Pharmacology of neurotransmitters Flashcards
Are cations excitatory or inhibitory in AP?
Excitatory
Are anions excitatory or inhibitory in AP?
Inhibitory
Basic role of adrenaline in the body
Increase HR and blood flow
Basic role of noradrenaline in the body
Vasoconstriction
Basic role of dopamine in the body
feelings of pleasure, addiction, movement, motivation
Basic role of serotonin in the body
well-being, happiness, sleep cycle, digestive system regulation
What is the monoamine hypothesis’
deficiency of monoamine neurotransmitters causes depression
Evidence for the monoamine hypothesis
Drugs that restore brain monoamine levels are effective antidepressants
Drugs that reduce brain monoamines (e.g. reserpine, clonidine) cause depression
Evidence against the monoamine hypothesis
Antidepressants increase monoamines immediately but clinical benefits can take weeks
35% benefit in first week
benefit may be due to longer term downstream actions of monoamines on cellular protein expression
Not all depression responds to antidepressants
It’s an oversimplification
Other mechanisms e.g. hypothalamic- pituitary-adrenal/thyroid axis involved
what breaks down monoamines
monoamine oxidase
example of tricyclic antidepressent
amitriptyline
MOA of TCA
block reuptake of monoamines
Example of SSRI
citalopram, sertroline
example of serotonin and noradrenaline reuptake inhibitor
duloxetine
example of noradrenaline reuptake inhibitor
reboxetine
example of a monoamine oxidase inhibitor
moclobemide
describe the mesolimbic pathway of dopamine
Mesolimbic pathway – dopamine produced in ventrotegmental area is released in the nucleus accumbens and amygdala
Responsible for motivation and reward
This pathway is thought to be overactive in addiction and mood disorders
Role of nucleus accumbens
pleasure seeking, reward behaviour
role of the amygdala
negative symptoms: aggression, fear
describe the mesocortical pathway for dopamine
Mesocortical pathway– dopamine produced in ventrotegmental area is released in the prefrontal cortex
Responsible for cognitive control, motivation, and emotional response
This pathway is associated with negative symptoms of schizophrenia, which include avolition, alogia and flat affect
what is avolition
no motivation
what is alogia
not speaking
describe the nigrostriatal pathway of dopamine
Nigrostriatal pathway – dopamine produced in substantia nigra is released in the basal ganglia
Responsible for motor coordination
This pathway is underactive in Parkinson’s disease
describe the tuberoinfundibular pathway of dopamine
Tuberoinfundibular pathway (AKA tuberohypophyseal)– projects from the infundibular nucleus in the tuberal region of the hypothalamus to the median eminence of the hypothalamus
Dopamine is released into the hypophyseal portal system which supplies the pituitary gland
Negative feedback for prolactin
Responsible for feedback mechanism of lactation
Match: … uses …
-basal ganglia
-motor cortex
___________________________
-Ach
-dopamine
basal ganglia- dopamine
motor cortex- Ach
role of dopamine in movement
regulates movements- upregulates movements you want, downregulates ones you don’t
symptoms associated with low dopamine and high ACh
tremor
rigidity
bradykinesia
treatment for Parkinsons
Raise dopamine: Dopamine precursor L Dopa (+ dopa decarboxylase inhibitor) Releases dopamine e.g. amantadine Dopamine agonists e.g. ropinirole, cabergoline, rotigotine
Lower Ach: Antimuscarinic drugs Block Ach receptors benzatropine procyclidine orphenadrine
Why give dopa decarboxylase inhibitors alongside levodopa
as without it the drug would be broken down before it crosses the BBB
role of the prefrontal cortex
regulates attention and cognition
example of first generation/ typical antipsychotics
haloperidol
chlorpromazine
MOA of 1st generation/typical antipsychotics
block D2 receptors in mesolimbic/mesocortical, nigrostriatal and tuberoinfundibular pathways and chemoreceptor trigger zone (brain stem)
example of 2nd generation/atypical antipsychotics
olanzapine
risperidone
clozapine
MOA of 2nd generation/atypical antipsychotics
block D2 receptors in mesolimbic/mesocortical pathway,
examples of extrapyramidal side effects
Parkinsonism
Akathisia
Tardive dyskinesia
side effects caused by blocking the tuberoinfundibular pathway
gynaecomastia
galactorrhoea
menstrual disturbance
basic role of Ach in the body
thought, learning and memory. activates muscle action in the body
NTs of SNS
adrenaline and noradrenaline
Role of SNS
inc CO, bronchodilation, pupillary dilation, reduce digestion and absorption and reduce renal elimination
NTs of PNS
ACH
Role of PNS
normalise CO, normalise bronchodilation, pupillary constriction, increase absorption and digestion and increased renal elimination
side effects of antimuscarinics
dry mouth
constipation
urinary retention
increased intraocular pressure
basic pathology of Alzheimer’s disease
loss of cholinergic neurons
decreased
acetylcholine levels
reduced choline acetyltransferase (Ach synthesising enzyme)
cognitive impairment correlates with loss of cholinergic input
example of cholinesterase inhibitor
donepezil
rivastigmine
galantamine
basic role of GABA in the body
high levels improve focus, low levels cause anxiety. contributes to motor control and vision. Inhibitory NT
