Caloric restriction’s epigenetic effects

This 2019 US review subject was caloric restriction (CR) without malnutrition:

“Cellular adaptation that occurs in response to dietary patterns can be explained by alterations in epigenetic mechanisms such as DNA methylation, histone modifications, and microRNA. Epigenetic reprogramming of the underlying chronic low-grade inflammation by CR can lead to immuno-metabolic adaptations that enhance quality of life, extend lifespan, and delay chronic disease onset.

Short- and long-term CRs produce significant changes in different tissues and across species, in some animal models even with sex-specific effects. Early CR onset may cause a different and even an opposite effect on physiological outcomes in animal models such as body weight.”

 


Charts usually don’t have two different values plotted on the same axis. There wasn’t evidence that equated survival with methylation drift per the above graphic. Methylation drift should point in the opposite direction of survival, if anything.

No mention was made of the epigenetic clock method of measuring age acceleration, although recent diet studies have used it. The sole citation of an age acceleration study was from 2001, which was unacceptable for a review published in 2019.

The review provided many cellular-level details about the subject. However, organism-level areas weren’t sufficiently evidenced:

1. Arguments for an effect usually include explanations for no effect as well as opposite effects. The reviewers didn’t provide direct evidence for why, if caloric restriction extended lifespan, caloric overabundance produced shorter lifespans.

2. Caloric restriction evidence was presented as if only it was responsible for organism-level effects. Other mechanisms may have been involved.

An example of such a mechanism was demonstrated in a 2007 rodent study Reduced Oxidant Stress and Extended Lifespan in Mice Exposed to a Low Glycotoxin Diet which compared two 40%-calorie-restricted diets.

The calories and composition of both diets were identical. However, advanced glycation end product (AGE) levels were doubled in standard chow because heating temperatures were “sufficiently high to inadvertently cause standard mouse chow to be rich in oxidant AGEs.”

The study found that a diet with lower chow heating temperatures increased lifespan and health span irrespective of caloric restriction!

  • The low-AGE calorie-restricted diet group lived an average of 15% longer (>20 human equivalent years) than the standard calorie-restricted diet group. 40% of the low-AGE calorie-restricted diet group were still alive when the last standard calorie-restricted diet group member died.
  • The standard calorie-restricted diet group also had significantly more: 1) oxidative stress damage; 2) glucose and insulin metabolism problems; and 3) kidney, spleen, and liver injuries.

https://academic.oup.com/advances/article-abstract/10/3/520/5420411 “Epigenetic Regulation of Metabolism and Inflammation by Calorie Restriction” (not freely available)

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A drug that countered effects of a traumatizing mother

This 2019 US rodent study concerned transmitting poor maternal care to the next generation:

“The quality of parental care received during development profoundly influences an individual’s phenotype, including that of maternal behavior. Infant experiences with a caregiver have lifelong behavioral consequences.

Maternal behavior is a complex behavior requiring the recruitment of multiple brain regions including the nucleus accumbens, bed nucleus of the stria terminalis, ventral tegmental area, prefrontal cortex, amygdala, and medial preoptic area. Dysregulation within this circuitry can lead to altered or impaired maternal responsiveness.

We administered zebularine, a drug known to alter DNA methylation, to dams exposed during infancy to the scarcity-adversity model of low nesting resources, and then characterized the quality of their care towards their offspring.

  1. We replicate that dams with a history of maltreatment mistreat their own offspring.
  2. We show that maltreated-dams treated with zebularine exhibit lower levels of adverse care toward their offspring.
  3. We show that administration of zebularine in control dams (history of nurturing care) enhances levels of adverse care.
  4. We show altered methylation and gene expression in maltreated dams normalized by zebularine.

These findings lend support to the hypothesis that epigenetic alterations resulting from maltreatment causally relate to behavioral outcomes.”


“Maternal behavior is an intergenerational behavior. It is important to establish the neurobiological underpinnings of aberrant maternal behavior and explore treatments that can improve maternal behavior to prevent the perpetuation of poor maternal care across generations.”

The study authors demonstrated intergenerational epigenetic effects, and missed an opportunity to also investigate transgenerational epigenetically inherited effects. They cited reference 60 for the first part of the above quotation, but that reviewer misused the transgenerational term by applying it to grand-offspring instead of the great-grand-offspring.

