stress

Question 1

stress response systems

Answer 1

two simultaneous response systems
sympathetic nervous system: fight or flight
HPA axis: CRH stimulate the secretion of ACTH, which stimulate the secretion of cortisol. Cortisol binding to the glucocorticoid receptor shuts off the stress response system, but chronic binding desensitizes receptor

Question 2

corticosterone (CORT)

Answer 2

the major stress hormone secreted from the adrenal glands during real or perceived threat;
chronic CORT & stress induce persistent depressive-like behavior: anhedonic-like behavior (sucrose consumption can be used to model anhedonia in rodents), rigid perseverative decision-making, diminished motivation

Question 3

experiment: habits are insensitive to changes in the relationship between actions and their outcomes

Answer 3

reinforced response vs degraded response
choice test
stressor is corticosterone
corticosterone along is sufficient to replicate this effect

Question 4

experiment: progressive ratio conditions

Answer 4

decreased BDNF with less response

local BDNF infusion reverses corticosterone-induced phenotype

hippocampal BDNF is essential for the antidepressant effects of classical antidepressants; stressor exposure reduces hippocampal BDNF

Question 5

stressor exposure

Answer 5

exposed to the stressor remodeling the dendrites;
dendrite arbor of CA3 neurons of subordinate decreases;
dendritic remodeling to stressor is dynamic;

Question 6

prolonged stressor exposure

Answer 6

CRH in hypothalamus and cortisol in adrenal gland increases;

desensitization and a failure in negative feedback

Question 7

anxiety is associated with CRH systems

Answer 7

anxiety = prolonged response to potential threat
CRH is elevated in depression and chronic anxiety;
CRH receptor antagonists are being tested for their utility as anti-anxiety drugs;
these compounds may also have utility in the treatment of addictive-like behaviors by reducing the ‘stress’ associated with opioid withdrawal

Question 8

assess anxiety-like behavior in rodents

Answer 8

1. observation of naturally-occurring behaviors in response to mildly adverse events
   - rodents bury aversive things
   - marble burying and shock
   - probe burying task
   - anxiolytics decrease burying behavior
   - pup vocalization assay
   - ultrasonic vocalization assay
   - elevated plus maze: anxiolytics increase time spent in the open arms
   - light-dark and open field tests: anxiolytics increase time in vulnerable locations
   - novelty-suppressed feeding task: anxiolytics and antidepressants decrease latency to feed
2. conflict models
   vogel conflict test - a thirsty mouse licks a spout that delivers water. Every 10th lick results in a small shock delivered to the tongue. Anxiolytics increase the number of punished licks.