1 Chapter Four Psychopharmacology

2 Psychopharmacology  the study of the effects of drugs on affect, cognition, and behavior Photodisc/Getty Images

3 Types of Neurochemicals  Neurotransmitters affect adjacent cells across the synapse.  Neuromodulators diffuse away from the synapse to target cells some distance away.  Circulating neurohormones reach even more distant target cells.

4 Neurotransmitters

5 Acetylcholine (ACh)  Neuromuscular junction (movement)  Central nervous system (learning and memory)

6 Dopamine  Movement  Reinforcement  Planning

7 Serotonin  Mood  Appetite  Sleep

8 Glutamate  The major excitatory neurotransmitter of the central nervous system.  Extended presence may be toxic

9 GABA  GABA is the major inhibitory neurotransmitter of the central nervous system.  The GABA A receptor interacts with a number of drugs.

10 Why is Inhibition Important?  Tetanospasmin (tetanus toxin) hitches a ride to the central nervous system from a wound site using the retrograde transport system within axons.  The toxin binds to receptor sites for gamma-aminobutyric acid (GABA), and can ’ t be dislodged.  Without normal inhibitory input from GABA, muscles begin to go into sudden, involuntary contractions, or spasms.

11 Drug Actions at the Synapse  Agonists boost the activity of a neurotransmitter.  Antagonists interfere with the action of a neurotransmitter.

12 Lifespan of a neurotransmitter 1. Synthesis 2. Storage 3. Release 4. Action on the target cell 5. Deactivation

13 Deactivation of Neurotransmitters

14 Drugs and Serotonin

15 Drugs and Acetylcholine

16 Agonists and Antagonists Copyright © Houghton Mifflin Company. All rights reserved. Go to Slide Show View (press F5) to play the video or animation. (To exit, press Esc.) This media requires PowerPoint® 2000 (or newer) and the Macromedia Flash Player (7 or higher). [To delete this message, click inside the box, click the border of the box, and then press delete.] Click in this box to enter notes.

17 Basic Principles of Drug Effects  Placebo effects  Individual differences Gender Size Genetics

Allyn & Bacon 2004 Principles of Pharmacology Routes of Administration Intravenous (IV) injection:  Injection of a substance directly into a vein. Intraperitoneal (IP) injection:  The Injection of a substance into the peritoneal cavity- the space that surrounds the stomach, intestines, liver, and other abdominal organs. Inhalation:  Administration of a vaporous substance into the lungs.

Allyn & Bacon 2004 Principles of Pharmacology Routes of Administration Intramuscular (IM) injection:  Injection of a substance into a muscle. Subcutaneous (SC) injection:  Injection of a substance into the space beneath the skin. Oral administration:  Administration of a substance into the mouth, so it is swallowed.

20 Method of Administration Affects Blood Concentration Basic Principles of Drug Effects

21  Tolerance the need to administer more of a drug to produce the same effects may occur due to:  changes in enzymes  changes at the level of the synapse  learning  Withdrawal occurs when some drugs are discontinued, leads to behavioral effects that are typically the opposite of the effects produced by the drug Basic Principles of Drug Effects

22 Tolerance and Withdrawal

23 Addiction  a compulsive need to readminister a drug.  The dopamine reward system, including the nucleus accumbens, has been implicated in addiction.  Addiction is the result of complex physical and environmental variables, making it extremely challenging to treat.

24 Pleasure and Reward  Olds and Milner (1954) reported that rats would work for electrical self-stimulation of the brain (ESB).

25 ESB and the Mesolimbic System  ESB is very strong in the medial forebrain bundle (MFB).  MFB makes connections between the midbrain and the limbic system.  Many neurons in this system use dopamine.  This system may function as a “reward circuit.”

26 ESB, Dopamine and the Nucleus Accumbens  ESB in the ventral tegmentum is associated with increased release of dopamine in the nucleus accumbens.  These circuits may underlie natural reward and addictive behaviors.

27 Pleasure and Reward  Heath (1963) investigated ESB in human participants.

28 Stimulants  Stimulant drugs increase alertness and mobility.  This class includes: Nicotine Cocaine Amphetamine Ecstasy (MDMA) Caffeine © CORBIS

29 Caffeine in Common Products

30 Cocaine  Dopamine reuptake inhibitor  Effects: Alertness, elevated mood, confidence, well-being High doses – symptoms similar to schizophrenia (hallucinations, paranoid delusions, repetitive movements) © Michael S. Yamashita/CORBIS

31 MDMA (Ecstasy)  MDMA increases the release of serotonin, which has a toxic effect on serotonergic neurons. After MDMA administration Courtesy Una D. McCann, Johns Hopkins Medical Institute Normal brain tissue

32 Other drug types  Alcohol  Opiates  Hallucinogens