Oxytocin receptors within the caudal lateral septum regulate social approach-avoidance, long-term social discrimination, and anxiety-like behaviors in adult male and female rats.

OTR signaling promotes social approach or facilitates social avoidance, depending on the brain region involved. The lateral septum plays a critical role in regulating social interactions and memory. We investigated the role of OTR signaling in the caudodorsal lateral septum (LSc.

Lasting effects of adolescent social instability stress on dendritic morphology in the nucleus accumbens in female and male Long Evans rats.

Social instability stress (SS) in adolescence in rats leads to long-lasting changes in social behaviour and reward-related behaviour relative to control rats. Given the role of the nucleus accumbens (NAc) in such behaviours, we investigated the morphology of medium spiny neurons (MSNs), which are most neurons in the NAc, in adult female and male rats exposed to SS in adolescence. Irrespective of sex, SS rats had increased number of dendritic spines in both the core and shell regions of the NAc (2.

Acute and long-term sex-dependent effects of social instability stress on anxiety-like and social behaviours in Wistar rats.

Adolescence is a critical time of social learning in which both the quantity and quality of social interactions shape adult behavior and social function. During adolescence, social instability such as disrupting or limiting social interactions can lead to negative life-long effects on mental health and well-being in humans. Animal models on social instability are critically important in understanding those underlying neurobiological mechanisms.

Within versus between group designs, and not timing of onset of puberty, influence sex and age differences in intake of palatable food in rats.

Understanding normative development of sensitivity to palatable food in adolescence is key to developing animal models for preclinical research of disorders of reward systems (e.g., eating disorders).

Social Instability Stress in Adolescence and Social Interaction in Female Rats.

Adolescence is a critical time of brain development for regions governing social behaviour and social learning. Social experiences influence the ongoing maturation of the neural structures and ultimately modify the social behaviour of adults in response to social cues. Social instability stress in adolescence (SS; daily 1-hour isolation + change of cage partner in postnatal days [PND] 30-45) leads to a long-lasting reduction in social interaction in SS rats compared with non-stressed (CTL) rats in males; here we investigate females.

Endocannabinoid system contributions to sex-specific adolescent neurodevelopment.

With an increasing number of countries and states adopting legislation permitting the use of cannabis for medical purposes, there is a growing interest among health and research professionals into the system through which cannabinoids principally act, the endocannabinoid system (ECS). Much of the seminal research into the ECS dates back only 30 years and, although there has been tremendous development within the field during this time, many questions remain. More recently, investigations have emerged examining the contributions of the ECS to normative development and the effect of altering this system during important critical periods.

Adolescent social instability stress leads to immediate and lasting sex-specific changes in the neuroendocrine-immune-gut axis in rats.

Social instability stress (SS; daily 1 h isolation and change of cage partner from postnatal day (P) 30-45) in adolescence produces elevations in corticosterone during the procedure in male and female rats, but no lasting changes in hypothalamic-pituitary-adrenal (HPA) responses to psychological stressors, although deficits in social and cognitive function are evident in adulthood. Here we investigated the effects of SS in corticosterone response to an immune challenge (lipopolysaccharide, LPS, 0.1 mg/kg), on gene expression in the hippocampus, and on gut microbiota, when tested soon- (P46) or long- (P70) after SS.

Preclinical methodological approaches investigating of the effects of alcohol on perinatal and adolescent neurodevelopment.

Despite much evidence of its economic and social costs, alcohol use continues to increase. Much remains to be known as to the effects of alcohol on neurodevelopment across the lifespan and in both sexes. We provide a comprehensive overview of the methodological approaches to ethanol administration when using animal models (primarily rodent models) and their translational relevance, as well as some of the advantages and disadvantages of each approach.

Facing off with the phalangeal phenomenon and editorial policies: A commentary on Swift-Gallant, Johnson, Di Rita and Breedlove (2020).

Swift-Gallant et al. (2020) provide a thought-provoking perspective on the topic of digit ratio research, research that has had some prominence in the journal Hormones and Behavior, and is research that has garnered much controversy. In this commentary on their paper, we add to the discussion of why there is skepticism of the use of digit ratios as a measure of individual differences in prenatal androgens, we comment on the mis-use of the facial width-to-height ratio as a measure of individual differences in testosterone, the grey areas in the interpretation of evidence, and we address the concern raised in their article regarding editorial policies at Hormones and Behavior (spoiler alert: there are no secret policies).

