Part 4 Adrenoceptor agonists §1. , receptor agonists §2. receptor agonists §3. receptor agonists.
Drugs - Wofford Collegewebs.wofford.edu/steinmetzkr/Teaching/Psy230PDFs/Drugs.pdf · •...
Transcript of Drugs - Wofford Collegewebs.wofford.edu/steinmetzkr/Teaching/Psy230PDFs/Drugs.pdf · •...
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Drugs
2 Outline
• Neurotransmitters • Agonists and Antagonists • Cocaine & other dopamine agonists • Alcohol & its effects / Marijuana & its effects • Synthetic & Designer Drugs: Ecstasy
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3 Classes of Neurotransmitters
• 6 basic classes of NT: Peptides, Gases, Purines, Acetylcholine, Monoamines, and Amino Acids
4 Neurotransmitters
• Glutamate: general excitatory neurotransmitter • GABA: general inhibitory neurotransmitter (Cl-) • Substance P: incoming pain signals • Endorphins: pain management • Serotonin (5-HT): sleep & mood • Dopamine (DA): pleasure center & movement • Norepinephrine (NE): sympathetic nervous system
(induces aroused, heightened state)
• Acetylcholine (ACh): parasympathetic nervous system (induces calm, resting state) & motor system
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5 Synthesis of NTs
• Enzymes modify basic chemicals
6 Synthesis of Catecholamines
• Phenylalanine (dietary nutrient) • PKU – Phenylketonuria – genetic
deficit of enzyme to metabolize phenylalanine = mental retardation
• Metabolized to Tyrosine • Enzymes modify:
– Tyrosine → Dopa – Dopa → Dopamine – Dopamine → Norepinephrine – Norepinephrine → Epinephrine
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7 Synaptic events
8 Outline
• Neurotransmitters • Agonists and Antagonists • Cocaine & other dopamine agonists • Alcohol & its effects / Marijuana & its effects • Synthetic & Designer Drugs: Ecstasy
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9 Agonists
• A drug which – stimulates the effects of a particular
neurotransmitter – or acts to enhance the transmitter’s
effect.
10 Agonists
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11 Antagonists
• A drug which inhibits or counteracts the effects of a particular neurotransmitter
12 Drug Actions at the Synapse
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13 Drugs working at Dopamine Synapse
14 Norepinephrine (NE)
• Activates fight or flight resources
• Depression associated with norepinephrine depletion
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15 Serotonin (5-HT)
• Reuptake or monoamine oxidase deactivates
• Important in sleep regulation, depression, & mood disorders
16 Gamma-aminobutyric Acid (GABA)
• Main effect is to inhibit action of other neurons
• Lower levels associated with anxiety or panic attacks
• decreased levels in Huntington's disease
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17 Outline
• Neurotransmitters • Agonists and Antagonists • Cocaine & other dopamine agonists • Alcohol & its effects / Marijuana & its effects • Synthetic & Designer Drugs: Ecstasy
18 Dopaminergic System
• VTA – ventral tegmental area – Reward, motivation,
planning • Substantia Nigra
– Motor control • Parkinson's disease
associated with dopamine depletion
• Also associated with schizophrenia
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19 Cocaine
• Cocaine blocks the reuptake of dopamine • Dopamine Build-up = pleasure feeling in the nucleus
of accumbens & heightened arousal / alertness Cocaine blocks the recycling of dopamine
everywhere in the CNS • In the areas that control your breathing and heart rate
dopamine increases activity resulting in heart attacks and loss of breathing control.
Overstimulation can kill neurons. Excess dopamine can produce psychosis.
20 Drug Video
http://www.youtube.com/watch?v=4OS2C4NemJI
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21 Ritalin
• Blocks DA uptake gradually • Leads to increased concentration
22 Outline
• Neurotransmitters • Agonists and Antagonists • Cocaine & other dopamine agonists • Alcohol & its effects / Marijuana & its effects • Synthetic & Designer Drugs: Ecstasy
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23 The Effects of Alcohol
• Alcohol is very fat-soluble – easy access through the blood-brain barrier – interfere with the structure of the cell membrane &
receptors in the membrane • RESULT: inhibits Na+ transport into all neurons
• The effects of alcohol seen in all systems - motor, vision, cognitive, etc. – nonspecific to a NT
24 The Effects of Alcohol
• Alcohol impairs cognitive judgment so that people unintentionally hurt or kill themselves.
• Alcohol can reduce breathing and heart rate so much that the processes stop.
• Large amounts and chronic use of alcohol can damage neurons so that they die.
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25 Outline
• Neurotransmitters • Agonists and Antagonists • Cocaine & other dopamine agonists • Alcohol & its effects / Marijuana & its effects • Synthetic & Designer Drugs: Ecstasy
26 THC – Marijuana
• Endogenous NTs for cannabinoid receptors: – Anandamine:
• inhibits the pre-synaptic release of glutamate in hippocampal neurons (↓LTP)
• inhibits the autonomic nervous system: relaxation, hypothermic, ↓ ocular pressure
• analgesic effects in the spinal cord – 2-AG:
• inhibits LTP in hippocampus and suppresses pain sensations in the spinal cord
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27 Cannabinoid Receptor Density
• Black labels CB receptors: high density in cerebellum, cortex, basal ganglion, & hippocampus
28 Outline
• Neurotransmitters • Agonists and Antagonists • Cocaine & other dopamine agonists • Alcohol & its effects / Marijuana & its effects • Synthetic & Designer Drugs: Ecstasy
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29 What is Ecstasy?
• Synthetic derivative of methamphetamine
30 Ecstasy - mimics both dopamine & serotonin neurotransmitters
• Ecstasy = artificial stimulation of dopamine and serotonin neurons to a higher degree than normal
• This over-stimulation can selectively kill the neurons that normally release dopamine & serotonin
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31 Neurodegenerative Effects
Level of dysfunction
32 Neurodegenerative Effects
Level of dysfunction
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33 Drugs & Mechanisms of Action DRUG: Behavioral: Mechanism:
Amphetamine Excitement, elevated mood
Increased release of dopamine
Cocaine Excitement, elevated mood
Blocks dopamine reuptake
Methylphenidate (Ritalin)
Increased concentration
Blocks dopamine reuptake gradually
Nicotine Stimulant effects, tremors
Activates acetylocholine (ACh) receptor (neuromuscular synapses), increases dopamine in nucleus of accumbens
Alcohol Relaxation, intoxication
Inhibits Na flux, activates GABA, inhibits dopamine
Opiates Relaxation, decrease pain
Stimulates endorphin receptors
34 Drugs & Mechanisms of Action DRUG: Behavioral: Mechanism:
Phencyclidine (PCP)
Intoxication, hallucinations thought / memory disorders
Inhibits NMDA-type glutamate receptors (found in specific areas in the temporal and occipital lobes)
Marijuana Intensified sensory, reduced pain, inhibit learning
Activates anandamide receptors (hippocampus, basal ganglion, cerebellum)
LSD Distorted sensations
Stimulates serotonin receptors
Caffeine Increased arousal
Vasoconstrictor, blocks adenosine (effectively increasing dopamine & ACh)
MDMA (ecstasy) Euphoria, hallucinations
Stimulates release of dopamine, activates serotonin receptors
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35 For next time…
• Read Ch. 5 • Study for Exam 1