Pair Housing Research Articles

Sex differences in testosterone reactivity and sensitivity in a non-model gerbil

Although testosterone (T) is a key regulator in vertebrate development, physiology, and behaviour in both sexes, studies suggest that its regulation may be sex-specific. We measured circulating T levels in Baluchistan gerbils (Gerbillus nanus) in the field and in the lab all year round and found no significant sex differences. However, we observed sex differences in circulating T levels following gonadotropin-releasing hormone (GnRH) challenge and T implants in this non-model species. Whereas only males elevated T following a GnRH challenge, females had higher serum T concentrations following T implant insertion. These differences may be a result of different points of regulation along the hypothalamic-pituitary–gonadal (HPG) axis. Consequently, we examined sex differences in the mRNA expression of the androgen receptor (AR) in multiple brain regions. We identified AR and β-actin sequences in assembled genomic sequences of members of the Gerbillinae, which were analogous to rat sequences, and designed primers for them. The distribution of the AR in G. nanus brain regions was similar to documented expression profiles in rodents. We found lower AR mRNA levels in females in the striatum. Additionally, G. nanus that experienced housing in mixed-sex pairs had higher adrenal AR expression than G. nanus that were housed alone. Regulation of the gerbil HPG axis may reflect evolutionary sex differences in life-history strategies, with males ready to reproduce when receptive females are available, while the possible reproductive costs associated with female T direct its regulation upstream.

Abstract WP143: Identification of Socially-Regulated Circulating Microrna Signatures in Stroke

Introduction: Epidemiological and clinical studies strongly support that social isolation (SI) is associated with higher mortality after stroke. SI has been identified as a risk factor in a wide variety of diseases, including stroke. However, few studies have attempted to identify the underlying mechanisms contributing to the detrimental effect of SI. To better understand systemic and global regulation networks governed by social factors, and in an attempt to identify viable biomarkers, we profiled changes in circulating microRNA (miRNA) expression in aged stroke mice after SI. Methods: Aged C57BL/6 mice (18-20 months) of both sexes were pair-housed (PH) or socially isolated (SI) for two weeks prior to sham or a 60-minute middle cerebral artery occlusion surgery. Mice were sacrificed two weeks after surgery and blood samples were obtained for profiling of plasma miRNAs. Using whole miRNAome analysis, differentially expressed miRNAs by isolation, stroke and sex differences were comprehensively identified and compared using bioinformatics. We further used mimic and antagomiR treatments to confirm a potential role of the identified miRNAs. Results: Stroke significantly changed 8 miRNAs including miR-467d-3p ( P =0.0014), miR-376b-3p ( P =0.013) and miR-297c-5p ( P =0.016) in PH groups (sham vs. stroke). In a comparison between PH vs. SI in stroke mice, stroke SI mice showed a differential miRNA profile (11 miRNAs) including let-7 family potentially targeting Dicer protein, a key enzyme for miRNA biogenesis. Interestingly, compared to sham SI mice, stroke SI mice had a 2-fold increase in the number of altered miRNAs (21 miRNAs) including miR-129-1-3p ( P =0.0075), miR-28a-3p ( P =0.0091) and miR-204-5p ( P =0.016). Finally, we found a strong sex difference in miRNA expression in response to SI. Conclusions: We identified several key miRNAs as potential biomarkers for 1) stroke, 2) SI and 3) SI/stroke. These miRNA signatures are highly unique and create a complex gene-regulatory network that depends on the social environment. Our data provide potential biomarkers and identify several miRNAs that could lead to significant improvements in diagnosis of elderly patients at elevated risk for the detrimental effects of loneliness.

Effects of pair housing on voluntary alcohol intake in male and female Wistar rats.

