Noradrenaline ( Norepinephrine )
A hormone and neurotransmitter produced by the adrenal glands.
It is involved in the fight or flight system and neurotransmission in the sympathetic nervous system. It is synthesised from dopamine.
Author Archives: Kenzo Le Vaillant
Definition: Adrenaline
Adrenaline ( Epinephrine )
A hormone ad neurotransmitter produced in the adrenal glands. It is involved in the fight or flight response and synthesised from noradrenaline.
Related
Definition: Catecholamines
Catecholamines
Hormones produced in the adrenal glands such as noradrenaline, adrenaline or dopamine.
Related
Adrenal gland
Adrenaline
Noradrenaline
Dopamine
What does stress do to memory?
Introduction
This page is the first part of a study of the article
Stress effects on memory: An update and integration by
Lars Schwabe, Marian Joëls, Benno Roozendaal, Oliver T. Wolf and Melly S. Oitzl
The stress response
A stressor is, in one way, something that causes a change in the body and the stress response is what tries to bring the body back to its normal state.
The regulation of the body environment is called “Homeostasis”.
In a stress response, this is done by the release of hormones, neurotransmitters and peptides by the 2 stress systems :
The SAM axis that mainly releases catecholamines like adrenaline and noradrenaline causing increased heart rate and blood flow to skeletal muscles.
Catecholamines
Hormones produced in the adrenal gland released in response to stress.
Adrenaline
A.K.A. Epinephrine
A hormone and neurotransmitter produced by the adrenal glands. It is involved in the fight or flight response. It is synthesised from noradrenaline.
Noradrenaline
A.K.A. Norepinephrine
A hormone and neurotransmitter produced by the adrenal glands. It is involved in the fight or flight response and the neurotransmission in the sympathetic nervous system. It is synthesised from dopamine.
Skeletal muscle
Muscles connected to the bones that cause voluntary movement.
The HPA axis that releases glucocorticoids from the adrenal cortex.
Adrenal cortex
The outer largest part of the adrenal gland that produces hormones such as cortisol, androgens and aldosterone.
These hormones regulate different functions such as metabolism and blood pressure, puberty and sexual behaviours, blood salt content.
These two systems work in different ways but combined, they cause many changes to the body.
More about the neurobiology of stress
The effects of stress on memory
Stress has different effects on all stages of memory.
It can cause both positive and negative effects at any of these stages.
When the stress appears before the learning, the memory may be improved if the stress is related to it, if it has any emotional value and what kind of emotion or depending on the time between the stress and learning events.
If the stress is after the learning, the effects become slightly predictable.
When it appears during the consolidation process, the stress molecules usually enhance memory. Especially for emotional memories.
However, when it comes before, during or after memory retrieval, it usually impairs memory. Again, this effect is stronger on emotional memories.
Next Part :
Definition: BDNF
Brain derived neurotropic factor
A nwurotrophin, type of protein, released from the hypothalamus, involved in plasticity an transmission.
In stress, it is involved in the remodelling of dendrites.
Related
Definition: Endocannabinoid
Endocannabinoid
Neurotransmitters that regulate the structural changes in the brain that end the short term response to stress and familiarize to repeating stressors.
They are endogenous lipid-based retrograde neurotransmitters that bind to cannabinoid receptors.
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Endogenous
Retrograde neurotransmitters
Cannabinoid receptor
Definition: Corticotrophin releasing factor
Corticotrophin releasing factor (CRF) or corticotrophin releasing hormone (CRH)
A hormone secreted by the hypothalamus and the regulator of the HPA axis.
When released, it causes acetylcholine and glucocorticoid to be released.
The acethylcholin will then bind to the adrenal cortex, releasing cortisol in humans or corticosterones in other mammals.
Related
Acetylcholine
Adrenal cortex
Cortisol
Definition: Flashbulb memory
Flashbulb memory
Memories of the circumstances of when a very surprising event happened.
Related
The hippocampus, genetics and molecules of stress
Introduction
This page is the third part of a study of articles.
An overview on stress neurobiology: Fundamental concepts and its consequences by Rumi Iqbal Doewes, Lekshmi Gangadhar and Saranyadevi Subburaj
The hippocampus
The hippocampus receives input from many regions including the dentate gyrus and the entorhinal cortex.
It also sends both excitatory and inhibitory messages to various regions. These outputs result in indirect inhibition of impulses to the PFC.
The hippocampus also sends to the PFC and the BLA. These connections are important in memory and the management of reactions to psychological stress.
The relation of the hippocampus and the BLA goes both ways, meaning they both send to and receive from each other.
During moments of strong emotions, these links are activated while the PFC, that would suppress the amygdala, is inhibited. This enables the creation of long term flashbulb memories.
Flashbulb memories
Memories of the circumstances of when a very surprising event happened.
Stress and genetics
There are many ways that stress has an impact on the genes.
An example is glucocorticoids. These hormones, released in response to stress, have an impact on the activation of transcription and the stimulation of epigenetics.
Lab experiments have found that stress, in all forms, blocks certain genes in the hippocampus although these changes were different for each situation.
In addition, corticosterone alone wasn’t able to produce the same changes meaning it isn’t the only factor.
These changes may have long term effects as rats expressed to extreme stress for 3 weeks did not return to completely the same state. Stress reactions were also found to be different.
The molecules in stress
Several molecules are releases during stress.
Glucocorticoids are of course one. Another is the corticotrophin releasing factor(CRF).
This is involved in the HPA axis but also in the stress induced remodelling of the dendrites in a region of the hippocampus.
Corticotrophin release factor
CRF or corticotrophin releasing hormone (CRH)
A hormone secreted by the hypothalamus and the regulator of the HPA axis.
When released, it causes acethylcholin and glucocorticoid to be released.
The acethylcholin will then bind to the adrenal cortex, releasing cortisol in humans or corticosterones in other mammals.
The Tissue plasminogen activators, whose release is stimulated by the CRF, is also involved in the remodelling of dendrites by stress but also in the loss of spines in the same region and the MeA.
Lipocalin-2 is another molecule released during stress as well as Endocannbinoids and BDNF.
Endocanabinoid
Regulate the structural changes in the brain that end the short term response to stress and familiarize to repeating stressors.
BDNF
Brain derived neurotropic factor
A protein released from the hypothalamus, involved in plasticity an transmission.
In stress, it is involved in the remodelling of dendrites.
Part 1 : The amygdalas reaction to two different stressors
Previous part : The amygdalas reaction to two different stressors
Definition: Threat response system
Threat response system
The brains circuits that prepare and respond to a threat.
The main area is the amygdala.
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