Here are the most popular of the 65 posts I’ve made so far in 2018, starting from the earliest:
This 2018 Polish review subject was the relationship between melatonin and depression:
“Although melatonin has been known about and referred to for almost 50 years, the relationship between melatonin and depression is still not clear. In this review, we summarize current knowledge about the genetic and epigenetic regulation of enzymes involved in melatonin synthesis and metabolism as potential features of depression pathophysiology and treatment.
Melatonin has an antidepressant effect by:
- Maintaining the body’s circadian rhythm,
- Regulating the pattern of expression of the clock genes in the suprachiasmatic nucleus (SCN) and
- Modifying the key genes of serotoninergic neurotransmission that are linked with a depressive mood.
Light input causes the release of γ-aminobutyric acid (GABA) by the SCN, and the inhibitory signal is transmitted to the pineal gland to inhibit melatonin production.
Melatonin is produced via the metabolism of serotonin in two steps which are catalyzed by serotonin N-acetyltransferase (SNAT) and acetylserotonin-O-methyltransferase (ASMT). Serotonin, SNAT, and ASMT are key melatonin level regulation factors.
Both melatonin and serotonin are synthesized from the same amino acid, tryptophan. People on a high tryptophan diet (>10 mg/kg body weight per day) have a significantly lower level of depressive symptoms, irritation, and anxiety than people on a low tryptophan diet (<5 mg/kg body weight per day).
To our knowledge, there are only 2 studies in the literature that characterize mRNA expression of ASMT in the peripheral blood of recurrent DD [depressive disorders]. [They] have demonstrated the reduced mRNA expression of ASMT in patients with depression and cognitive impairment. Surprisingly, these studies, despite promising results, have not been replicated. Moreover, no analysis of other melatonin related-genes as potential biomarkers of depression has been provided.
The main monoamine hypothesis of the pathophysiology of depression indicates that depression is induced by a change in the level of ≥1 monoamines such as serotonin, noradrenaline, and dopamine. The evidence for the serotonergic theory is an observation that antidepressants such as tricyclic antidepressants, selective serotonin reuptake inhibitors, and noradrenaline reuptake inhibitors increase the level of serotonin in the brain.
We focus on serotonin as a neurotransmitter which is a precursor of melatonin synthesis. In a depressed patient, serotonin synthesis is impaired and the poor precursor availability may prevent the formation of an adequate amount of melatonin. However, only a few studies have analyzed the relationship between serotonin and melatonin levels and the correlation with the blood serum.”
At eight cents a day ($.04 for women) melatonin is a cheap and effective supplement.
I hadn’t considered possible antidepressant effects until reading this review. More human studies are needed.
https://www.karger.com/Article/Pdf/489470 “Pathophysiology of Depression: Molecular Regulation of Melatonin Homeostasis – Current Status” (not freely available)
This 2018 Loma Linda review subject was gestational hypoxia:
“Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue.
An understanding of the specific hypoxia-induced environmental and epigenetic adaptations linked to specific organ systems will enhance the development of target-specific inhibition of DNA methylation, histone modifications, and noncoding RNAs that underlie hypoxia-induced phenotypic programming of disease vulnerability later in life.
A potential stumbling block to these efforts, however, relates to timing of the intervention. The greatest potential effect would be accomplished at the critical period in development for which the genomic plasticity is at its peak, thus ameliorating the influence of hypoxia or other stressors.
With future developments, it may even become possible to intervene before conception, before the genetic determinants of the risk of developing programmed disease are established.”
Table 3 “Antenatal hypoxia and developmental plasticity” column titles were Species | Offspring Phenotypes of Disorders and Diseases | Reference Nos.
This review was really an ebook, with 94 pages and 1,172 citations in the pdf file. As I did with Faith-tainted epigenetics, I read it with caution toward recognizing the influence of the sponsor’s biases, and any directed narrative that ignored evidence contradicting the narrative, and any storytelling.
See if you can match the meaning of the review’s last sentence (“intervene before conception” quoted above) with the meaning of any sentence in its cited reference Developmental origins of noncommunicable disease: population and public health implications.
One review topic that was misconstrued was transgenerational epigenetic inheritance of hypoxic effects. The “transgenerational” term was used inappropriately by several of the citations, and no cited study provided evidence for gestational hypoxic effects through the F2 grandchild and F3 great-grandchild generations.
