progesterone level (late pregnancy, lactation, progesterone-treated ovariectomized rats) inhibited the prolactin response less in OFA than in SD or Wistar rats. Ether exposure inhibited the prolactin and oxytocin responses to suckling only in OFA rats. Diazepam treatment increased pup survival rate and the prolactin response to suckling. Hypothalamic total PR mRNA content, assayed by RT-PCR, was higher in pregnant OFA rats compared with SD and Wistar rats, but the PRB/PRA protein ratio determined by Western blot was lowest in Wistar rats, intermediate in OFA rats, and highest in SD rats. The heightened sensitivity to stress of lactating OFA rats may contribute to their lactational deficit and be caused by a combination of hypoprolactinemia and reduced inhibitory capacity of progesterone.

Glutamic acid decarboxylase 65 and 67 expression in the lateral septum is up-regulated in association with the postpartum period in mice

The postpartum period in mammals undergoes a variety of physiological adaptations, including metabolic, behavioral and neuroendocrine alterations. GABA signaling has been strongly linked to various emotional states, stress responses and offspring protection. However, whether GABA signaling may change in the lateral septum (LS), a core brain region for regulating behavioral, emotional and stress responses in postpartum mice has not previously been examined. In this study, we tested whether the expression of two isoforms of glutamic acid decarboxylase (GAD), GAD65 (GAD2) and GAD67 (GAD1), the rate-limiting enzyme for GABA synthesis, exhibits altered expression in postpartum mice relative to nonmaternal, virgin mice. Using microdissected septal tissue from virgin and age-matched postpartum females, quantitative real-time PCR and Western blotting were carried out to assess GAD mRNA and protein expression, respectively. We found both protein and mRNA expression of GAD67 in the whole septum was up-regulated in postpartum mice. By contrast, no significant difference in the whole septum was observed in GAD65 expression. We then conducted a finer level of analysis using smaller microdissections and found GAD67 to be significantly increased in rostral LS, but not in caudal LS or medial septum (MS). Further, GAD65 mRNA expression in rostral LS, but not in caudal LS or MS was also significantly elevated in postpartum mice. These findings suggest that an increased GABA production in rostral LS of the postpartum mice via elevated GAD65 and GAD67 expression may contribute to multiple alterations in behavioral and emotional states, and responses to stress that occur during the postpartum period. Given that rostral LS contains GABA neurons that are projection neurons or local interneurons, it still needs to be determined whether the function of elevated GABA is for local or distant action or both.

Paternal responsiveness is associated with, but not mediated by reduced neophobia in male California mice (Peromyscus californicus)

Hormones associated with pregnancy and parturition have been implicated in facilitating the onset of maternal behavior via reductions in neophobia, anxiety, and stress responsiveness. To determine whether the onset of paternal behavior has similar associations in biparental male California mice (Peromyscus californicus), we compared paternal responsiveness, neophobia (novel-object test), and anxiety-like behavior (elevated plus maze, EPM) in isolated virgins (housed alone), paired virgins (housed with another male), expectant fathers (housed with pregnant pairmate), and new fathers (housed with pairmate and pups). Corticotropin-releasing hormone (CRH) and Fos immunoreactivity (IR) were quantified in brain tissues following exposure to a predator-odor stressor or under baseline conditions. New fathers showed lower anxiety-like behavior than expectant fathers and isolated virgins in EPM tests. In all housing conditions, stress elevated Fos-IR in the hypothalamic paraventricular nucleus (PVN). Social isolation reduced overall (baseline and stress-induced) Fos- and colocalized Fos/CRH-IR, and increased overall CRH-IR, in the PVN. In the central nucleus of the amygdala, social isolation increased stress-induced CRH-IR and decreased stress-induced activation of CRH neurons. Across all housing conditions, paternally behaving males displayed more anxiety-related behavior than nonpaternal males in the EPM, but showed no differences in CRH- or Fos-IR. Finally, the latency to engage in paternal behavior was positively correlated with the latency to approach a novel object. These results suggest that being a new father does not reduce anxiety, neophobia, or neural stress responsiveness. Low levels of neophobia, however, were associated with, but not necessary for paternal responsiveness.

