Class 10 - Stress: Epigenetics, neuroalterations, and mental health Flashcards
What are the 2 dimensions of childhood adversity?
threat and deprivation
In the romanian institutionalization study, what was found about children who remained institutionalized for longer (3)?
- blunted cortisol response to acute stress
- elevated cortisol throughout the day
- more synchronicity btw HR and breathing (not good; want to be able to breathe slow when HR high)
The promoter region of a DNA sequence contains _____
transcription factor binding sites
What is RNA polymerase? Where does it bind?
- enzyme responsible for synthesizing an RNA molecule from DNA template during transcription
- binds to promoter region w assistance of transcription factors
more RNA molecules observed is an indication that ___
the gene is active (there is gene transcription)
What is the translation phase in genes? Where does it take place?
- RNA sequence produced in transcription is translated to proteins
- mRNA binds to ribosome which decodes its sequence to produce proteins
- takes place in cytoplasm (outside nucleus)
Epigenetics is the study of how ___ and ___ can cause changes that affect _____
behaviours and the environment can affect the way your genes work
(T/F) epigenetics involves editing of genes
FALS, changes expression, not the genes themselves
What are the two most common forms of epigenetic mechanisms?
DNA methylation and histone modifications
What are the 2 types of histone modifications?
- acetylation (unfolds DNA; makes more accessible for transcription so increases gene expression)
- deacetylation (coils DNA; less accessible for transcription so less gene expression)
What are histones?
- proteins that structure DNA
(histone modification/methylation) is a more precise form of epigenetics
methylation
Coiled DNA means (increased/decreased) gene expression
DECREASED
What is DNA methylation?
- methyl group binds to cytosine (C) in DNA
- acts as physical barrier preventing binding of transcription factors to promoter region
- more methylation = less gene expression
What is the Developmental Origins of Health and Disease hypothesis (DoHaD)?
- environmental exposures during critical periods of prenatal/early postnatal dev can influence long-term health outcomes
What is wrong with the quote from the Time magazine cover: “The new science of epigenetics reveals how the choices you make can change your genes - and those of your kids”
- epigenetics can’t “change” genes, just how they function
(T/F) all methylation is passed on to the child via reproduction (explain!)
FALSE, most gets erased during gametogenesis but “imprinting control regions” of genome escape reprogramming and maintain parental methylation patterns
In agouti mice, the agouti gene is always turned (on/off). Methylation of the agouti gene is ass w (activation/deactivation) of agouti gene AND a change in phenotype (fur colour)
- always ON
- ass w DEACTIVATION of agouti gene
What happens to offspring when a pregnant agouti mouse is fed a diet of methyl supplementation?
- offspring mostly not agouti mice
What was the study that inaugurated the field of neuroscience epigenetics?
- Michael Meany
- was able to categorize epigenetic programming by maternal behavior (in rats)
What were the findings of Michael Meany’s study on epigenetic programming by maternal behavior?
- maternal care evokes changes in DNA methylation and chromatin structure!!
- good maternal care increases GR gene expression (helps w negative feedback system of HPA axis)
- changes could be reversed by cross-fostering to low care mothers!
How can we translate epigenetic findings in humans?
- examine brain post mortem
What did researchers find in the postmortem brains of suicide victims w history of childhood abuse vs no history?
- decreased levels of glucocorticoid receptor (GR) mRNA
- increased methylation of promoter region for GR
How do we know that there is low transcription of glucocorticoid receptors (impeding neg feedback of HPA axis) in live children who are victims of maltreatment?
- looked @ methylation patterns in blood
Prenatal stress alters the (structure/function) of the brain, especially in the ____, ____, and ____
- structure AND function
- hippocampus, amygdala, and prefrontal cortex
Elevated cortisol during early pregnancy are ass w increased _____ development in the fetus and poor ____ in (girls/boys) before puberty
- increased right amygdalar dev
- poor emotional dev in GIRLS
What enzyme mediates stimulatory effects of tactile contact in facilitating growth and development?
ornithine decarboxylase (ODC)
(T/F) pups can get ornithine decarboxylase via milk
FALSE, need physical contact!
What is one implication of the importance of ornithine decarboxylase in growth for human babies?
- practice of stimulating growth and dev in preemies by increasing handling (skin to skin contact)
What is psychosocial dwarfism?
- syndrome in infants who experience little/no physical contact
- compromised growth and development despite adequate nutrition
- disrupted GH secretion and absence of tissue responsiveness to exogenous GH
What is the link between attachment style and stress response?
- secure attachment = more adaptive stress response
- less cortisol in acute stress and quicker rebalancing
What are 3 findings about the benefits of secure attachment in the cortisol response?