A number of different voluntary alcohol intake paradigms are available for home cage drinking studies. Traditionally, these paradigms involve single housing in order for individual intake to be measured. This study aimed at investigating the effects of pair housing on voluntary alcohol intake. Male and female Wistar rats were housed in pairs or individually for studies of voluntary alcohol intake using the modified intermittent access paradigm with alcohol access during three consecutive days per week followed by four days of water only. Individual intake of 20% alcohol solution and water was measured during 12 sessions, i.e., 4 weeks. Pair-housed animals could interact freely with their cage mate for four consecutive days each week and were then separated by an inserted mesh divider for three consecutive days each week during alcohol intake sessions. Alcohol intake and preference were compared between pair-housed and individually housed rats. The results revealed higher alcohol intake in females than in males. Pair-housed males had a higher alcohol intake and preference during the first 3 weeks, but not during the fourth week, compared to individually housed males No effect of housing condition was observed in female rats. The alcohol intake was higher on the first day of access relative to the two consecutive days in pair-housed males and higher on the first two days relative to the third day in female rats. Social rank or female estrus cycle had no effect on alcohol intake or preference. Taken together, the use of a divider during alcohol intake sessions had no impact on alcohol intake in female rats and may not exert long-term influences in male rats. Future studies are needed in order to elucidate whether the use of a divider can constitute an experimental refinement as an alternative to individual housing in studies of voluntary alcohol intake using the limited access and/or intermittent access paradigms.

Behavioral predictors of pairing success in rhesus macaques (Macaca mulatta).

Pair housing is one of the most important components of behavioral management for caged macaques; however, it can result in aggression and injury if partners are incompatible. Knowing when to proceed and when to stop social introductions can be challenging, and can have consequences for the partners. We examined whether behavior early in social introductions predicted success (i.e., partners remained cohoused with full contact for at least 28 days) in 724 female-female and 477 male-male rhesus macaque pairs. We took cage side one-zero focal observations on pairs during the first 2 days of full contact, recording social and aggressive behaviors. The majority of pairs (79.6% of female and 83.0% of male) were successful. The most common behaviors exhibited by pairs during these observations were maintaining proximity, tandem threats, and anxiety. Mounting was also relatively common in male pairs. Grooming and close social contact (e.g., touching) were not common in our study. Several behaviors observed on Day 1 significantly predicted pairing success. For females, these included proximity, tandem threat, rump present, mount, and groom. Day 1 predictors of success for male pairs included proximity, tandem threat, rump present, mount, and social contact. Fewer behaviors predicted success on Day 2. Maintaining proximity on Day 2 predicted success for both sexes, but tandem threat predicted success only for females. Behaviors that predicted incompatibility for females on Day 1 included displace, grimace, threat, bite, and other aggressive contacts. Day 1 predictors of separation for male pairs were displaced, grimace, and abnormal behavior. The only Day 2 behavior that correlated with incompatibility was grimace, which was predictive for males. Interestingly, aggression did not predict incompatibility for male pairs. Identifying behaviors exhibited by monkeys early in the pair introduction that are predictive of long-term compatibility can shape pairing decisions, reducing later stress and potential injury.

Effects of Pair Versus Individual Housing on Performance, Health, and Behavior of Dairy Calves.

Simple SummaryIn modern dairy farming systems, calves are often housed in individual pens or hutches, which results in less social interaction with their peers during the milk-feeding period. The aim of this study was to evaluate the effects of pair versus individual housing on performance, health, and behavior of dairy calves from the milk-feeding period to the first week after mixing. Results showed that pair versus individual housing had no effects on body weight, starter intake or average daily gain during the milk-feeding period, while pair housing increased the growth performance of calves during weaning and postweaning periods, and the beneficial effects of pair housing on growth faded after calves were mixed and moved to group housing. Paired calves showed higher diarrhea frequency only in week three. The behavior of calves was altered at different periods, including increased time spent in feeding, chewing and ruminating, and decreased self-grooming time, and a drop of non-nutritive manipulation for all calves after they were mixed and moved to group housing. We also found less social contact may lead to more non-nutritive manipulation.The aim of this study was to evaluate the effects of pair versus individual housing on performance, health, and behavior of dairy calves. Thirty female Holstein dairy calves were assigned to individual (n = 10) or pair housing (n = 10 pairs). The results showed that both treatments had a similar starter intake and average daily gain (ADG) during the preweaning period. During weaning and postweaning periods, paired calves had a higher starter intake, and the ADG of paired calves continued to increase but calves housed individually experienced a growth check. Paired calves showed higher diarrhea frequency only in week three. The results on behavior showed that feeding, chewing and ruminating time increased, and self-grooming time decreased with age during weaning and postweaning periods, and paired calves spent less time feeding, standing and self-grooming but more time lying during this time. After mixing, feeding, and chewing and ruminating time continued to rise, and self-grooming time continued to decline for both treatments. All calves spent less time standing and non-nutritive manipulation after mixing, and previously individually housed calves tended to increase non-nutritive manipulation. These results showed that pair housing improved growth during weaning and postweaning periods and that calves altered their behavior at different phases. Less social contact may lead to more non-nutritive manipulation.

