Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Psychopharmacology psychopharmacology The study of the effects of drugs on the nervous system and on behavior. drug effect The changes a drug produces in an animal’s physiological processes and behavior. site of action A location at which molecules of drugs interact with molecules located on or in cells of the body, thus affecting some biochemical processes of these cells. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Principles of Psychopharmacology
Pharmacokinetics The process by which drugs are absorbed, distributed within the body, metabolized, and excreted. Molecules of drugs must cross several barriers to enter the body and find their way to their sites of action. Some molecules pass through these barriers easily and quickly; others do so very slowly. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Effects of Repeated Administration tolerance A decrease in the effectiveness of a drug that is administered repeatedly. sensitization An increase in the effectiveness of a drug that is administered repeatedly. withdrawal symptom The appearance of symptoms opposite to those produced by a drug when the drug is administered repeatedly and then suddenly no longer taken. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Placebo Effects placebo (pla see boh) An inert substance that is given to an organism in lieu of a physiologically active drug; used experimentally to control for the effects of mere administration of a drug. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Sites of Drug Action antagonist A drug that opposes or inhibits the effects of a particular neurotransmitter on the postsynaptic cell. agonist A drug that facilitates the effects of a particular neurotransmitter on the postsynaptic cell. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Effects on Production of Neurotransmitters The first step is the synthesis of the neurotransmitter from its precursors. In some cases the rate of synthesis and release of a neurotransmitter is increased when a precursor is administered; in these cases the precursor itself serves as an agonist. (See step 1 in Figure 4.4.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Effects on Production of Neurotransmitters The steps in the synthesis of neurotransmitters are controlled by enzymes. Therefore, if a drug inactivates one of these enzymes, it will prevent the neurotransmitter from being produced. Such a drug serves as an antagonist. (See step 2 in Figure 4.4.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Effects of Storage and Release of Neurotransmitters Some of the transporter molecules that fill synaptic vesicles are capable of being blocked by a drug. Molecules of the drug bind with a particular site on the transporter and inactivate it. Because the synaptic vesicles remain empty, nothing is released when the vesicles eventually rupture against the presynaptic membrane. The drug serves as an antagonist. (See step 3 in Figure 4.4.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Effects of Storage and Release of Neurotransmitters Some drugs act as antagonists by preventing the release of neurotransmitters from the terminal button. They do so by deactivating the proteins that cause synaptic vesicles to fuse with the presynaptic membrane and expel their contents into the synaptic cleft. Other drugs have just the opposite effect: They act as agonists by binding with these proteins and directly triggering release of the neurotransmitter. (See steps 4 and 5 in Figure 4.4.) Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Effects on Receptors direct agonist A drug that binds with and activates a receptor. receptor blocker A drug that binds with a receptor but does not activate it; prevents the natural ligand from binding with the receptor. direct antagonist A synonym for receptor blocker. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Effects on Reuptake or Destruction of Neurotransmitters Two processes accomplish that task: Molecules of the neurotransmitter are taken back into the terminal button through the process of reuptake, or they are destroyed by an enzyme. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Neurotransmitters and Neuromodulators
Because neurotransmitters have two general effects on postsynaptic membranes—depolarization (EPSP) or hyperpolarization (IPSP)—one might expect that there would be two kinds of neurotransmitters: excitatory and inhibitory. In the brain most synaptic communication is accomplished by two neurotransmitters: one with excitatory effects (glutamate) and one with inhibitory effects (GABA). Copyright © 2014 Pearson Education, Inc. All Rights Reserved

The excretion of acetylcholine activates the cerebral cortex and facilitates learning. Information that is learned and remembered is transmitted by neurons that secrete glutamate and GABA. Secretion of norepinephrine increases vigilance and enhances readiness to act when a signal is detected. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Secretion of histamine enhances wakefulness. Secretion of serotonin suppresses certain categories of species- typical behaviors and reduces the likelihood that the animal acts impulsively. Secretion of dopamine in some regions of the brain generally activates voluntary movements but does not specify which movements will occur. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

