Prenatal stress produces offspring who as adults have cognitive, emotional, and memory deficiencies

This 2018 French/Italian/Swiss rodent study used the prenatally restraint stressed (PRS) model to create problems that could be resolved by various chemicals:

“S 47445 is a positive modulator of glutamate AMPA-type receptors, possessing neurotrophic and enhancing synaptic plasticity effects as well as pro-cognitive and anti-stress properties.

Most of studies examining the antidepressant effects of new molecules are carried out using behavioral tests performed in unstressed animals.

Corticosterone-treated mice and rats exposed to chronic stress are models that do not recapitulate the early programming of stress-related disorders, which likely originates in the perinatal period. The PRS rat model is characterized by a prolonged corticosterone response to stress and by abnormal behavior.

All the behavioral alterations induced by PRS..were corrected by chronic S 47445 administration at both doses.”


The paper included a section comparing S 47445 to ketamine:

“Ketamine, however, causes severe cognitive impairment and psychotomimetic [mimics the symptoms of psychosis, reference not freely available] effects that are direct consequences of the prolonged inhibition of NMDA receptors in cortical and hippocampal interneurons, and seriously limit the chronic administration of the drug in the clinical setting. [reference not freely available]

S 47445 by inducing a direct activation of AMPARs displayed an antidepressant activity without the adverse effect of ketamine. Indeed, contrary to ketamine, S 47445 presented no psychotomimetic effects and induced no occurrence of spontaneous epileptic seizures. [reference freely available] Moreover, S 47445 also presented pro-cognitive properties.”

Compare the above with this April 2018 Chicago Tribune story that had opinions with no linked references:

“..ketamine, an anesthetic used to sedate both people and animals before surgery. It’s also a notorious street drug, abused by clubgoers seeking a trancelike, hallucinatory high. But in recent years, numerous studies have found that ketamine can be an effective and speedy treatment for people with depression.”

Which coverage better informed us?


Treating prenatal stress-related disorders with an oxytocin receptor agonist was performed by several of this paper’s coauthors. One of this paper’s references to it was:

“We have already reported that depolarization-evoked glutamate release in the ventral hippocampus is negatively correlated with risk-taking behavior of PRS rats, and that such correlation can be corrected by chronic treatment with monoaminergic/melatoninergic antidepressants or oxytocin receptor agonist. Thus, an impairment of glutamatergic transmission in the ventral hippocampus lies at the core of the pathological phenotype of PRS rats.”

Looking at the above graphic of the experimental design, I’m not sure why the term perinatal (occurring during or pertaining to the phase surrounding the time of birth) was used in the paper’s title and content to describe the stress period. The pregnant females were stressed three times daily every day during the second half of pregnancy up until delivery, so the prenatal (previous to birth) term was more applicable.


So, how does this study help humans?

One takeaway is to avoid stressing pregnant mothers-to-be if her children will be expected to become adults without cognitive, emotional, and behavioral problems.

The study demonstrated one way prenatal events cause lifelong effects. The PRS model provides another example of why it’s useless to ask adult humans to self-report the causes of epigenetic problems in their lives when these originated before birth, during infancy, or in early childhood well before humans develop the cognitive capability to recognize such situations. It’s incomprehensible that this unreliable paradigm is still given significant weight in stress experimental designs, especially when they:

“..do not recapitulate the early programming of stress-related disorders, which likely originates in the perinatal period.”

Also, the relevant difference between humans and PRS rats is that we can ourselves individually change our responses to experiential causes of ongoing adverse effects. Standard methodologies can only apply external treatments such as those mentioned above.

https://www.sciencedirect.com/science/article/pii/S0028390818301291 “The reduction in glutamate release is predictive of cognitive and emotional alterations that are corrected by the positive modulator of AMPA receptors S 47445 in perinatal stressed rats” (not freely available) Thanks to coauthors Stefania Maccari and Dr. Jerome Mairesse for providing a copy.