301 Effects of housing system on performance and behavior of dairy calves before and after weaning

Abstract The aim of this study was to evaluate the effects of housing system on performance and behavior of dairy calves during pre-weaning (d 1–42), weaning (d 43–56), post-weaning (d 57–63) and mixing (d 64–70) period. Thirty-seven newborn Holstein dairy calves were allocated to individual (n = 17) or pair housing (n = 10 pairs). After that, calves remained in their pens until d 63 ± 1, and then PH group and IH group were mixed and moved to 6 group pens randomly. Starter intake, fecal consistency scores and body weight were collected. Instantaneous scan-sampling with 5-min intervals was used to collect the behavioral observations (lying, ruminating, standing, eating, drinking, walking, self-grooming, manipulating object) for 48 h beginning on d 43, 50, 57 and the second day after mixing. Data were analyzed by mixed effect model with treatment, time, and the interaction between them as fixed effects, and animal within treatment as a random effect. During post-weaning period, PH group had higher starter intake (P = 0.02) and average daily gain (P = 0.02) than IH group. PH group weighed more on d 63 (P = 0.002) and d 70 (P = 0.002). PH group had higher diarrhea frequency than IH group in week 3 (P = 0.03). PH increased lying time in week 8 (P = 0.03) and walking time during post-weaning period (P = 0.05), yet IH group spent more time standing in week 8 (P = 0.008), eating during post-weaning period (P = 0.008), self-grooming during weaning period (week 7, P = 0.007; week 8, P = 0.03). Furthermore, previous housing system had no effect on calves’ behavior after mixing. In conclusion, Pair housing during post-weaning period improved performance of calves and housing system had on effect on behavior after mixing. Figure 1. ADG (mean±SEM) for calves housed individually (n = 17 calves) or in pairs (n = 10 pairs). PH = calves housed in pairs; IH = calves housed individually. * P ≤ 0.05, † P < 0.10. Figure 2. BW (mean±SEM) for calves housed individually (n = 17 calves) or in pairs (n = 10 pairs). PH = calves housed in pairs; IH = calves housed individually. * P ≤ 0.05, † P < 0.10. Figure 3. Diarrhea frequency for calves housed individually (n = 17 calves) or in pairs (n = 10 pairs) before 63d. PH = calves housed in pairs; IH = calves housed individually. * P ≤ 0.05. Figure 4. Time (mean±SEM) for calves (n = 6) performing each behavior as affected by different housing system during weaning, post-weaning and mixing period.* P ≤ 0.05.

Pair housing makes calves more optimistic

Individual housing of dairy calves is common farm practice, but has negative effects on calf welfare. A compromise between practice and welfare may be housing calves in pairs. We compared learning performances and affective states as assessed in a judgement bias task of individually housed and pair-housed calves. Twenty-two calves from each housing treatment were trained on a spatial Go/No-go task with active trial initiation to discriminate between the location of a teat-bucket signalling either reward (positive location) or non-reward (negative location). We compared the number of trials to learn the operant task (OT) for the trial initiation and to finish the subsequent discrimination task (DT). Ten pair-housed and ten individually housed calves were then tested for their responses to ambiguous stimuli positioned in-between the positive and negative locations. Housing did not affect learning speed (OT: F1,35 = 0.39, P = 0.54; DT: F1,19 = 0.15, P = 0.70), but pair-housed calves responded more positively to ambiguous cues than individually housed calves (χ21 = 6.79, P = 0.009), indicating more positive affective states. This is the first study to demonstrate that pair housing improves the affective aspect of calf welfare when compared to individual housing.

Key animal welfare issues in commercially raised dairy calves: social environment, nutrition, and painful procedures

Dairy calf welfare concerns are growing and new evidence suggests that the early life environment influences appropriate physical, behavioral, and cognitive development lasting into adulthood. This review highlights key evidence for the impacts of housing, diets, and painful procedures on calf welfare. We argue that these topics are currently critical welfare concerns, but are not the only points of concern. In addition to environmental requirements to maintain optimal health, dairy calves experience other challenges including social and nutritional restrictions. Individual housing is associated with impaired behavioral development and cognitive ability. Pair and group housing can mitigate some of these negative effects and should be encouraged. Restrictive milk allowances (<15% of body weight) lead to poor growth and hunger; these welfare concerns can be addressed with proper enhanced milk allowances and gradual weaning programs. Finally, dehorning is a critical animal welfare issue when pain control is withheld; calves show negative behavioral, physiological, and emotional responses during and after dehorning. The combined use of local anaesthetics and analgesics can mitigate these effects. An industry shift toward providing social companionship, enhanced milk allowances, and pain control during painful procedures would help to improve the welfare of dairy calves in intensive commercial rearing facilities.

