Drugs - Wofford College · Drugs 2 Outline • Neurotransmitters • Agonists and Antagonists •...

1

1

Drugs

2 Outline

•  Neurotransmitters •  Agonists and Antagonists •  Cocaine & other dopamine agonists •  Alcohol & its effects / Marijuana & its effects •  Synthetic & Designer Drugs: Ecstasy

2

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

3

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

4

7 Synaptic events

8 Outline


5

9 Agonists

• A drug which – stimulates the effects of a particular

neurotransmitter – or acts to enhance the transmitter’s

effect.

10 Agonists

6

11 Antagonists

•  A drug which inhibits or counteracts the effects of a particular neurotransmitter

12 Drug Actions at the Synapse

7

13 Drugs working at Dopamine Synapse

14 Norepinephrine (NE)

•  Activates fight or flight resources

•  Depression associated with norepinephrine depletion

8

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

9

17 Outline


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

10

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

11

21 Ritalin

•  Blocks DA uptake gradually •  Leads to increased concentration

22 Outline


12

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.

13

25 Outline


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

14

27 Cannabinoid Receptor Density

•  Black labels CB receptors: high density in cerebellum, cortex, basal ganglion, & hippocampus

28 Outline


15

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

16

31 Neurodegenerative Effects

Level of dysfunction

32 Neurodegenerative Effects

Level of dysfunction

17

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

18

35 For next time…

•  Read Ch. 5 •  Study for Exam 1

Drugs - Wofford College · Drugs 2 Outline • Neurotransmitters • Agonists and Antagonists •...

Documents

Transcript of Drugs - Wofford College · Drugs 2 Outline • Neurotransmitters • Agonists and Antagonists •...