Testosterone,oxytocin, and the development of human parental care

The steroid testosterone (T) and neuropeptide oxytocin (OT) have each been implicated in the development of parental care in humans and animals, yet very little research addressed the interaction between these hormones at the transition to parenthood in mothers and fathers. One hundred and sixty mothers and fathers (80 couples) were visited 1 and 6 months after the birth of their first child, plasma OT and T were assayed at each time-point, and interactions between each parent and the infant were observed and micro-coded for two key parental behaviors; affectionate touch and parent-infant synchrony. T showed gender-specific effects. While paternal T was individually stable across the first six months of parenting and predicted lower father-infant synchrony, maternal T was neither stable nor predictive of maternal behavior. An interaction of OT and T showed that T has complex modulatory effects on the relations of OT and parenting. Slope analysis revealed that among fathers, only when T was high (+ 1SD), negative associations emerged between OT and father affectionate touch. In contrast, among mothers, the context of high T was related to a positive association between OT and maternal touch. Our findings, the first to test the interaction of OT and T in relation to observed maternal behavior, underscore the need for much further research on the complex bidirectional effects of steroid and neuropeptide systems on human mothering and fathering.     

Fathers' decline in testosterone and synchrony with partner testosterone during pregnancy predicts greater postpartum relationship investment

The transition to parenthood has been associated with declines in testosterone among partnered fathers, which may reflect males' motivation to invest in the family. Moreover, preliminary evidence has found that couples show correlations in hormone levels across pregnancy that may also be linked to fathers' preparation for parenthood. The current study used repeated-measures sampling of testosterone across pregnancy to explore whether fathers' change in T, and correlations with mothers' T, were associated with fathers' and mothers' postpartum investment.In a sample of 27 couples (54 individuals) expecting their first child, both parents' salivary testosterone was measured multiple times across pregnancy. At approximately 3.5 months postpartum, participants rated their investment, commitment, and satisfaction with their partner. A multilevel model was used to measure change in testosterone over time and associations between mother and father testosterone. Fathers who showed stronger declines in T across pregnancy, and stronger correlations with mothers' testosterone, reported higher postpartum investment, commitment, and satisfaction. Mothers reported more postpartum investment and satisfaction if fathers showed greater prenatal declines in T. These results held even after controlling for paternal investment, commitment, and satisfaction measured prenatally at study entry.Our results suggest that changes in paternal testosterone across pregnancy, and hormonal linkage with the pregnant partner, may underlie fathers' dedication to the partner relationship across the transition to parenthood.     

Acute effects of corticosterone injection on paternal behavior in California mouse (Peromyscus californicus) fathers

Glucocorticoids are thought to mediate the disruption of parental behavior in response to acute and chronic stress. Previous research supports their role in chronic stress; however, no study has experimentally tested the effects of acute glucocorticoid elevation on paternal behavior. We tested the prediction that acute corticosterone (CORT) increases would decrease paternal behavior in California mouse fathers and would lead to longer-term effects on reproductive success, as even short-term increases in CORT have been shown to produce lasting effects on the hypothalamic-pituitary-adrenal axis. First-time fathers were injected with 30 mg/kg CORT, 60 mg/kg CORT or vehicle, or left unmanipulated. Interactions between the male and its pup(s) were recorded 1.5–2 h after injection and scored for paternal and non-paternal behavior. Treatment groups were combined into control (unmanipulated + vehicle, n = 15) and CORT (30 mg/kg + 60 mg/kg, n = 16) for analysis based on resulting plasma CORT concentrations. CORT treatment did not alter paternal or non-paternal behaviors or any long-term measures (male body mass or temperature, pup growth rate, pup survival, interbirth interval, number or mass of pups born in the second litter). Fathers showed a significant rise in body mass at day 30 postpartum, followed by a decrease in body mass after the birth of the second litter; however, this pattern did not differ between the CORT and control groups. In summary, acute elevation of plasma CORT did not alter direct paternal behavior, body mass, or reproductive outcomes, suggesting that acute CORT elevation alone does not overtly disrupt paternal care in this biparental mammal.     