One omitted topic was gestational hypoxic effects of caffeine. The first paper that came up for my PubMed search of “caffeine pregnancy hypoxia” was an outstanding 2017 Florida rodent review Long-term consequences of disrupting adenosine signaling during embryonic development that had this paragraph and figure:
“One substance that fetuses are frequently exposed to is caffeine, which is a non-selective adenosine receptor antagonist. We discovered that in utero alteration in adenosine action leads to adverse effects on embryonic and adult murine hearts. We find that cardiac A1ARs [a type of adenosine receptor] protect the embryo from in utero hypoxic stress, a condition that causes an increase in adenosine levels.
After birth in mice, we observed that in utero caffeine exposure leads to abnormal cardiac function and morphology in adults, including an impaired response to β-adrenergic stimulation. Recently, we observed that in utero caffeine exposure induces transgenerational effects on cardiac morphology, function, and gene expression.”
Why was this review and its studies omitted? It was on target for both gestational hypoxia and transgenerational epigenetic inheritance of hypoxic effects!
It was alright to review smoking, cocaine, methamphetamine, etc., but the most prevalent drug addiction – caffeine – couldn’t be a review topic?
The Loma Linda review covered a lot, but I had a quick trigger due to the sponsor’s bias. I started to lose “faith” in the reviewers after reading the citation for the review’s last sentence that didn’t support the statement.
My “faith” disappeared after not understanding why a few topics were misconstrued and omitted. Why do researchers and sponsors ignore, misrepresent, and not continue experiments through the F3 generation to produce evidence for and against transgenerational epigenetic inheritance? Where was the will to follow evidence trails regardless of socially acceptable beverage norms?
The review acquired the taint of storytelling with the reviewers’ assertion:
“..timing of the intervention. The greatest potential effect would be accomplished at the critical period in development for which the genomic plasticity is at its peak, thus ameliorating the influence of hypoxia or other stressors.”
Contradictory evidence was in the omitted caffeine study’s graphic above which described two gestational critical periods where an “intervention” had opposite effects, all of which were harmful to the current fetus’ development and/or to following generations. Widening the PubMed link’s search parameters to “caffeine hypoxia” and “caffeine pregnancy” returned links to human early life studies that used caffeine in interventions, ignoring possible adverse effects on future generations.
This is my final curation of any paper sponsored by this institution.
https://www.physiology.org/doi/abs/10.1152/physrev.00043.2017 “Gestational Hypoxia and Developmental Plasticity” (not freely available) Thanks to coauthor Dr. Xiang-Qun Hu for providing a copy.
This 2018 US Veterans Administration review subject was resiliency and stress responses:
“Neurobiological and behavioral responses to stress are highly variable. Exposure to a similar stressor can lead to heterogeneous outcomes — manifesting psychopathology in one individual, but having minimal effect, or even enhancing resilience, in another.
We highlight aspects of stress response modulation related to early life development and epigenetics, selected neurobiological and neurochemical systems, and a number of emotional, cognitive, psychosocial, and behavioral factors important in resilience.”
The review cited studies I’ve previously curated:
- The truth about complex traits and GWAS that I curated yesterday;
- Conscious mental states should not be the first-choice explanation of behavior on the first day of this blog, February 1, 2015; and
- Manufacturing PTSD evidence with machine learning, but I had a different view of the study than the reviewers’ favorable one.
There were two things I didn’t understand about this review. The first was why the paper isn’t freely available. It’s completely paid for by the US taxpayer, and no copyright is claimed. I recommend contacting the authors for a copy.
The second was why the VA hasn’t participated in either animal or human follow-on studies to the 2015 Northwestern University GABAergic mechanisms regulated by miR-33 encode state-dependent fear. That study’s relevance to PTSD, this review’s subject, and the VA’s mission is too important to ignore. For example:
“Fear-inducing memories can be state dependent, meaning that they can best be retrieved if the brain states at encoding and retrieval are similar.
“It’s difficult for therapists to help these patients,” Radulovic said, “because the patients themselves can’t remember their traumatic experiences that are the root cause of their symptoms.”
The findings imply that in response to traumatic stress, some individuals, instead of activating the glutamate system to store memories, activate the extra-synaptic GABA system and form inaccessible traumatic memories.”
I curated the research in A study that provided evidence for basic principles of Primal Therapy. These researchers have published several papers since then. Here are the abstracts from three of them:
“Pharmacological treatments for psychiatric illnesses are often unsuccessful. This is largely due to the poor understanding of the molecular mechanisms underlying these disorders. We are particularly interested in elucidating the mechanism of affective disorders rooted in traumatic experiences.