Micro RNA 181c-5p: A promising target for post-stroke recovery in socially isolated mice

Dysregulation of microRNAs (miRNAs) has been tied to several neurological disorders, including ischemic stroke. It has also been established that social environments can modulate miRNA profiles. We have previously shown that post-stroke social isolation (SI) is linked to poor stroke outcomes and that miR-181c-5p emerged as one of few lead miRNAs that was downregulated in both stroke and SI. Therefore, in this study we examined the potential role of miR-181c-5p mimic in reversing the detrimental effects of post-stroke SI. Two to three-month-old C57BL/6 male mice were pair-housed (PH) for at least two weeks. After two weeks, mice underwent stroke survival surgery using middle cerebral artery occlusion (MCAO) and were randomly assigned to one of two housing conditions: stroke isolation (ST-ISO) or stroke pair-housing with a healthy partner (ST-PH). ST-ISO mice were randomized to receive either miR-181c-5p mimic or a scrambled RNA (7 mg/kg i.v./day×drug) control at 24 h and 48 h after stroke. The effects of miR-181c-5p mimic treatment were evaluated at 1, 3, and 7 days after stroke at histological, behavioral, and biochemical levels. Target genes of miR-181c-5p were then analyzed by qPCR using an RT2 Profiler qPCR Array of pre-coated miR-181c gene targets. Temporal profile expression data suggested that miR-181c-5p was significantly downregulated (p < 0.05 vs ST-PH) up to 7 days after post-stroke SI. MiR-181c-5p mimic treatment significantly increased miR-181c-5p expression in brain tissue and showed partial swift recovery in sensorimotor deficit. Target gene analysis identified downregulation of several calcium signaling-related genes, e.g., Cpne2 and Gria 1 & 2 after miR-181c-5p mimic treatment. In summary, present data suggests that miR-181c-5p is a potential target for post-stroke SI. Data also suggests that genes related to calcium and glutamate signaling might be involved in the beneficial effect of the miR-181c-5p mimic.

Sex and housing conditions modify the effects of adolescent caffeine exposure on anxiety-like and depressive-like behavior in the rat.

Previously observed antidepressant-like effects of caffeine in adolescent rats have been shown in individually housed (IH) rats. Because IH presents a social stressor that may create depressant-like effects in control animals, this study sought to compare the effects of chronic caffeine in IH and pair-housed (PH) adolescent male and female rats. Housing conditions began on postnatal day 24 (P24) and half of the rats were provided caffeine (0.25 g/l) in their drinking water beginning on P28. Open-field behavior was assessed on P42, a light/dark test was conducted on P43, and a forced swim test was conducted on P44-P45. PH and caffeine separately increased behavior in the open-field test and females reared more than males. In the light/dark test, IH animals and males showed greater anxiety-like behavior than PH animals and females, respectively. In the forced swim test, PH animals showed less overall immobility and caffeine decreased immobility in IH rats and PH females but increased immobility in PH males. Swimming behavior was higher in PH rats overall and caffeine increased swimming in IH rats but decreased swimming in PH rats. Climbing behavior was increased by caffeine in all groups except PH males with the greatest increase in PH females. We conclude that the effects of caffeine on depressive-like and anxiety-like behavior in adolescents are dependent on sex and housing conditions.

Influence of Social Isolation During Prolonged Simulated Weightlessness by Hindlimb Unloading.