Intranasal oxytocin,but not vasopressin,augments neural responses to toddlers in human fathers

This study investigates paternal brain function with the hope of better understanding the neural basis for variation in caregiving involvement among men. The neuropeptides oxytocin (OT) and vasopressin (AVP) are implicated in paternal caregiving in humans and other species. In a double-blind, placebo-controlled, within-subject pharmaco-functional MRI experiment, we randomized 30 fathers of 1–2 year old children to receive either 24 IU intranasal OT before one scan and placebo before the other scan (n = 15) or 20 IU intranasal AVP before one scan and placebo before the other scan (n = 15). Brain function was measured with fMRI as the fathers viewed pictures of their children, unknown children and unknown adults, and as they listened to unknown infant cry stimuli. Intranasal OT, but not AVP, significantly increased the BOLD fMRI response to viewing pictures of own children within the caudate nucleus, a target of midbrain dopamine projections, as well as the dorsal anterior cingulate (dACC) and visual cortex, suggesting that intranasal oxytocin augments activation in brain regions involved in reward, empathy and attention in human fathers. OT effects also varied as a function of order of administration such that when OT was given before placebo, it increased activation within several reward-related structures (substantia nigra, ventral tegmental area, putamen) more than when it was given after placebo. Neither OT nor AVP had significant main effects on the neural response to cries. Our findings suggest that the hormonal changes associated with the transition to fatherhood are likely to facilitate increased approach motivation and empathy for children, and call for future research that evaluates the potential of OT to normalize deficits in paternal motivation, as might be found among men suffering from post-partum depression.     

Maternal thyroid hormone trajectories during pregnancy and child behavioral problems

There is ample evidence demonstrating the importance of maternal thyroid hormones, assessed at single trimesters in pregnancy, for child cognition. Less is known, however, about the course of maternal thyroid hormone concentrations during pregnancy in relation to child behavioral development. Child sex might be an important moderator, because there are sex differences in externalizing and internalizing behavioral problems. The current study examined the associations between maternal thyroid hormone trajectories versus thyroid assessments at separate trimesters of pregnancy and child behavioral problems, as well as sex differences in these associations. In 442 pregnant mothers, serum levels of TSH and free T4 (fT4) were measured at 12, 24, and 36 weeks gestation. Both mothers and fathers reported on their children's behavioral problems, between 23 and 60 months of age. Latent growth mixture modeling was used to determine the number of different thyroid hormone trajectories. Three trajectory groups were discerned: 1) highest and non-increasing TSH with lowest fT4 that decreased least of the three trajectories; 2) increasing TSH and decreasing fT4 at intermediate levels; 3) lowest and increasing TSH with highest and decreasing fT4. Children of mothers with the most flattened thyroid hormone trajectories (trajectory 1) showed the most anxiety/depression symptoms. The following trimester-specific associations were found: 1) lower first-trimester fT4 was associated with more child anxiety/depression, 2) higher first-trimester TSH levels were related to more attention problems in boys only. A flattened course of maternal thyroid hormone concentrations during pregnancy was a better predictor of child anxiety/depression than first-trimester fT4 levels.     

Difficulties with emotion regulation moderate the association between childhood history of maltreatment and cortisol reactivity to psychosocial challenge in postpartum women

Exposure to child maltreatment can lead to long-term emotional difficulties and dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis. However, no prior work has examined emotion regulation as a moderator of the association between childhood history of maltreatment and cortisol response to psychosocial challenge. Amongst a sample of 140 postpartum women, associations between childhood maltreatment, emotion regulation, and cortisol response to a computerized Emotional Stroop paradigm were examined using structural equation modeling. Three saliva samples (baseline, 20- and 40-min post-challenge) were collected and later assayed for cortisol. Stepwise regression analyses revealed that difficulties with emotion regulation significantly moderated the association between maternal history of child maltreatment and cortisol reactivity (β = − 0.17, CI_.95 = − 0.31, − 0.04, t = − 2.51, p = 0.01). Specifically, women with higher child maltreatment scores and greater difficulties with emotion regulation displayed reduced cortisol reactivity. This finding suggests that diminished emotion regulation capacity may uniquely contribute to blunted physiological reactivity in postpartum women exposed to higher levels of child maltreatment. As the postpartum period has significant implications for maternal well-being and infant development, these findings are discussed in terms of adaptive responsivity, maternal behaviour, and clinical practice.     

