Neurobiology D

Front 1

How does the synthes of acetylcholine occurs ?

Back 1

*the synthesis of acetylcholine takes place in the cytoplasm through the acetylation of choline by the enzyme choline acetyl transferase (CAT).
*the acetyl donor, acetyl-CoA, is prepared in the mitochondria.
following its synthesis, the Ach is actively transported into secretory vesicles.

Front 2

What is known about reuptake mechanism of acetylcholine?

Back 2

It has no reuptake mechanism.

Front 3

What 2 function does acetylcholinesterase?

Back 3

*deacytilation of acetylcholine
*converting heroin to morphine

Front 4

Where acetylcholinesterase can be found?

Back 4

in the cholinergic synapses. Its tethred to the postsynaptic membrane with the GPI anchor.

Front 5

How does GPI attachment take place?

Back 5

GPI anchors are a very common way of anchoring proteins to membranes. Attachment is via a glyco group (consisting of a chain of sugars) which is attached to one of the membranephospholipids, namely phosphatidyl inositol (the same phospholipids which, on the inner bilayer is broken down to generate second messengers).

Front 6

What happens with choline after the breakdown of acetylcholine?

Back 6

choline is reuptaken with the presynaptic terminal and can be reused.

Front 7

What is interteresting about basal forebrain?

Back 7

In the basal forebrain there is a very prominent cluster of cholinergic neuron cell bodies.

Front 8

How is basal forebrain also called?

Back 8

the basal nucleus or basal forebrain nucleus

Front 9

What does the neurons in basal forebrain?

Back 9

They are responsible for inducing of alertness and attention.
(*This is likely the reason why nicotine (and smoking) has been associated with alertness and increased cognitive function.
Nicotine can cross the blood-barrier and flood the brain. In the reward center of the brain it acts on nicotinic receptors to induce addiction.)

Front 10

What is the experimental evidence for a role of basal forebrain cholinergic neuron involvement in attention?

Back 10

*electro-lesions - disrupting of animal's atention.
*microdialysis experiments have been conducting showing that there is an increase in acetylcholine in the cortex during an attention task

Front 11

How does one conduct an attention task experiment? (SUSTAINED ATTENTION TASK) (непрерывный)

Back 11

* een extra thirsty rat must pay attention to get water
* the rat has learned that some 3 lightdiods frequence is correlated with water so he must pay attention to recognize it.

Front 12

How are the acetylcholine levels determined in the sustained attention task?

Back 12

* micridyalisis to obtain the fraction in the cortex
* measure of acetylcholine lvls

Front 13

What shows the systained attention task?

Back 13

The results showed that animals that were forced to pay attention in order to obtain the water displayed dramatic increases in the level of acetylcholine (extracellular, thus indicative of release from nerve terminals).

Front 14

Where do acetylcholine functions?

Back 14

CNS, periphery: autonomic and somatic.

Front 15

How do the catecholamines produced?

Back 15

*chatecholamines are produced in a chain of enzymatic reactions starting with the amino acid tyrosine.
*

Front 16

What is the rate limiting step in the production of the catecholamines?

Back 16

*the rate-limiting enzyme in the production of catecholamine is tyrosine hydroxylase, TH.
*for this reason, factors which regulate the production of catecholamines usually act on this enzyme

Front 17

Which catecholamines do u know?

Back 17

adrenaline, noradrenaline, dopamine.

Front 18

Which receptors has dopamine?

Back 18

There are 5 G-protein coupled receptors specific for dopamine, D1 and D5 being stimulatory (acts via Gs) and D2-D4 being inhibitory (acts via Gi).

Front 19

Which receptors are there for noradrenaline?

Back 19

For noradrenaline there is the so-called beta-adrenergic receptor (Gs) and, of lesser importance the alpha-adrenergic receptor (usually acts via Gq).

Front 20

What is the way of localizing catecholamines en of SMNTs?

Back 20

*immunocytochemistry on the enzymes that catalyzes SMNT formation + enzyme downstream this enzyme to be sure of.
* SMNTs to small to use them t oimmunocytochemistry. They will be washen away.

Front 21

Which enzym is involved in the breakdown of catecholamines?

Back 21

Monoamineoxidase

Front 22

Is catecholamine being reuptaken by the presynaps?

Back 22

yes

Front 23

How do cocaine works?