The hindlimb unloading (HU) model has been used extensively to simulate the cephalad fluid shift and musculoskeletal disuse observed in spaceflight with its application expanding to study immune, cardiovascular and central nervous system responses, among others. Most HU studies are performed with singly housed animals, although social isolation also can substantially impact behavior and physiology, and therefore may confound HU experimental results. Other HU variants that allow for paired housing have been developed although no systematic assessment has been made to understand the effects of social isolation on HU outcomes. Hence, we aimed to determine the contribution of social isolation to tissue responses to HU. To accomplish this, we developed a refinement to the traditional NASA Ames single housing HU system to accommodate social housing in pairs, retaining desirable features of the original design. We conducted a 30-day HU experiment with adult, female mice that were either singly or socially housed. HU animals in both single and social housing displayed expected musculoskeletal deficits versus housing matched, normally loaded (NL) controls. However, select immune and hypothalamic-pituitary-adrenal (HPA) axis responses were differentially impacted by the HU social environment relative to matched NL controls. HU led to a reduction in % CD4+ T cells in singly housed, but not in socially housed mice. Unexpectedly, HU increased adrenal gland mass in socially housed but not singly housed mice, while social isolation increased adrenal gland mass in NL controls. HU also led to elevated plasma corticosterone levels at day 30 in both singly and socially housed mice. Thus, musculoskeletal responses to simulated weightlessness are similar regardless of social environment with a few differences in adrenal and immune responses. Our findings show that combined stressors can mask, not only exacerbate, select responses to HU. These findings further expand the utility of the HU model for studying possible combined effects of spaceflight stressors.

Effect of individual vs pair housing during the pre-weaning period on dairy calf well-being to four months of age

Pair housing of dairy calves during the pre-weaning period helps meet the natural social needs of the calf and has been shown to improve growth and starter intake during the pre-weaning period as compared to individual housing. However, there is little evidence to suggest that pair housed calves maintain their social and growth advantages past the weaning phase. The objective of this study was to investigate the effect of pair housing on measures of behavioral and physiologic well-being during the first four months of life.

Group housing with young mice relieves Alzheimer's disease behaviors in aging mice.

Due to the increase in human life expectancy, a higher number of individuals are experiencing age-related cognitive impairments. Therefore, it is important to investigate the methods to tackle the effects of aging. The mice were divided into the following groups: the aging mice (male, 20 months) and young mice (male, 2 months) were pairing-housed together in the same cage and lasted for at least one month (Aging-Young). The following tests were performed for the mice in different groups: Open field test, Morris water maze (MWM) test, Contextual fear conditioning test, Novel Object Recognition (NOR) test, Pain threshold test, Olfactory habituation/dishabituation test, T-maze test, Electrophysiological recordings. In this study, we housed aging and young mice together, and found that the paired housing for one-month improved the learning and memory of the aging mice. These mice exhibited better performance on the Morris water maze (MWM) test, a longer freezing duration in the contextual fear conditioning test, a higher alternation rate in the T-maze test, and an increased preference for novel objects in the novel object recognition (NOR) test. The paired housing with young mice also improved the impaired long-term potentiation (LTP) in aging mice. Our results suggest that the paired housing with young mice has beneficial effects on learning and memory of aging mice. The manipulation of the systemic environment may, therefore, provide a new strategy for aging rejuvenation.

Oxytocin and pair compatibility in adult male rhesus macaques (Macaca mulatta).

Pair housing is considered one of the best ways of promoting psychological wellbeing for caged macaques. However, incompatible partnerships can result in stress or aggression. Though previous studies have analyzed the role of variables such as age, weight, gender, and temperament on pair compatibility, few have examined the relationship between physiological parameters and pair compatibility. Oxytocin is known to promote prosocial nonsexual behavior in various primate species and may serve as an indicator of pair compatibility. In this study, we examined the association between peripheral oxytocin levels and prosocial behaviors in isosexual pairs of male rhesus macaques. We hypothesized that animals that demonstrated high levels of prosocial behaviors would have higher oxytocin levels than those showing low levels of the behavior. In addition, to elucidate the relationship between oxytocin and compatibility, we compared peripheral oxytocin between the highly affiliative animals and single-housed males identified as having multiple unsuccessful pair attempts with multiple partners. We collected plasma oxytocin on 40 pairs of monkeys that had lived together for at least 1 month and 20 single-housed animals. Further, we simultaneously collected behavioral data on the pairs, recording prosocial interactions (e.g., groom, play). Oxytocin varied among individuals, but was highly correlated between members of a pair (r = 0.58, p < .001). Additionally, prosocial behavior was positively correlated with plasma oxytocin (r = 0.38, p < .02). However, contrary to our expectations, oxytocin did not differ between single and highly affiliative pair-housed animals (F(1,38) = 0.71, p = .40). Our results suggest that oxytocin may be associated with the quality of isosexual pairs of male macaques. More work is needed to determine the nature of this relationship.