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How well do single-mother rodent studies inform us about human fathers?

Two items before getting to the review:

This 2018 Australian review subject was paternal intergenerational and transgenerational transmission of biological and behavioral phenotypes per this partial outline:

“Evidence for non-genetic inheritance of behavioral traits in human populations

  • Intergenerational inheritance modulating offspring phenotypes following paternal exposure to trauma
  • Epigenetic inheritance via the germline following paternal environmental exposures
  • Limitations of research on epigenetic inheritance in human populations

The transgenerational impact of stressful paternal environments

  • Impact of paternal stress on affective behaviors and HPA-axis regulation of progeny
  • Influence of paternal stress exposure on offspring cognition
  • Role of sperm-borne microRNAs in the epigenetic inheritance of stress

Sexually dimorphic aspects of paternal transgenerational epigenetic inheritance”

The review was comprehensive, and filled in the above outline with many details towards the goal of:

“This exciting new field of transgenerational epigenomics will facilitate the development of novel strategies to predict, prevent and treat negative epigenetic consequences on offspring health, and psychiatric disorders in particular.”

The reviewers also demonstrated that current intergenerational and transgenerational research paradigms exclude a father’s child care behavior.


The fact that studies use rat and mouse species where fathers don’t naturally provide care for their offspring has warped the translation of findings to humans. The underlying question every animal study must answer is: how can its information be used to help humans? I asked in A limited study of parental transmission of anxiety/stress-reactive traits:

“How did parental behavioral transmission of behavioral traits and epigenetic changes become a subject not worth investigating? These traits and effects can be seen everyday in real-life human interactions, and in every human’s physiology.

Who among us doesn’t still have biological and behavioral consequences from our experiences of our father’s child care actions and inactions? Why can’t researchers and sponsors investigate these back to their sources that may include grandparents and great-grandparents?

Such efforts weren’t apparent in the review’s 116 cited references that included:

The reviewer in the latter has been instrumental in excluding behavioral inheritance mechanisms from these research paradigms, leading to my questions:

  1. “If the experimental subjects had no more control over their behavioral stress-response effects than they had over their DNA methylation, histone modification, or microRNA stress-response effects, then why was such behavior not included in the “epigenetic mechanisms” term?
  2. How do behavioral inheritance mechanisms fall outside the “true epigenetic inheritance” term when behavioral stress-response effects are shown to be reliably transmitted generation after generation?
  3. Wouldn’t the cessation of behavioral inheritance mechanisms confirm their status by falsifiability as was similarly done with studies such as the 1995 Adoption reverses the long-term impairment in glucocorticoid feedback induced by prenatal stress?”

Translating rodent studies into human mothers’ behavioral transmission of biological and behavioral phenotypes isn’t hampered by the studied species’ traits as it is for human fathers. But sponsors would have to support human research that may not produce politically-correct findings.


http://www.translatingtime.org provides an inter-species comparative timeline. For example, an input of:

  • Species 1: Human
  • Process: Lifespan
  • Location: Whole Organism
  • Days (post-conception): 270
  • Species 2: Mouse

produces a list of event predictions. Note how many significant events occur before humans are born at day 270, assuming everything goes right with our developmental processes! Also, the model predictions for humans end at post-conception day 979, three weeks short of when we celebrate our second birthday.

https://www.nature.com/articles/s41380-018-0039-z “Transgenerational epigenetic influences of paternal environmental exposures on brain function and predisposition to psychiatric disorders” (not freely available) Thanks to Dr. Shlomo Yeshurun for providing a full copy.

A study of gene-environment interactions

This 2018 Hungary/UK study used Bayesian analysis to better understand gene-environment interactions that produce depression:

“Most genetic studies do not consider the effect of stressors which may be one reason for the lack of replicable results in candidate gene studies, GWAS [genome-wide association studies] and between human studies and animal models..Animal models of depression usually imply environmental factors, such as chronic unpredictable stress or learned helplessness.