- less cortisol after inoculations
- buffers effects of poverty
- interventions on parent-child relationship can improve cortisol response
attachment security (moderates/mediates) the relationship between _____ and ______
moderates; childhood experience and cellular aging
IN ANIMALS:
- females have (greater/weaker) basal concentrations of corticosterone
- females secrete (greater/weaker) concentration of corticosterone in response to stressors
- adrenal gland is larger in (males/females)
- females have GREATER basal concentrations of corticosterone
- females secrete GREATER concentration of corticosterone in response to stressors
- adrenal gland is larger in FEMALES
It seems that sex differences in stress hormones are ______, rather than _____, by hormones
activated rather than organized
IN HUMANS:
- (men/women) face more stressors
- stress affects attention and cognitive function more in (men/women)
- (men/women) are more likely to experience childhood trauma and suffer higher lvls of childhood stress
- WOMEN face more stressors
- stress affects attention and cognitive function more in MEN
- WOMEN are more likely to experience childhood trauma and suffer higher lvls of childhood stress
(T/F) stress inhibits testosterone production in men
TRUE, leads to reduced sexual motivation and performance
In men and women, glucocorticoids at high concentrations can suppress ___ and ___ secretion
GnRH and LH
How can social status in males impact the role of stress on reproduction?
- dominant males have higher lvls of enzyme that counteracts elevated glucocorticoid concentrations to ensure fertility!
What is the effect of exercise on stress in males?
- moderate exercise increases T
- mild exercise counteracts effects of stress
- excessive exercise acts as stress and causes sustained glucocorticoid secretion leading to low T conc
How does stress lead to erectile dysfunction?
- stress makes it difficult to establish parasympathetic activity in the penis (bc of stress-induced high sympathetic output)
- need parasympathetic activation for erection, sympathetic should only come online during ejaculation
What are 2 potential hormonal consequences for women who are very stressed or exercise excessively?
- amenorrhea
- less frequent LH pulses
How can fasting act as a stressor?
- increases blood glucocorticoid conc
What is hyperandrogenism?
- mechanism of reproductive impairment in females
- caused by overactive adrenal cortices and androgens
- increased androgen conc disrupts negative feedback mechanisms of GnRH and gonadotropins
- can cause acne, male pattern balding, abnormal hair growth, virilization
What is the function of the hippocampus in the stress response? How is it altered by chronic stress?
- helps shut off stress response (inhibits HPA axis)
- structural changes: fewer connections, smaller volume
- functional changes: diff w memory, learning
What is the function of the prefrontal cortex in the stress response? How is it altered by chronic stress?
- helps shut off stress response (inhibits HPA axis)
- structural changes: fewer/altered connections
- functional changes: difficulty regulating thoughts, emotions, behaviour
What is the function of the amygdala in the stress response? How is it altered by chronic stress?
- turns on stress hormones and increases HR
- structural changes: altered connections and volume
- functional changes: hyperreactive stress response
Affective disorders are often characterized in terms of a ___
continuum
How is the HPA axis affected in depression?
- negative feedback system impaired
- higher blood conc of cortisol!
What is the link between depression and thyroid hormones?
- depressed ppl have low thyroid function
- treatment of depression w thyroid hormone supplementation is only effective in patients w hypothyroidism
What is the link between depression and estradiol?
- women w past perimenopausal depression show improvement in depression symptoms when treated w estradiol
What 3 hormonal/neurological changes are associated with PTSD?
- disregulation of HPA axis (blunted stress resp)
- reduced hippocampal volume
- deficits in short-term memory
How does SAD affect hormones?
- cyclic disruptions in serotonin-carbohydrate regulating mechanisms
- display more serotonin transporter activity in fall/winter which leads to less available serotonin in synaptic cleft
How are carbohydrates linked to hormones?
- tryptophan is converted to serotonin in brain
- when we eat carbs, pancreas secretes insulin which facilitates uptake of sugars and non-tryptophan amino acids to peripheral cells
- leads to higher tryptophan in blood which means more tryptophan crosses blood brain barrier leadings to higher production of serotonin
- serotonin ass w decrease in appetite
What is the best treatment for SAD?
- light treatment to try to change circadian rhythms
- only works in conjunction w dietary adjustments
- exposure should be a few hours in the morning
What are 6 possible physical problems of anabolic steroid use in MEN?
- baldness
- headaches
- dev of breasts
- enlarged prostate
- reduced sperm count
- shrinkage of testicles
What are 5 possible physical problems of anabolic steroid use in WOMEN?
- increase in facial and body hair
- deepened voice
- reduced breast size
- menstrual problems
- enlarged clitoris
What psychiatric symptom is common among abusers of androgens?
mania or hypomania
What are 12 physical problems ass w anabolic steroid use in both men and women?
- 2 behavior/mood
- 1 skin
- 1 heart
- 1 liver
- 3 tummy
- 1 sexual organs
- 1 circulation
- 2 movement/body
- aggressive behavior
- mood swings
- severe acne
- high BP and heart disease
- liver damage
- nausea
- bloating
- urinary and bowel problems
- sexual dysfunction and infertility
- strokes and blood clots
- aching joints
- increased risk of tendon injuries
What are 4 psychological variables that modulate stress physiology?
- control
- predictability
- outlets for frustration
- habituation
