Case 8 - Yaffas Notes Flashcards
what are the three functional divisions of the striatum
sensorimotor - putamen
associative - globus pallidus
limbic/ventral - ventral tegmental area
what are the four main dopamine pathways
nigrostriatal pathway
mesocortical pathway
mesolimbic pathway
tuberoinfundibulnar pathway
where does increase of dopamine happen
occurs in the associative striatum of the nigrostrital pathway not the mesolimbic
what does chronic blockage of the nigrostrital pathway cause
hyperkinetic movement disorder known as neuroleptic induced tardive dyskenesia
what does the tuberoinfundibulnar pathway originate
projects from the hypothalamus to the anterior pititary gland
what do neurones do in this pathway
inhibit prolactin release
what happens in the postpartum state
the activity of these dopamine neurones is decreased and prolactin levels can therefore rise during breastfeeding so that lactation can occur
what are elevated prolactin levels associated with
breast pathology such as amenorrhea and sexual dysfunction
such problems can occur after antipsychotics that block the D2 receptors
what are the classification of schizophrenia
paranoid schizophrenia - dominated by delusions and hallucinations - positive symptoms
residual schizophrenia - predominant negative symptoms
what receptors affect dopamine release
D3 receptors
what receptors does resperidone have high affinity for
the 5HT and the dopamine D2 receptors
mode of action of resperidone
effective for treating the positive and negative symptoms owing to its loose binding affinity for the D2 receptors and additional 5HT antagonism compared to first generation antipsychotics which are strong, non specific dopamine D2 receptor antagonists
what is the mechanism of action
blockade of D2 receptors in the ventral striatum, alleviating positive symptoms of schizophrenia such as hallucinations and delusions
Blockade of serotonergic 5HT receptors in the mesocortical tract, cause an excess of dopamine, resulting in an increase in dopamine transmission, and an elimination of core negative symptoms
Dopamine receptors in the nigrostrital pathway are not affected by resperidone and extrapyrimdal effects are avoided
what is the main side effect of resperidone
weight gain
what is clozapine
atypical antipsychotic
combination of antagnosistc effects at D2 receptors in the mesolimbic pathway and 5HT2A receptors in the frontal cortex
D2 antagonism relieves positive symptoms while the 5HT2A antagonism alleviates the negative symptoms
what is the main side effect of clozapine
sedation
what is the psychoactive substance in weed
THC
what are the CB1 receptors
mediate most effects of cannabinoids on the CNS
these are involved in physiological processes such as appetite, pain, sensation and memory. these receptors are responsible for the euphoric and anti convulsive effects
what are the CB2 receptor
found in the periphery and are expressed mainly in the immune system and hamemopeitic cells
what are cannabinoid receptors activated by
THC - through the production of an endocannabinoid (ligand known as anandamide)
endocannabunoids - produced by humans
what are endocannabinoids
substances produced in the brain
They are used in retrograde signalling between neurones, in to temporarily reduce the amount of conventional neurotransmitter released
Their production is Ca+ dependent
They are produced in post synaptic GABA neurones
what is the mode of action of euphoria
GABA is released into the synaptic cleft and binds to the endocannabinids source
This lead to the production of endocannabinoids
Endocannabinoids released from the depolarised post synaptic GABA neurone bind to CB1 receptors In the pre-synpatic GABA. Neurone and cause a reduction in GABA release
This causes a decrease in the inhibitory effects in the brain, thus leading to euphoria
what is the mode of action of anticonvulsives
cannabinoids are thought to have a regulatory role in the striatum in terms of glutamatergic signals from the corticostriatal fibres
Intense firing of corticostrital neurones leads to release of glutamate which causes an influx of Ca ions in the post synaptic membrane
Constant glutamate release causes Ca2+ ions to build up in the post synaptic membrane
This accumulation causes Ca2+ ions to synthesise endocannabinoids in the medium sized striatal neurones
These stimulate CB1 receptors on the pre-synpatic corticostrital fibres leading to a decreased release of glutamate
some extra regulations for section 2 under the MHA
For section 2 under the MHA, must be signed by two approved health professions and nearest relative or other approved health professions
doctors must have seen you within 5 days of each other
One of the two AMPH must be approved under section 12
Section 2 can’t be renewed but the patient may be transferred onto section 3