To date, the research of mental disorders in general has focused on the causal role of individual genes and proteins, an approach that is inconsistent with the proposed polygenetic nature of these disorders. We recently took an alternative direction, by establishing the role of miRNAs in the coding of stress-related, fear-provoking memories.
Here we describe in detail our work on the role of miR-33 in state-dependent learning, a process implicated in dissociative amnesia, wherein memories formed in a certain brain state can best be retrieved if the brain is in the same state. We present the specific experimental approaches we apply to study the role of miRNAs in this model and demonstrate that miR-33 regulates the susceptibility to state-dependent learning induced by inhibitory neurotransmission.”
“State-dependent learning (SDL) is a phenomenon relating to information storage and retrieval restricted to discrete states. While extensively studied using psychopharmacological approaches, SDL has not been subjected to rigorous neuroscientific study.
Here we present an overview of approaches historically used to induce SDL, and highlight some of the known neurobiological mechanisms, in particular those related to inhibitory neurotransmission and its regulation by microRNAs (miR).
We also propose novel cellular and circuit mechanisms as contributing factors. Lastly, we discuss the implications of advancing our knowledge on SDL, both for most fundamental processes of learning and memory as well as for development and maintenance of psychopathology.”
“Retrieval of fear memories can be state-dependent, meaning that they are best retrieved if the brain states at encoding and retrieval are similar. Such states can be induced by activating extrasynaptic γ-aminobutyric acid type A receptors (GABAAR) with the broad α-subunit activator gaboxadol. However, the circuit mechanisms and specific subunits underlying gaboxadol’s effects are not well understood.
Here we show that gaboxadol induces profound changes of local and network oscillatory activity, indicative of discoordinated hippocampal-cortical activity, that were accompanied by robust and long-lasting state-dependent conditioned fear. Episodic memories typically are hippocampus-dependent for a limited period after learning, but become cortex-dependent with the passage of time.
In contrast, state-dependent memories continued to rely on hippocampal GABAergic mechanisms for memory retrieval. Pharmacological approaches with α- subunit-specific agonists targeting the hippocampus implicated the prototypic extrasynaptic subunits (α4) as the mediator of state-dependent conditioned fear.
Together, our findings suggest that continued dependence on hippocampal rather than cortical mechanisms could be an important feature of state-dependent memories that contributes to their conditional retrieval.”
Here’s an independent 2017 Netherlands/UC San Diego review that should bring these researchers’ efforts to the VA’s attention:
“Post-traumatic stress disorder (PTSD) is a psychiatric disorder that can develop following exposure to or witnessing of a (potentially) threatening event. A critical issue is to pinpoint the (neuro)biological mechanisms underlying the susceptibility to stress-related disorder such as PTSD, which develops in the minority of ~15% of individuals exposed to trauma.
Over the last few years, a first wave of epigenetic studies has been performed in an attempt to identify the molecular underpinnings of the long-lasting behavioral and mental effects of trauma exposure. The potential roles of non-coding RNAs (ncRNAs) such as microRNAs (miRNAs) in moderating or mediating the impact of severe stress and trauma are increasingly gaining attention. To date, most studies focusing on the roles of miRNAs in PTSD have, however, been completed in animals, using cross-sectional study designs and focusing almost exclusively on subjects with susceptible phenotypes.
Therefore, there is a strong need for new research comprising translational and cross-species approaches that use longitudinal designs for studying trajectories of change contrasting susceptible and resilient subjects. The present review offers a comprehensive overview of available studies of miRNAs in PTSD and discusses the current challenges, pitfalls, and future perspectives of this field.”
Here’s a 2017 Netherlands human study that similarly merits the US Veterans Administration’s attention:
“Posttraumatic stress disorder (PTSD) affects many returning combat veterans, but underlying biological mechanisms remain unclear. In order to compare circulating micro RNA (miRNA) of combat veterans with and without PTSD, peripheral blood from 24 subjects was collected following deployment, and isolated miRNA was sequenced.
PTSD was associated with 8 differentially expressed miRNA. Pathway analysis shows that PTSD is related to the axon guidance and Wnt signaling pathways, which work together to support neuronal development through regulation of growth cones. PTSD is associated with miRNAs that regulate biological functions including neuronal activities, suggesting that they play a role in PTSD symptomatology.”
See the below comments for reasons why I downgraded this review’s rating.
https://link.springer.com/article/10.1007/s11920-018-0887-x “Stress Response Modulation Underlying the Psychobiology of Resilience” (not freely available)
This 2018 Loma Linda review subject was epigenetic interventions for aging:
“Epigenomic markers of aging, global DNA hypomethylation and promoter-specific hypermethylation may be engendered by iron and HCys [homocysteine] retention.