Early-stage paired housing improves social interaction in neuronal Uba6-deficient mice

UBA6 is an alternative enzyme for ubiquitin activation in vertebrates that plays a pivotal role in early mouse development. Previously, we reported that the Uba6 brain-specific knockout (NKO) mouse is a novel autism spectrum disorder (ASD) mouse model that displays decreased social behavior and communication. To determine the therapeutic impact of environmental stimulation in ASDs, we investigated the behavioral and molecular changes of the NKO and control mice after exposure to environmental enrichment and paired housing in different developmental phases. Our results demonstrated that early paired housing could diminish the ASD phenotypes of NKO mice such as impaired nest building and social interaction and anxiety. Additionally, increased histone acetylation in the amygdala was observed in NKO mice after paired housing without a change in Ube3a levels. Our data suggest that paired housing at an early time point can play a crucial role in ameliorating ASD behavior and can be applied in other ASD animal models or clinical settings.

Pair-housing rats does not protect from behavioral consequences of an acute traumatic experience.

Posttraumatic stress disorder (PTSD) is an extremely debilitating disease with a broad array of associated symptoms, making the disorder difficult to diagnose and treat. In humans, patients seem to benefit from group therapy or other means of promoting social behavior. To test these effects on our rodent model of PTSD, adult, male rats were housed in either single or pair conditions prior to and during an acute stressor to induce PTSD-like behaviors in these rats. Subsequently, rats were assessed for PTSD-like symptoms to determine the effect of social housing on stress-induced phenotypes. Posttrauma phenotypes, including enhanced fear conditioning and anxiety-related behavior, persisted regardless of the animal's housing condition. It is possible that any housing driven improvements to stress-induced phenotypes would require longer periods of pair housing than were used in these experiments. Although PTSD patients show improved health outcomes following social interaction or group therapy, the fear and anxiety phenotypes seen following an acute stressor in an animal model of the disease endured despite an animal's housing condition. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Effects of Isolated or Enriched Housing at Adolescence Upon Ethanol Intake and Anxiety Responses, In Rats Exposed to Prenatal Ethanol

Abstract&#x0D; Prenatal alcohol exposure (PAE) is highly prevalent worldwide, and can affect alcohol intake and anxiety responses in the offspring. It is still relatively unknown how PAE interacts with stress exposure at adolescence, and there is a scarcity of treatments to reduce the impact of PAE. The present study assessed alcohol (ethanol) intake and anxiety responses after PAE and tested the modulation of these responses by different housing conditions during early adolescence. Pregnant dams were exposed for 22 hours/day, from gestational day 0, throughout pregnancy, and until postnatal day 7 (PD 7), to a single bottle of 10% ethanol that was mixed in tap water and sucralose (EtOH Group), or to a single bottle of tap water and sucralose (CTRL Group). During PDs 21-42 the offspring was exposed to standard pair housing, isolated housing or enriched housing. Immediately after, they were pair-housed and tested for ethanol intake in 24-hour access, intermittent 2-bottle choice sessions conducted over 4 weeks, and for anxiety responses in the light-dark box test. The EtOH offspring exhibited heightened anxiety (i.e., greater avoidance of the white area of the light-dark box) at PD21, when compared to control (CTRL) rats. Isolated housing induced greater avoidance of the white area, when compared to standard or enriched housing, on PDs 42 and 70. There were no significant EtOH versus CTRL differences in relative (i.e., percent preference vs. water) ethanol intake, yet overall fluid intake and absolute (g/kg) ethanol intake were significantly lower in EtOH versus CTRL rats. Enriched housing during adolescence had a suppressing effect upon absolute ethanol intake during the first week of testing, an effect more noticeable in CTRL than in PAE rats. The present study indicates that PAE or isolated housing is associated with an anxiety-like phenotype. The protracted PAE protocol here employed caused a generalized reduction of intake behaviours. Environmental enrichment was associated with a subtle, yet significant, reduction in absolute ethanol intake.&#x0D;

Hand Wipes: A Useful Tool for Assessing Human Exposure to Poly- and Perfluoroalkyl Substances (PFASs) through Hand-to-Mouth and Dermal Contacts.

