Synopsis
For cooperative species, there can be great value in the synchronization of physiological states to coordinate group behavioral states. This is evident in naked mole-rats (Heterocephalus ...glaber), which have the most extreme form of cooperative breeding in mammals. Colonies have a single reproductive female, “the queen,” and 1–3 breeding males. These breeders are supported by adult “subordinates,” which are all socially suppressed into a pre-pubertal state. Subordinates cooperate in colony maintenance, defense, and alloparental care. Prior work has reported that there may be social sharing of hormones among individuals in the colony because when the queen is pregnant, subordinates of both sexes develop enlarged nipples and female subordinates can develop vaginal perforation. We sought to document the hormonal changes and mechanisms behind these observations. We found that subordinate estradiol levels were elevated during the queen’s pregnancy and were correlated with queen levels. To determine if this occurs by direct hormone-sharing, where group members uptake the hormones of conspecifics through excreta or the skin, we then tested whether treating a single subordinate in the colony with estradiol would induce the same effect in other colony members. It did not, which indicates that the influence on group estradiol levels may be specific to cues from the queen. These queen cues may be behavioral in nature, as we found that queens were less aggressive during pregnancy, which prior work has suggested may relax reproductive suppression of subordinates. Yet, levels of queen aggression alone were not associated, or were weakly associated, with their colony’s estradiol levels, though our sample size examining this particular relationship was low. This is suggestive that additional queen cues of reproductive status, beyond just aggression, may be relevant in influencing the subordinate hormonal change, or that the relationship between aggression and colony estradiol levels is more subtle and would need to be elucidated with a larger sample size. These results have implications for how cooperative breeders coordinate reproduction and alloparental care, and how social cues can influence individual and group physiology.
The central circadian pacemaker, the suprachiasmatic nucleus (SCN), encodes day length information by mechanisms that are not well understood. Here, we report that genetic ablation of miR-132/212 ...alters entrainment to different day lengths and non-24 hr day-night cycles, as well as photoperiodic regulation of Period2 expression in the SCN. SCN neurons from miR-132/212-deficient mice have significantly reduced dendritic spine density, along with altered methyl CpG-binding protein (MeCP2) rhythms. In Syrian hamsters, a model seasonal rodent, day length regulates spine density on SCN neurons in a melatonin-independent manner, as well as expression of miR-132, miR-212, and their direct target, MeCP2. Genetic disruption of Mecp2 fully restores the level of dendritic spines of miR-132/212-deficient SCN neurons. Our results reveal that, by regulating the dendritic structure of SCN neurons through a MeCP2-dependent mechanism, miR-132/212 affects the capacity of the SCN to encode seasonal time.
Display omitted
•miR-132/212 modulates entrainment to seasonal photoperiods•Ablation of miR-132/212 reduces dendritic spine density of SCN clock neurons•Photoperiod regulates miR-132/212 expression and dendritic morphology in hamsters•miR-132/212 acts through MeCP2, and downstream BDNF and mTOR are involved
Seasonal adaptation is believed to require plasticity in the SCN, although the mechanisms are unclear. Mendoza-Viveros et al. report that miR-132/212 modulates dendritic protrusion density and photoperiodic adaptation in mice and hamsters, by regulating the expression of MeCP2, and downstream BDNF and mTOR signaling.
The neuropeptide oxytocin regulates a wide variety of social behaviors across diverse species. However, the types of behaviors that are influenced by this hormone are constrained by the species in ...question and the social organization that a particular species exhibits. Therefore, the present experiments investigated behaviors regulated by oxytocin in a eusocial mammalian species by using the naked mole-rat (Heterocephalus glaber). In Experiment 1, adult non-breeding mole-rats were given intraperitoneal injections of either oxytocin (1mg/kg or 10mg/kg) or saline on alternate days. Animals were then returned to their colony and behavior was recorded for minutes 15–30 post-injection. Both doses of oxytocin increased huddling behavior during this time period. In Experiment 2, animals received intraperitoneal injections of either oxytocin (1mg/kg), an oxytocin-receptor antagonist (0.1mg/kg), a cocktail of oxytocin and the antagonist, or saline across 4 testing days in a counterbalanced design. Animals were placed in either a 2-chamber arena with a familiar conspecific or in a small chamber with 1week old pups from their home colony and behaviors were recorded for minutes 15–30 post-injection. Oxytocin increased investigation of, and time spent in close proximity to, a familiar conspecific; these effects were blocked by the oxytocin antagonist. No effects were seen on pup-directed behavior. These data suggest that oxytocin is capable of modulating affiliative-like behavior in this eusocial species.
