BIPN 154 LIM Midterm#1

What is the first response to stress?

Fight or flight response: functions that establish and support the body energy reserves at rest, in stressful situations, were immediately intensifies and completely interrupted in order to mobilize energy, which allows for an improvement of potential escape and attack and/or defense responses/

When does flight or fight response kick in?

in the face of imminent physical danger or as a result of a more psychological threat

What are the physiological changes associated with the fight or flight response

1. Rapid heart beat and breathing: provides oxygen

2. Pale or flushed skin: blood flow to skin surface dec. to inc flow to brain, legs and arms

3. Dilated pupils: more light = better vision

4. Trembling: muscles become tense and primed for action

What is the difference between sympathetic NS and parasympathetic NS?

SNS: responds to "stressed" thoughts and produces a stress response to these thoughts and mood

PNS: responds to "calming" thoughts and relaxes the body by producing a resting response

What is General Adaptation syndrome?

a set of non-specific responses that develop in three stages

1. Alarm stage

2. Resistance stage

3. Exhaustion stage

Describe Alarm Stage of General adaptation syndrome?

Sensing danger triggers the stress response. This causes the secretion of stress hormones into the bloodstream, to go to target spots to bring about the fight or flight physiological changes.

Describe the resistance stage of the General adaptation syndrome

The stress response changes are engaged to give the body an extra boost in energy and resources to deal with the threat

Describe the Exhaustion stage of the General Adapatation Syndrome?

After the threat has passed the stress response ends and the stress hormones are used or expelled the body enter a recovery phase were it recovers from the stress response changes and rebuild its energy stores for next time a stress response is needed

Define Allostasis, Allostatic load and Allostatic Overload.

Allostasis: away from homeostasis

Allostasis Load: The amount at which you stray from homeostasis

Overload: too far from homeostasis, too stressed

What is the major consequence of chronically repeated stress stimuli?

There is a baseline status change in the levels of stress mediators

What is the first phase in Stress Response?

Sympathetic Adrenomeddullar System: SAM provides an immediate physiological, psychological and emotional adaptation , that has a short lasting response (a burst of adrenaline/epinephrine)

What is the first part in Phase 1 of SAM?

Epinephrine and NE are released.

Amygdala -->> Hypothalamus -->> sympathetic NS, which causes adrenal medulla to release E and NE into the bloodstream.

What determines which stress response pathway is activated?

If the danger is perceived as more threatening or persists for more than a few minutes it the HPA pathway will be activated.

If it is a minor threat or short scare the SAM pathway with be activated

What are the effects of the release of E and NE?

Inc HR, BP, dilated pupils, more oxygen, more blood flow to vital organs

Describe Phase 2 of the Stress Response?

Hypothalamic Pituitary Adrenal Axis (HPA):

Amygdala -->> hypothalamus released corticotropins releasing hormone (CRH). CRH -->> pituitary gland, which released adrenocorticotropic hormone (ACTH). ACTH -->> Adrenal Cortex, released cortisol into bloodstream

What is the difference between the effects of E and NE versus cortisol?

Cortisol is longer lasting effects and it elicits a more significant response because its effects are broader and more potent

What is a patch clamp and what is it used for?

this patches the cell neuron, which gives the ability to record the activity of the individual neuron.

1. You can compare the activity between two cells

2. When you want to compare electrophysiological property of a single cell

What is in-vivo extracellular recording used for?

A general area recording

What NTs are released to create and EPSP?

Glutamate and ACh

What NTs are released to create and IPSP?

GABA

How NMDAr and AMPAr different?

AMPAr always have a constant flow of ions through them, but NMDAr don't.

NMDAr are CA2+ influx dependent bc they have a MG2+ plug.

NMDAr are important in LTD and LTP processes.

What is the main function of GABAr?

responsible for silencing neurons by having an influx of Cl-

Describe Optogenetics.

A major tool for manipulating the brain

Channelrhodopsin: blue light, activates neurons

Hallorhodopsin: green light, silences neurons

Describe Chemogenetics

hM3D: causes activation of neuron

hM4D: inhibits cell

What is the same and what is different between optogenetics and chemogenetics

The method of delivery is the same for both (virus)

Difference is chemogenetics do not need an optic fiber

How do you know that PVN neurons expressing CRH are activated during stress response?

