You will be presented with the abstract, introduction, and discussion section from a biomedical research article. Your task is to create a summary that a layperson can understand, capturing the essence of the research article. Keep essential scientific terms, but ensure that the language remains clear and the concepts are explained in an uncomplicated manner.

Title: Sexually dimorphic neuronal responses to social isolation}
Article:
Abstract:
Many species use social networks to buffer the effects of stress. The mere absence of a social network, however, may also be stressful. We examined neuroendocrine, PVN CRH neurons and report that social isolation alters the intrinsic properties of these cells in sexually dimorphic fashion. Specifically, isolating preadolescent female mice from littermates for <24 hr increased first spike latency( FSL) and decreased excitability of CRH neurons. These changes were not evident in age-matched males. By contrast, subjecting either males( isolated or grouped) or group housed females to acute physical stress( swim), increased FSL. The increase in FSL following either social isolation or acute physical stress was blocked by the glucocorticoid synthesis inhibitor, metyrapone and mimicked by exogenous corticosterone. The increase in FSL results in a decrease in the excitability of CRH neurons. Our observations demonstrate that social isolation, but not acute physical stress has sex-specific effects on PVN CRH neurons.
Introduction:
Survival threats trigger a repertoire of behavioral and endocrine adjustments( Cannon, 1932). The endocrine changes rely on the immediate engagement of the hypothalamic pituitary adrenal( HPA) axis which is controlled by corticotropin releasing hormone( CRH) neurons in the paraventricular nucleus of the hypothalamus( PVN). Although it is essential for survival, the dysregulation of the stress response is implicated in the emergence of numerous neuropsychiatric diseases( Tost et al., 2015). Interestingly, many of these psychopathologies show sex-specific differences which may be a consequence of sexual dimorphism of the neuroendocrine response to stress( Bale and Epperson, 2015). This sexual dimorphism may result in different response sensitivity to the same stressor and/or differences in which stimuli males and females perceive as stressful. Human studies demonstrating that young girls exhibit greater corticosteroid( CORT) stress reactivity to social stress tests than boys( Gunnar et al., 2009; de Veld et al., 2012) suggest, for example, that young females are more responsive to changes in social situations. Consistent with this idea, are demonstrations that, in comparison to males, females take greater advantage of social support and group dynamics to manage stress( Taylor et al., 2000). Here we hypothesized that disrupting the social network would elicit neurobiological changes preferentially in female mice.
Discussion:
Our findings demonstrate that brief social isolation( <24 hr) affects the biophysical properties of PVN CRH neurons in a sexually dimorphic fashion. We report an increase in FSL and a decrease in neuronal excitability in socially-isolated female, but not in age-matched, male mice. By contrast, an acute physical stress( swim) increased FSL in group-housed females and single-housed males. In addition, social isolation occluded the effects of swim stress on female mice. CORT is both necessary for the isolation( females) and swim stress( males and females) induced increases in FSL and sufficient to increase FSL in the absence of stress. Finally, we noted the effect of social isolation was graded in female mice with paired mice exhibiting FSLs that were intermediate to those observed from group-housed or single mice. We examined the underlying conductance and report that it is sensitive to millimolar concentrations of 4-AP and insensitive to millimolar concentrations of TEA. In addition, FSL was profoundly sensitive to pre-hyperpolarizing pulses, which remove channel inactivation and make rapidly inactivating K channels available for opening in response to depolarizations. The features of these channels are consistent with Kv4 channels previously described in the PVN( Lee et al., 2012). They do, however, exhibit a more hyperpolarized activation threshold in comparison to kinetically similar 4-AP sensitive channels reported in PVN parvocellular neurosecretory cells in rat( Luther and Tasker, 2000). We failed to note any differences in overall current density or voltage-dependent activation or recovery from inactivation. We did, however, observe an increase in the decay time constant of rapidly inactivating K currents in socially-isolated female mice compared to male mice, providing a potential underlying mechanism for the prolonged FSL in response to depolarization. The longer FSL we observed is not a classically defined characteristic