Easing maternal anxiety: an update

Maternal mental health is an important public health issue because of its effects not only on the mother's well-being and functional status, but also her relationship with her partner and the development of her children. There is accumulating evidence of the adverse sequelae of maternal anxiety on fetal development, obstetrical complications, pregnancy outcomes such as low birth weight, and subsequent child development. Evaluation of maternal anxiety and intervention to reduce these symptoms, may ensure optimal developmental outcomes, particularly in high-risk infants such as those born at very low birth weights. This article will outline recent advances in our understanding of the etiology, assessment and impact of maternal anxiety, and describe intervention strategies to promote maternal well-being.

Is it all in the family? The effects of early social structure on neural-behavioral systems of prairie voles (Microtus ochrogaster)

The transition to parenthood is generally associated with a reduction in anxiety or anxiety-like behavior across a wide range of species. In some species, juveniles provide supplementary parental care for younger siblings, a behavior known as alloparenting. Although the fitness consequences of alloparenting behavior have been a focus of evolutionary research, less is known about how alloparenting behavior impacts affective states. In the socially monogamous prairie vole (Microtus ochrogaster), most juveniles exhibit alloparenting behavior, making the species an ideal model for examining the effects of alloparenting on future behavioral outcomes. We randomly assigned juvenile voles to alloparenting (AL) or no alloparenting (NoAL) groups and behaviorally phenotyped them for anxiety-like and social behaviors using the elevated plus maze (EPM), open field test (OFT), startle box, social interaction test, juvenile affiliation test, and partner preference test. AL voles displayed more anxiety-like and less exploratory behaviors than NoAL voles, spending significantly less time in the open arms of the EPM and center of an open field. We dissected the CA1 region of the hippocampus and the bed nucleus of the stria terminalis (BNST) from brains of behaviorally phenotyped voles and nontested siblings as well. Decreased brain-derived neurotrophic factor (BDNF) expression in CA1 has generally been associated with increased anxiety-like behavior in other rodents, while an anxiogenic role for BDNF in BNST is less established. Western blot analyses showed that alloparenting experience increased expression of BDNF in the BNST but decreased BDNF expression in the CA1 region of hippocampus (CA1) of nontested voles. There were similar differences in BNST BDNF of behaviorally phenotyped voles, and BDNF levels within this region were negatively correlated with exploratory behavior (i.e. time in center of OFT). Our results suggest that BDNF signaling in BNST and CA1 fluctuate with alloparenting experience, and they contribute to an increasingly complex "BDNF hypothesis" in which behavioral effects of this molecule are region-specific.

Variation in maternal and anxiety-like behavior associated with discrete patterns of oxytocin and vasopressin 1a receptor density in the lateral septum

The relationship between anxiety and maternal behavior has been explored across species using a variety of approaches, yet there is no clear consensus on the nature or direction of this relationship. In the current study, we have assessed stable individual differences in anxiety-like behavior in a large cohort (n=57) of female F2 hybrid mice. Using open-field behavior as a continuous and categorical (high vs. low) measure we examined the relationship between the anxiety-like behavior of virgin F2 females and the subsequent maternal behavior of these females. In addition, we quantified oxytocin (OTR) and vasopressin (V1a) receptor density within the lateral septum to determine the possible correlation with anxiety-like and maternal behavior. We find that, though activity levels within the open-field do predict latency to engage in pup retrieval, anxiety-like measures on this test are otherwise not associated with subsequent maternal behavior. OTR density in the dorsal lateral septum was found to be negatively correlated with activity levels in the open-field and positively correlated with frequency of nursing behavior. V1a receptor density was significantly correlated with postpartum licking/grooming of pups. Though we do not find support for the hypothesis that individual differences in trait anxiety predict variation in maternal behavior, we do find evidence for the role of OTR and V1a receptors in predicting maternal behavior in mice and suggest possible methodological issues (such as distinguishing between trait and state anxiety) that will be a critical consideration for subsequent studies of the anxiety-maternal behavior relationship. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.

Both oxytocin and vasopressin are mediators of maternal care and aggression in rodents: from central release to sites of action

In the mammalian peripartum period, the activity of both the brain oxytocin and vasopressin system is elevated as part of the physiological adaptations occurring in the mother. This is reflected by increased expression and intracerebral release of oxytocin and vasopressin, as well as increased neuropeptide receptor expression and binding. In this review we discuss the functional role of the brain oxytocin and vasopressin system in the context of maternal behavior, specifically maternal care and maternal aggression in rodents. In order to enable the identification of significant and peptide-specific contributions to the display of maternal behavior, various complementary animal models of maternal care and/or maternal aggression were studied, including rats selectively bred for differences in anxiety-related behavior (HAB and LAB dams), monitoring of local neuropeptide release during ongoing maternal behavior, and local pharmacological or genetic manipulations of the neuropeptide systems. The medial preoptic area was identified as a major site for oxytocin- and vasopressin-mediated maternal care. Furthermore, both oxytocin and vasopressin release and receptor activation in the central amygdala and the bed nucleus of the stria terminalis play an important role for maternal aggression. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.