Relevance of functional polymorphisms in seven candidate genes previously implicated in animal and human studies on a depression-related phenotype given various recent stress exposure levels was assessed with Bayesian relevance analysis in 1682 subjects.

Our data support the strong causative role of the environment modified by genetic factors, similar to animal models.”

From the Methods and Materials section:

“In order to identify recent negative life events (RLE) we used the List of Threatening Experiences questionnaire which queried problems related to illnesses/injuries, financial difficulties, problems related to intimate relationships, and social network occurring in the last year. Based on corresponding items the number of RLEs was counted for each subject, and categorized (low = 0–1, moderate = 2, high = 3/more).”

One item from the findings, and two from the cited references were:

“5-HTTLPR [serotonin transporter], the most extensively investigated polymorphism with respect to interaction with life events, showed only very low relevance.

Compared to heritability which accounts for 37–42% in the variance in general population samples, influence of environmental effects is estimated at 63% in depression.

Etiologically relevant distal and proximal stressors are relatively common, and while frequency of severe life events is estimated to be one in every 3–4 years, depression is triggered in only about one fifth of those with acute stress exposure.”


The methods of this study bypassed problems with GWAS and provided evidence for the lasting effects of “Etiologically relevant distal..stressors.” This was another way of saying that traumatic experiences beginning from the earliest parts of our lives still affect our biology and behavior.

As mentioned in Changing an individual’s future behavior even before they’re born, GWAS:

“Focuses on the average effect of alternative alleles averaged in a population.”

What this methodology often missed was:

“When phenotypic variation results from alleles that modify phenotypic variance rather than the mean, this link between genotype and phenotype will not be detected.”

The problems found in GWAS may also be found in epigenome-wide association studies. Researchers conducting DNA methylation analyses in particular may benefit from changing their approach if what they’re doing follows the GWAS paradigm.

Using twins to estimate the extent of epigenetic effects summarized three studies’ methods that showed:

“The epigenetic effects of each of our unique experiences of our non-shared environment predominately determine our individual physiology.”

This study’s approach should be considered, given the almost 2:1 relative impacts of environmental over genetic factors in influencing our biology and behavior. It’s especially indicated when human studies don’t replicate animal studies’ findings from strictly controlled experimental environments.


It wasn’t the study’s purpose to evaluate effective treatments for depression. Yet the abstract ended with:

“Galanin-2 receptor, BDNF and X-type purin-7 receptor could be drug targets for new antidepressants.”

The researchers were very careful to document the benefits of using a different approach to a problem. I hope that in the future, they will maintain their carefulness and independence in their approach to solutions, and not be influenced by:

“Consultancy, speaking engagements and research for Bristol-Myers Squibb, AstraZeneca, Eli Lilly, Schering Plough, Janssen-Cilag and Servier..share options in P1vital..consultancy fees from Alkermes, Lundbeck-Otsuka Ltd., Janssen-Cilag Ltd and fees for speaking from Lundbeck.”

https://www.nature.com/articles/s41598-018-22221-z “Significance of risk polymorphisms for depression depends on stress exposure”

Sleep and adult brain neurogenesis

This 2018 Japan/Detroit review subject was the impact of sleep and epigenetic modifications on adult dentate gyrus neurogenesis:

“We discuss the functions of adult‐born DG neurons, describe the epigenetic regulation of adult DG neurogenesis, identify overlaps in how sleep and epigenetic modifications impact adult DG neurogenesis and memory consolidation..

Whereas the rate of DG neurogenesis declines exponentially with age in most mammals, humans appear to exhibit a more modest age‐related reduction in DG neurogenesis. Evidence of adult neurogenesis has also been observed in other regions of the mammalian brain such as the subventricular zone, neocortex, hypothalamus, amygdala, and striatum.

Adult‐born DG neurons functionally integrate into hippocampal circuitry and play a special role in cognition during a period of heightened excitability and synaptic plasticity occurring 4–6 weeks after mitosis..Adult DG neurogenesis is regulated by a myriad of intrinsic and extrinsic factors, including:

  • drugs,
  • diet,
  • inflammation,
  • physical activity,
  • environmental enrichment,
  • stress, and
  • trauma.”


