1. Chapter Four Psychopharmacology Version Dated 21 Sep 2009

2. CHAPTER 4 PSYCHOPHARMACOLOGY

3. Neurotransmitters, Neuromodulators, and Neurohormones Identifying Neurotransmitters – Must be synthesized within the neuron – In response to an action potential, the substance is released in sufficient quantities to produce an effect in the postsynaptic cell – We should be able to duplicate the action of a suspected neurotransmitter experimentally on a postsynaptic cell – Some mechanism exists that ends the interaction between the neurotransmitter and the postsynaptic cell

4. Figure 4.2 Major Categories of Neurotransmitters, Neuromodulators, and Neurohormones

5. Neurotransmitters Types of Neurotransmitters – Small molecule transmitters – meet all or most of criteria and play a vital role in neurotransmission – Neuropeptides – at least 40 act as neurotransmitters, neuromodulators, and neurohormones – Gaseous neurotransmitters – some gases transfer information from one cell to another

6. Table 4.1 Features of Small-Molecule Transmitters and Neuropeptides

7. Figure 4.3 The Distribution of Cholinergic Systems in the Brain

8. Figure 4.4 Catecholamines Share a Common Synthesis Pathway

9. Figure 4.5 Dopaminergic Systems in the Brain

10. Figure 4.6 Noradrenergic Systems in the Brain

11. Figure 4.8 The Distribution of Serotonergic Pathways in the Brain

12. Figure 4.9 The NMDA Glutamate Receptor

13. Figure 4.10 The GABA A Receptor Interacts with Several Drugs

14. Figure 4.11 Distribution of Opiate Receptors in the Human Brain

15. Drug Actions at the Synapse Agonists enhance the activity of a neurotransmitter Antagonists reduce the activity of a neurotransmitter

16. Drug Actions at the Synapse Neurotransmitter Production – Manipulating the synthesis of a neurotransmitter will affect the amount available for release Neurotransmitter Storage – Interfering with the storage of a neurotransmitters in vesicles within a neuron Neurotransmitter Release – Drugs can modify the release of a neurotransmitter in response to the arrival of an action potential

17. Drug Actions at the Synapse Receptor Effects – Can mimic the action of a neurotransmitter at the site – Can block the synaptic activity by occupying a binding site – Can influence the activity of the receptor Reuptake Effects and Enzymatic Degradation – Deactivation of neurotransmitters

18. Figure 4.12 Drug Interactions at the Cholinergic Synapse

19. Figure 4.14 Drug Interactions at the Dopaminergic Synapse

20. Figure 4.15 Drug Interactions at the Serotonergic Synapse

21. Basic Principles of Drug Effects Administration of Drugs – Method of administration leads to different effects on nervous system – Blood-brain barrier Individual Differences – Drug effects influenced by body weight, gender, and genetics Placebo Effects – User expectations influence drug effects – Double-blind experiment

22. Figure 4.16 Concentration of a Drug in the Blood Supply Depends on the Method of Administration

23. Basic Principles of Drug Effects Tolerance and Withdrawal – Tolerance = lessened effects as a result of repeated administration – Withdrawal = occurs when substance use is discontinued; opposite of the effects caused by the discontinued drug Addiction – Compulsive need to use the drug repeatedly – Causes of addiction – Treatment of addiction

24. Figure 4.17 Tolerance and Withdrawal Can Result from Compensation

25. Figure 4.18 The Nucleus Accumbens Participates in Reward and Addiction

26. Effects of Psychoactive Drugs Stimulants – increase alertness and mobility – Caffeine – antagonist for adenosine – Nicotine – agonist at the nicotinic cholinergic receptor – Cocaine and Amphetamine Cocaine – dopamine reuptake inhibitor Amphetamine – stimulates dopamine and norepinephrine release and inhibits their reuptake – Club Drugs: Ecstasy and GHB MDMA – stimulates release of serotonin and oxytocin; toxic to serotonergic neurons GHB – mimics inhibitory effects of GABA

27. MDMA Ecstasy Destroys Serotonergic Neurons

28. Figure 4.20 Caffeine Content of Common Products

29. Effects of Psychoactive Drugs Opiates – Synthesized from sap of opium poppy – Morphine, codeine, heroin – Endorphin receptors Marijuana – THC – agonist at receptors for endogenous cannabinoids – Cannabinoid receptors in the hippocampus and prefrontal cortex

30. Effects of Psychoactive Drugs Other hallucinogens – have the ability to produce false perceptions – Mushrooms – agonist for GABA and glutamate – Mescaline – acts on serotonergic neurons – Phencyclidine (PCP) – antagonist at the NMDA glutamate receptor – LSD – serotonergic agonist

31. Effects of Psychoactive Drugs Alcohol – Agonist at the GABA A receptor – Stimulates dopaminergic reward pathways – Damaging effects on health St. John’s Wort – Effective for mild depression – Interactions with other drugs