From stress to postpartum mood and anxiety disorders: how chronic peripartum stress can impair maternal adaptations

The peripartum period, in all mammalian species, is characterised by numerous adaptations at neuroendocrine, molecular and behavioural levels that prepare the female for the challenges of motherhood. These changes have been well characterised and, while they are necessary to ensure the survival and nurturance of the offspring, there is growing belief that they are also required for maternal mental health. Thus, while increased calmness and attenuated stress responsivity are common characteristics of the peripartum period, it also represents a time of increased susceptibility to mood disorders. While a number of risk factors for these disorders are known, their underlying aetiology remains poorly understood, due at least in part to a lack of appropriate animal models. One translatable risk factor is stress exposure during the peripartum period. In the following review we first describe common peripartum adaptations and the impact postpartum mood disorders have on these. We then discuss the known consequences of peripartum stress exposure on such maternal adaptations that have been described in basic research.

Piloting the perinatal obsessive-compulsive scale (POCS): development and validation

Onset/worsening of obsessive-compulsive disorder (OCD) during the perinatal period are frequently seen clinically. No specific tool assessing the unique content, context, severity, and onset of perinatal OCD exists. A self-report scale of perinatal obsessions and compulsions, the Perinatal Obsessive-Compulsive Scale (POCS), was developed and validated. A total of 162 women (67 pregnant, 95 postpartum) participated in this pilot study. They completed the POCS as well as the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). The POCS has good construct validity, reflected by representative items, high internal consistency, good concurrent validity and discriminative capacity. The most common obsessions were fear of having an unhealthy baby at birth, contamination, the baby being taken away, and infant death. Behavioral compulsions such as repeating rituals, asking for reassurance, checking, and cleaning mirrored these obsessions. The POCS helps clinicians detect perinatal OCD while giving perinatal women an opportunity to openly discuss socially sensitive issues.

Inhibition of 5α-reductase activity in late pregnancy decreases gestational length and fecundity and impairs object memory and central progestogen milieu of juvenile rat offspring

Psychological, physical and/or immune stressors during pregnancy are associated with negative birth outcomes, such as preterm birth and developmental abnormalities. In rodents, prenatal stressors can alter the expression of 5α-reductase enzymes in the brain and may influence cognitive function and anxiety-type behaviour in the offspring. Progesterone plays a critical role in maintaining gestation. In the present study, it was hypothesised that 5α-reduced progesterone metabolites influence birth outcomes and/or the cognitive and neuroendocrine function of the offspring. 5α-Reduced steroids were manipulated in pregnant Long-Evans rats via the administration of vehicle, the 5α-reduced, neuroactive metabolite of progesterone, 5α-pregnan-3α-ol-20-one (3α,5α-THP, allopregnanolone; 10 mg/kg/ml, s.c.), or the 5α-reductase inhibitor, finasteride (50 mg/kg/ml, s.c.), daily from gestational days 17-21. Compared to vehicle or 3α,5α-THP treatment, finasteride, significantly reduced the length of gestation and the number of pups per litter found in the dams' nests after parturition. The behaviour of the offspring in hippocampus-dependent tasks (i.e. object recognition, open field) was examined on post-natal days 28-30. Compared to vehicle-exposed controls, prenatal 3α,5α-THP treatment significantly increased motor behaviour in females compared to males, decreased progesterone content in the medial prefrontal cortex (mPFC) and diencephalon, increased 3α,5α-THP and 17β-oestradiol content in the hippocampus, mPFC and diencephalon, and significantly increased serum corticosterone concentrations in males and females. Prenatal finasteride treatment significantly reduced object recognition, decreased hippocampal 3α,5α-THP content, increased progesterone concentration in the mPFC and diencephalon, and increased serum corticosterone concentration in female (but not male) juvenile offspring, compared to vehicle-exposed controls. Thus, inhibiting the formation of 5α-reduced steroids during late gestation in rats reduces gestational length, the number of viable pups per litter, and impairs cognitive and neuroendocrine function in the juvenile offspring.