Back 23

It inhibits dopamine transporter so its signals getting stronger ( in the reward centrum of the brain).

Front 24

How do the dopamine transporters work?

Back 24

*DA in transported inside the neuron if Na extracellular > Na intracellular.
* DA is cotransported with natrium inside the cell.
*Na/K ATPase mantain Na concentration inside the cell.
*If Na ex. < Na in. than it will be efflux of DA. (only in axon, cell body, dendrites).

Front 25

What do amphetamines do?

Back 25

*they have similar structure with dopamine.
*amphetamines can reverse pumping of DA by DAT.
*CaMKII phosphorylated DAT >> reverse transport.
*measure of dopamine in extracellular lvl using amperometry.

Front 26

How is the amphetamine leading to an activation of CaMKII and thus reversing the direction of dopamine pumping?

Back 26

The possibility exists that amphetamine could control DAT via activation of a G protein and a intracellular signaling cascade that leads to activation of CaMKII associated with DAT. NOT PROVEN YET.

Front 27

From which acid is serotonin synthesized?

Back 27

*Tryptophaan
*Tryptophan is one of the so-called “essential” amino acids because the body itself can not make this amino acid it must be obtained from the diet.

Front 28

What for effect has serotonin in brains?

Back 28

“calming” or “mood elevating” effect

Front 29

How does serotonin reuptake transporter prozac influences serotonin homeostase?

Back 29

*By blocking serotonin reuptake prozac up-regulates serotonin signaling.
*in blocking the reuptake mechanisms the serotonin in the synapse can be broken down, rather than being reused. >>> may be that the serotonin system becomes less effective, due to a lack of serotonin to load the presynaptic secretory vesicles. (depression tretment).

Front 30

Which receptors sirotonin has?

Back 30

There is a large family of receptors for serotonin, most metabotropic (i.e. G protein coupled) although one is a ion channel type receptor.

Front 31

Which receptor has glutamic acid?

Back 31

Glutamic acid has both ionotropic and metabotropic receptors.The metabotropic receptor is linked to the Gq protein, thus generating IP3 and DAG as second messengers.

Front 32

Where is glutamate synthesized ?

Back 32

In astrocytes, (glutamate cant cross BBB)

Front 33

What are the four major functions of glial cells.

Back 33

(1) to surround neurons and hold them in place,
(2) to supply nutrients to neurons
(3) to isolate one neuron from another
(4) to destroy and remove the carcasses of dead neurons (clean up).

Front 34

Which three types of supporting cell in CNS do u know?

Back 34

astrocytes, oligodendrocytes and microglia.

Front 35

How is glutamate processed in astrocytes?

Back 35

*in astrocytes glutamate is made via the citric acid cycle
*once synthesized glutamate is converted in glutamine.
*glutamine is secreted ( its not neurotransmitter yet)
*pumps on the glutaminergic neuron pick up the glutamine and convert it to glutamate and package it in secretory vesicles.
*Upon release the glutamate is taken up by the astrocyte and recycled as glutamine to the neuron

Front 36

What is the function of the glutamate receptors on the astrocytes?

Back 36

*glutamate can, via these receptors, regulate the activity of the glutamate transporters (high glutamate, high transporter function).
*Glutamate can induce morphological changes in the astrocytes such that they wrap more tightly around the synapse.
A tight wrap mean lots of glutamate transporters near the synapse and thus fast attenuation of glutamate signals.

Front 37

Why is glutamate toxic to brain?

Back 37

It is thought that the glutamate causes overstimulation of NMDA receptors which leads to toxic levels of Ca2+ in the neurons.

Front 38

How is the function of glutamate on the receptors on the astrocytes (regulation of microcirculation in brains)is observed?

Back 38

*magnetic resonance imaging (fMRI)
*2 MRI scans
*substraction of 3-d scans
*coloring
*color code shows increase in blood flow.

Front 39

What is BOLD ?

Back 39

The signal that is used in the construction of the brain images is referred to as blood oxygen level dependent signal or bold signal…the images are often referred to as BOLD images.
Oxygenated and deoxyhemoglobin give very different magnetic resonance signals….with an increase in blood flow there is an almost instantaneous drop in the amount of deoxyhemoglobin.

Front 40

How is the blood flow in brains controlled?