The indoor environment contributes considerably to human exposure to poly- and perfluoroalkyl substances (PFASs). This study estimated the human exposure to PFASs from the indoor environment through hand-to-mouth and dermal contacts using hand wipes. An analytical method was developed to determine 25 PFASs in hand wipe samples collected as a composite sample from both hands of 60 adults. Polyfluoroalkyl phosphate esters (PAPs) were the predominant PFASs in the hand wipe samples (medians between 0.21 and 0.54 ng per sample). Positive and significant correlations were observed between PAPs, perfluorooctanesulfonate (PFOS), and perfluorooctanoate (PFOA) in hand wipes. Low frequency of daily hand washing (≤8 times day-1) was associated with 30-50% higher concentrations of PFOS, PFOA, and 8:2diPAP in hand wipes. Further, significant correlations between paired hand wipes and house dust samples were observed for PFOS, PFOA, and 6:2diPAP. Also, a significant correlation between PFOS in hand wipes and EtFOSE in indoor air was found. This finding indicates either a common source of exposure or a transformation of EtFOSE to PFOS in the environment or on the hands. The contributions of direct and indirect exposure to perfluoroalkyl acids (PFAAs) showed that PFOA contributed the highest exposure to adults via hand-to-mouth and dermal contacts, followed by PFOS. The median of estimated daily intakes via hand-to-mouth and dermal contacts (for hands only) for PFOA were 0.83 and 0.50 pg·kg bw-1·day-1, respectively. This study gives a first indication that PFAS concentrations in hand wipes can be used as a proxy for the exposure to PFASs from indoor environments, but further studies are needed to confirm this.

Effects of housing conditions on behaviors and biochemical parameters in juvenile cynomolgus monkeys (Macaca fascicularis).

To investigate the effects of environmental enrichment on laboratory monkeys, we studied behavioral and physiological differences following changes in housing conditions. Ten male and female juvenile cynomolgus monkeys were first housed in pairs for 8 weeks after quarantine/acclimatization (singly housed) and subsequently housed alone for the next 8 weeks. Monkeys were subjected to evaluations of body weight gain, stereotypic or affiliative behaviors, cortisol, 4-ethylphenyl sulfate (4EPS) and catecholamine concentrations in biological samples, and blood chemistry tests under both housing conditions. Under paired housing, the stereotypic behavioral score decreased in both sexes, and the affiliative behavioral score increased in males and showed an increasing trend in females. Under single housing, the stereotypic score increased in both sexes, and the affiliative score decreased in males. Paired housing decreased serum calcium and urine cortisol concentrations in both sexes and decreased plasma cortisol in males and plasma 4EPS concentrations in females. The stereotypic score was positively correlated with serum calcium, plasma and urine cortisol, and plasma 4EPS concentration and negatively correlated with the affiliative score. The feces painting score, affiliative score, and plasma cortisol and serum calcium concentrations showed sex differences, suggesting differences in responsiveness to environmental changes between males and females. In conclusion, paired housing improved behavioral abnormalities in juvenile cynomolgus monkeys, suggesting that it may be an effective environmental enrichment paradigm. Calcium, cortisol, and 4EPS concentrations in biological samples may be useful indices for evaluating the effects of environmental enrichment.

When to change your tune? Unpaired and paired male house wrens respond differently to anthropogenic noise

In response to anthropogenic noise, many bird species adjust their song frequency, presumably to optimize song transmission and overcome noise masking. But the costs of song adjustments may outweigh the benefits during different stages of breeding, depending on the locations of potential receivers. Selection might favor unpaired males to alter their songs because they sing to attract females that may be widely dispersed, whereas paired males might not if mates and neighbors are primary receivers of their song. We hypothesized male house wrens (Troglodytes aedon) respond differently to noise depending on their pairing status. To test our hypothesis we synthesized pink noise, which mimics anthropogenic noise, and played it at three intensities in territories of paired and unpaired focal males. We recorded their songs and analyzed whether song structure varied with pairing status and noise treatment. To validate our study design, we tested whether noise playback affected measurement of spectral song traits and changed noise levels within territories of focal males. Consistent with our predictions, unpaired males sang differently than paired males, giving longer songs at higher rates. Contrary to predictions, paired males changed their songs by increasing peak frequency during high intensity noise playback, whereas unpaired males did not. If adjusting song frequency in noise is beneficial for long-distance communication we would have expected unpaired males to change their songs in response to noise. By adjusting song frequency, paired males reduce masking and produce a song that is easier to hear. However, if females prefer low frequency song, then unpaired males may be constrained by female preference. Alternatively, if noise adjustments are learned and vary with experience or quality, unpaired males in our study population may be younger, less experienced, or lower quality males.