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Janelle Leboutillier

PSYB64: Introduction to Physiological Psychology Lecture 4: Psychopharmacology, Genetics and Development Overview  Quiz and term test updates  Quick review  Neuromodulation  Reading chapter updates  Practice questions Now a little about Psychopharmacology  Identifying Neurotransmitters o Types of neurotransmitters  Drug actions at the synapse o Agonists & antagonists o Neurotransmitter production, storage & release  Basic principles of drug effects  NOTE: Lecture content is from Chapter 4. You are only responsible for the content covered in these lecture slides Identifying Neurotransmitters  Identifying Neurotransmitters 1. Must be synthesized within the neuron 2. In response to an action potential, the substance is released in sufficient quantities to produce an effect in the postsynaptic cell 3. We should be able to duplicate the action of a suspected neurotransmitter experimentally on a postsynaptic cell 4. Some mechanism exists that ends the interaction between the neurotransmitter and the postsynaptic cell Neurotransmitters  Types of Neurotransmitters (3) 1. Small molecule transmitters – meet all or most of criteria and play a vital role in neurotransmission o Eg: Acetylcholine (Ach) 2. Neuropeptides – at least 40 act as neurotransmitters, neuromodulators, and neurohormones 3. Gaseous neurotransmitters – some gases transfer information from one cell to another Characteristics of Selected Neurotransmitters NEUROTRANSMITTER LOCATIONS FUNCTIONS  Neuromuscular junction  Movement  Preganglionic autonomic synapses  Autonomic function Acetylcholine (Ach)  Postganglionic parasympathetic synapses  Learning and memory  Basal forebrain projections to hippocampus and amygdala; the septum; the brainstem  Substantia nigra and basal ganglia  Movement  Ventral tegmentum projections to hippocampus,  Reinforcement Dopamine amygdala, and nucleus accumbens  Planning  Ventral tegmentum projections to frontal lobe of the cortex  Pons (especially locus coeruleus, which projects  Arousal and vigilance widely to spinal cord and brain)  Mood Norephinephrine  Medulla  Hypothalamus  Postganglionic sympathetic synapses NEUROTRANSMITTER LOCATIONS FUNCTIONS  Projections originate in the pons,  Sleep Serotonin  particularly the raphe nucleus, and project widely  Appetite in the brain and spinal cord  Mood Glutamate  Widely distributed in the central nervous system  Excitation  Long-term memory  Widely distributed in the central nervous system  Inhibition GABA  Mood  Seizure threshold Andenosine  Central nervous system neuromodulator  Pain modulation triphosphate  Autonomic nervous system  Inhibition (ATP)  Frequently found in axons containing catecholamines  Periaqueductal gray  Pain reduction  Hypothalamus  Feelings of well-being  Pituitary gland Endorphins  Limbic system  Basal ganglia  Spinal cord  Ventral tegmentum Substance P  Spinal cord  Pain  Central and peripheral nervous systems  Relaxes smooth muscle  Smooth muscle cells in blood vessels Nitric oxide (NO)  Erection  Possible retrograde signaling What is a ‘Drug’?  A very vague term  All ingested substances alter bodily function  ‘Drug’ is reserved for things that have pronounced effects when ingested in small quantities Examples of Commonly Used Drugs and Their Effects Drug Behavioral Effects Mode of Action Caffeine Arousal; less need for sleep; reduces Blocks adenosine receptor sites headache Nicotine Alertness; muscular relaxation Stimulates nicotinic Ach receptors Reduced anxiety; mild euphoria; loss of Stimulates GABA receptors; acts as an motor coordination antagonist at the NMDA glutamate Alcohol receptor; stimulates dopaminergic systems St. John’s Wort Reduction of mild depression Inhibits MAO and serotonin reuptake (over-the-counter) Drug Actions at the Synapse  Agonists enhance the activity of a neurotransmitter  Antagonists reduce the activity of a neurotransmitter How do you think a drug could affect the synapse?  Pre-synaptically? Easier to release; stop binding the vesicle to the membrane  Post-synaptically? Open ion channels or change sensitivity, affect re-uptake *Drug Actions at the Synapse (Pre)*  Neurotransmitter Production o Manipulating the synthesis of a neurotransmitter will affect the amount available for release  Neurotransmitter Storage o Interfering with the storage of a neurotransmitters in vesicles within a neuron  Neurotransmitter Release o Drugs can modify the release of a neurotransmitter in response to the arrival of an action potential *Drug Actions at the Synapse (Post)*  Receptor Effects o Can mimic the action of a neurotransmitter at the site o Can block the synaptic activity by occupying a binding site o Can influence the activity of the receptor  Reuptake Effects and Enzymatic Degradation o Deactivation of neurotransmitters Drug Interactions at the Cholinergic Synapse (Figure 4.12)  Drugs can interact with many ongoing processes at the synapse  Agonists at the cholinergic synapse, which appear in green, include black widow spider venom, nicotine, and dietary choline  Spider venom enhances ACh release, and nicotine activates ACh receptors  Increased intake of dietary choline can increase production of ACh  Antagonists, which appear in red, include botulin toxin, curare, and organophosphates  Botulin toxin blocks the release of ACh, and curare blocks ACh receptors  Organophosphates break down the enzyme AChE, so they technically serve as ACh agonists  Although a reduction in AChE activity might initially boost ACh activity, it eventually has a toxic effect on ACh receptors. Drug Interactions at the Dopaminergic Synapse (Figure 4.14)  L-dopa serves as a dopaminergic agonist by promoting increased dopamine synthesis, and amphetamine increases the release of dopamine  Cocaine, amphetamine, and methylphenidate are dopamine reuptake inhibitors  Apomorphine activates dopaminergic receptors  Reserpine exerts an antagonistic effect by interfering with the uptake of monoamines into synaptic vesicles  Some medications used to treat schizophrenia block dopaminergic receptors. Basic Principles of Drug Effects  Administration of Drugs o Method of administration leads to different effects on nervous system o Blood-brain barrier  Individual Differences o Drug effects influenced by body weight, gender, and genetics  Placebo Effects o User expectations influence drug effects o Double-blind experiment Concentration of a Drug in the Blood Supply Depends on the Method of Administration (Figure 4.16)  Drug effects are dependent on the concentration of the drug in the blood supply, and some methods of administration produce effective concentrations faster than others (affects Ach and nicotinic)  In the case of nicotine, smoking a cigarette produces a much faster increase in blood nicotine concentration than chewing an equivalent dose of tobacco  However, chewing tobacco produces higher sustained concentrations of nicotine than smoking does Video: Nicotine, Smoking & Genetics  o Three studies identify an association between genetic varioation at a location on chromosome 15 and risk of lung cancer o However, they disagree on whether the link is direct or mediated through nicotine dependence Alcohol and Herbal Remedies  Alcohol o Agonist at the GABA receptor o Stimulates dopaminergic reward pathways o Damaging effects on health  St. John’s Wort o Often herbal remedies are chosen as opposed to prescription medicines by individuals o Effective for mild depression  Acts as a selective serotonin reuptake inhibitor o Interactions with other drugs  Can be negative interactions with chemotherapy Overview of Lecture  Development and Genetics  Know Table 5.1  Not sure about genes and genetics? Stay around for a quick review
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