May | 2024 | Surface Your Real Self

A 2024 rodent study followed up earlier studies of perinatal stress:

“Stress is a multisystemic and multiscale reaction experienced by living beings in response to a wide range of stimuli, encompassing a highly complex order of biological and behavioral responses in mammals, including humans. In the present study, we evaluated changes in mRNA levels in 88 regions of interest (ROIs) in male rats both exposed to perinatal stress and not exposed.

Depending on critical life stage (e.g., perinatal life, infancy, childhood, adolescence, aging), duration, and type of stressor, different effects can be detected by examining behavioral and physiological functions. Stress is related to several cognitive processes, including spatial and declarative memory (involving the hippocampus), fear and memories of emotionally charged events (involving the amygdala), and executive functions and fear extinction (involving the prefrontal cortex).

This PRS paradigm is a well-characterized animal model in which offspring is exposed to stress during pregnancy and after birth because of receiving defective maternal care. Offspring exhibit behavioral hyperreactivity, as well as increased susceptibility to drug addiction and decreased risk-taking behavior.

Starting from day 11 of gestation until delivery, pregnant females were subjected to restraint in a transparent plastic cylinder and exposed to bright light during three daily sessions of 45 min. Since gestational stress induces a <40% reduction of maternal behavior in stressed mothers, we refer to the whole procedure as Perinatal Stress.

Intercorrelation between the orbitofrontal cortex (OFC) and various brain regions such as the thalamus and amygdala were found disrupted in the PRS group. These functional correlations appear to be associated with regulation of executive functions, goal-directed behavior, and directed attention. Also, discrete functional links between the OFC and limbic regions and striatum were lost in the PRS group.

Decreased expression of the Homer1a gene across multiple brain regions after perinatal stress exposure may derange normal architecture of glutamatergic synapses during neurodevelopment and after birth. Changes at the glutamatergic synapse have been considered pivotal in adaptive stress behaviors.

Our results show that PRS preferentially reinforces the centrality of subcortical nodes, resulting in increased centrality of structures such as amygdala, caudate-putamen, and nucleus accumbens, suggestive of reduced cortical control over these regions. In conclusion, when analyzing Homer gene expression after stress exposure not only in terms of quantitative changes compared to the control group, but also as a basis for conducting brain connectivity graph analysis, we observed that perinatal stress could significantly affect the functional connectivity of brain regions implicated in modeling pathophysiology of severe psychiatric disorders.”

https://www.sciencedirect.com/science/article/pii/S0278584624001003 “Perinatal stress modulates glutamatergic functional connectivity: A post-synaptic density immediate early gene-based network analysis”

A 2024 human cell study investigated endothelial cell memories of hyperglycemia:

“Transient exposure to high glucose induces enduring transcriptional and chromatin alterations in endothelial cells (ECs). Activation of the NRF2 pathway with sulforaphane can mitigate these cellular memories, offering valuable insight into mechanisms and management of diabetes-associated complications.

Remarkably, sulforaphane not only prevents most of the aforementioned alterations caused by high glucose (HG), but it can also revert them once established. Although NRF2-independent chemoprotective mechanisms for sulforaphane have been described, our data showing that NRF2 gene overexpression resulted in a similar outcome suggest that beneficial effects conferred by sulforaphane in our HG and memory treatments occur mainly through activation of the NRF2 pathway.

We hypothesize that transient hyperglycemia impacts the epigenetic and functional states of enhancers, priming them to amplify or sustain the transcriptional changes. This mechanism mirrors how inflammation can imprint an enhancer’s epigenetic memory in immune cells and ECs. Ergo, in diabetes patients, repetitive cycles of pathological hyperglycemia could set enhancers into a pathological memory state.

The metabolic memory phenomenon has been studied for over three decades, yet currently, there are no specific treatments to ameliorate diabetes-associated vascular complications, which comprise the leading causes of morbidity and mortality in patients with this disease. Our study highlights the potential use of sulforaphane to revert high-glucose–induced transcriptional and epigenetic memories in human ECs.”

https://www.life-science-alliance.org/content/7/8/e202302382 “Reversal of high-glucose–induced transcriptional and epigenetic memories through NRF2 pathway activation”

A seven-month-long back-and-forth official correspondence history among these researchers and peer reviewers was also published in the Reviewer Comments pdf file, which was informative as to what was and wasn’t included in this study. For examples, in response to peer review comments, the researchers performed an unplanned in vivo rodent study that wasn’t added because it didn’t continue long enough to confirm in vitro human cell primary results. A five-item limitation section was added to this study, though.