Some of what the review stated was contradicted by other evidence. For example, arguments for sleep were based on the memory consolidation paradigm, but evidence against memory consolidation wasn’t cited for balanced consideration.

It reminded me of A review that inadvertently showed how memory paradigms prevented relevant research. That review’s citations included a study led by one of those reviewers where:

“The researchers elected to pursue a workaround of the memory reconsolidation paradigm when the need for a new paradigm of enduring memories directly confronted them!”

Some of what this review stated was speculation. I didn’t quote any sections that followed:

 “We go one step further and propose..”

The review also had a narrative directed toward:

“Employing sleep interventions and epigenetic drugs..”

It’s storytelling rather than pursuing the scientific method when reviewers approach a topic as these reviewers did.

Instead of reading the review, I recommend this informative blog post from a Canadian researcher who provided scientific contexts rather than a directed narrative to summarize what is and isn’t known so far in 2018 about human neurogenesis.

http://onlinelibrary.wiley.com/doi/10.1002/stem.2815/epdf “Regulatory Influence of Sleep and Epigenetics on Adult Hippocampal Neurogenesis and Cognitive and Emotional Function”

Sex-specific impacts of childhood trauma

This 2018 Canadian paper reviewed evidence for potential sex-specific differences in the lasting impacts of childhood trauma:

“This paper will provide a contextualized summary of neuroendocrine, neuroimaging, and behavioral epigenetic studies on biological sex differences contributing to internalizing psychopathology, specifically posttraumatic stress disorder and depression, among adults with a history of childhood abuse.

Given the breadth of this review, we limit our definition [of] trauma to intentional and interpersonal experiences (i.e., childhood abuse and neglect) in childhood. Psychopathological outcomes within this review will be limited to commonly explored internalizing disorders, specifically PTSD and depression.

Despite the inconsistent and limited findings in this review, a critical future consideration will be whether the biological effects of early life stress can be reversed in the face of evidence-based behavioral interventions, and furthermore, whether these changes may relate to potentially concurrent reductions in susceptibility to negative mental health outcomes.”


It was refreshing to read a paper where the reviewers often interrupted the reader’s train of thought to interject contradictory evidence, and display the scientific method. For example, immediately after citing a trio of well-respected studies that found:

“Psychobiological research on relationships linking impaired HPA axis functioning and adult internalizing disorders are suggestive of lower basal and afternoon levels of plasma cortisol in PTSD phenotype.”

the reviewers stated:

“However, a recent meta-analysis suggests no association between basal cortisol with PTSD.”

and effectively ended the cortisol discussion with:

“Findings are dependent upon variance in extenuating factors, including but not limited to, different measurements of:

  • early adversity,
  • age of onset,
  • basal cortisol levels, as well as
  • trauma forms and subtypes, and
  • presence and severity of psychopathology symptomology.”

The reviewers also provided good summaries of aspects of the reviewed subject. For example, the “Serotonergic system genetic research, childhood trauma and risk of psychopathology” subsection ended with:

“Going forward, studies must explore the longitudinal effects of early trauma on methylation as well as comparisons of multiple loci methylation patterns and interactions to determine the greatest factors contributing to health outcomes. Only then, can we start to consider the role of sex in moderating risk.”


I don’t agree with the cause-ignoring approach of the behavior therapy mentioned in the review. Does it make sense to approach one category of symptoms:

“the biological effects of early life stress..”

by treating another category of symptoms?

“can be reversed in the face of evidence-based behavioral interventions..”

But addressing symptoms instead of the sometimes-common causes that generate both biological and behavioral effects continues to be the direction.

After receiving short-term symptom relief, wouldn’t people prefer treatments of originating causes so that their various symptoms don’t keep bubbling up? Why wouldn’t research paradigms be aligned accordingly?