Through a transgenic animal:

Parent#1: Expresses CRE recombinase under specific promoter

Parent#2: CRE reporter line: expressed GFP or any other reporter gene (YFP, luciferase)

Offspring: will express CRE and have GFP expression wherever CRE is expressed (promoter specific)

What is the difference between immunostaining and CRE fluorescent ?

Immunostaining is with DEAD tissue and CRE transgenic mice are alive

What are the 4 types of extracellular signaling?

Endocrine, Paracrine, Autocrine and membrane bound signal

Describe endocrine signalling

the signaling molecules transported through the circulatory system and act on target cells distant from their site of synthesis

Describe Paracrine signalling.

The signaling molecules released by a cell affect only those target cells in close proximity

Describe Autocrine signalling.

cells respond to substance that they themselves release

Describe membrane bound signaling.

portions attached to the membrane of one cell can interact with cell-surface receptors on adjacent cells

What are the differences between SAM and HPA Pathways?

1. Hormone is different (NE and E vs. Cortisol)

2. Outcomes are different (short term SR vs. long term SR)

3.Pathways are different

4. Secretion site is different (Adrenal medulla vs Adrenal cortex)

What happens when mineral corticoids are released?

1. Retention of sodium ions and water by kidneys

2. Increase blood volume and BP

What happens when Glucocorticoids are released?

1. Proteins and fats broken down and converted to glucose, leading to increased blood glucose

2. Immune system may be suppressed

What is special about an Adrenergic receptor?

It uses a g-protien signalling, that causes a cascade of events and an increased/amplified signal

What is the major difference between Cortisol and NE/E? and why is this relevant when understanding why cortisol is used for longterm stress response?

Cortisol can penetrate the cell membrane whereas E and NE cannot. This allow it to have a more cell wide response?

What is the difference between alpha and beta adrenergic receptors?

alpha: response to NE

beta: respond to E: B1 is heart contraction, B2 smooth muscle relaxation

What is the main function of the Hypothalamus?

Controls homeostasis, it links the NS to the endocrine system via the pituitary gland.

What is Corticotropin-releasing hormone?

CRH: signals the pituitary gland to produce a hormone called adrenocorticotropic hormone (ACTH). ACTH -->> triggers the production of cortisol, an important stress hormone

What would immunostaining be used for?

Immunostaining after a stressful event to see immediate early genes that mark the neurons that were active to figure out where activation occurs, but you have to be dead.

What is Adrenocorticotropic hormone (ACTH)?

It is a peptide hormone that is released from the pituitary gland

Why is the Locus Coeruleus important? and where is it located?

This is where the NE neurons are located. In the central noradrenergic system

What are the functions of NE neurons?

1. Make most diffuse connection in the brain

2. involved in regulation of arousel, attention, sleep cycle, anxiety, etc.

3. Works as pacemaker to keep you awake

4. usually increased the brains responsiveness

How is the activity of NE neurons controlled?

By your mental state

Describe the Restraint stress test and OFT.

Center: no stress response

Border: stressed

When stressed there is an increase in c-fos markers in the LC NE neurons, showing that LC NE neurons are activated when under stressful situations

Where are CRH neurons located in the brain?

Everywhere

What are the two types of trace we can do?

fluorescent tracing: fluorogold or YFP (must have ChR2 tagged with YFP for it to be viable)

What is the main glucocorticoid in humans? rodents?

Cortisol, Corticosterone

What is the major mineralcorticoid?

Aldosterone

How are the stress and Immune system linked?

Cortisol prevent proliferation of T-cells by rendering T-cells unresponsive to cytokines

How is cortisol linked to metabolism?

Cortisol -->> gluconeogenesis in liver, increased glucose production

Cortisol dec the production of leptin-->> inc food intake BUT...

When cortisol inc, our cells become resistant to insulin

What are the two receptors for glucocorticoids?

Mineralcorticoid receptor and glucocorticoid receptor.

What is difference between MR and GRs?

GR: widely distributed across brain, activated as hormone levels rise following stress

MR: expressed in neurons only, mostly in hippocampus

What is the role of MRs

they mediate the rapid and transient increase of miniature excitatory postsynaptic currents (mEPSC) after treatment with corticosterone.

It increase the release probability of glutamate

What is the role of cortisol in long-term behavioral changes?

Cortisol binds to GR and they respond to longterm change, especially at the synapse (LTD and LTP)

What is the induction of LTP dependent on?

repetitive titanic stimulation of synapses causes Ca2+ influx and NMDAr activation

What is the end result of Early-LTP that causes a greater response?