The effects of social instability stress and subsequent ethanol consumption in adolescence on brain and behavioral development in male rats.

Excessive drinking in adolescence continues to be a problem, and almost a quarter of young Canadians have reported consuming five or more alcoholic drinks in one occasion in recent surveys. The consequences of such drinking may be more pronounced when commenced in adolescence, given the ongoing brain development during this period of life. Here, we investigated the consequences of 3 weeks' intermittent access to ethanol in mid-adolescence to early adulthood in rats, and the extent to which a stress history moderated the negative consequences of ethanol access.

Effects of oxytocin receptor antagonism on social function and corticosterone release after adolescent social instability in male rats.

Oxytocin influences social behaviour and hypothalamic-pituitary-adrenal (HPA) function. We previously found that social instability stress (SS) from postnatal day 30 to 45 increased oxytocin receptor (OTR) densities in the lateral septum and nucleus accumbens of adolescent male rats. Here, we investigated social behaviour and HPA function in adolescent male SS rats compared with age- and sex-matched controls after intraperitoneal treatment with an OTR antagonist L-368,899 (OTR-A).

Sex-specific effects of CB1 receptor antagonism and stress in adolescence on anxiety, corticosterone concentrations, and contextual fear in adulthood in rats.

There is a paucity of research regarding the role of endogenous cannabinoid signalling in adolescence on brain and behaviour development. We previously demonstrated effects of repeated CB1 receptor antagonism in adolescence on socioemotional behaviours and neural protein expression 24-48 h after the last drug administration in female rats, with no effect in males. Here we investigate whether greater effects would be manifested after a lengthier delay.

A rapid enhancement of locomotor sensitization to amphetamine by estradiol in female rats.

Estradiol moderates the effects of drugs of abuse in both humans and rodents. Estradiol's enhancement of behavioral effects resulting from high (>2.5mg/kg) doses of amphetamine is established in rats; there is less evidence for the role of estradiol in locomotor effects elicited by lower doses, which are less aversive, increase incentive motivation, involve different neural mechanisms than higher doses, and often more readily reveal group differences than do higher doses.

Effects of CB1 receptor antagonism and stress exposures in adolescence on socioemotional behaviours, neuroendocrine stress responses, and expression of relevant proteins in the hippocampus and prefrontal cortex in rats.

Little is known about the consequences of altered endocannabinoid signalling in adolescence. We hypothesized that CB1 receptor antagonism (AM251, 1 mg/kg) and stress exposures (1 h confinement stress) in adolescence (daily, postnatal days 30-44) would interact to increase neuroendocrine stress responses and anxiety when investigated a minimum of 24 h after drug and stress treatments; these treatment effects were independent of each other. Changes in homecage behaviour and in weight gain confirmed that both males and females were sensitive to the treatments.

Social instability stress in adolescent male rats reduces social interaction and social recognition performance and increases oxytocin receptor binding.

Social experiences in adolescence are essential for displaying context-appropriate social behaviors in adulthood. We previously found that adult male rats that underwent social instability stress (SS) in adolescence had reduced social interactions with unfamiliar peers compared with non-stressed controls (CTL). Here we determined whether SS altered social recognition and social reward and brain oxytocin and vasopressin receptor density in adolescence.

The sexual preference of female rats is influenced by males' adolescent social stress history and social status.

Ongoing development of brain systems for social behaviour renders these systems susceptible to the influence of stressors in adolescence. We previously found that adult male rats that underwent social instability stress (SS) in mid-adolescence had decreased sexual performance compared with control males (CTL). Here, we test the hypotheses that SS in adolescence decreases the "attractiveness" of male rats as sexual partners compared with CTL rats and that dominance status is a protective factor against the effects of SS.

Intracellular signalling and plasma hormone profiles associated with the expression of unconditioned and conditioned fear and anxiety in female rats.

There is considerable overlap in the neural regions and intracellular signalling pathways implicated in anxiety and fear, although less is known in females. Here, we investigated whether unconditioned and conditioned fear are associated with distinct patterns of expression of extracellular signal-regulated kinase-1 and -2 (ERK1/2), protein kinase B (Akt), and calcineurin (CaN) (proteins that are key regulators of the expression of and/or memory processes of fear and anxiety) in the dorsal and ventral hippocampus, medial prefrontal cortex, and amygdala (important regions in neural fear circuitry) of adult female rats, and used a multivariate approach to find patterns of signalling that might discriminate between the different states of fear. To isolate fear to the conditioned cue from generalized fear to the test context, rats were conditioned to an auditory tone (i.