There were resources available to replicate the study authors’ previous findings, which didn’t show anything new. Why not use such resources to uncover evidence even more applicable to humans by extending experiments to great-grand-offspring that have no potential germline exposure to the initial damaging cause?

Could a study design similar to A limited study of parental transmission of anxiety/stress-reactive traits have been integrated? That study’s thorough removal of parental behavior would be an outstanding methodology to confirm by falsifiability whether parental behavior is both an intergenerational and a transgenerational epigenetic inheritance mechanism.

Rodent great-grand-offspring can be studied in < 9 months. It takes > 50 years for human studies to reach the transgenerational generation. Why not attempt to “prevent the perpetuation of poor maternal care across generations?”

Isn’t it a plausible hypothesis that humans “with a history of maltreatment mistreat their own offspring?” Isn’t it worth the extra effort to extend animal research to investigate this unfortunate chain?

https://www.nature.com/articles/s41598-019-46539-4 “Pharmacological manipulation of DNA methylation normalizes maternal behavior, DNA methylation, and gene expression in dams with a history of maltreatment”

OCD and neural plasticity

This 2019 New York rodent study investigated multiple avenues to uncover mechanisms of obsessive-compulsive disorder:

“Psychophysical models of OCD propose that anxiety (amygdala) and habits (dorsolateral striatum) may be causally linked. Numerous genetic and environmental factors may reduce striatum sensitivity and lead to maladaptive overcompensation, potentially accounting for a significant proportion of cases of pathological OCD-like behaviors.

Our results indicate that both the development and reversal of OCD-like behaviors involve neuroplasticity resulting in circuitry changes in BLA-DLS and possibly elsewhere.”


The researchers explored two genetic models of OCD, showed why these insufficiently explained observed phenomena, then followed up with epigenetic investigations. They demonstrated how and the degree to which histone modifications and DNA methylation regulated both the development and reversal of OCD symptoms.

The researchers also carelessly cited thirteen papers outside the specific areas of the study to support one statement in the lead paragraph:

“Novel studies propose that modulations in gene expression influenced by environmental factors, are connected to mental health disorders.”

Only one of the thirteen citations was more recent than 2011, and none of them were high-quality studies.

https://www.nature.com/articles/s41598-019-45325-6.pdf “Amelioration of obsessive-compulsive disorder in three mouse models treated with one epigenetic drug: unraveling the underlying mechanism”

Do delusions have therapeutic value?

This 2019 UK review discussed delusions, aka false beliefs about reality:

“Delusions are characterized by their behavioral manifestations and defined as irrational beliefs that compromise good functioning. In this overview paper, we ask whether delusions can be adaptive notwithstanding their negative features.

We consider different types of delusions and different ways in which they can be considered as adaptive: psychologically (e.g., by increasing wellbeing, purpose in life, intrapsychic coherence, or good functioning) and biologically (e.g., by enhancing genetic fitness).”


1) Although the review section 4 heading was Biological Adaptiveness of Delusions, the reviewers never got around to discussing the evolved roles of brain areas. One mention of evolutionary biology was:

“Delusions are biologically adaptive if, as a response to a crisis of some sort (anomalous perception or overwhelming distress), they enhance a person’s chances of reproductive success and survival by conferring systematic biological benefits.”

2) Although section 5’s heading was Psychological Adaptiveness of Delusions, the reviewers didn’t connect feelings and survival sensations as origins of beliefs (delusions) and behaviors. They had a few examples of feelings:

“Delusions of reference and delusions of grandeur can make the person feel important and worthy of admiration.”

and occasionally sniffed a clue:

“Some delusions (especially so‐called motivated delusions) play a defensive function, representing the world as the person would like it to be.”

where “motivated delusions” were later deemed in the Conclusion section to be a:

“Response to negative emotions that could otherwise become overwhelming.”

3) Feelings weren’t extensively discussed until section 6 Delusions in OCD and MDD, which gave readers the impression that feelings were best associated with those diseases.

