5- Psychoactive Drugs Flashcards by Laura Mantle

5 types of drugs that act on the dopamine system

L-DOPA
Antipsychotic drugs
Recreational drugs
Cocaine
Amphetamine

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What does L-DOPA treat?

Parkinson’s disease

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What is Parkinson’s caused by?

A loss of dopamine neurons

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What do Parkinson’s patients have difficulty doing?

Initiating movements

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How does L-DOPA treat Parkinson’s?

Compensates for the loss of neurons

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What can L-DOPA do to make dopamine?

Cross the blood-brain barrier and enzymes in neurons convert precursor to dopamine

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How does L-DOPA cause relief from Parkinson’s symptoms?

It increases in the brain

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What side effects are common with L-DOPA?

Hallucinations, delusions, other psychotic symptoms

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What do antipsychotic drugs treat?

Psychotic disorders

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What is schizophrenia caused by?

An excess of dopamine- thought to be an excess of mesolimbic dopamine

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How do antipsychotic drugs operate?

By interfering with dopamine receptors in the brain- acting as blockers

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What receptor do antipsychotic drugs block?

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What do antipsychotic drugs reduce operation of?

The dopamine system

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What does antipsychotic drugs efficacy hinge on?

Ability to bind to a D2 receptor

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What is the side effect of antipsychotic drugs often binding to nigrostriatal pathways by mistake?

Can affect motor functions- very similar to Parkinson’s disease

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Why is dopamine implicated in recreational drugs?

Dopamine is involved in producing reward and pleasure

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What was cocaine previously used as?

As mental illness treatment and a coca-cola ingredient

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When and why was cocaine banned?

In 1922 because people became aware of harmful effects

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Short-term effects of cocaine use (7 points)

Increased energy levels
Decreased appetite
Mental alertness
Increased heart rate and blood pressure
Constricted blood vessels
Increased temperature
Dilated pupils

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Long-term effects of cocaine use (5 points)

High risk of addiction
Irritability and mood disturbances
Restlessness
Paranoia
Auditory hallucinations

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Medical consequences of cocaine use (4 points)

Cardiovascular (disturbances in heart rhythms, heart attacks)
Respiratory (chest pain, respiratory failure)
Neurological (strokes, seizures, headaches)
Gastrointestinal (abdominal pain, nausea)

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How does cocaine increase dopamine levels?

By inhibiting reuptake

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What happens when cocaine blocks the transporter opening?

It closes the passage and prevents the transporter from doing its job so dopamine remains high in the synapse

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What are amphetamine effects similar to?

Cocaine effects

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Amphetamine effects at low doses (7 points)

- Energised and attentive - Mood improvement - Reduced appetite - Increased wakefulness - Improved reaction time - Fatigue resistance - Increased muscle strength

Amphetamine effects at higher doses (3 points)

- Risk of psychosis - Addiction - Risk of seizure, stroke, coma, heart attack

What are amphetamines prescribed for?

ADHD, narcolepsy, obesity, depression

Why are amphetamines rarely prescribed now?

As there is a high risk of harm

What do amphetamines cause the neuron to do?

Release more dopamine

What do amphetamines disrupt?

Storage of dopamine into vesicles

With amphetamines, dopamine is released without...

Triggering an action potential

What is the difference between amphetamines and cocaine?

Amphetamines are less euphoric but more stimulating than cocaine

How are amphetamines similar to cocaine? (2 points)

1. Increased dopamine signalling in the mesolimbic pathway 2. Increased dopamine in the nigrostriatal pathway leads to enhanced basal ganglia and thalamic activity

3 types of drugs that act on the serotonin system

1. Selective serotonin reuptake inhibitors (SSRIs) 2. MDMA (ectasy) 3. Hallucinogens

Example of an SSRI

Prozac

How do SSRIs inhibit reuptake of serotonin?

By blocking transporter

What can more serotonin in the synapse exert influence on?

Other neurons

Are all patients responsive to SSRIs?

What is the half-life of fluoxetine (prozac)?

1-4 days

What does MDMA trigger a neuron to do?

Release more serotonin

How does MDMA enter a cell?

Via a passage of serotonergic transporter and triggers release of serotonin

What can MDMA also have effects on?