I was encouraged by the intergenerational and transgenerational focus of one of the reviewer’s research:

“Dr. Gonzalez’s current research focus is to understand the mechanisms by which early experiences are transmitted across generations and how preventive interventions may affect this transmission.”

This line of hypotheses requires detailed histories, and should uncover causes for many effects that researchers may otherwise shrug off as unexplainable individual differences. Its aims include the preconception through prenatal periods where the largest epigenetic effects on an individual are found. There are fewer opportunities for effective “preventive interventions” in later life compared with these early periods.

Unlike lab rats, women and men can reach some degree of honesty about our early lives’ experiential causes of ongoing adverse effects. The potential of experiential therapies to allow an individual to change their responses to these causes deserves as much investigation as do therapies that apply external “interventions.”

https://www.sciencedirect.com/science/article/pii/S0272735817302647 “Biological alterations affecting risk of adult psychopathology following childhood trauma: A review of sex differences” (not freely available) Thanks to lead author Dr. Ashwini Tiwari for providing a copy.

An emotional center of our brains

This 2018 McGill/UC San Diego rodent study was on the dentate gyrus area of the hippocampus:

“Early life experience influences stress reactivity and mental health through effects on cognitive-emotional functions that are, in part, linked to gene expression in the dorsal and ventral hippocampus. The hippocampal dentate gyrus (DG) is a major site for experience-dependent plasticity associated with sustained transcriptional alterations, potentially mediated by epigenetic modifications.

Peripubertal environmental enrichment increases hippocampal volume and enhances dorsal DG-specific differences in gene expression..Overall, our transcriptome and DNA methylation data support a model of regional and environmental effects on the molecular profile of DG neurons.”

The study thoroughly investigated several areas. I’ll quote a few parts with the section heading.

Introduction:

“The dorsal hippocampus, corresponding to the posterior hippocampus in primates, associates closely with cognitive functions and age-related cognitive impairments. In contrast, the ventral hippocampus, (anterior region in primates) is implicated in the regulation of emotional states and vulnerability for affective disorders. This functional specialization is reflected in patterns of gene expression.”

Results subsections:

“Environmental enrichment promotes hippocampal neurogenesis – hippocampal volume is enlarged in mice raised in an enriched environment (EE) compared with standard housing (SH) in both the dorsal and ventral poles..EE also associates with >60% more newborn neurons.

Specialization of gene expression in dorsal and ventral DG – Gene expression was more affected by EE in dorsal than ventral DG, and dorsal DG has twice as many differentially-expressed genes.

DNA methylation differences between dorsal and ventral DG – Each of the three forms of methylation [CpG, non-CpG, and hmC (hydroxymethylation)] exhibited a distinct genomic distribution in dorsal and ventral DG..A key advantage of whole-genome DNA methylation profiling is the ability to identify differentially methylated regions (DMRs), often far from any gene body, that mark tissue-specific gene regulatory elements..This strong bias, with ~40-fold more hypomethylated regions in the dorsal DG, contrasts with the balanced number of differentially expressed genes in dorsal and ventral DG, suggesting an asymmetric role for DNA methylation in region-specific gene regulation. Despite their small number, ventral hypomethylated DMRs marked key developmental patterning transcription factors..which are linked to the proliferation, maintenance and survival of neural stem cells.

DNA methylation correlates with repression at some genes – CG and non-CG DNA methylation are associated with reduced gene expression, while hmC associates with increased expression..dorsal DMRs were also enriched at genes that were up- and down-regulated in EE, although over half of dorsal up-regulated genes, and >98.5% of ventral up-regulated genes, contained no DMRs that could explain their region-specific differential expression.”

Discussion:

  • “a The cell stages occurring within the subgranular zone of the dentate gyrus are shown together with a schematic illustration of possible relative proportions consistent with our data. RGL Radial glia-like progenitor, NSC Neural stem cell.
  • b Key genes associated with the RGL stage are up-regulated in ventral DG relative to dorsal DG.
  • c We propose that mCH [non-CpG methylation] accumulates mainly in mature neurons.”

