3 and 4. 

catechlamines are synthesised from tyrosine and these include noradrenaline, adrenaline and dopamine. the brain lacks phenyalanine hydroxylase. it converts Phe to Tyr thus Tyr is transported into the brain from blood

dopamine is associated with motor function and is lost in which disease?

which enzymes are involved in catabolism of catecholamines?

Parkinson's disease.

catabolism involves monoamine oxidase (MAO) and catechol 0-methyltransferase (COMT)

slowness of movement.

this is a multifactorial dsease involving age, environmental factors and genetics.

substantia nigra pars compacta

(shit thats a mouthfull)

as substantia nigra specifially uses dopamine, PD results in >50% depletion of this transmitter

by a simultaneous admnistration of a Dopa decarboxylase inhibitor which cannot penetrate the blood-brain barrier.

also inhibitors of MAO and COMT can be given to inhibit dopamine degradation.

PD patients are usually given a cocktail of L-dopa, DDI, MAO and COMT

serotonin (5-HT) is synthethised from tryptophan by which two enzymes?

how many different types of receptors does it bind to?

tryptophan hydroxylase and 5-hydroxytryptophan (5-HTP) decarboxylase.

14 different types of receptors

in ralation to serotonin, what affect do hallucegenic drugs such as LSD have?

the action of serotonin can be terminated mainly by reuptake from the synapse via the 5-HT reuptake transporter on the presynaptic neuron. what else can inactivate the action?

they act as 5-HT agonists and mimick the action of serotonin at 5-HT_2A receptors.

serotonin action can also be terminated by MAO.

true or false?

amino acids are present at a higher concentration (30mM) than in any other body tissue

true.

these are all non essential amino acids made in situ from glycolytic and citric acid cycle intermediates.

dicarboxylic amino acids glutamate and aspartate are excitatory whereas glycine and GABA are inhibitory

Glutamate and GABA are major transmitters in the brain.

hypothalamus, proteins, cleavage

peptide transmitters have slow potsynaptic effects and their actions are terminated by extracellular proteases. they are often co-released with other transmitters. includes opioids - endophins, enkephalins and dynorphins

other examples are substance P, neurotensin, vasoactive intestinal peptide (VIP)

it diffuses from nerve terminals inot adjacent cells forming covalent linkages to a multiplicity of targets, which maybe enzymes or other targets. 

inactivation presumably involves diffusion away.

ionotropic receptor - fast, few milliseconds and always stimulatory - transmitter acts directly on a ligand gated ion channel to open the channel

metabotropic receptor - slow up to hours, can trigger opening/closing of a seperate ion channel and also other effects on cell - acts indirectly on a GPCR

nitotinic is direct

muscarinic is indirect and has five subtypes

M1,M2,M3,M4,& M5

how a G protein acts indirectly on an ion channel. A...... binds to receptor. GTP exchnages for G.... on the a...... subunit. G protein dissociates from receptor with its 3 subunits also doing the same. the aplha subunit activates the ion channel. it is inactivated by h....... of G..... to G.....

the 3 subunits recombine and attach to the receptor which can bind another agonist

some g proteins can stimulate or inhibit enzyme targets instead of acting on ion channels. the most common of these tragets are the enzymes: adenylate cyclase, guanylate cyclase and phospholipase C.

what are the corresponding second messengers?

adenylate cyclase = cyclic AMP or cAMP

guanylate cyclase = cyclic GMP or cGMP

phospholipase C = Inositol triphosphate and diacylglycerol

these can then cause a slow response in the cell 

structure of ligand gated receptors -composed of 4 or 5 different subunits arranged around a central pore. eg:nicotinic acetylcholine, GABA_A, glycine, 5-HT₃ receptors

nicotinic receptor has five subunits from a possible 17 thus there are many combinations that differ in skeletal muscle, autonomic ganglia,brain. the alpha subunit binds to acetylcholine resulting in a conformational change which opens the central ion channel.

structure of G protein coupled receptors

made from a single protein with 7 membrance spanning alpha helices = 7 transmembrane receptor (7TM)

eg: muscarinic acetylcholine, alpha-adrenergic and Beta-adrenergic receptors, all 5-HT receptors except 5HT₃, rhodopsin, olfactory receptors and many others

tricyclic antidepressants bblock noradrenaline and s.......... re-uptake

SSRIs are administered for d....... obsessive compulsive disorder and also block serotonin re-uptake

serotonin, depression

they activate GABA receptors

MAO inhibitors are given for Parkinson's and depression. they block the breakdown of biogenic amines.

L dopa

acetylcholinetransferase inhibitors are administered in Alzheimer's disease to block the breakdown of acetylcholine