•Peripheral oxytocin administration increases huddling in the naked mole-rat colony.•Peripheral oxytocin administration also increases investigation of and proximity between familiar conspecifics.•Co-administration with an oxytocin antagonist blocks the effect of oxytocin on investigation and proximity.•Oxytocin mediates social affiliation in eusocial naked mole-rats.
Sexual dimorphism in skeletal muscle is prominent in mammals, with males typically having larger and stronger muscles than females. Furthermore, neuromuscular systems with sexual functions are ...remarkably sexually dimorphic in a wide variety of vertebrates. Endocrine mechanisms are of central importance for sexual differentiation of these traits, and anabolic actions of gonadal testosterone have been intensively studied. Here we review the relationship between androgen receptor (AR) and sexual differentiation of neuromuscular systems. We focus our review on the hypotheses that sexual dimorphism and androgen responsiveness of neuromuscular systems is a function of the amount of AR expressed by muscle and that AR in muscle is a key mechanism on which evolution acts to shape individual and species differences in reproductive behavior.
•Humans, rodents, and wild mammals share biological generalities in maternal programming.•Maternal androgens, photoperiod, microbiome and immunity influence offspring phenotype.•Milk is a rich source ...of maternal hormones, microbiota, immune factors and exosomes.•Milk exosomes transfer microRNA into offspring cells and may induce biological changes.•The extent of maternal programming cannot be fully understood by examining a single cue.
The perinatal period is a sensitive time in mammalian development that can have long-lasting consequences on offspring phenotype via maternal effects. Maternal effects have been most intensively studied with respect to two major conditions: maternal diet and maternal stress. In this review, we shift the focus by discussing five major additional maternal cues and their influence on offspring phenotype: maternal androgen levels, photoperiod (melatonin), microbiome, immune regulation, and milk composition. We present the key findings for each of these topics in mammals, their mechanisms of action, and how they interact with each other and with the maternal influences of diet and stress. We explore their impacts in the contexts of both predictive adaptive responses and the developmental origins of disease, identify knowledge gaps and research opportunities in the field, and place a particular emphasis on the application and consideration of these effects in non-model species and natural ecological systems.
Research in the neurobiology of sex differences is inherently influenced by the study species that are used. Some traditional animal research models, such as rats and mice, show certain sex ...differences in the brain that have been foundational to neurobiological research. However, subsequent work has demonstrated that these differences are not always generalizable, especially to species with different social structures and sex-associated roles or behaviors. One such example is the naked mole-rat (Heterocephalus glaber), which has an unusual social structure among mammals. Naked mole-rats live in large groups where reproduction is restricted to a dominant female, called the "queen," and often only one breeding male. All other animals in the group, the "subordinates," are socially suppressed from reproduction and remain in a prepubescent state as adults, unless they are removed from the presence of the queen. These subordinates show little to no sex differences in external morphology, neural morphology, or behavior. However, there are a suite of neurobiological differences between subordinate and breeding naked mole-rats. After naked mole-rats attain breeding status, many of the classically sexually differentiated brain regions increase in volume (paraventricular nucleus, medial amygdala, bed nucleus of the stria terminalis). There are additionally social status differences in sex hormone receptor expression in the brain, as well as other changes in gene expression, some of which also show sex differences - though not always in the predicted direction based on other rodent studies. Data from naked mole-rats show that it is critical to consider the evolved social structure of a species when studying sex differences in the brain.
Physiotherapy informed by Acceptance and Commitment Therapy (PACT) is a novel intervention that is related to improved disability and functioning in people with chronic lowback pain. This study ...explored physiotherapists experiences over time of the PACT training programme and intervention delivery.
A longitudinal qualitative study using semi-structured, in-depth, individual interviews at three time points was conducted.
A phenomenological approach underpinned the methods. Interviews followed topic-guides developed a priori. Transcribed interviews were coded inductively to generate themes. Data were member checked by participants and validated by two researchers.