Plasticity of the parental brain: a case for neurogenesis

Profound behavioural changes occur in the mother at parturition, together with extensive remodelling of neural circuits. These changes include neurochemical, morphological and functional plasticity. The continuous generation of new neurones in the hippocampus and the olfactory system is an additional form of neuroplasticity that contributes to motherhood. This review describes the reciprocal relationships between hippocampal and olfactory neurogenesis and parental behaviour. Studies in rodents demonstrate that parturition and interactions with the young affect both cell proliferation and survival in a different manner across neurogenic zones. Species in which an individual recognition of the offspring is formed, such as sheep, show a down-regulation of neurogenesis during the perinatal period. This would function to decrease cell competition, favouring the selection of newborn neurones involved in olfactory recognition of the young. Also, in biparental species, increases in olfactory neurogenesis occur in the father in response to pup exposure during the early postpartum period. Oestradiol, corticosterone and prolactin changes associated with parturition are the main physiological factors involved in the regulation of neurogenesis that have been determined so far. In the father, prolactin mediates an enhancement of olfactory neurogenesis. Contradictory evidence indicates a functional link between neurogenesis and parenting behaviour. Mice receiving focal irradiation of the olfactory neurogenic subventricular zone show few disturbances in the expression of maternal behaviour, whereas a reduction of both hippocampal and olfactory neurogenesis as a result of the infusion of an anti-mitotic agent induces behavioural deficits. Disrupting prolactin signalling abolished increased paternal neurogenesis and offspring recognition by the father, and rescuing this neurogenesis restored recognition behaviour. More studies that selectively suppress the changes of neurogenesis are needed to confirm the role of new neurones in regulating parenting behaviour.

Immune stress in late pregnant rats decreases length of gestation and fecundity, and alters later cognitive and affective behaviour of surviving pre-adolescent offspring

Immune challenge during pregnancy is associated with preterm birth and poor perinatal development. The mechanisms of these effects are not known. 5α-Pregnan-3α-ol-20-one (3α,5α-THP), the neuroactive metabolite of progesterone, is critical for neurodevelopment and stress responses, and can influence cognition and affective behaviours. To develop an immune challenge model of preterm birth, pregnant Long-Evans rat dams were administered lipopolysaccharide [LPS; 30 μg/kg/ml, intraperitoneal (IP)], interleukin-1β (IL-1β; 1 μg/rat, IP) or vehicle (0.9% saline, IP) daily on gestational days 17-21. Compared to control treatment, prenatal LPS or IL-1β reduced gestational length and the number of viable pups born. At 28-30 days of age, male and female offspring of mothers exposed to prenatal IL-1β had reduced cognitive performance in the object recognition task compared to controls. In females, but not males, prenatal IL-1β reduced anxiety-like behaviour, indicated by entries to the centre of an open field. In the hippocampus, progesterone turnover to its 5α-reduced metabolites was lower in prenatally exposed IL-1β female, but not in male offspring. IL-1β-exposed males and females had reduced oestradiol content in hippocampus, medial prefrontal cortex and diencephalon compared to controls. Thus, immune stress during late pregnancy reduced gestational length and negatively impacted birth outcomes, hippocampal function and central neurosteroid formation in the offspring.

Exposure to chronic pregnancy stress reverses peripartum-associated adaptations: implications for postpartum anxiety and mood disorders

Maternal adaptations, such as decreased anxiety and attenuated stress responsiveness, are necessary to enable successful postnatal development of the offspring. However, there is growing evidence that they are also required to protect the mental health of the mother and that exposure to chronic stress during pregnancy may prevent such adaptations. Overcrowding stress (24 h) and restraint stress (2 × 1 h) were employed on alternate days between pregnancy d 4-16 to examine the impact of chronic pregnancy stress on relevant behavioral, neuroendocrine, and neuronal peripartum adaptations. To determine whether the chronic stress-induced alterations were specific to the peripartum period, we included virgins as controls. Validating the stress procedure, we demonstrated decreased body-weight gain and increased adrenal weight in stressed dams, relative to their nonstressed controls. Chronic stress prevented a number of peripartum adaptations, including basal plasma hypercorticosterone levels, increased oxytocin mRNA expression in the hypothalamic paraventricular nucleus, and anxiolysis. However, chronic stress did not prevent the peripartum-associated decrease in CRH mRNA expression or attenuate corticosterone response to an acute stressor, nor did it affect hypothalamic vasopressin mRNA expression. Illustrating the specificity of these stress-induced changes to the peripartum period, none of these parameters were affected in stressed virgins. Although chronic stress did not alter depression-related behavior, it reversed the response to acute imipramine treatment and increased active maternal behavior in lactation. Thus, prevention of the peripartum-associated increases in basal corticosterone and oxytocin system activity by pregnancy stress reveal two alterations that may increase the risk of postpartum psychiatric disorders, particularly anxiety.