Back 40

*Glutamate, acting on metabotrobic receptors on the astrocyte, generates a Ca2+ wave;
*wave >>> release of prostaglandings>>>Ca2+ -dependent activation of phospholipase A2 which generates arachadonic acid> COX-1-dependent conversion of arachadonic acid to prostagandins. The prostaglandins then diffuse from the astrocyte to the blood vessels to induce muscle relaxation and consequently vasodilation.

Front 41

How was the braincirculation studied ?

Back 41

*brain slices electrostimulation to release glutamate
*video imaging to observe bloodvessels.
*laser scanning microscope to observe calcium waves.

Front 42

How it was proven that calcium stumilates vasodiliation in astrocytes and not vasoconstriction?

Back 42

* to create a Ca2+ signal in the astrocytes and observe the consequences in the blood vessel
*astrocytes expressed with GFP
*injection of fluorescent particles in blood capillaries.
*introducing of calcium probe
*introducing of caged calcium
* so alles could be imaged.
(stimulating of astrocytes with electrode have proven that glutamate stimulates vasodilation)

Front 43

How does BD and KIR channels inhibits vasodilation?

Back 43

*high [Ca+] in astrocytes
*influx kalium
*[K] lowers
*KIR activation on smooth muscle
*Na+ influx - hyperpolarisation - [Ca] lowers > muscle relaxation

Front 44

What are KIR and BD channels?

Back 44

KIR: potassium channel on smooth muscle cells
BK: kalium channels on astrocytes.

Front 45

What is faster mechanism muscle relaxation or vasodilation ?

Back 45

relaxation - fast
stimulation - low

Front 46

How does muscle relaxation works with NO and PG?

Back 46

ca extracellular>> ampa rec on post synaps> depolarization > ca influx >> camk >> NOS,A2> NO, PG > diffusion of NO , PG >> muscle relaxation.

Front 47

What is the advantage of NO, PG vasodilation?

Back 47

vasodilation is directly controlled by port synaptic activity.

Front 48

Why postsynaptic mechanism of vasodilation is so potent?

Back 48

The vasodilation can be activated through LTP so the respons will be long term.

Front 49

How is GABA made?

Back 49

GABA is made in a single step from the amino acid glutamic acid by the enzyme glutamic acid decarboxylase, GAD.

Front 50

What for sort neurotransmitter is GABA?

Back 50

GABA is an inhibitory neurotransmitter, working on either GABAa receptors (Cl- channels) or GABAb receptors (G protein coupled receptor working through Gi).

Front 51

What occurs by stiff man syndrome?

Back 51

*spasms and stiffness often come at times of stress (e.g. crossing a busy road).
*autoimmune desease
*antibodyes cannot cross BBB so its only a CNS desease.

Front 52

Which chloride channels are there and where do they are?

Back 52

*NKCC1 - driven by Na,K gradients, importer, expressed in all cells.
*NKCC2 - Cl exchanger, only in neurons, the energy from Na/K ATPase.

Front 53

What receptor exist for glycine?

Back 53

Its receptor is a Cl- channel; the Glycine receptor is stimulatory in young animals due to the efflux of Cl- (same situation as with GABA and the GABAa receptor described earlier).

Front 54

What is inhibitor of glycine receptor ?

Back 54

Strychine. It specifically blocks Gly R channels and in doing so stimulates the CNS (this over stimulation can result in death)

Front 55

What does NMDA receptor?

Back 55

An additional receptor for glycine is the NMDA receptor where it acts as an obligatory co-agonist, with glycine binding to th eNR1 subunits and glutamate to the NR2 subunits

Front 56

glycine is small and crosses BBB where and how is concentration glycine maintained?

Back 56

Glycine transporters are to be found on the glycinergic neurons themselves and in astrocytes, which wrap around glycine synapses.
These transporters pump out the glycine such that sub uM levels are reached and thus the receptors are not activated until there is an increase in glycine due to its release from the presynaptic terminal.

Front 57

Why is the weaken transporter used in the synapses with NMDA?

Back 57

*because glycine is needed voor NMDA action but no to many glycine.
* the direction of weak transporter can be easely reversed.

Front 58

How is the direction of the glycine transporters can be reversed?

Back 58

* The energy from the Na+ gradient is required voor glycine transport inside the cell
* Within the AMPA activation there is Na+ influx so the glycine can be transported out of the neuron togather with Na+.