Eight clinical physiotherapists from three secondary care centres in the United Kingdom (n = 5 female; age, 24 to 44 years; duration of practice, 3 to 14 years) were included.
Five themes emerged from the data. Experiential learning techniques were challenging but valued because they bridged theoretical principles and concepts with practice. Ongoing individual and group supervision was beneficial, but required tailoring and tapering. PACT delivery extended physiotherapy skills and practice, including techniques that acknowledged and addressed patient treatment expectations. With experience, participants desired greater flexibility and autonomy to tailor PACT delivery.
PACT training and delivery were acceptable to physiotherapists. Existing skills were developed and additional, applicable approaches were provided that addressed psychosocial and behavioural aspects of chronic low back pain.
Objectives
A randomized controlled trial of a new type of Physiotherapy informed by Acceptance and Commitment Therapy (PACT), found that it improved functioning in people with chronic low back pain ...compared to usual physiotherapy care. Fidelity evaluation is necessary to understand trial processes and outcomes. This study evaluated PACT treatment fidelity including delivery, receipt, and enactment.
Design
A mixed‐methods study nested within a randomized controlled trial was conducted.
Methods
A total of 72 (20% of total) PACT treatment audio files were independently assessed by two raters, according to a novel framework developed to measure PACT treatment content adherence, therapeutic alliance, ACT competence, and treatment enactment. Interview transcripts from 19 trial participants randomized to PACT were analysed thematically for evidence of treatment receipt and enactment.
Results
PACT physiotherapists delivered treatment as intended with high content adherence and satisfactory therapeutic alliance, but ACT competence was low. Qualitative findings indicated participant receipt of 11/17 and enactment of 3/17 components; 89% (n = 17) and 47% (n = 9) of participants reported treatment receipt and enactment of at least one component, respectively.
Conclusions
This mixed‐methods study of PACT treatment demonstrated high fidelity reflecting treatment content delivery and receipt, and therapeutic alliance. There was some evidence of treatment enactment in participants with chronic low back pain. Low ACT competence could be addressed through additional support and adaptations to therapeutic processes for delivery by physiotherapists.
Notable for the current discussion, there is compelling evidence for at least limited theory of mind (i.e., the ability to recognize mental states in others such as their goals, intentions, ...perceptions, knowledge, and/or beliefs) in diverse non-human animals. Whereas it is important to acknowledge doubt concerning the extent to which the adaptive performance of other animals or even human infants reflects true understanding of the mental states of others rather than resulting from more simple behavioral rules (see Penn and Povinelli, 2007), we believe it is fair to say diverse species have remarkably sophisticated social behavior, enabling behavioral responses that adapt to mental states of conspecifics. ...in bluehead wrasse (Thalassoma bifasciatum), adult females can undergo complete sex change based on social cues, becoming sperm-producing males if the existing dominant male is removed from their habitat (Warner and Swearer, 1991). Discussion about the intersections between genes and environment in the evolution of human sex and gender differences is ongoing (e.g., Smuts, 1995; Eagly and Wood, 2013; Liesen, 2013; Neuberg and Sng, 2013; Barker, 2015) and it has been argued that the social environment and/or culture are not entirely distinct from genetic and epigenetic mechanisms (see for example Jablonka and Lamb, 2014; Fine et al., 2017).
The vast majority of what is considered fact about adult neurogenesis comes from research on laboratory mice and rats: where it happens, how it works, what it does. However, this relative exclusive ...focus on two rodent species has resulted in a bias on how we think about adult neurogenesis. While it might not
us from making conclusions about the evolutionary significance of the process or even prevent us from generalizing to diverse mammals, it certainly does not help us achieve these outcomes. Here, we argue that there is every reason to expect striking species differences in adult neurogenesis: where it happens, how it works, what it does. Species-specific adaptations in brain and behavior are paramount to survival and reproduction in diverse ecological niches and it is naive to think adult neurogenesis escaped these evolutionary pressures. A neuroethological approach to the study of adult neurogenesis is essential for a comprehensive understanding of the phenomenon. Furthermore, most of us are guilty of making strong assertions about our data in order to have impact yet this ultimately creates bias in how work is performed, interpreted, and applied. By taking a step back and actually placing our results in a much larger, non-biomedical context, we can help to reduce dogmatic thinking and create a framework for discovery.
PDF
