topic 7- stress and mood disorders Flashcards
(26 cards)
what is the stress response?
stress stimulates sympathetic and inhibits the parasympathetic.
what systems are stimulated when stressed?
adrenal hormones- control of secretion of clucocorticoids by the Adrenal Cortex and cateholamines of adrenal medulla.
adrenal hormones…
pre-ganglionic neurons of SNS stimulate adrenal medulla- release adrenaline and noradrenaline into blood. The adrenaline makes and releases cortisol- ATCH released by pituitary gland.
ACTH release is stimulated by…
corticotropin-releasing hormone which is released by paraventricular nucleus of hypothalamus.
which area indirectly activates by the stress response
Subgenual anterior cingulate cortex.
activation of stress response:
amygdala-central nucleus- homeostatic challenges, Medial nucleus of amygdala- psychogenic challenges. Amygdala activates SNS and HPA axis.
HPA axis…
negative feedback: direct from cortisol on PVN via glucocorticoid receptors.
major depression
has to be persistent and debilitating and it is 2x as common in women.
dysregulated HPA axis…
common in effective disorders- both pathological increases and descreases in cortisol lead to depressive symptoms.
chronic stress- positive feedback
self-perpetuates itself- amygdala stimulates the HPA axis- glucocorticoids activate the locus coeruleus.
what is the reduced negative feedback meant in relation to chronic stress?
repeated stimulation by glucocoricoids reduces sensitivity of receptors in hippocampus.
What is the relationship between major depressive disorder and sleep
REM is entered too early, this deprivation has long term effects and many anti depressants suppress REM
chronic stress impacts what monoamines/
noradrenaline, serotonin and dopamine.
what are the roles of mono-amines in depression?
reserpine induces depression, lower levels of 5-hydroxyindoleacetic acid in spinal fluid and tryptophan depletion experiments.
SSRI’s
ingested, lipids, different types have different half lives.
what is meant by the adaptation of auto-receptors?
initially SSRIs increase 5HT in synpase, autoreceptors respond to this and reduce 5HT release. No change in 5HT levels, it takes 2 weeks to adaapt. the adaptation dials down the negative feedbacl and lead to a gradual increase in release of 5HT.
ketamine
anasthetic and analgesic- powder, pills and injection. Biological half life 10-15 mins.
STE of ketamine
low: euphoria, disconnect from thorughts, perceptions. High: mind-body disconnect, k-holing.
physiological action of ketamine
NDMA-R antagonist: anasthesia and dissociation.
ket as an antidepressant:
injection has significant impact- work through new synapse formation in ACC.
addictiveness of ketamine
physical: tolerance build up and withdrawal symptoms.
Psychological: NDMA-R antagonists can influence dopamine release in nAcc.
Benzodiazepines;
ingested, reach peak in 60 mins, lipid soluble, half life- 90m to 6 days
short term effects of Benzos clincally:
sleeping pills, anxiolytic, recovery from alcohol withdrawal and anticolvulsant
physiological action behind Benzo’s
facilitate GABA which exist throughout the brain