4) In the Introduction, sections 4, 5, and 7 How Do We Establish and Measure Adaptiveness, the reviewers discussed feeling meaning in life, but without understanding:

  1. Feelings = meaning in life, as I quoted Dr. Arthur Janov in The pain societies instill into children:

    “Without feeling, life becomes empty and sterile. It, above all, loses its meaning.

  2. Beliefs (delusions) defend against feelings.
  3. Consequentially, the stronger and more numerous beliefs (delusions) a person has, the less they feel meaning in life.

5) Where, when, why, and how do beliefs (delusions) arise? Where, when, why, and how does a person sense and feel, and what are the connections with beliefs (delusions)?

The word “sense” was used 29 times in contexts such as “make sense” and “sense of [anxiety, coherence, control, meaning, purpose, rational agency, reality, self, uncertainty]” but no framework connected biological sensing to delusions. Papers from other fields have detailed cause-and-effect explanations and precursor-successor diagrams for every step of a process.


Regarding the therapeutic value of someone else’s opinion of a patient’s delusions – I’ll reuse this quotation from the Scientific evidence page of Dr. Janov’s 2011 book “Life Before Birth: The Hidden Script that Rules Our Lives” p.166:

“Primal Therapy differs from other forms of treatment in that the patient is himself a therapist of sorts. Equipped with the insights of his history, he learns how to access himself and how to feel.

The therapist does not heal him; the therapist is only the catalyst allowing the healing forces to take place. The patient has the power to heal himself.

Another way Dr. Janov wrote this was on p.58 of his 2016 book Beyond Belief as quoted in Beyond Belief: The impact of merciless beatings on beliefs:

No one has the answer to life’s questions but you. How you should lead your life depends on you, not outside counsel.

We do not direct patients, nor dispense wisdom upon them. We have only to put them in touch with themselves; the rest is up to them.

Everything the patient has to learn already resides inside. The patient can make herself conscious. No one else can.”

https://onlinelibrary.wiley.com/doi/full/10.1002/wcs.1502 “Are clinical delusions adaptive?”

Our brains are shaped by our early environments

This 2019 McGill paper reviewed human and animal studies on brain-shaping influences from the fetal period through childhood:

“In neonates, regions of the methylome that are highly variable across individuals are explained by the genotype alone in 25 percent of cases. The best explanation for 75 percent of variably methylated regions is the interaction of genotype with different in utero environments.

A meta-analysis including 45,821 individuals with attention-deficit/hyperactivity disorder and 9,207,363 controls suggests that conditions such as preeclampsia, Apgar score lower than 7 at 5 minutes, breech/transverse presentations, and prolapsed/nuchal cord – all of which involve some sort of poor oxygenation during delivery – are significantly associated with attention-deficit/hyperactivity disorder. The dopaminergic system seems to be one of the brain systems most affected by perinatal hypoxia-ischemia.

Exposure to childhood trauma activates the stress response systems and dysregulates serotonin transmission that can adversely impact brain development. Smaller cerebral, cerebellar, prefrontal cortex, and corpus callosum volumes were reported in maltreated young people as well as reduced hippocampal activity.

Environmental enrichment has a series of beneficial effects associated with neuroplasticity mechanisms, increasing hippocampal volume, and enhancing dorsal dentate gyrus-specific differences in gene expression. Environmental enrichment after prenatal stress decreases depressive-like behaviors and fear, and improves cognitive deficits.”


The reviewers presented strong evidence until the Possible Factors for Reversibility section, which ended with the assertion:

“All these positive environmental experiences mentioned in this section could counterbalance the detrimental effects of early life adversities, making individuals resilient to brain alterations and development of later psychopathology.”

The review’s penultimate sentence recognized that research is seldom done on direct treatments of causes:

“The cross-sectional nature of most epigenetic studies and the tissue specificity of the epigenetic changes are still challenges.”

Cross-sectional studies won’t provide definitive data on cause-and-effect relationships.

The question that remains to be examined is: How can humans best address these early-life causes to ameliorate their lifelong effects?

https://onlinelibrary.wiley.com/doi/full/10.1111/dmcn.14182 “Early environmental influences on the development of children’s brain structure and function” (not freely available)

Epigenetic factors affecting female rat sexual behavior

This 2018 Baltimore/Montreal rodent study found:

“If sexually naïve females have their formative sexually rewarding experiences paired with the same male, they will recognize that male and display mate-guarding behavior towards him in the presence of a female competitor. Female rats that display mate-guarding behavior also show enhanced activation of oxytocin and vasopressin neurons in the supraoptic and paraventricular hypothalamic nucleus.