Use of the light-dark box to compare the anxiety-related behavior of virgin and postpartum female rats

Postpartum female rodents are less anxious than diestrous virgins and this difference contributes to dams' ability to adequately care for pups and defend the nest. Low postpartum anxiety has been observed in many behavioral paradigms but the results of previous studies using the light-dark box have been inconsistent. We here reexamined the usefulness of the light-dark box to assess differences between postpartum and diestrous virgin female rats in their anxiety-related behavior. We found a significant effect of reproductive state, such that dams spent more time in the light chamber than did diestrous virgins. This difference required recent physical contact with pups because a four-hour separation from pups reduced dams' time spent in the light chamber by half, similar to what we previously found for litter-separated dams tested in an elevated plus maze. We then examined if dams' low-anxiety behavior in the light-dark box depends on high GABA(A) receptor activity by inhibiting the receptor at different binding sites using (+)-Bicuculline to target the GABA site, FG-7142 to target the benzodiazepine site, and pentylenetetrazol to target the picrotoxin site. Only pentylenetetrazol was consistently anxiogenic in dams, while having little effect in diestrous virgins. Thus, the light-dark box can be a useful paradigm to study differences between postpartum and diestrous virgin female rats in their anxiety-related behaviors, and this difference is influenced by dams' recent contact with pups and GABA(A) receptor neurotransmission particularly affected by activity at the picrotoxin site.

Progesterone attenuates depressive behavior of younger and older adult C57/BL6, wildtype, and progesterone receptor knockout mice

Progesterone may have actions independent of intracellular progestin receptors (PRs) to influence depressive behavior. To investigate this, we examined effects of progesterone (P; 10mg/kg, SC) on the depressive behavior of mice in the forced swim test (FST). In Experiment 1, subjects were 4 to 6 months old, intact or ovariectomized (OVX) female and intact or gonadectomized (GDX) male, C57/BL6 mice. Progesterone reduced depressive behavior of young diestrous and OVX mice but male mice were impervious to effects of P. In Experiment 2, subjects were intact aged (20-28 months old) C57/BL6 female and male mice. Progesterone reduced depressive behavior of aged female and male C57/BL6 mice, albeit effects were greater among males. In Experiment 3, effects of P were examined in 4 to 6 months old, gonadally-intact, female and male mice that were wildtype or PR knockouts (PRKOs). Progesterone decreased depressive behavior of young adult, wildtype and PRKO mice, which showed greater immobility than did their wildtype counterparts. In Experiment 4, subjects were 18-24 months old wildtype or PRKO mice (Exp 4). Progesterone decreased immobility among wildtype and PRKO mice (which were not different in terms of their baseline depressive behavior). Together these data demonstrate that P decreases depressive behavior of young and older adult C57/BL6, wildtype and PRKO mice, which suggest that acute anti-depressant effects of P may occur independent of actions at "classic" PRs.

Autoradiographic analysis of GABAA receptor binding in the neural anxiety network of postpartum and non-postpartum laboratory rats

Postpartum female rats exhibit a suppression of anxiety-related behaviors when compared to diestrous virgin females, pregnant females, and males. This blunted anxiety promotes optimal maternal care and involves elevated GABA neurotransmission, possibly including greater density of GABA(A) and benzodiazepine receptors in the postpartum brain. We here examined autoradiographic binding of [(3)H]muscimol to measure the total population of GABA(A) receptors and [(3)H]flunitrazepam to assess density of benzodiazepine sites in the medial prefrontal cortex, bed nucleus of the stria terminalis, amygdala, hippocampus, and periaqueductal gray of female rats sacrificed on day 7 postpartum, day 10 of pregnancy, or as diestrous virgins. A group of sexually naïve male rats was also included. We found that [(3)H]muscimol binding did not differ among groups in any site but that diestrous virgin females had greater [(3)H]flunitrazepam binding in the CA1 and dentate gyrus of the hippocampus compared to mid-pregnant females and males. Notably, postpartum and diestrous virgin females did not significantly differ in binding of either ligand in any site examined. This is the first study to evaluate the densities of GABA(A) and benzodiazepine binding sites simultaneously across three female reproductive states and sex with a focus on brain sites influencing anxiety-related behaviors. The results suggest that changes in other GABA(A) receptor characteristics such as subunit composition, or increased presynaptic GABA release during interactions with offspring, must instead play a greater role in the postpartum suppression of anxiety in laboratory rats.