Front 59

Where are the strong/weak transporters voor glycine found?

Back 59

The strong transporter is primarily found in the spine and brain stem, those regions where glutamine functions as a neurotransmitter on its own receptor.
In fact, it is often used as a marker for glycinergic neurons.
The weak transporter has a very wide distribution, where it can control the local glycine concentration under the saturation level of the NMDA receptor co-agonist

Front 60

What happens by human encephaolopathy?

Back 60

*uncontrolled seizures and mental retardation.
*an inborn error of glycine metabolism
*Glycine is broken down in the mitochondria by a complex of four enzymes called the glycine cleavage system.
*accomulation of glycine

Front 61

Which two families of NMDA receptors there are and which aa do they bind?

Back 61

*NR1 + NR2 = glutamate
*the NR1/NR3 receptor was not sensitive to glutamate or NMDA but gave depolarization in response to glycine.

Front 62

Which ourines there are?

Back 62

adenine, adenine + ribose sugar = adenosine, adenosine + 3 fosfaar groups = ATP.

Front 63

Which receptors there are for different purines?

Back 63

*purine: 4 P1 receptors, G-coupled protein receptors.
*ATP: 2 klasses of P2 receptors, P2X are ion channel receptors and P2Y are G protein coupled receptors
* adenine: orphan receptors

Front 64

Which function does purine receptors doing?

Back 64

housekeeping functions, signaling of cell damage and mediating sensory signal transduction.

Front 65

Describe the houskeeping function of purines?

Back 65

*purines are coreleased with neurotransmitters.
* activated purine receptors in postsynaps.
* regulating biosynthetic enzymes making neurotransmitter or the activity of pumps responsible for pumping the transmitter substances into vesicles in preparation for the next round of exocytosis).
*purine receptors regulate Ca concentration >> regulates AMPA receptors >> glutamate transport.

Front 66

Can ATP receptors inhibit / stimulate release of neurotransmitters?

Back 66

yes, there are 6 receptors that carry out the autocrine action of ATP .

Front 67

How does purines involved by signalling the cell damage?

Back 67

*In the periphery high concentrations of purine receptors are found on the sensory terminals of pain receptors.
*In the case of tissue and cell damage purines can leak out of the damaged cells and activate the receptors.
Activation of these receptors is perceived as pain in the CNS.

Front 68

How does the signalling from respiratory system with purines works?

Back 68

O2 *oxygen levels are measured by Glomus cells.
*low pO2 stimulates the Glomus cells to release ATP which then acts on P2X2 receptors in sensory nerve terminals within the caroid body.
*The sensory information ultimately makes it way to the respiratory center in the brain stem, which is responsible for setting the rate of respiration.

CO2* low pH >> Ca signal in astrocytes >> release ATP >>
ATP acts on purine receptors on the neurons in the respiratory center.

Front 69

Which receptors are there in the respiratory center?

Back 69

P2X,P2Y

Front 70

How does the signalling from the taste buds works?

Back 70

*the receptor potential of the gustatory receptor cell lead to a release of ATP
*P2X2 and P2X3

Front 71

How is signalling from the bladder regulated?

Back 71

*activation of strech receptors >> release of ATP
*ATP acts on P2X3 receptors in the sensory nerve terminals

Front 72

How does adenosine affects faling in sleep?

Back 72

*the cholinergic neurons in the attention centers possess adenosine A1 receptors
*Activation of these receptors suppresses the cholinergic neurons and thus we have reduced alertness and a tendency to fall asleep.

Front 73

How does coffeine works?

Back 73

Blocks the action of adenosine.

Front 74

What do u know about aspartaat?

Back 74

*perharbs ionotropic receptors.
*structural similarity to glutamate.

Front 75

What do u know about D serine?

Back 75

D-serine is produced by astrocytes and can bind to the glycine site in NR1 subunits of the NMDA receptor and in doing so substitute for glycine.

Front 76

What do u know about trace amines?

Back 76

* neurotransmitters of insect world but they are also found in mammalian brain.
* responsible for mood.

Front 77

What do u know about endo cannabinoids?

Back 77

* large lipid molecules
* transport from post to pre synaps.
* pain suppresion
* the cannabinoid 1 receptor (a G-protein coupled receptor) is the most abundant GPCR in the CNS.

