Biology subjects

Kopec, A. M.

Publications and source records attributed to Kopec, A. M..

9 recordsLinked to original sources

bioRxiv2023

Microglial synaptic pruning in the nucleus accumbens during adolescence sex-specifically influences splenic immune outcomes

Strong social support promotes a variety of positive health outcomes in humans and rodent models, while social isolation in rodents shortens lifespan, perceived social isolation (i.e. loneliness) can increase mortality by up to 50% in humans. How social relationships lead to these drastic health effects is unclear, but may involve modulation of the peripheral immune system. The reward circuitry of the brain and social behaviors undergo a critical period of development during adolescence. We published that microglia-mediated synaptic pruning occurs in the nucleus accumbens (NAc) reward region during adolescence to mediate social development in male and female rats. We hypothesized that if reward circuitry activity and social relationships directly impact the peripheral immune system, then natural developmental changes in the reward circuitry and social behaviors during adolescence should also directly impact the peripheral immune system. To test this, we inhibited microglial pruning in the NAc during adolescence, and then collected spleen tissue for mass spectrometry proteomic analysis and ELISA validation. We found that the global proteomic consequences of inhibiting microglial pruning in the NAc were similar between the sexes, but target-specific examination suggests that NAc pruning impacts Th1 cell-related immune markers in the spleen in males, but not females, and broad neurochemical systems in the spleen in females, but not males. Please note, if this preprint will be pushed further to publication it will not be by me (AMK), as I am leaving academia. So, Im going to write more conversationally.

neuroscience↗

bioRxiv2023

Impaired microglia-mediated synaptic pruning in the nucleus accumbens during adolescence results in persistent dysregulation of familiar, but not novel social interactions in sex-specific ways

Evolutionarily conserved, peer-directed social behaviors are essential to participate in many aspects of human society. These behaviors directly impact psychological, physiological, and behavioral maturation. Adolescence is an evolutionarily conserved period during which reward-related behaviors, including social behaviors, develop via developmental plasticity in the mesolimbic dopaminergic reward circuitry of the brain. The nucleus accumbens (NAc) is an intermediate reward relay center that develops during adolescence and mediates both social behaviors and dopaminergic signaling. In several developing brain regions, synaptic pruning mediated by microglia, the resident immune cells of the brain, is important for normal behavioral development. In rats, we previously demonstrated that microglial synaptic pruning also mediates NAc and social development during sex-specific adolescent periods and via sex-specific synaptic pruning targets. In this report, we demonstrate that interrupting microglial pruning in NAc during adolescence persistently dysregulates social behavior towards a familiar, but not novel social partner in both sexes, via sex-specific behavioral expression. This leads us to infer that naturally occurring NAc pruning serves to reduce social behaviors primarily directed toward a familiar conspecific in both sexes, but in sex-specific ways.

neuroscience↗

bioRxiv2023

Microglia-mediated synaptic pruning in the nucleus accumbens during adolescence: A preliminary study of the proteomic consequences and putative female-specific pruning target

Adolescence is a period of copious neural development, particularly in the reward circuitry of the brain, and reward-related behavioral development, including social development. One neurodevelopmental mechanism that appears to be common across brain regions and developmental periods is the requirement for synaptic pruning to produce mature neural communication and circuits. We published that microglia-C3-mediated synaptic pruning also occurs in the nucleus accumbens (NAc) reward region during adolescence to mediate social development in male and female rats. However, both the adolescent stage in which microglial pruning occurred, and the synaptic pruning target, were sex specific. NAc pruning occurred between early and mid-adolescence in male rats to eliminate dopamine D1 receptors (D1rs), and between pre- and early adolescence in female rats (P20-30) to eliminate an unknown, non-D1r target. In this report, we sought to better understand the proteomic consequences of microglial pruning in the NAc, and what the female pruning target might be. To do this, we inhibited microglial pruning in the NAc during each sexs pruning period and collected tissue for mass spectrometry proteomic analysis and ELISA validation. We found that the proteomic consequences of inhibiting microglial pruning in the NAc were inversely proportional between the sexes, and a novel, female-specific pruning target may be Lynx1. Please note, if this preprint will be pushed further to publication it will not be by me (AMK), as I am leaving academia. So, Im going to write more conversationally.

neuroscience↗

bioRxiv2023

Social aging trajectories are sex-specific, sensitive to adolescent stress, and most robustly revealed during social tests with familiar stimuli

