Neurobiological aspects of stress Flashcards
Who is attributed as the father of stress?
Hans Selye, 17 time nominee of Nobel prize
How did Hans Selye discover the stress response?
After injecting a rat with a ovarian extract noted distinct changes
Changes were the same when other things were injected or control groups were put in uncomfortable circumstances.
He called it: General Adaptive Syndrome
Briefly describe the stress response and how glucocorticoids effect our physiology?
Stress illicit brain areas:
PVN of Hypothalamus and stimulate piturity gland via CRH/CRF
This releases ACTH to the adrenals, which release cortisol.
Cortisol is a Glucocorticoid:
It metabolises glucose
Synthesised by adrenal gland
Classified as a steroid
Once released by adrenals, every cell in the body has a cortisol receptor and it is picked up by either:
Mineralocotticoid receptors in Low levels
Gluccocortcoid Receptors in High Levels
It binds to ligand gates in the cytoplasm, translocates into the nucleus and binds with Response Factor:
Results in:
Energy metabolism
Electrolyte and blood pressure change
Immune response
How does the endocrine system differ from the nervous system?
Endocrine system releases hormones via glands which travel in bloodstream via chemical reactions, often transcripted, slow reaction, long lasting. Involuntary
Nervous system using electrcical impulses via neurons, fast and short lived. Involuntary and voluntary
How does the Recent Life Changes Questionnaire work?
Using 5 categories; Work Financial Personal and Social Exercise Health
; you mark how severe your change has been giving you a Life Change Units score.
300 or 500 plus for 6 month or 1 year as bench mark
What did the Twin study of Kendler et al show us regarding stress and depression?
That trait neuroticism was the major factor in the effect of stressful life events.
What is the effect of high GC levels in animals and humans?
Animals:
Depressive like symptoms Decreased neurogenesis Decreased synaptic Plasticity Monoamine dysfunction Reduced volume of hippocampus
All symptoms also found in depressed patients
Humans:
Mania to start then depression after a few weeks
Why is the negative feedback loop so important in the HPA axis?
Without it we develop a GC resistance which continues the release of cortisol without limit.
What is the difference between Hyper and Hypo HPA axis activity?
In Hyper there is an excess of cortisol: MDD with melancholic features (Non reactive)
HPA Hypoactivity : Atypical depression (reactive mood)
What is the relationship of corticosterone and neurogenesis?
Increase will disrupt neurogenesis
Adrenalectomy will increase it
What did the millennium article put forward as a theory of depression?
Since fox odour and other stressors reduced neurogenesis in animals and exercise and antidepressants did the opposite it was proposed that high cortisol could be the a risk factor in depression.
Jacobs
What did Wohleb and colleagues find out regarding microglia and depression and anxiety?
When exposed to CUS:
Rats showed CSF 1 increase and microglia changes. Depressive symptoms were observed.
When CSF 1 was blocked depressive symptoms were alleviated.
Therefore: Connectivity of Neurons and microglia responsible in depression and anxiety.
What was found when Human hippocampal progenitor cells were treated with high levels of cortisol?
Neurogenesis was reduced
Reduction in DCX-postive and MAP2-Positive cells
Further:
When treated with a GR receptor blocker, both DCX and MAP2 were reduced significantly and this was reduced by Sertraline.
What is useful about the CAR?
It shows unique associations with lifestyle factors and psychological factors. Often different from the rest of the day.
What are preferred methods to measure cortisol levels?
Salvia: multiple times during day, particallry at waking. Good to show short term response
Hair: Good to show long term response and easy to collect.