Birth weight and other perinatal factors and childhood CNS tumors: A case–control study in California

AimsWe conducted a large registry-based study in California to investigate the association of perinatal factors and childhood CNS tumors, with analysis by tumor subtype.MethodsWe linked California cancer and birth registries to obtain information on 3308 cases and 3308 controls matched on age and sex. We examined the association of birth weight, gestational age, birth order, parental ages, maternal conditions during pregnancy, newborn abnormalities and the risk of childhood CNS tumors using conditional logistic regression, with adjustment for potential confounders.ResultsThe odds ratio (OR) per 1000 g increase in birth weight was 1.11 (95% CI: 0.99–1.24) for total childhood CNS tumors, 1.17 (95% CI: 0.97–1.42) for astrocytoma and 1.28 (95% CI: 0.90–1.83) for medulloblastoma. Compared to average-for-gestational age, large-for-gestational age infants were at increased risk of glioma (OR = 1.86, 95% CI: 0.99–3.48), while small-for-gestational age infants were at increased risk of ependimoma (OR = 2.64, 95% CI: 1.10–6.30). Increased risk of childhood CNS tumors was observed for 5-year increase in maternal and paternal ages (OR = 1.06, 95% CI: 1.00–1.12 and 1.05, 95% CI: 1.00–1.10 respectively). Increased risk of astrocytoma was detected for 5-year increase in paternal age (OR = 1.08; 95% CI: 1.00–1.16) and increased risk of glioma for maternal age ≥ 35 years old (OR = 1.87; 95% CI: 1.00–3.52). Maternal genital herpes during pregnancy was associated with a pronounced increase in risk of total CNS tumors (OR = 2.74; 95% CI: 1.16–6.51). Other (non-sexually transmitted) infections during pregnancy were associated with decreased risk of total CNS tumors (OR = 0.28, 95% CI: 0.09–0.85). Maternal blood/immune disorders during pregnancy were linked to increased risk of CNS tumors (OR = 2.28, 95% CI: 1.08–4.83) and medulloblastoma (OR = 7.13, 95% CI: 0.82–61.03). Newborn CNS abnormalities were also associated with high risk of childhood CNS tumors (OR = 4.08, 95% CI: 1.13–14.76).ConclusionsOur results suggest that maternal genital herpes, blood and immunological disorders during pregnancy and newborn CNS abnormalities were associated with increased risk of CNS tumors. Maternal infections during pregnancy were associated with decreased risk of CNS tumors. Advanced maternal and paternal ages may be associated with a slightly increased risk of CNS tumors. Factors associated with CNS tumor subtypes varied by subtype, an indicator of different etiology for different subtypes.     

Melanin-concentrating hormone in the medial preoptic area reduces active components of maternal behavior in rats

Melanin-concentrating hormone (MCH) is an inhibitory neuropeptide mainly synthesized in neurons of the lateral hypothalamus and incerto-hypothalamic area of mammals that has been implicated in behavioral functions related to motivation. During lactation, this neuropeptide is also expressed in the medial preoptic area (mPOA), a key region of the maternal behavior circuitry. Notably, whereas MCH expression in the mPOA progressively increases during lactation, maternal behavior naturally declines, suggesting that elevated MCHergic activity in the mPOA inhibit maternal behavior in the late postpartum period. To explore this idea, we assessed the maternal behavior of early postpartum females following bilateral microinfusions of either MCH (50 and 100 ng/0.2 μl/side) or the same volume of vehicle into the mPOA. As expected, females receiving 100 ng MCH into the mPOA exhibited significant deficits in the active components of maternal behavior, including retrieving and nest building. In contrast, nursing, as well as other behaviors, including locomotor activity, exploration, and anxiety-like behavior, were not affected by intra-mPOA MCH infusion. The present results, together with previous findings showing elevated expression of this neuropeptide toward the end of the postpartum period, suggest that modulation of mPOA function by MCH may contribute to the weaning of maternal responsiveness characteristic of the late postpartum period.     

