catecholamines Flashcards
tyrosine
the rate limiting step for all catcholamines
D1 like receptors (D1, D5)
stimulate adenyl cyclase activity and cAMP synthesis
metabotropic receptors
- interact with G-proteins
- turn on intercellular signaling cascades that create positive metabolism
D2 like receptors
the action… the one about adenyl
inhibit adenyl cyclase activity and cAMP synthesis
D2 like receptors
D2, D3 and D4 are metabotropic but only D2 acts as an auto receptor and postsynaptic receptor
reuptake
transporter proteins move neurotransmitters from cleft back into presynaptic terminal via Na and K concentration gradients
- molecules are repackaged into vesicles or broken down for parts
enzymatic degradation
catechol-o-methyltransferase(COMT) transfers a methyl group onto the catecholamines
- monoamine oxidase (MAO) oxidizes the amine group of catecholamines after reuptake
mesocorticolimbic dopamine
involved in emotionally based behviours
- motivation
- incentive
- salience
- reward
nigrostriatal dopamine
plays essential role in the control of voluntary motor movement
- parkinson’s disease is a progressive loss of dopaminergic neurons in the substania nigra
catecholamine release
- nerve impulse reaches terminal
- voltage gated calcium channels detect change in voltage and open, calcium comes in
- calcium sensors trigger exocytosis
- amphetamines and methamphetamines drive DA release in the absence of any action potentials
dopamine
occurs predominantly inside vesicles
norepinephrine
central production
- locus coeruleus
- raphe nuclei
epinepherine
peripheral production
- adrenal medulla
alpha 1 (a1)
operate via phosphoinositide 2nd messenger system
alpha 2 (a2)
a2 receptors reduce synthesis of cAMP (like D2-like)
beta adrenoreceptors
b1 and b2 stimulate adenyl cyclase and enhance synthesis of cAMP (like D1- like)
sympathetic nervous system
- short preganglionic fibers in thoracic and lumbar spinal regions
- long lost- ganglionic fibers reach target tissues
parasympathetic nervous system
- long preganglionic fibers in cranial and sacral spinal regions
- short post- ganglionic fibers live near target tissues
beta blockers
- prevent normal binding via competitive antagonism
- used to reduce systems of the fight or flight respinse
vagus nerves
- centrally released hormones reach the target organs in the periphery
- peripherally released hormones cannot cross BBB
- peripheral epinephrine facilitates the consolidation of emotional memories
- peripheral norep and ep can indirectly influence brain activity by stimulating cranial nerve X via beta blockers
dopamine synthesis
tyrosine -> DOPA -> dopamine