Front 78

What do u know about NO and CO?

Back 78

* CO is more peripheral
* NO is more central
* NO - regulation of blood pressure.

Front 79

What do u know about hydrogen sulphide?

Back 79

* its gas that made in the brain
* neurotransmitter

Front 80

What are the nine steps of the synaptic vesicle cycling?

Back 80

1. Docking
2. Priming (hemifusion, of one layer of PM with PM of the cel)
3. Fusion ( release of secretory molecules, complete fusion with Ca efflux)
4.Endocytosis ( coating with clathrin , reacidification )
5. Translocation
6. Fusion with endosome
7. Budding ( neurotransmitter uptake)
8. Translocation to the plasma membrane.

Front 81

What is a protein that plays a common link between endo- and exocytosis?

Back 81

*synaptotagamin
-the Ca2+ sensor induces EXOCYTOSIS
-binds the protein AP2, which initiates the formation of clathrin-coated pits, essential for ENDOCYTOSIS.

Front 82

What is the local cycle of the vesicles?

Back 82

the vesicle stays on or near the membrane and is reloaded with transmitter for another exocytotic event or a variation on this theme is that vesicle is brought into the cell but stays in the vicinity of the active zone where it is reloaded and returned to the membrane.

Front 83

Which two types of secretory vesicles there are?

Back 83

*SMNTs, the so-called electron-lucent vesicles
*neuropeptides :dense-core vesicles (also called dense-core granules, particularly in endocrine cells).

Front 84

What is the differences in SMNT and neuropeptides vesicles?

Back 84

* no recycling of neuropeptides - they are broken down in the extacellular space.
* SMTS are fast acting
* neurotransmitters are not
*the release of NT is not perse presynaps, such NTs has more diffuse working and can reach other neurons.
*The SMNTs act fast (ionotropic) and the neuropeptides induce more permanent changes (metabotropic) to the post-synaptic neurons.
*Secondly, neuropeptides are thought to be released only under conditions of high frequency discharges (in contrast to SMNTs which are released each time a action potential reaches the terminal).

Front 85

Which two factors are there ensuring that the neuropeptide will not be depleted within the terminal?

Back 85

* release of very small amount of NTs is effective ( nMs)
*neuropeptides are thought to be released only under conditions of high frequency discharges

Front 86

How are both neuropeptides and SMNTs release is affected by APs?

Back 86

*Low frequency discharge >>> Ca efflux >>> release of any SMNT

*If Ca is sufficient strong >>> rhyanodyne receptors >>> extracellular Ca release >>> release of core dense vesicles.

Front 87

What is the correlation of "Kiss and Run" mode with low frequency discharge?

Back 87

*with LTD the secretory granules do not fuse completely with the cell membrane but rather form a so-called fusion pore.
*this type of fusion leads to release of SMNTs but not NTs.
* the NTs are in the gel like matrix in the centre of secretory granule in contrast to SMNTs that had no gel like matrix.

Front 88

What function does LTDs and HTDs have?

Back 88

LTSs: "Breed and feed"
HTDs: "Fight or flight"

Front 89

What messages are in the neuropeptide component of the exocytotic signal fot the "Fight or Flight response"?

Back 89

*Neuropeptide Y which causes vasoconstriction and a redistribution of blood within the circulatory system
*enkephalin, an endogenous opiate which is an analgesic (kills pain in the absence of the loss of consciousness).

Front 90

How does endocytosis works?

Back 90

*clathrin-mediated
*The protein clathrin plus adaptors proteins are responsible for forming so-called “coated-pits” on the membrane that initiate the process of endocytosis.

Front 91

What is the evidence that adrenaline/noradrenaline is released during both LFD and HFD?

Back 91

*perforated patch mode
*ampereometric measures.
*HFD - strong ampereometric spikes >>> release of granules.
LFD - weak ampereometric spikes >>> granules pores.

Front 92

What is the evidence that there is a fusion pore?

Back 92

* introducing of small and big fluorescent particles in the granule.
* small particles were released during fusion , big were not.

Front 93

What is the evidence that neuropeptide is differentially released?

Back 93

* mark the endocytozed granules.
* the peptide content of the granule was determined with antibodies.
* high antibody signal wiht LFD and low signal with HFD