Addiction
Types of addiction:
Shopping.
Gambling.
Alcohol.
Drugs.
Communications between neurons:
Transmission of information between neurons relies on chemical signals released and
received at the synapse- drugs affect this process.
Neurotransmitter receptors:
Neurotransmitters are chemical messengers released from presynaptic neuron at synapses.
Neurotransmitter receptors on postsynaptic membrane are specific to different types of
neurotransmitters.
Lock and key mechanism.
Presence of neurotransmitter unlocks and activates the receptor.
Drugs also fit the lock:
Agonists:
Drugs that mimics or increases the actions of the transmitters.
doesn’t mean excitation as some transmitters are inhibitory.
Antagonists:
Drugs that block or decrease the actions of the transmitters.
Doesn’t mean inhibition as some transmitters are excitatory.
Drugs affect neurotransmission:
Presynaptic processes:
1- Transmitter production.
2 -Transmitter release.
3- Transmitter clearance.
Postsynaptic processes:
4- Transmitter receptors.
5- Cellular processes.
Transmitter production:
Prevent or reduce production of neurotransmitters by:
Blocking transmission of raw materials required for neurotransmitter production down the
axon.
Prevent the storage of neurotransmitter within the vesicles.
Transmitter release:
Increase, decrease or stop neurotransmitter released by:
, Altering amount of neurotransmitter released.
Altering presynaptic detection of neurotransmitter release.
Transmitter clearance:
Changing the rate at which neurotransmitter is removed from the synaptic cleft by:
Preventing reuptake of neurotransmitter into presynaptic membranes.
Blocking enzymes that degrade leftover neurotransmitter.
Transmitter receptors:
Hijacking neurotransmitter receptors by acting as:
Agonists:
Receptors are activated.
LSD activates serotonin receptors in visual cortex causing hallucinations.
Antagonists:
Receptors are blocked.
Cellular processes:
Altering postsynaptic cellular processes by:
Altering the number of postsynaptic receptors.
Upregulation-= increased sensitivity.
Downregulation= decreased sensitivity.
Dopamine:
Meslstriatal pathway:
Originated in substance nigra of midbrain and is important for motor control.
Mesolimbic pathway:
Originates in ventral tegmental area and is important for motivation and reward.
Opioid peptides:
Endogenous opioids:
Enkephalins, endorphins and dynorphins.
Important for reducing perception of pain and producing feelings of pleasure.
Serotonin:
Pathways originate from midbrain and brainstem in the raphe nuclei.
Important for control of mood, vision, sexual behaviour, anxiety and sleep.
Norepinephrine:
Pathways originate from midbrain and brainstem in the locus coeruleus and lateral
tegmental area.
Important for control of alertness, mood, and sexual behaviour.
Functional classes of drugs:
Drugs that relieve severe symptoms:
Antipsychotics.
Antidepressants.
Anxiolytics.
Types of addiction:
Shopping.
Gambling.
Alcohol.
Drugs.
Communications between neurons:
Transmission of information between neurons relies on chemical signals released and
received at the synapse- drugs affect this process.
Neurotransmitter receptors:
Neurotransmitters are chemical messengers released from presynaptic neuron at synapses.
Neurotransmitter receptors on postsynaptic membrane are specific to different types of
neurotransmitters.
Lock and key mechanism.
Presence of neurotransmitter unlocks and activates the receptor.
Drugs also fit the lock:
Agonists:
Drugs that mimics or increases the actions of the transmitters.
doesn’t mean excitation as some transmitters are inhibitory.
Antagonists:
Drugs that block or decrease the actions of the transmitters.
Doesn’t mean inhibition as some transmitters are excitatory.
Drugs affect neurotransmission:
Presynaptic processes:
1- Transmitter production.
2 -Transmitter release.
3- Transmitter clearance.
Postsynaptic processes:
4- Transmitter receptors.
5- Cellular processes.
Transmitter production:
Prevent or reduce production of neurotransmitters by:
Blocking transmission of raw materials required for neurotransmitter production down the
axon.
Prevent the storage of neurotransmitter within the vesicles.
Transmitter release:
Increase, decrease or stop neurotransmitter released by:
, Altering amount of neurotransmitter released.
Altering presynaptic detection of neurotransmitter release.
Transmitter clearance:
Changing the rate at which neurotransmitter is removed from the synaptic cleft by:
Preventing reuptake of neurotransmitter into presynaptic membranes.
Blocking enzymes that degrade leftover neurotransmitter.
Transmitter receptors:
Hijacking neurotransmitter receptors by acting as:
Agonists:
Receptors are activated.
LSD activates serotonin receptors in visual cortex causing hallucinations.
Antagonists:
Receptors are blocked.
Cellular processes:
Altering postsynaptic cellular processes by:
Altering the number of postsynaptic receptors.
Upregulation-= increased sensitivity.
Downregulation= decreased sensitivity.
Dopamine:
Meslstriatal pathway:
Originated in substance nigra of midbrain and is important for motor control.
Mesolimbic pathway:
Originates in ventral tegmental area and is important for motivation and reward.
Opioid peptides:
Endogenous opioids:
Enkephalins, endorphins and dynorphins.
Important for reducing perception of pain and producing feelings of pleasure.
Serotonin:
Pathways originate from midbrain and brainstem in the raphe nuclei.
Important for control of mood, vision, sexual behaviour, anxiety and sleep.
Norepinephrine:
Pathways originate from midbrain and brainstem in the locus coeruleus and lateral
tegmental area.
Important for control of alertness, mood, and sexual behaviour.
Functional classes of drugs:
Drugs that relieve severe symptoms:
Antipsychotics.
Antidepressants.
Anxiolytics.