Parental precaution: neurobiological means and adaptive ends

Humans invest precious reproductive resources in just a few offspring, who remain vulnerable for an extended period of their lifetimes relative to other primates. Therefore, it is likely that humans evolved a rich precautionary psychology that assists in the formidable task of protecting offspring. In this review, we integrate precautionary behaviors during pregnancy and postpartum with the adaptive functions they may serve and what is known of their biological mediators, particularly brain systems motivating security and attachment. We highlight the role of reproductive hormones in (i) priming parental affiliation with young to incentivize offspring protection, (ii) focusing parental attention on cues of potential threat, and (iii) facilitating maternal defense against potentially dangerous conspecifics and predators. Throughout, we center discussion on adaptive responses to threats of disease, accident and assault as common causes of child mortality in the ancestral past.

Dopamine and oxytocin interactions underlying behaviors: potential contributions to behavioral disorders

Dopamine is an important neuromodulator that exerts widespread effects on the central nervous system (CNS) function. Disruption in dopaminergic neurotransmission can have profound effects on mood and behavior and as such is known to be implicated in various neuropsychiatric behavioral disorders including autism and depression. The subsequent effects on other neurocircuitries due to dysregulated dopamine function have yet to be fully explored. Due to the marked social deficits observed in psychiatric patients, the neuropeptide, oxytocin is emerging as one particular neural substrate that may be influenced by the altered dopamine levels subserving neuropathologic-related behavioral diseases. Oxytocin has a substantial role in social attachment, affiliation and sexual behavior. More recently, it has emerged that disturbances in peripheral and central oxytocin levels have been detected in some patients with dopamine-dependent disorders. Thus, oxytocin is proposed to be a key neural substrate that interacts with central dopamine systems. In addition to psychosocial improvement, oxytocin has recently been implicated in mediating mesolimbic dopamine pathways during drug addiction and withdrawal. This bi-directional role of dopamine has also been implicated during some components of sexual behavior. This review will discuss evidence for the existence dopamine/oxytocin positive interaction in social behavioral paradigms and associated disorders such as sexual dysfunction, autism, addiction, anorexia/bulimia, and depression. Preliminary findings suggest that whilst further rigorous testing has to be conducted to establish a dopamine/oxytocin link in human disorders, animal models seem to indicate the existence of broad and integrated brain circuits where dopamine and oxytocin interactions at least in part mediate socio-affiliative behaviors. A profound disruption to these pathways is likely to underpin associated behavioral disorders. Central oxytocin pathways may serve as a potential therapeutic target to improve mood and socio-affiliative behaviors in patients with profound social deficits and/or drug addiction.

Maternal behaviour is associated with vasopressin release in the medial preoptic area and bed nucleus of the stria terminalis in the rat

The neuropeptide arginine vasopressin was recently shown to be an important regulator of female social behaviour, including maternal care and aggression. A key brain site for vasopressin- as well as oxytocin-mediated maternal care is the medial preoptic area (MPOA). Together with the adjacent bed nucleus of the stria terminalis (BNST), these brain regions are considered to form a 'super-region' for maternal behaviour. In the present study, we investigated the vasopressin and oxytocin systems within the MPOA and the BNST during maternal care in lactating rats in more detail. Binding to V1a and oxytocin receptors in the BNST and to oxytocin receptors in the MPOA was increased in lactation. Furthermore, microdialysis revealed that vasopressin release significantly increased (MPOA) or tended to increase (BNST) during different phases of maternal care (i.e. with or without suckling stimulus). In support, manipulations of V1a receptors in the MPOA are known to alter maternal care. We now show that local injection of a selective V1a receptor antagonist bilaterally into the BNST did not affect maternal care, but reduced maternal aggression and tended to lower anxiety-related behaviour. The release of oxytocin did not change in any of the brain regions during maternal care. The results obtained indicate that locally-released vasopressin within the MPOA and the BNST is important for the maintenance of complex maternal behaviours, including maternal care and aggression, respectively.