of CRH neurons and, in fact, the absence of this delay has been used previously to categorize putative CRH neurons( Hoffman et al., 1991; Wamsteeker Cusulin et al., 2013b). Our findings demonstrate that the biophysical characteristics of neurons are flexible and exquisitely sensitive to specific experiences. Whilst synaptic changes in the PVN( Inoue et al., 2013; Kuzmiski et al., 2010; Wamsteeker Cusulin et al., 2013a) and other brain regions have been investigated, this is, to the best of our knowledge, one of the first reports of rapid intrinsic plasticity in neurons following acute stress. Our observations add to a number of observations that intrinsic( synapse autonomous) plasticity can have a profound effect on the output of neural networks( Shah et al., 2010; Kourrich et al., 2015;O'Leary et al., 2014). In addition, as electrical fingerprints have been used to identify specific cell types, investigators should use caution when interpreting the data as the physiological or psychological state of the animal may have a dramatic impact on these fingerprints. Similarly, since neurons in the PVN can express multiple neuromodulators, caution must also be exercised when interpreting data from a genetically identified cell population. We have previously shown, using immunohistochemistry, that overlap between the genetically identified CRH cell population in PVN and non-CRH neurons is minimal( <5% for vasopressin/CRH or oxytocin/CRH; <<1% for thyrotropin releasing hormone/CRH or somatostatin/CRH)( Wamsteeker Cusulin et al., 2013b). These findings demonstrate that males and females react differently to some stressors but not others. Specifically, social isolation has definitive, CORT-dependent effects on CRH neurons in female, but not male mice. By contrast, both males and females show indistinguishable responses to an acute physical swim stress. These findings highlight the importance of carefully considering both the sex of the animal and the stressor modality when designing studies investigating neurobiological effects of stress. Indeed recent work demonstrating sex-specific expression of fear responses in rodents( Gruene et al., 2015) serves as a corollary to our observations and when taken together suggests that strategies for coping with stress are sex-specific. In particular, our findings highlight the importance of a social network in females and provides a neurobiological framework for further testing the underlying thesis of ‘tend and befriend’ strategy for females in response to stress( Taylor et al., 2000). Finally, as our observations report sex-specific differences in response to stress in the first two weeks post-weaning, they provide clear evidence for biological effects on the stress axis that are independent of circulating gonadal hormones( McCarthy and Arnold, 2011). This exquisite sensitivity of the brain during the pre-adolescent period( Foilb et al., 2011) raises intriguing questions about the long-term consequences of subtle environmental and social manipulations on stress responses and behavior in males and females later in life.
Many species , including humans , use social interaction to reduce the effects of stress . In fact , the lack of a social network may itself be a source of stress . Recent research suggests that young girls are more sensitive to social stress than boys . This could mean that social networks are more important for females in general , and that young females from different species , such as mice , may be more sensitive to social isolation than males . However , few studies have examined how social isolation affects the brain cells that control the release of stress hormones . As such , it remains unknown whether isolating individuals from their social group impacts on the brain in sex-specific ways . Senst , Baimoukhametova et al . now show that the brains of young male and female mice react differently to social isolation . Less than a day after separation from their littermates , the activity in the brain cells of female mice became markedly different from that of isolated males . In contrast to social isolation , the physical stress of being made to swim produced similar changes in the brains of both male and female mice . Further experiments then showed that the changes in the brain cells that control the release of stress hormones required a signalling chemical called corticosterone , which is produced in response to stressful situations . This suggests that , in repsonse to soical isolation , the females are experiencing more stress than the males . Following on from this work , one future challenge will be to investigate if reuniting a social group erases the effects of social isolation on the brain . Further experiments could also examine the behavioural and physiological effects of social isolation , including how females respond to later stressful events .