Norepinephrine and dopamine transporters

What does MDMA indirectly increase?

Hormones such as oxytocin

What is the duration of MDMA action?

4-6 hours

How long does it take for serotonin levels to normalise with MDMA?

Within 24-48 hours

Do hallucinogens act as agonists or antagonists?

Agonists

What can hallucinogens cause?

Distortion in a person's perception of reality, and can cause changes in thoughts, moods and consciousness

4 examples of hallucinogens

LSD Psilocin Mescaline DMT

What is the discussion regarding hallucinogens and SSRIs?

Whether hallucinogens should be used as a therapeutic treatment when people aren't responsive to SSRIs

What area does nicotine bind to nicotonic receptors and what does this lead to?

Ventral tegmental area, leads to neural activity that triggers release of dopamine in the mesolimbic pathway

When is nicotine released?

By burning a cigarette

What is smoking a major risk factor? (6 points)

Heart attacks Strokes Bronchitis Cancers High blood pressure Alzheimer's disease

How addictive is nicotine?

Highly

Effects nicotine has on the central nervous system (4 points)

- Pleasure - Arousal and enhanced vigilance - Improved task performance - Anxiety relief

Effects of nicotine on the cardiovascular system (5 points)

- Increased heart rate - Increased cardiac output - Increased blood pressure - Coronary vasoconstriction - Cutaneous vasoconstriction

Effects of nicotine on other systems (3 points)

- Appetite suppression - Increased metabolic rate - Skeletal muscle relaxation

What is the half-life of nicotine?

30 minutes

3 individual differences in elimination of nicotine

Smokers metabolise faster Gender differences Genetic differences

What is the most widely consumed stimulant?

Caffeine

What is the caffeine molecule structurally similar to?

Adenosine

What is adenosine?

An inhibitory neurotransmitter that suppresses CNS activities

What does caffeine do to adenosine receptors?

Block them

What can caffeine cause?

Increased release of other neurotransmitters

Effects of caffeine in the cortex at normal doses (4 points)

- Rewarding effect, feel competent - Alertness, sustained attention, faster thought - Reduced fatigue, lower need for sleep - Fine motor coordination, timing accuracy and arithmetic may be impaired

Effects of caffeine with heavy doses (5 points)

- Agitation - Anxiety - Tremors - Panting - Insomnia

How long does it take for caffeine to be absorbed?

Within 45 minutes

How is caffeine distributed?

Rapidly, circulating through body

How big are caffeine molecules?

Small enough to cross the blood-brain barrier

Why does the half-life of caffeine vary?

According to liver enzyme level

Why are some people more sensitive to caffeine?

They have more efficient metabolism due to enzymes

What is the major psychoactive ingredient in cannabis/marijuana?

Tetrahydrocannabinol

What receptor does cannabis bind to?

The cannaboid CB1 receptor

What does cannabis trigger?

The release of dopamine

What does the mesolimbic dopamine release from cannabis lead to?

Feelings of euphoria

2 potential medical benefits of cannabis

Can act as a painkiller for chronic pain Can be as effective as opioids

2 consequences of long-term habitual cannabis use

Associated with a decline in memory function More brain tissue loss the longer cannabis is smoked regularly

What is another word for alcohol?

Ethanol

How is alcohol function at a cellular level understood?

Poorly

How is alcohol a depressant?

It suppresses neural activities in the CNS

What mechanism is involved in alcohol?

Alcohol triggers release of GABA and leads brain into a 'sedation' state

What does alcohol increase release in?

Dopamine in the mesolimbic pathway

2 things that alcohol decreases

- Serotonin and noradrenaline: increases risk of depression - Glutamate: impaired memory

3 things alcohol increases

- Dopamine in the brain reward circuit - Endogenous opiates - GABA: sedation, motor impairments

How does alcohol cross the blood-brain barrier?

Easily by diffusion

How is alcohol metabolised?

By liver

What is alcohol transformed to?

Water and CO2

What is Korsakoff's syndrome?

A chronic memory disorder

2 consequences of Korsakoff's syndrome

- Persistent learning and memory problems (retrograde and anterograde amnesia) - Action coordination difficulty

What is heavy alcohol use linked to in the brain?

Brain shrinkage particularly in prefrontal lobes