Induction of androgenetic development of the brook charr (Salvelinus fontinalis) × Arctic charr (Salvelinus alpinus) hybrids in eggs derived from the parental species

Failure of interspecific androgenesis between brook charr (Salvelinus fontinalis, Mitchill 1814) and Arctic charr (Salvelinus alpinus, L.) has been attributed to the conflict between the egg cytoplasm of one species and the sperm nucleus of the other species. To overcome this incompatibility, sperm derived from the brook charr × Arctic charr hybrid male was used to induce androgenetic development in eggs originating from the parental species as well as their hybrids. The eggs were subjected to 420 Gy of X-radiation to damage the maternal nuclear DNA and inseminated with untreated sperm. Haploid zygotes were exposed to high hydrostatic pressure shock (7000 psi for 4 min), which was applied 420 min after insemination to inhibit the first cell cleavage and recover the diploid state of the zygote. The androgenetic diploid offspring that hatched from the brook charr, the Arctic charr and the hybrids eggs had survival rates of 4.7 ± 0.6%, 1.2 ± 0.4% and 16.8 ± 0.5%, respectively. Drastic mortality among the hatched androgenetic individuals was observed within the first five months of rearing. Cytogenetic analysis of the androgenetic progenies exhibited residues of the irradiated maternal nuclear genome in the form of radiation-induced chromosome fragments in 47% of the specimens that were examined. Interactions between the egg cytoplasm and the sperm nucleus, the low quality of the gametes, the expression of homozygous paternal lethal alleles and the incomplete inactivation of the maternal chromosomes were identified as factors responsible for the large mortality among androgenetic embryos and hatchlings.     

Seed storage and germination in Kumara plicatilis,a tree aloe endemic to mountain fynbos in the Boland,south-western Cape,South Africa

Seed storage under appropriate conditions is a relatively inexpensive means of safeguarding plant genetic material for ex situ conservation. Post-storage germination trials are used to determine the viability of stored seeds, and hence the efficacy of the particular storage treatment. Kumara plicatilis (= Aloe plicatilis) is a tree aloe endemic to mountain fynbos in the Boland, south-western Cape. The viability and germination behaviour of K. plicatilis seeds were assessed for seeds stored for four and nine months at − 80 °C, 4 °C, 25 °C and under ambient conditions in a laboratory. Seeds were germinated under controlled conditions and germination rates and percentages determined. Ungerminated seeds were tested for viability using tetrazolium salt. Seed viability was not significantly reduced during storage. Seeds stored at − 80 °C for four and nine months exhibited the fastest germination rate overall (both 5.9 ± 0.3 weeks, mean ± S.E.), and slowest was for seeds stored under ambient conditions for four and nine months (both 7.8 ± 0.4 weeks). All seed lots showed similar percentage germination after four months of storage (78.0–90.4%). The highest percentage germination overall was for seeds stored at − 80 °C for four months (90.4%) and the lowest was for seeds kept at 4 °C and − 80 °C for nine months (39.2 and 39.6%, respectively). Respective percentage viability for ungerminated seeds in these two treatments was 82% and 87%, respectively, indicating the induction of secondary dormancy. Induced dormancy triggered by protracted cold temperatures may be an adaptation that enables seeds to survive prolonged extreme conditions that are unfavourable for germination. Further research on the long-term storage of aloe seeds would be beneficial for developing long-term seed storage and germination testing protocols for ex situ conservation.     