Infusions of anti-sense oligonucleotides for DARPP-32 to the ventral tegmental area reduce effects of progesterone- and a dopamine type 1-like receptor agonist to facilitate lordosis

Manipulating dopamine and/or adenosine 3',5' monophosphate regulated phosphoprotein of 32 kDa (DARPP-32) can influence sexual behavior of rodents. The ventral tegmental area (VTA) is an important brain site for progestogens to facilitate sexual behavior of rodents. We hypothesized that, in the VTA, dopamine type 1-like receptor (D1)-mediated increases in progesterone (P4)-facilitated lordosis involve DARPP-32. To investigate this, ovariectomized hamsters and rats, primed with estradiol (E2; 10 microg), received infusions to the VTA of saline vehicle or sense or anti-sense oligonucleotides targeted against DARPP-32 (4 nM). Subjects were then administered P4 via subcutaneous injection (hamsters: 200 microg; rats: 0 or 100 microg). Hamsters and rats were pre-tested for lordosis 3.5 h post-P4 injections, and then infused with the D1 agonist SKF38393 (100 ng) or vehicle to the VTA, and re-tested for sexual behavior 30 min later. Anti-sense oligonucleotides targeted against DARPP-32, but not infusions of sense oligonucleotides, to the VTA blocked the ability of systemic P4 to enhance receptive behavior of hamsters and rats. Similarly, SKF38393-mediated increases in P4-facilitated sexual behaviors were blocked by DARPP-32 anti-sense oligonucleotides to the VTA. The same pattern of effects was not observed in rats that were primed with E2-alone. Together, these findings suggest that, in the midbrain VTA, P4's actions to facilitate sexual behavior of female rodents, involving D1 receptors, may require DARPP-32.

Evaluation of changes in postnatal care using the "Parents' Postnatal Sense of Security" instrument and an assessment of the instrument's reliability and validity

BACKGROUND

A sense of security is important for experiences of parenthood in the early postpartum period. The objectives of this study were to evaluate two models of postnatal care using a questionnaire incorporating the Parents' Postpartum Sense of Security (PPSS) instrument and to test the validity of the PPSS instrument.

METHODS

Postal surveys were sent to 234 mothers who had experienced two different forms of postnatal care (study group and control group) and returned by 86.8%. These two groups of mothers were compared for total scores on the PPSS instrument. Demographic variables and mothers' opinions about care interventions were also compared and these variables were tested for correlations with the total PPSS score. A regression analysis was carried out to assess areas of midwifery care which might affect a sense of security. The internal consistency and concurrent validity of the instrument were tested for the total population.

RESULTS

there were no significant differences between the groups for scores on the PPSS instrument. A total of three variables predicted 26% of the variability on the PPSS scores for the study group and five variables predicted 37% of the variability in the control group. One variable was common to both: "The midwives on the postnatal ward paid attention to the mother as an individual". There were significant correlations between the total PPSS scores and scores for postpartum talks and visits to the breastfeeding clinic. There was also a significant correlation between the single question: "I felt secure during the first postpartum week" and the total PPSS score. Tests for internal consistency and concurrent validity were satisfactory.

CONCLUSION

The proposed new model of care neither improved nor impaired mothers' feelings of security the week following birth. Being seen as an individual by the midwife who provides postnatal care may be an important variable for mothers' sense of postnatal security. It is possible that postpartum talks may encourage the processing of childbirth experiences in a positive direction. Availability of breastfeeding support may also add to a sense of security postpartum. The PPSS instrument has shown acceptable reliability and validity.