The insertion of AMPAr; even with the same amount of glutamate released, the response is stronger because there are more receptors

Describe the ONSET of actions of Glucocorticoids.

1. SNS is activated and CRH is released

2. Non-genomic MRs enhance attention and vigilance to optimize sensory processing in support of perception of novel information

Describe the Recovery and Adaptation phases of Glucocorticoids.

This marks a further increase in glucocorticoid secretion and activation of the lower-affinity membrane and genomic GRs

Describe the onset, recovery and adaptation of stress regarding MRs and GRs

(MR) Onset: enhanced excitability, onset stress reaction

(GR) Recovery: suppressed excitability, containment of stress

(GR) Adaptation: consolidation of experience in memory to ensure adaptive behavior in future

MR controls the onset of the stress response, which is terminated through GR

What is the main difference between MR and GR

MR is involved in the appraisal, risk assessment and reactivity to stress situation and GR is involved in the memory storage, recovery and termination of the stress

What is significant about the negative feedback loop cortisol has?

CORT-mediated negative feedback is fundamental for the termination of the HPA axis response to stress

When cortisol levels are high (stress is high), it supressed the activity of the hypothalamus and Anterior Pituitary as a negative feedback to decrease the level of cortisol.

What are some symptoms of Dopamine Deficiency?

Lack of Joy, focus, hopelessness, loss of appetite

What are some symptoms of serotonin deficiency?

anxiety, moodiness, lack of confidence, obsessive behaviors, insomnia

What contains the majority of the dopamine population

Ventral Tegmental Area (VTA)

What is the main precursor of Dopamine Signalling?

Tyrosine Hydroxylase: eventually --> Dopamine-->NE-->>E

Explain how researchers figured out that TH levels correlates to dopamine levels?

Used a TH-Cre animal and injected it with AAV virus tagged with YFP into the VTA.

YFP was only expressed in TH expressing cells (Bc tissue specific promoter). Meaning if fluorescent occurred in VTA where injection of virus took place, then TH was also being expressed in these neurons since Cre is only expressed in TH neurons.

What is the main function of dopamine signaling in the VTA?

It signals a reward prediction error

What is the Juxtacellular recording-labeling technique?

What is the important precursor for Serotonin signaling?

5-Hydroxyl-L-Tryptophan (5HTP)

Describe how researchers found out Serotonin neuron has specific roe in a certain type of behavior? and what was it?

Social interaction

When the serotonin neuron was stimulates rodents were more social

What is the function of the Prefrontal Cortex?

Executive function: relating to abilities to differentiate among conflicting thoughts, determine good and bad, etc

Vital to the sense of self and other necessary for healthy interpersonal relationship and decision making

What is the role of the Ventromedial prefrontal cortex (vmPFC)?

This part of the PFC helps us make decisions based on the bigger picture, it is very involved in social control, regulating our emotions

What is the connection between the Prefrontal Cortex and Anxiety Behavior?

blocking the excitation of the Prefrontal cortex leads to dec stress response

blocking the inhibition of the PFC leads to inc stress response

What is the Amygdala?

The fear center

What are the major nuclei in the amygdala?

Central nucleus of the amygdala (CeA): major output nucleus and received and processes pain information

Basal Lateral Amygdala (BLA): the lateral nuclei recieves majority of sensory information and then is processed by the Basolateral complex and is sent as output to Central nucleus

What is the BLA involved in?

Controlling the HPA axis

Describe the Amygdala and Cortex during stress and non stress conditions.

Non stress: brains activity for intelligent regulation of behavior, thought and emotion

Stress: activates stress pathways in the hypothalamus and brainstem, which evokes high levels of NE and DA

Describe the two ways of tracing connections.

Antergrade tracing: ID of Efferent projections, uptake of the tracers by cell body and the axon is labeled

Retrograde Tracing: ID of the Origing of afferent projection, uptake of tracer by axon, cell body is labeled

What can be transported into a transgenic rodent via a virus?

1. Fluorescent reporters

2. Activity Reporter

3. Optogenetic tools

4. Protiens of interest

Why is FLEX (flip excision switch) an important tool?

you can inject a virus into the rodent containing and inverted sequence of interest and only where Cre is expressed the sequence will reorient itself, expressing this gene only in specific cells