Social networks and support are integral to health and wellness across the lifespan, and social engagement may be particularly important during aging. However, social behavior and social cognition decline naturally during aging across species. Social behaviors are in part supported by the reward circuitry, a network of brain regions that develops during adolescence. We published that male and female rats undergo adolescent social development during sex-specific periods, pre-early adolescence in females and early-mid adolescence males. Although males and females have highly dimorphic development, expression, and valuation of social behaviors, there is relatively little data indicating whether social aging is the same or different between the sexes. Thus, we sought to test two hypotheses: (1) natural social aging will be sex-speciifc, and (2) social isolation stress restricted to sex-specific adolescent critical periods for social development would impact social aging in sex-specific ways. To do this, we bred male and female rats in-house, and divided them randomly to receive either social isolation for one week during each sexs respective critical period, or no manipulation. We followed their social aging trajectory with a battery of five tests at 3, 7, and 11 months of age. We observed clear social aging signatures in all tests administered, but sex differences in natural social aging were most robustly observed when a familiar social stimulus was included in the test. We also observed that adolescent isolation did impact social behavior, in both age-independent and age-dependent ways, that were entirely sex-specific. Please note, this preprint will not be pushed further to publication (by me, AMK), as I am leaving academia. So, its going to be written more conversationally.

neuroscience↗

bioRxiv2023

Morphine exposure during adolescence induces enduring social changes dependent on adolescent stage of exposure, sex, and social test

Drug exposure during adolescence, when the reward circuitry of the brain is developing, can permanently impact reward-related behavior. Epidemiological studies show that opioid treatment during adolescence, such as pain management for a dental procedure or surgery, increases the incidence of psychiatric illness including substance use disorders. Moreover, the opioid epidemic currently in the United States is affecting younger individuals raising the impetus to understand the pathogenesis of the negative effects of opioids. One reward-related behavior that develops during adolescence is social behavior. We previously demonstrated that social development occurs in rats during sex-specific adolescent periods: early to mid-adolescence in males (postnatal day (P)30-40) and pre-early adolescence in females (P20-30). We thus hypothesized that morphine exposure during the female critical period would result in adult sociability deficits in females, but not males, and morphine administered during the male critical period would result in adult sociability deficits in males, but not females. We found that morphine exposure during the female critical period primarily resulted in deficits in sociability in females, while morphine exposure during the male critical period primarily resulted in deficits in sociability primarily in males. However, depending on the test performed and the social parameter measured, social alterations could be found in both sexes that received morphine exposure at either adolescent stage. These data indicate that when drug exposure occurs during adolescence, and how the endpoint data are measured, will play a large role in determining the effects of drug exposures on social development.

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bioRxiv2022

Baseline and morphine-induced rat microglial phagocytic activity is regulated by sex, brain region, and density interactions ex vivo

Opioids have long been used for clinical pain management, but also have addictive properties that have contributed to the ongoing opioid epidemic. While opioid activation of opioid receptors is well known to contribute to reward and reinforcement, data now also suggest that opioid activation of immune signaling via toll-like receptor 4 (TLR4) may also play a role in addiction-like processes. TLR4 expression is enriched in immune cells, and in the nervous system is primarily expressed in microglia. Microglial phagocytosis is important for developmental, homeostatic, and pathological processes. To examine how morphine impacts microglial phagocytosis, we isolated microglia from adult male and female rat cortex and striatum and plated them in vitro at 10,000 (10K) or 50,000 cells/well densities. Microglia were incubated with neutral fluorescent microbeads to stimulate phagocytosis in the presence of one of four morphine concentrations. We found that the brain region from which microglia are isolated and plating density, but not morphine concentration, impact cell survival in vitro. We found that 10- 12M morphine, but not higher concentrations, increases phagocytosis in striatal microglia in vitro independent of sex and plating density, while 10-12M morphine increased phagocytosis in cortical microglia in vitro independent of sex, but contingent on plating density. Finally, we demonstrate that the effect of 10-12M morphine in striatal microglia plated at 10K density is mediated via TLR4, and not {micro}ORs. Overall, our data suggest that in rats, a morphine-TLR4 signaling pathway increases phagocytic activity in microglia independent of sex. This may be useful information for better understanding the possible neural outcomes associated with morphine exposures.

