How drugs control the brain Flashcards
What is the main inhibitory system
The GABAergic system
Outline the features of the GABAergic system
Widespread distribution throughout the brain, inhibitory neurons keep the excitation in check.
too much GABA- loss of consciousness and coma
too little GABA- Leads to convulsions and seizures
What types of neurones use Gaba and what type uses glutamine
GABA uses local interneurons and GLU uses projection neurons
What are the two types of GABA receptors
GABA ionotropic receptors and GABA metabotropic receptors
What are some features of GABA Ionotropic receptors
Ligand-gated CL- channel, Fast IPSPs (mainly GABAergic interneurons.
What are some features of GABA Metabotropic receptors
G-protein coupled receptors, both pre and post synaptic.
Name a direct agonist and antagonist for ionotropic receptors
Muscimol- agonist, bicuculline- antagonist
Name some indirect agonists for ionotropic receptors
Benzodiazepine, Barbiturates (increases duration of channel opening, anaesthesia and epilepsy treatment) and alcohol
What are the effects of barbiturates and alcohol
Both have same effect to enhance GABA activity and the effects are additive, combining may be fatal.
Name the agonist for metabotropic receptors and outline some features
Baclofen, used as a muscle relaxant to reduce spasticity
results in a slow hyperpolarizing current.
Name 3 systems in the dopaminergic system
Nigrostriatal system (75% of brain DA), mesolimbic system and mesocortical system
What receptors use dopamine
Only via metabotropic receptors.
Outline the diff dopamine receptors
5 diff broad categories, can produce excitatory and inhibitory receptors, D1 Like receptors (1&5) associated with Gs subproteins,
D2-like (2,3&4) is associated with Gi receptors
Outline the nigrostriatal system
cell bodies in the substantia nigra project to the striatum and dysfunction of this system can lead to: parkinsons disease and huntingtons disease.
types of drugs that can affect the system is: L-DOPA, MAO inhibitors, dopamine receptor agonists- treatment for parkinsons disease.
Outline the mesolimbic system
cell bodies in the ventral tegmental area project to the limbic system, role in reinforcement of several categoires of stimuli inc drug abuse.
Outline the mesocortical system
VTA projections to the prefrontal cortex, dysfunction: schizophrenia, drugs: typical antipychotics ( DA receptor antagonists, increases DA turnover and blockade of postsynaptic receptors.
Outline the seretonergic system
seretonin is synthesised in nine raphe nuclei in reticular formation to a diff part of the brain.
What are some functions that seretonin is involved in
mood, sleep, pain, emotion and appetite.
What type of receptor does seretonin have
metabotropic and ionotropic receptors
What are some drugs that affect seretonin
SSRI’s E.G. Fluoxetine (prozac), increase seretonin function by preventing its uptake, treatment for depression and anxiety disorders.
MDMA, causes seretonin transporters to run in reverse to increase seretonin release and block reuptake.
Outline the noradrenergic system
projections from the locus coeruleus throughout the brain, role in arousal and attention,
Outline the adrenergic system
primarily in lateral tegmental area and projects to the thalamus and hypothalamus.
Outline the cholinergic system
in the periphery, ach at NMJ and synapses in the autonomic ganglia. in the brain we find it in the basal forebrain complex ( cholinergic innervation of the hippocampus and the neocortex) and the brainstem complex which innervates the dorsal thalamus and telencephalon.
disorders of the cholinergic system
in the periphery: myasthenia gravis- autoimmune disease leads to muscle weakness and loss of muscle acitivity.
brain: alzheimers disease, loss of cholinergic neurons in the basal ganglia.
epilepsy: autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) associated with mutation in the nicotinic receptor genes.
outline AChi
treatment for alzheimers and myasthenia gravis, by prolonging effect of alzheimers.