Why do human brain studies that include the hippocampus overwhelmingly ignore its role in our emotions? For example, the researchers of Advance science by including emotion in research could find only 397 suitable studies performed over 22 years from 1990 to 2011. There were tens or hundreds of times more human brain studies done during the same period that intentionally excluded emotional content!

The current study provided physiological bases for dialing back the bias of human brain research focusing exclusively on cognitive functions without also investigating attributes of emotional processing. I look forward to seeing 2018 human studies that are designed to correct this recurring research deficiency.

https://www.nature.com/articles/s41467-017-02748-x “Environmental enrichment increases transcriptional and epigenetic differentiation between mouse dorsal and ventral dentate gyrus”

How to cure the ultimate causes of migraines?

Most of the spam I get on this blog comes in as ersatz comments on The hypothalamus couples with the brainstem to cause migraines. I don’t know what it is about the post that attracts internet bots.

The unwanted attention is too bad because the post represents a good personal illustration of “changes in the neural response to painful stimuli.” Last year I experienced three three-day migraines in one month as did the study’s subject. This led to me cycling through a half-dozen medications in an effort to address the migraine causes.

None of the medications proved to be effective at treating the causes. I found one that interrupted the progress of migraines – sumatriptan, a serotonin receptor agonist. I’ve used it when symptoms start, and the medication has kept me from having a full-blown migraine episode in the past year.

1. It may be argued that migraine headache tendencies are genetically inherited. Supporting personal evidence is that both my mother and younger sister have migraine problems. My father, older sister, and younger brother didn’t have migraine problems. Familial genetic inheritance usually isn’t the whole story of diseases, though.

2. Migraine headaches may be an example of diseases that are results of how humans have evolved. From Genetic imprinting, sleep, and parent-offspring conflict:

“..evolutionary theory predicts: that which evolves is not necessarily that which is healthy.

Why should pregnancy not be more efficient and more robust than other physiological systems, rather than less? Crucial checks, balances and feedback controls are lacking in the shared physiology of the maternal–fetal unit.

Both migraine causes and effects may be traced back to natural lacks of feedback loops. These lacks demonstrate that such physiological feedback wasn’t evolutionarily necessary in order for humans to survive and reproduce.

3. Examples of other processes occurring during prenatal development that also lack feedback loops, and their subsequent diseases, are:

A. Hypoxic conditions per Lack of oxygen’s epigenetic effects are causes of the fetus later developing:

  • “age-related macular degeneration
  • cancer progression
  • chronic kidney disease
  • cardiomyopathies
  • adipose tissue fibrosis
  • inflammation
  • detrimental effects which are linked to epigenetic changes.”

B. Stressing pregnant dams per Treating prenatal stress-related disorders with an oxytocin receptor agonist caused fetuses to develop a:

  • “defect in glutamate release,
  • anxiety- and depressive-like behavior,

and abnormalities:

  • in social behavior,
  • in the HPA response to stress, and
  • in the expression of stress-related genes in the hippocampus and amygdala.”

1. What would be a treatment that could cure genetic causes for migraines?

I don’t know of any gene therapies.

2. What treatments could cure migraines caused by an evolved lack of feedback mechanisms?

We humans are who we have become, unless and until we can change original causes. Can we deal with “changes in the neural response to painful stimuli” without developing hopes for therapies or technologies per Differing approaches to a life wasted on beliefs?

3. What treatments could cure prenatal epigenetic causes for migraines?

The only effective solution I know of that’s been studied in humans is to prevent adverse conditions like hypoxia from taking place during pregnancy. The critical periods of our physical development are over once we’re adults, and we can’t unbake a cake.

Maybe science will offer other possibilities. Maybe it will be necessary for scientists to do more than their funding sponsors expect?

BTW, comments are turned off for the above-mentioned post. Readers can comment on this post instead.