Perinatal depression and DNA methylation of oxytocin-related genes: a study of mothers and their children

The present study investigated the association of perinatal depression (PD) with differential methylation of 3 genomic regions among mother and child dyads: exon 3 within the oxytocin receptor (OXTR) gene and 2 intergenic regions (IGR) between the oxytocin (OXT) and vasopressin (AVP) genes. Maternal PD was assessed at 5 time-points during pregnancy and postpartum. Four groups were established based on Edinburgh Postnatal Depression Scale (EPDS) cut-off scores: no PD, prenatal or postpartum depressive symptoms only and persistent PD (depressive symptoms both prenatally and postpartum). Salivary DNA was collected from mothers and children at the final time-point, 2.9 years postpartum. Mothers with persistent PD had significantly higher overall OXTR methylation than the other groups and this pattern extended to 16/22 individual CpG sites. For the IGR, only the region closer to the AVP gene (AVP IGR) showed significant differential methylation, with the persistent PD group displaying the lowest levels of methylation overall, but not for individual CpG sites. These results suggest that transient episodes of depression may not be associated with OXTR hypermethylation. Validation studies need to confirm the downstream biological effects of AVP IGR hypomethylation as it relates to persistent PD. Differential methylation of the OXTR and IGR regions was not observed among children exposed to maternal PD. The consequences of OXTR hypermethylation and AVP IGR hypomethylation found in mothers with persistent PDS may not only impact the OXT system, but may also compromise maternal behavior, potentially resulting in negative outcomes for the developing child.     

Postpartum ovarian activity of Santa Inês lactating ewes fed diets containing soybean hulls as a replacement for coastcross (Cynodon sp.) hay

The Santa Inês, a Brazilian hair sheep, has a non-seasonal breeding activity. Data regarding the duration of the postpartum anestrous period in Santa Inês lactating ewes is lacking and the objective of this trial was to determine the effects of replacing neutral detergent fibre (NDF) provided by coastcross (Cynodon sp.) hay with NDF contained in soybean hulls (SH) on the postpartum ovarian activity—as measured by the serum progesterone (P₄) concentration. Fifty-six lactating ewes (body weight 56.1 ± 6.8 kg) were individually penned and used in a randomized complete block design with 14 blocks and four treatments. The SH NDF replaced 33 (SH33), 67 (SH67), or 100% (SH100) of the NDF contributed by coastcross hay in the control diet (SH0). This resulted in a SH inclusion at rates of 0, 25, 54, and 85% of the dietary dry matter (DM). Blood samples were collected twice weekly from the 14th to 84th day postpartum and the serum P₄ concentrations determined by radioimmunoassay (RIA). It was estimated that the 1st postpartum ovulation occurred 6 days before the date that a serum P₄ ≥ 1 ng/ml concentration was first recorded. The mean body condition score (BCS; 0–5 scale) was 3.0 ± 0.19 on day 14 postpartum and the mean BCS at day 56 postpartum increased linearly (P < 0.01) with the inclusion levels of SH (3.09, 3.24, 3.34, and 3.36, respectively). Treatments did not differ significantly in the induction of postpartum days to the resumption of ovarian luteal activity (34.1 ± 15.3 days postpartum). On days 25, 50, and 75 postpartum 36, 80, and 100% of the ewes had resumed ovarian activity, respectively. Non-esterified fatty acid concentration decreased quadratically (P < 0.05) with the SH inclusion, with values of 0.323, 0.244, 0.204, and 0.216 mequiv./l for the SH0, SH33, SH67, and SH100 treatments being recorded, respectively. Replacement of the NDF provided by coastcross hay with the NDF from the SH did not influence the duration of the postpartum anestrous period in Santa Inês lactating ewes. Considering a 150-day gestation period and the 34 days postpartum anestrous demonstrated in the present study, the current production system of a lambing interval of 8 months (3 lambing events in 2 years) may not be optimizing the production potential and a system in which the lambing interval is shortened by at least 1 month may be feasible.     

