Enduring neuroimmunological consequences of developmental experiences: From vulnerability to resilience

Level of Cytokines and C3 Complement in the Blood of Rats under Conditions of Chronic Unpredictable Stress of Different Durations

The parameters of the cytokine profile and functional activity of the complement system in the blood of rats were studied during different time periods of chronic unpredictable mild stress using a model of sequentially alternating low-intensity stress effects for 1, 2, 3, and 4 weeks. In the dynamics of observation, a general tendency towards multidirectional fluctuations in the concentration of cytokines was revealed: an increase in IL-10, but a decrease in IL-4 in comparison with the control. Statistically significant changes in the level of IL-10 were noted after 2, 3, and 4 weeks, IL-4 - after 2 and 4 weeks of stress loads. The percentage of lysis of the C3 component in rats gradually increased by the 2nd week of chronic stress, but then decreased and practically did not differ from the control values (intact animals) by the end of the study. These results illustrate the specificity of changes in the indicators of the C component of the complement system and the cytokine profile of the blood reflecting activity of the cellular and humoral components of the immune response in rats exposed to repeated stress factors of different origins and duration.

Future Directions in the Mental Health of Transgender Youth: Towards a Social-Affective Developmental Model of Health Disparity

Mental health disparities in transgender and gender diverse (TGD) youth are well-documented. These disparities are often studied in the context of minority stress theory, and most of this research focuses on experiences of trauma and discrimination TGD youth experience after coming out. However, TGD youth may be targets of violence and victimization due to perceived gender nonconformity before coming out. In this Future Directions, we integrate research on attachment, developmental trauma, and effects of racism and homophobia on mental health to propose a social-affective developmental framework for TGD youth. We provide a clinical vignette to highlight limitations in current approaches to mental health assessment in TGD youth and to illustrate how using a social-affective developmental framework can improve clinical assessment and treatment approaches and deepen our understanding of mental health disparities in TGD people.

Developmental impact of peripheral injury on neuroimmune signaling

A peripheral injury drives neuroimmune interactions at the level of the injury and throughout the neuraxis. Understanding these systems will be beneficial in the pursuit to target persistent pain that involves both neural and immune components. In this review, we discuss the impact of injury on the development of neuroimmune signaling, along with data that suggest a possible cellular immune memory. We also discuss the parallel effects of injury in the nervous system and immune related areas including bone marrow, lymph node and central nervous system-related cells. Finally, we relate these findings to patient populations and current research that evaluates human tissue.

Remembering through the genome: the role of chromatin states in brain functions and diseases

Chromatin is the physical substrate of the genome that carries the DNA sequence and ensures its proper functions and regulation in the cell nucleus. While a lot is known about the dynamics of chromatin during programmed cellular processes such as development, the role of chromatin in experience-dependent functions remains not well defined. Accumulating evidence suggests that in brain cells, environmental stimuli can trigger long-lasting changes in chromatin structure and tri-dimensional (3D) organization that can influence future transcriptional programs. This review describes recent findings suggesting that chromatin plays an important role in cellular memory, particularly in the maintenance of traces of prior activity in the brain. Inspired by findings in immune and epithelial cells, we discuss the underlying mechanisms and the implications for experience-dependent transcriptional regulation in health and disease. We conclude by presenting a holistic view of chromatin as potential molecular substrate for the integration and assimilation of environmental information that may constitute a conceptual basis for future research.

Preweaning environmental enrichment alters neonatal ultrasonic vocalisations in a rat model for prenatal infections

OBJECTIVE

Maternal infections are a well-known risk factor for neurodevelopmental defects. Such defects are associated with a range of symptoms, and environmental enrichment (EE) could be a promising approach to rehabilitate these. We used the well-established prenatal poly I:C (polyinosinic-polycytidylic acid) model in rats to examine the effects of preweaning EE on rat pups' ultrasonic vocalisations (USVs) when separated from their mothers. USVs are one of the earliest indicators of a pup's functional level and, thus, well-suited as a marker of neurodevelopmental abnormalities.

METHODS

We used a two-by-two factorial design in which pregnant Sprague-Dawley rats received either saline or the viral mimic poly I:C, and one group of pups was exposed to preweaning enrichment. We measured maternal separation-induced USVs both before postnatal day (PND) 7 and after preweaning enrichment on PND 14.

RESULTS

Poly I:C significantly reduced the number of USVs on PND 7. EE interacted with the poly I:C treatment in that poly I:C pups in the enrichment group called more, whereas saline pups in the enriched environment called less on PND 14 than the respective controls.

CONCLUSION

We showed that the effects of maternal poly I:C on the offspring's USVs could be reduced by early EE. If replicated, it could open novel and safe avenues for treating children of mothers who were exposed to infections during pregnancy.

At the Crossroad Between Resiliency and Fragility: A Neurodevelopmental Perspective on Early-Life Experiences

Postnatal development of the brain is characterized by sensitive windows during which, local circuitry are drastically reshaped by life experiences. These critical periods (CPs) occur at different time points for different brain functions, presenting redundant physiological changes in the underlying brain regions. Although circuits malleability during CPs provides a valuable window of opportunity for adaptive fine-tuning to the living environment, this aspect of neurodevelopment also represents a phase of increased vulnerability for the development of a variety of disorders. Consistently, accumulating epidemiological studies point to adverse childhood experience as a major risk factor for many medical conditions, especially stress- and anxiety-related conditions. Thanks to creative approaches to manipulate rodents’ rearing environment, neurobiologist have uncovered a pivotal interaction between CPs and early-life experiences, offering an interesting landscape to improve our understanding of brain disorders. In this short review, we discuss how early-life experience impacts cellular and molecular players involved in CPs of development, translating into long-lasting behavioral consequences in rodents. Bringing together findings from multiple laboratories, we delineate a unifying theory in which systemic factors dynamically target the maturation of brain functions based on adaptive needs, shifting the balance between resilience and vulnerability in response to the quality of the rearing environment.