In other regions secretion of dopamine reinforces ongoing behaviors and makes them more likely to occur at a later time. Because particular drugs can selectively affect neurons that secrete particular neurotransmitters, they can have specific effects on behavior. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Acetylcholine Acetylcholine is the primary neurotransmitter secreted by efferent axons of the central nervous system. All muscular movement is accomplished by the release of acetylcholine, and ACh is also found in the ganglia of the autonomic nervous system and at the target organs of the parasympathetic branch of the ANS. Three systems have received the most attention from neuroscientists: those originating in the dorsolateral pons, the basal forebrain, and the medial septum. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Acetylcholine The acetylcholinergic neurons located in the dorsolateral pons play a role in REM sleep (the phase of sleep during which dreaming occurs). Those located in the basal forebrain are involved in activating the cerebral cortex and facilitating learning, especially perceptual learning. Those located in the medial septum control the electrical rhythms of the hippocampus and modulate its functions, which include the formation of particular kinds of memories. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Acetylcholine acetyl-CoA (a see tul) A cofactor that supplies acetate for the synthesis of acetylcholine. choline acetyltransferase (ChAT) The enzyme that transfers the acetate ion from acetyl coenzyme A to choline, producing the neurotransmitter acetylcholine. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Acetylcholine botulinum toxin (bot you lin um) An acetylcholine antagonist; prevents release by terminal buttons. black widow spider venom A poison produced by the black widow spider that triggers the release of acetylcholine. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Acetylcholine neostigmine (nee o stig meen) A drug that inhibits the activity of acetylcholinesterase. nicotinic receptor An ionotropic acetylcholine receptor that is stimulated by nicotine and blocked by curare. muscarinic receptor (muss ka rin ic) A metabotropic acetylcholine receptor that is stimulated by muscarine and blocked by atropine. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Dopamine dopamine (DA) (dope a meen) A neurotransmitter; one of the catecholamines. L-DOPA (ell dope a) The levorotatory form of DOPA; the precursor of the catecholamines; often used to treat Parkinson’s disease because of its effect as a dopamine agonist. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Dopamine nigrostriatal system (nigh grow stry ay tul) A system of neurons originating in the substantia nigra and terminating in the neostriatum (caudate nucleus and putamen). mesolimbic system (mee zo lim bik) A system of dopaminergic neurons originating in the ventral tegmental area and terminating in the nucleus accumbens, amygdala, and hippocampus. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Dopamine mesocortical system (mee zo kor ti kul) A system of dopaminergic neurons originating in the ventral tegmental area and terminating in the prefrontal cortex. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Dopamine Parkinson’s disease A neurological disease characterized by tremors, rigidity of the limbs, poor balance, and difficulty in initiating movements; caused by degeneration of the nigrostriatal system. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Dopamine AMPT A drug that blocks the activity of tyrosine hydroxylase and thus interferes with the synthesis of the catecholamines. reserpine (ree sur peen) A drug that interferes with the storage of monoamines in synaptic vesicles. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Dopamine Several different types of dopamine receptors have been identified, all metabotropic. Of these, two are the most common: D1 dopamine receptors and D2 dopamine receptors. It appears that D1 receptors are exclusively postsynaptic, whereas D2 receptors are found both presynaptically and postsynaptically in the brain. Several drugs stimulate or block specific types of dopamine receptors. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Dopamine methylphenidate (meth ul fen i date) A drug that inhibits the reuptake of dopamine. monoamine oxidase (MAO) (mahn o a meen) A class of enzymes that destroy the monoamines: dopamine, norepinephrine, and serotonin. deprenyl (depp ra nil) A drug that blocks the activity of MAO-B; acts as a dopamine agonist. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Dopamine Dopamine has been implicated as a neurotransmitter that might be involved in schizophrenia, a serious mental disorder whose symptoms include hallucinations, delusions, and disruption of normal, logical thought processes. Drugs such as chlorpromazine, which block D2 receptors, alleviate these symptoms. chlorpromazine (klor proh ma zeen) A drug that reduces the symptoms of schizophrenia by blocking dopamine D2 receptors. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Norepinephrine norepinephrine (NE) (nor epp i neff rin) One of the catecholamines; a neurotransmitter found in the brain and in the sympathetic division of the autonomic nervous system. epinephrine (epp i neff rin) One of the catecholamines; a hormone secreted by the adrenal medulla; serves also as a neurotransmitter in the brain. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Norepinephrine fusaric acid (few sahr ik) A drug that inhibits the activity of the enzyme dopamine-- hydroxylase and thus blocks the production of norepinephrine. locus coeruleus (sur oo lee us) A dark-colored group of noradrenergic cell bodies located in the pons near the rostral end of the floor of the fourth ventricle. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Norepinephrine idazoxan A drug that blocks presynaptic noradrenergic 2 receptors and hence acts as an agonist, stimulating the synthesis and release of NE. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Serotonin The third monoamine neurotransmitter, serotonin (also called 5-HT, or 5-hydroxytryptamine), has also received much experimental attention. serotonin (5-HT) (sair a toe nin) An indolamine neurotransmitter; also called 5- hydroxytryptamine. PCPA A drug that inhibits the activity of tryptophan hydroxylase and thus interferes with the synthesis of 5-HT. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Serotonin fluoxetine (floo ox i teen) A drug that inhibits the reuptake of 5-HT. fenfluramine (fen fluor i meen) A drug that stimulates the release of 5-HT. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Serotonin LSD A drug that stimulates 5-HT2A receptors. MDMA A drug that serves as a noradrenergic and serotonergic agonist, also known as “ecstasy”; has excitatory and hallucinogenic effects. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Amino Acids GABA An amino acid; the most important inhibitory neurotransmitter in the brain. allylglycine A drug that inhibits the activity of GAD and thus blocks the synthesis of GABA. muscimol (musk i mawl) A direct agonist for the GABA binding site on the GABAA receptor. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

Amino Acids GABA bicuculline (by kew kew leen) A direct antagonist for the GABA binding site on the GABAA receptor. benzodiazepine (ben zoe dy azz a peen) A category of anxiolytic drugs; an indirect agonist for the GABAA receptor. Copyright © 2014 Pearson Education, Inc. All Rights Reserved

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