Hypocretinergic system in the medial preoptic area promotes maternal behavior in lactating rats

Hypocretin-1 and 2 (HCRT-1 and HCRT-2, respectively) are neuropeptides synthesized by neurons located in the postero-lateral hypothalamus, whose projections are widely distributed throughout the brain. The hypocretinergic (HCRTergic) system has been associated with the generation and maintenance of wakefulness, as well as with the promotion of motivated behaviors. In lactating rats, intra-cerebroventricular HCRT-1 administration stimulates maternal behavior, whilst lactation per se increases the expression of HCRT type 1 receptor (HCRT-R1). Due to the fact that HCRTergic receptors are expressed in the medial preoptic area (mPOA), a region critically involved in maternal behavior, we hypothesize that HCRT-1 promotes maternal behavior acting on this region. In order to evaluate this hypothesis, we assessed the maternal behavior of lactating rats following microinjections of HCRT-1 (10 or 100 μM) and the selective HCRT-R1 antagonist SB-334867 (250 μM) into the mPOA, during the first and second postpartum weeks. While intra-mPOA microinjections of HCRT-1 (100 μM) increased corporal pup licking during the second postpartum week, the blockade of HCRT-R1 significantly decreased active components of maternal behavior, such as retrievals, corporal and ano-genital lickings, and increased the time spent in nursing postures in both postpartum periods. We conclude that HCRTergic system in the mPOA may stimulate maternal behavior, suggesting that endogenous HCRT-1 is necessary for the natural display of this behavior.     

Does emotional dysregulation mediate the relationship between disability and depressive symptoms in older people?

BackgroundEmotion dysregulation has been consistently linked to psychopathology, and the relationship between disability and depressive symptomatology in old age is well-known.ObjectiveTo examine the mediational role of emotional dysregulation in the relationship between perceived disability and depressive symptomatology in older adults.MethodsTwo hundred eighty-three participants, aged 60–96 years (M ± SD = 74.22 ± 8.69; 62.9% women; 29.0% with long-term care support [LTC-S] and 71.0% community residents without LTC-S), were assessed with the Geriatric Depression Scale-8 (GDS-8), the World Health Organization Disability Assessment Schedule-2 (WHODAS-2), and the Difficulties in Emotion Regulation Scale-16 (DERS-16).ResultsA mediation model was established, which revealed: (1) a moderate association between WHODAS-2 and GDS-8 (β = 0.20; p < .001); (2) DERS-16 partially and weakly mediated the relationship between WHODAS-2 and GDS-8 (β = 0.003; p < .01). The model explained 31.9% of the variance of depressive symptoms. An inconsistent mediation model was obtained in the LTC-S group.ConclusionsGlobally, our findings indicate that disability has an indirect relationship with depressive symptomatology through emotional dysregulation (except for those in the LTC-S). Accordingly, we present suggestions for the treatment of depressive symptoms and for the inclusion of other emotion regulation variables in the study of the disability-depressive symptom link in future studies with older people in the LTC-S.     

Predictive value of cystatin C and beta-2 microglobulin in preeclampsia

The purpose of this study was to determine whether the levels of cystatin C and beta-2 microglobulin (B2M) are altered during the second trimester in the plasma of women who subsequently develop preeclampsia.Study designWe performed a case control study to compare the levels of cystatin C and B2M in women in whom preeclampsia ultimately developed (n = 30) and in pregnant women who remained normotensive throughout gestation (n = 60). The maternal plasma levels of cystatin C and B2M were measured by enzyme-linked immunosorbent assay. Blood samples were collected between 15 and 20 weeks’ gestation for fetal aneuploidy screening and frozen at ?20 °C until assay after groups had been selected.ResultsThe median concentrations of cystatin C and B2M were significantly higher in those who subsequently developed preeclampsia when compared to those of normal pregnancy (median 668.6 ng/ml and 418.3 μg/ml vs 413.7 ng/ml and 321.2 μg/ml, respectively).ConclusionsIn this study, the maternal plasma levels of cystatin C and B2M were significantly elevated in pregnant women who subsequently developed preeclampsia as compared with normotensive women. Alterations of these proteins antedate clinical symptoms and, thus, they may be useful for early identification of patients at the risk of developing preeclampsia.     