Glucocorticoid receptor translocation and expression of relevant genes in the hippocampus of adolescent and adult male rats.

We investigated whether pre-pubertal (postnatal day [P] 35) and post-pubertal adolescent (P45) and adult (P75) male rats differed in stressor-induced hormonal responses and in glucocorticoid receptor (GR) translocation because it has been proposed that negative feedback is maturing in adolescence and may be a basis for the prolonged activation of the HPA axis in adolescents compared with adults. The three age groups did not differ at baseline in plasma corticosterone or progesterone concentrations, and P35 had lower concentrations of testosterone than did both P45 and P75 rats, which did not differ. After 30min of restraint stress, plasma concentrations of corticosterone and progesterone increased to a greater extent in the adolescents than in the adults.

The Point Subtraction Aggression Paradigm as a laboratory tool for investigating the neuroendocrinology of aggression and competition.

A contribution to a special issue on Hormones and Human Competition.The ease of measuring steroids in saliva has led to an increase in investigating their role in competition and aggression in laboratory settings and using behavioral measures of aggression. We review here the Point-Subtraction-Aggression-Paradigm (PSAP) as a measure of costly aggression and we compare and contrast the PSAP to other aggression measures.

Sex and stress steroids in adolescence: Gonadal regulation of the hypothalamic-pituitary-adrenal axis in the rat.

This review provides an overview of the current understanding of the role of the hypothalamic-pituitary-gonadal (HPG) axis in regulating the hypothalamic-pituitary-adrenal (HPA) axis response to stressors. HPA function is influenced by both organizational (programming) and activational effects of gonadal hormones. Typically, in adult rats, estradiol increases and androgens decrease the HPA response to stressors, thereby contributing to sex differences in HPA function, and sensitivity of the HPA axis to gonadal steroids is in part determined by exposure to these hormones in early development.

Effects of CB1 receptor agonism and antagonism on behavioral fear and physiological stress responses in adult intact, ovariectomized, and estradiol-replaced female rats.

There is growing interest in the development of cannabis-based therapies for the treatment of fear and anxiety disorders. There are a few studies, but none in females, of the effects of the highly selective cannabinoid receptor type 1 (CB1) agonist, arachidonyl 2'-chlorethylamide (ACEA), on behavioral fear. In experiment 1 involving gonadally-intact females, ACEA (either 0.

Adolescent and adult male rats habituate to repeated isolation, but only adolescents sensitize to partner unfamiliarity.

We investigated whether adolescent male rats show less habituation of corticosterone release than adult male rats to acute vs repeated (16) daily one hour episodes of isolation stress, as well as the role of partner familiarity during recovery on social behavior, plasma corticosterone, and Zif268 expression in brain regions. Adolescents spent more time in social contact than did adults during the initial days of the repeated stress procedures, but both adolescents and adults that returned to an unfamiliar peer after isolation had higher social activity than rats returned to a familiar peer (p=0.002) or undisturbed control rats (p<0.

Differential effects of CB1 receptor agonism in behavioural tests of unconditioned and conditioned fear in adult male rats.

We investigated the effects of the highly selective CB1 receptor agonist ACEA and the CB1 receptor antagonist/inverse agonist AM251 on two behavioural tests of unconditioned fear, the elevated plus maze (EPM) and open field test (OFT), as well as on the recall and extinction of a conditioned auditory fear. Both ACEA and AM251 increased anxiety-like behaviour in the EPM and OFT. There was no effect of either drug on recall of the conditioned fear, and ACEA enhanced and AM251 impaired fear extinction.

Peer pressures: social instability stress in adolescence and social deficits in adulthood in a rodent model.

Studies in animal models generate and test hypotheses regarding developmental stage-specific vulnerability that might inform research questions about human development. In both rats and humans, peer relationships are qualitatively different in adolescence than at other stages of development, and social experiences in adolescence are considered important determinants of adult social function. This review describes our adolescent rat social instability stress model and the long-lasting effects social instability has on social behaviour in adulthood as well as the possible neural underpinnings.