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bioRxiv2021

Sex differences in choice-based thermal nociceptive tasks in adult rats

Interest in the role of sex as a biological variable continues to increase, including a mandate for the study of both sexes in NIH-funded research. Choice-based thermal nociceptive tests allow for the study of a more spontaneous response to thermal stimuli and avoidance behavior compared to traditional nociceptive assays, and their usage has been increasing in recent years. However, to date no comparison of naive male and female responses to such tests has been published. As sex differences are known to exist in both human chronic pain conditions and rodent models of nociception, it is critical to understand the impact of sex on any nociceptive assay. Herein, we examined the effect of sex on two choice-based thermal nociceptive tests, the thermal gradient test and the temperature place preference test, in adult rats. We report that marked sex differences exist in responses to these tests. Namely, the activation of a 10{degrees} C-to-47{degrees} C thermal gradient results in an increase in time spent in the 10{degrees} C zone in females, compared to a reduction in males. In a temperature place preference test pairing a surface temperature of 22{degrees} C with either 5{degrees} C, 10{degrees} C, 47{degrees} C, or 50{degrees} C, males spent less than 50% of their time in every non-22{degrees} C zone, but in females this was only observed when testing 50{degrees} C. Together, these results suggest that male rats show more avoidance behavior to non-ambient temperatures when given free access to multiple zones, including at temperatures which are milder than those typically used to evoke a nociceptive response in traditional hot and cold plate tests.

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bioRxiv2021

Morphine exposure bidirectionally alters c-Fos expression in a sex-, age-, and brain region-specific manner during adolescence

Drug and alcohol use during adolescence is common, and data in both humans and preclinical animal models clearly indicate drug exposure during adolescence increases the risk of substance use and other mental health disorders later in life. Adolescence is a period of social, emotional, and cognitive development, and is characterized by increased exploratory behavior, risk-taking, and peer-centered social interactions. These are thought to be behavioral manifestations of developmental plasticity in reward regions of the brain. Human data indicate that adolescence is not a unitary developmental period, but rather different neural and behavioral sequelae can be observed in early vs. late adolescence. However, most studies with rodent models examine a single adolescent age compared to a mature adult age, and often only in males. Herein, we sought to determine whether the acute response to the opioid morphine would also differ across adolescence, and by sex. By quantifying c-Fos positive cells, a proxy for neural activity, at different stages during adolescence (pre-, early, mid-, and late adolescence) and in multiple reward regions (prefrontal cortex, nucleus accumbens, caudate/putamen), we determined that acute morphine can either reduce or increase c-Fos expression dependent on adolescent age, sex, and brain region. These data suggest that heterogeneity in the consequences of adolescent opioid exposure may be due to the interaction between age- and sex-specific developmental profiles of reward processing in individual brain regions. In future studies, it will be important to add age within adolescence as an independent variable to fully capture the consequences of healthy or abnormal reward-related neural development.

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bioRxiv2020

ELAV-like proteins bind and stabilize C/EBP mRNA in the induction of long-term memory in Aplysia

Long-term memory (LTM) formation is a critical survival process by which an animal retains information about prior experiences in order to guide future behavior. In the experimentally advantageous marine mollusk Aplysia, LTM for sensitization can be induced by the presentation of two aversive shocks to the animals tail. Each of these training trials recruits distinct growth factor signaling systems that promote LTM formation. Specifically, whereas intact TrkB signaling during Trial 1 promotes an initial and transient increase of the immediate early gene apc/ebp mRNA, a prolonged increase in apc/ebp gene expression required for LTM formation requires the addition of TGF{beta} signaling during Trial 2. Here we explored the molecular mechanisms by which Trial 2 achieves the essential prolonged gene expression of apc/ebp. We find that this prolonged gene expression is not dependent on de novo transcription, but that apc/ebp mRNA synthesized by Trial 1 is post-transcriptionally stabilized by interacting with the RNA-binding protein ApELAV. This interaction is promoted by p38 MAPK activation initiated by TGF{beta}. We further demonstrate that blocking the interaction of ApELAV with its target mRNA during Trial 2 blocks both the prolonged increase in apc/ebp gene expression and the behavioral induction of LTM. Collectively, our findings elucidate both when and how ELAV proteins are recruited for the stabilization of mRNA in LTM formation. Significance StatementIn the present paper we significantly extend the general field of molecular processing in LTM by describing a novel form of pre-translational processing required for LTM which relies on the stabilization of a newly synthesized mRNA by a unique class of RNA binding proteins (ELAVs). In the broad field of molecular mechanisms of transcription-dependent LTM, there are now compelling data showing that important processing can occur after transcription of a gene, but before translation of the message into protein. Although the potential importance of ELAV proteins in LTM formation has previously been reported, to date there has been no mechanistic insight into the specific actions of ELAV proteins in stabilization of mRNAs known to be critical for LTM. Our new findings thus complement and extend this literature by demonstrating when and how this post-transcriptional gene regulation is mediated in the induction of LTM.

neuroscience↗