MiR-29/p53 axis may reverse age-related methylomic shifts, stabilizing both the genome and the epigenome, therefore removing a major risk factor of neurodegeneration. Lowering iron and HCys overload can be accomplished via chelation, blood donation and maintaining an adequate omega-6/omega-3 ratio.”
Sometimes it’s difficult to detect researchers’ biases. If a reader didn’t know about the funding sponsor’s mission:
“Each day we seek to extend the teaching and healing ministry of Jesus Christ”
they may view this paper as unbiased rather than as a directed narrative.
Consider the sponsor’s influence from the perspective of someone seeking treatment for Alzheimer’s disease. If a doctor in this review sponsor’s hospital system recommended chelation treatment, hope would be generated for the patient. Adopting the doctor’s belief about the treatment, though, would be contrary to other evidence per this review:
“In 2008, the NIH chelation trial stopped enrolling patients, approximately two years early.
There is no indication for exposing patients with dementia to the risks of chelation therapy because current chelators cannot help them.”
After reading another review that had this sponsor – The lack of oxygen’s epigenetic effects on a fetus – which also reflected the influence of the sponsor’s biases, and had a directed narrative that ignored evidence contradicting the narrative, and involved storytelling, I’m done curating any paper sponsored by this institution.
http://www.nrronline.org/downloadpdf.asp?issn=1673-5374;year=2018;volume=13;issue=4;spage=635;epage=636;aulast=Sfera;type=2 “Epigenetic interventions for brain rejuvenation: anchoring age-related transposons” (click the pdf button)
Two items before getting to the review:
- 94% of rodent genera are naturally uniparental;
- The Rattus and Mus genera used in almost all rodent research aren’t part of the 6% in which fathers also provide offspring care.
“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:
- Transgenerational epigenetic programming with stress and microRNA
- A cited study in What is epigenetic inheritance?
The reviewer in the latter has been instrumental in excluding behavioral inheritance mechanisms from these research paradigms, leading to my questions:
- “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?
- 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?
- 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.
This 2018 Italy/UK meta-analysis subject was the use of dietary supplement acetyl-L-carnitine to treat depression symptoms:
“Deficiency of acetyl-L-carnitine (ALC) appears to play a role in the risk of developing depression, indicating dysregulation of fatty acids transport across the inner membrane of mitochondria. However, the data regarding ALC supplementation in humans are limited. We thus conducted a systematic review and meta-analysis investigating the effect of ALC on depressive symptoms across randomized controlled trials (RCTs).
Pooled data across nine RCTs (231 treated with ALC versus 216 treated with placebo and 20 no intervention) showed that ALC significantly reduced depressive symptoms.
In three RCTs comparing ALC versus antidepressants (162 for each group), ALC demonstrated similar effectiveness compared with established antidepressants [fluoxetine (Prozac), duloxetine (Cymbalta), amisulpride (Solian) respectively below] in reducing depressive symptoms. In these latter RCTs, the incidence of adverse effects was significantly lower in the ALC group [79%] than in the antidepressant group.
From the Study selection subsection:
“Studies were excluded if:
- did not include humans;
- did not include a control group;
- did not use validated scales for assessing depression;
- did not report data at follow-up evaluation regarding tests assessing depression;
- included the use of ALC with another agent vs. placebo/no intervention.”
The Discussion section was informative regarding possible mechanisms of ALC affecting depression, pain, and linked symptoms. Several citations were of a review rather than of the original studies, however.
Research needs to proceed on to investigate therapies that address ultimate causes for depression and pain. Researchers and sponsors shouldn’t stop at just symptoms and symptom relief, notwithstanding the requirement from a statistical point of view for “future large scale trials.”
Here are other acetyl-L-carnitine topics I’ve curated:
- A common dietary supplement that has rapid and lasting antidepressant effects
- Familiar stress opens up an epigenetic window of neural plasticity
- A gaping hole in a review of nutritional psychiatry
https://journals.lww.com/psychosomaticmedicine/Citation/2018/02000/Acetyl_L_Carnitine_Supplementation_and_the.4.aspx “Acetyl-L-Carnitine Supplementation and the Treatment of Depressive Symptoms: A Systematic Review and Meta-Analysis” (not freely available)
This post has somehow become a target for spammers, and I’ve disabled comments. Readers can comment on other posts and indicate that they want their comment to apply here, and I’ll re-enable comments.