Presentation Slides 10, 11

Psychoactive drugs

Psychopharmacology

Study of how drugs affect the nervous system and behavior

Psychoactive Drugs

• A substance that acts to alter mood, thought, or behavior

• Used to manage neuropsychological illness

• Many promote cravings and can produce addiction

Ingestion

slow to moderate speed of effect

Inhalation

Moderate to fast speed of effect

Peripheral injection

Moderate to fat speed of effect

Central injection

Fast to very fast

Materials can move in and out of ___ easily

cappilaries in the body

Materials can’t move in and out of ___ easily

cappilaries in the brain

Pituitary Gland (Hypophysis)

Allows exchange of hypothalamic chemicals, which influence hormone secretion

Area Postrema

Allows entry of toxic substances to trigger vomiting

Pineal gland

Allows entry of hormones that regulate day–night cycles

Agonists

Drugs that increase the effectiveness of neurotransmission

Antagonists

Drugs that decrease the effectiveness of neurotransmission

Agoniststic action of drugs

mimic effects of another transmitter

Antagonistic action of drugs

bind receptor without activating it

Inverse agoniststic action of drugs

bind to receptor and initiate opposite effect of usual transmitter

in response to an agonist drug neurons …

down-regulate — fewer receptors available.

in response to an antagonist drug neurons …

up-regulate - more receptors available

Antianxiety Agents & Sedative Hypnotics

• Benzodiazepines, Barbiturates, Alcohol, and others

• Work on GABA receptors

Antipsychotic Agents

• Major tranquilizers and neuroleptics

• Dopamine (1st gen) or serotonin (2nd gen) antagonist

Antidepressants & Mood Stabilizers

Agonistic effects at serotonin, noradrenaline, acetylcholine, or dopamine receptors

Opioid Analgesics

• Induce analgesia or even europhoria

• All opioids are addicitve!

Stimulants & Psychedelics

• Affect mental or motor activity, arousal, perception, mood

• Behavioral or general stimulants

Benzodiazepines (antianxiety)

• Diazepan (Valium)

• Xanax

• Klonopin

Anaesthetic agents

• Barbiturates

• Alcohol

Other anaesthetics

• GHB

• Ketamine (Special K)

• PCP (Angel dust)

All sedative hypnotics work on the

GABA_A Receptor

Alcohol and barbiturates increase the influx of __, causing ___

Cl-, hyperpolarization

Benzodiazepines maximize ___ and ___ in response to GABA

channel opening times & frequency

Metabolic Tolerance

• Results from an increase in the enzymes needed to break down alcohol in the liver, blood, and brain

• Person metabolizes alcohol quickly, so blood alcohol levels (BAL) are reduced

Cellular Tolerance

• Results from an adjustment in the activities of the neurons to minimize the effects of alcohol

• Behavioral signs of intoxication low despite high BAL

Learned Tolerance

Results from learning to cope with daily demands under the influence– thus a reduction of outward signs

Disinhibition theory

Effects of alcohol result from depression of learned inhibitions in the neocortex that are based on reasoning and judgment and sparing subcortical regions

Learned behavior theory

Behavior under the influence of alcohol is learned behavior that is specific to the drug, culture, group, and setting

ketamine & phencyclidine block

glutamate synapses

Antidepressants

Act by improving transmission at serotonine, noradrenaline, histamine, Acetylcholine and Dopamine synapses

Amphetamine and cocaine

• DA agonists, block re-uptake

• The first one is also used in ADHD treatment

Metamphetamine (Meth, speed, crack)

• Amphetamine derivative, easy to produce

Derivatives such as Novocaine

• Reduce a cell’s permeability to Na+ ions and so reduce nerve conduction

• Used as local anesthetics

Bath Salts (acts like cocaine or meth)

• Effects can include agitations, seizures, chest pain, high blood pressure, and fast pulse.

• In addition, users can have hallucinations and extra-human strength, leading to criminal attacks and suicide.

Spice (synthetic canabinoid)

• Potential effects include extreme paranoia, delusions, tremors, anxiety, nightmares, hallucinations, vomiting, high blood pressure, fast pulse, and slow breathing.

• Reports of seizures after its use and of longer-lasting psychiatric problems.

• Users have committed suicide after smoking it

Abuse

1. Failure to fulfill major role obligations

2. Use in hazardous situations

3. Legal Problems

4. Use despite problems

Dependence

1. Tolerance

2. Withdrawal

3. Larger amounts/longer period than intended

4. Inability to, or persistent desire to, cut down

or control

5. A great deal of time spent obtaining, using, or

recovering

6. Important activities given up or reduced

7. Use despite problems caused or exacerbated by use

The SEEKING system

positively-valenced, energizing system that moves animals out into their environment to forage and experience

Appetitive system

makes mammals curious about their world and promotes goal-directed behavior toward a variety of goals and objects, such as food, shelter, sex.

Mesolimbic dopamine pathway

dopaminergic neurons that originate in the ventral tegmental area (VTA) of the brainstem terminate at the nucleus accumbens in the forebrain

Mesocortical dopamine pathway

dopaminergic neurons project from VTA to orbitofrontal cortex

Nucleus Accumbens

important structure for forming memories with respect to rewards

evidence that neurons in DA system are more responsive

to anticipation of reward and to lack of reward

Liking = pleasure produced by taking the drug (habituates)

• Neural basis: activity of opioid neurons

• Pleasure decreases in addiction – need for higher doses

• Endorphins: associated with pleasure in early use

Wanting = craving for drug (sensitizes)

• Neural basis: All drugs of abuse increase DA in the mesolimbic dopamine pathway

• DA neurons in midbrain that project to the noreadrenaline system, the frontal cortex and the limbic system

Addiction stages

• Activation of pleasure

• Classical conditioning

• Incentive salience