Sexual performance of Awassi ram lambs reared in different sex composition groups

The objective of this study was to evaluate the effect of sex composition of the group of lambs before puberty on later sexual performance in Awassi ram lambs. Thirteen Awassi ram lambs of the same age were raised in either all-male group (n = 7) or in a group mixed with females (n = 6) from weaning to puberty. Blood samples, body weights (BW) and scrotal circumferences (SC) of ram lambs were recorded between eight and 10 months of age. Sexual performance testing was performed at 9 months of age by individually exposing ram lambs to oestrous females on five occasions. Body weight and SC were greater (P < 0.01) in the all-male compared with the mixed group. Plasma testosterone concentrations were not influenced (P > 0.05) by treatment. Plasma testosterone concentrations were significantly correlated (P ≤ 0.05) with BW (r = 0.3) and SC (r = 0.4). No treatment effects were detected regarding bouts of leg-kicking. Bouts of anogenital sniffing, the frequency of mount attempts and mounting frequency were greater (P < 0.05) in the all-male group. Even though the frequency of raising the fat tail of females was similar between the two treatments, the mixed group tended to be (P = 0.08) more efficient in doing so than the all-male group (higher tail raising/mount). Results of the current study indicate that mixing groups of ram and ewe lambs before puberty may be insufficient to improve later sexual performance of ram lambs.     

Prolactin, Oxytocin, and the development of paternal behavior across the first six months of fatherhood

Animal studies have implicated the neuropeptides Prolactin (PRL) and Oxytocin (OT) in processes of maternal bonding and PRL has similarly been shown to play a role in the neurophysiology of fatherhood. Yet, very little is known on the involvement of PRL and OT in human fathering. Forty-three fathers and their firstborn infant were seen twice: in the second and sixth postpartum months. Paternal plasma PRL and OT were sampled at both time-points and analyzed with ELISA methods. At six months fathers were videotaped interacting with their child in social and exploratory play contexts and interactions were micro-analyzed for father-infant Affect Synchrony and father facilitation of child toy exploration. PRL and OT showed high individual stability across time and were correlated at the second observation. PRL was related to father-infant Coordinated Exploratory Play in the toy context whereas OT was associated with father-infant Affect Synchrony in the social context. Results point to the role of PRL and OT in the development of human fathering and underscore their differential relations with patterns of paternal care.     

Effect of resistance exercise on muscle steroid receptor protein content in strength-trained men and women

The purpose of this study was to examine the acute effect of resistance exercise (RE) on muscle androgen receptor (AR) and glucocorticoid receptor (GR) protein content. Fifteen resistance-trained men (n = 8; 21 ± 1 years, 175.3 ± 6.7 cm, 90.8 ± 11.6 kg) and women (n = 7; 24 ± 5 years, 164.6 ± 6.7 cm, 76.4 ± 15.6 kg) completed 6 sets of 10 repetitions of heavy squats. Blood samples were obtained before RE, after 3 and 6 sets of squats, and 5, 15, 30 and 70 min after RE. Muscle biopsies from the vastus lateralis were obtained before RE, and 10 min and 70 min after RE. Blood samples were analyzed for total and free testosterone concentrations and muscle samples were analyzed for AR and GR protein content. Circulating total testosterone increased significantly (p ≤ 0.05) in men and free testosterone increased in men and women with exercise. AR was significantly reduced at 70 min post-exercise in men and at 10 min post-exercise in women compared to pre-exercise. There were no changes in GR following RE, but GR was significantly higher in women compared to men. These findings support a current paradigm for stabilization followed by a reduction and then a rebound in the acute AR response to RE but demonstrate that gender differences exist in the timeline of the AR response.