Progesterone can enhance consolidation and/or performance in spatial, object and working memory tasks in Long-Evans rats

Progesterone has a ubiquitous role in reproduction and fitness and may influence cognitive performance. We examined the effects of administration of progesterone (a regimen that facilitates sexual behaviour) on consolidation of complex information in Long-Evans rats, Rattus norvegicus, that may be relevant for social engagement. We also examined the effects of subcutaneous progesterone administration (4 mg/kg versus oil vehicle placebo) on memory of ovariectomized rats during various cognitive tasks. Ovariectomized rats that received progesterone, versus the vehicle, immediately post-training were better able to find a hidden platform in the water maze. In a recognition task, rats that received progesterone spent more time in the novel arm of the Y-maze task than rats that received the vehicle. Ovariectomized rats that received progesterone immediately after training spent significantly more time exploring a novel object (compared to a familiar object) than did vehicle-administered rats. When socially relevant stimuli (i.e. objects with the scent of familiar or novel conspecifics) were used in the social cognition task, ovariectomized rats that received progesterone spent more time exploring the object with the novel conspecifics' scent than did vehicle-administered rats. Pairing of progesterone, but not the vehicle, conditioned a place preference to the originally nonpreferred side of the conditioning chamber. We found no significant differences in motor activity measures in these tasks due to progesterone treatment. These results suggest that progesterone's effects to improve cognitive processes with nonsocial and socially relevant stimuli, as well as have reinforcing effects, may underlie some of its salient effects on reproduction-related behaviours.

The role of maternal anxiety in the early postpartum period: screening for anxiety and depressive symptomatology in Greece

BACKGROUND

From birth to the first year postpartum, there is a critical period for the development of affective disorders. Maternal anxiety has received little attention even though it is associated with a number of adverse outcomes. Symptoms of anxiety often comorbid with depression and pertain a significant role in the maintenance of postpartum distress. The purpose of this study is to assess anxiety and depressive symptomatology in a Greek population and to examine their relationship. This study investigated the demographic and socio-psychological factors that are associated with the onset of the symptoms of postpartum distress.

METHOD

The study was conducted at the perinatal hospital Elena Venizelou in Greece. Two hundred thirty-five mothers met the inclusion criteria and participated in the study. The state-trait inventory was administered to screen symptoms of anxiety. It incorporates the state subscale that measures symptoms of temporal anxiety, and trait subscale that measures personality predisposition to anxiety. The Edinburgh postpartum depression scale (EPDS) inventory was administered to screen for symptoms of depression. The first assessment was conducted in 2-3 days after labor and the follow-up assessment was conducted in 3 months postpartum by telephone. A standard survey questionnaire was used for the purposes of collecting the demographic data.

RESULTS

Symptoms of postpartum depression had 14.5% of mothers on the first screening and 4.6% at the follow-up (EPDS >or= 14). State anxiety symptoms were manifested by 22.9% of the sample on the first screening and 12.6% at the follow-up. Trait anxiety symptoms exhibited 24.6% of the sample on the first screening and 14.3% at the follow-up. There was comorbidity between the symptoms of anxiety and depression. The comorbidity was evident even when the anxiety subscale of the EPDS was removed. State anxiety was correlated with primiparity, admission to the NICU and negative experience of labor. Trait anxiety was correlated with the marital status of the mother. The symptoms of depression were correlated with the young age of the mother and negative experience of labor.

CONCLUSION

Symptoms of maternal anxiety are common after labor in Greece and persist in the early postpartum period. This finding suggests that the impact of maternal anxiety should be considered when studying postpartum distress. The comorbidity amongst anxiety and depressive symptomatology persisted at 3 months postpartum making women more vulnerable to postpartum distress. Given this result screening prior to hospital discharge is essential as it can provide an indication of the mothers who are susceptible to developing affective disorders.

Regulation of maternal food intake and mother-pup interactions by the Y5 receptor

Neuropeptide Y (NPY) is increased in the hypothalamus during lactation. To investigate the role of the NPY Y5 receptor during lactation, an antisense oligodeoxynucleotide (ODN) targeted to the NPY Y5 receptor, an equivalent scrambled ODN or vehicle, was chronically infused into the 3rd ventricle of lactating rats from day 8 postpartum. Y5 antisense ODN treatment reduced Y5 positive cell number in the paraventricular nucleus and resulted in significant reductions in food intake and litter growth. Litters from pair-fed vehicle treated dams gained significantly more weight than the litters of Y5 antisense ODN treated dams suggesting that decreased maternal food intake is not the only mechanism involved in suppressing litter weight gain. When mother-litter interaction was examined on day 13 pp, Y5 antisense ODN treated dams spent significantly less time on the nest and had significantly shorter nest bouts. These results suggest that in addition to regulating feeding behaviour, the Y5 receptor subtype may have previously unrecognised roles in the control of nesting behaviour during lactation with subsequent effects on litter growth rates.