We examined the effect of a lysine-specific demethylase-1 inhibitor to block the action of demethylase enzymes and maintain the methylation state of corresponding genes. Female rats treated with the demethylase inhibitor failed to show any measure of mate guarding, whereas females treated with vehicle displayed mate guarding behavior. Demethylase inhibitor treatment also blocked the ability of familiar male cues to activate oxytocin and vasopressin neurons, whereas vehicle-treated females showed this enhanced activation.”

General principles and their study-specific illustrations were:

Histone modifications are a key element in gene regulation through chromatin remodeling. Histone methylation / demethylation does not have straightforward transcriptional outcomes as do other histone modifications, like acetylation, which is almost invariably associated with transcriptional activation.

What is of vital importance in regards to histone methylation / demethylation is the pattern of methylation that is established. Patterns of methylation incorporate both methylated and demethylated residues, and are what ultimately play a role in transcriptional outcomes.

In the present study, inhibiting LSD1 demethylase enzymes disrupted the ability of cells to properly establish histone methylation / demethylation patterns, thus creating a deficit in the cells’ ability to transcribe the gene products necessary for the enhanced induction of OT, AVP, and the subsequent mate-guarding behaviors we observed. This study is the first to demonstrate a definitive role of epigenetic histone modifications in a conditioned sexual response.”

https://www.sciencedirect.com/science/article/pii/S0031938418303421 “Inhibition of lysine-specific demethylase enzyme disrupts sexually conditioned mate guarding in the female rat” (not freely available)

Going off the rails with the biomarker paradigm

This 2018 US government rodent study used extreme dosages to achieve its directed goals of demonizing nicotine and extolling the biomarker paradigm:

“This study examined whether adolescent nicotine exposure alters adult hippocampus-dependent learning, involving persistent changes in hippocampal DNA methylation and if choline, a dietary methyl donor, would reverse and mitigate these alterations.

Mice were chronically treated with nicotine (12.6mg/kg/day) starting at post-natal day 23 (pre-adolescent), p38 (late adolescent), or p54 (adult) for 12 days followed by a 30-day period during which they consumed either standard chow or chow supplemented with choline (9g/kg).

Our gene expression analyses support this model and point to two particular genes involved in chromatin remodeling, Smarca2 and Bahcc1. Both Smarca2 and Bahcc1 showed a similar inverse correlation pattern between promoter methylation and gene expression.

Our findings support a role for epigenetic modification of hippocampal chromatin remodeling genes in long-term learning deficits induced by adolescent nicotine and their amelioration by dietary choline supplementation.”


Let’s use the average weight of a US adult male – published by the US Centers for Disease Control as 88.8 kg – to compare the study’s dosages with human equivalents:

  1. Nicotine at “12.6mg/kg/day” x 88.8 kg = 1119 mg. The estimated lower limit of a lethal dose of nicotine has been reported as between 500 and 1000 mg!
  2. Choline at “9g/kg” x 88.8 kg = 799 g. The US National Institutes of Health published the Tolerable Upper Intake Levels for Choline as 3.5 g!!

Neither of these dosages are even remotely connected to human realities:

  1. The human-equivalent dosage of nicotine used in this study would probably kill an adult human before the end of 12 days.
  2. What effects would an adult human suffer from exceeding the choline “Tolerable Upper Intake Level” BY 228 TIMES for 30 days?

Isn’t the main purpose of animal studies to help humans? What’s the justification for performing animal studies simply to promote an agenda?


A funding source of this study was National Institute on Drug Abuse (NIDA) Identification of Biomarkers for Nicotine Addiction award (T-DA-1002 MG). Has the biomarker paradigm been institutionalized to the point where research proposals that don’t have biomarkers as goals aren’t funded?

https://www.sciencedirect.com/science/article/pii/S107474271830193X “Choline ameliorates adult learning deficits and reverses epigenetic modification of chromatin remodeling factors related to adolescent nicotine exposure” (not freely available)