How drugs control the brain

Question 1

What is the main inhibitory system

Answer 1

The GABAergic system

Question 2

Outline the features of the GABAergic system

Answer 2

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

Question 3

What types of neurones use Gaba and what type uses glutamine

Answer 3

GABA uses local interneurons and GLU uses projection neurons

Question 4

What are the two types of GABA receptors

Answer 4

GABA ionotropic receptors and GABA metabotropic receptors

Question 5

What are some features of GABA Ionotropic receptors

Answer 5

Ligand-gated CL- channel, Fast IPSPs (mainly GABAergic interneurons.

Question 6

What are some features of GABA Metabotropic receptors

Answer 6

G-protein coupled receptors, both pre and post synaptic.

Question 7

Name a direct agonist and antagonist for ionotropic receptors

Answer 7

Muscimol- agonist, bicuculline- antagonist

Question 8

Name some indirect agonists for ionotropic receptors

Answer 8

Benzodiazepine, Barbiturates (increases duration of channel opening, anaesthesia and epilepsy treatment) and alcohol

Question 9

What are the effects of barbiturates and alcohol

Answer 9

Both have same effect to enhance GABA activity and the effects are additive, combining may be fatal.

Question 10

Name the agonist for metabotropic receptors and outline some features

Answer 10

Baclofen, used as a muscle relaxant to reduce spasticity

results in a slow hyperpolarizing current.

Question 11

Name 3 systems in the dopaminergic system

Answer 11

Nigrostriatal system (75% of brain DA), mesolimbic system and mesocortical system

Question 12

What receptors use dopamine

Answer 12

Only via metabotropic receptors.

Question 13

Outline the diff dopamine receptors

Answer 13

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

Question 14

Outline the nigrostriatal system

Answer 14

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.

Question 15

Outline the mesolimbic system

Answer 15

cell bodies in the ventral tegmental area project to the limbic system, role in reinforcement of several categoires of stimuli inc drug abuse.

Question 16

Outline the mesocortical system

Answer 16

VTA projections to the prefrontal cortex, dysfunction: schizophrenia, drugs: typical antipychotics ( DA receptor antagonists, increases DA turnover and blockade of postsynaptic receptors.

Question 17

Outline the seretonergic system

Answer 17

seretonin is synthesised in nine raphe nuclei in reticular formation to a diff part of the brain.

Question 18

What are some functions that seretonin is involved in

Answer 18

mood, sleep, pain, emotion and appetite.

Question 19

What type of receptor does seretonin have

Answer 19

metabotropic and ionotropic receptors

Question 20

What are some drugs that affect seretonin

Answer 20

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.

Question 21

Outline the noradrenergic system

Answer 21

projections from the locus coeruleus throughout the brain, role in arousal and attention,

Question 22

Outline the adrenergic system

Answer 22

primarily in lateral tegmental area and projects to the thalamus and hypothalamus.

Question 23

Outline the cholinergic system

Answer 23

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.

Question 24

disorders of the cholinergic system

Answer 24

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.

Question 25

outline AChi

Answer 25

treatment for alzheimers and myasthenia gravis, by prolonging effect of alzheimers.