Chapter 4B: Chapter 4 The Chemistry of Behavior: Neurotransmitters and Neuropharmacology Flashcards
Antipsychotics (neuroleptics)
Class of drugs used to treat schizophrenia
First-generation antipsychotics
Selectively target dopamine D2 receptors
Antagonists
Reduce positive (onset of new) symptoms of schizophrenia, like delusions and hallucinations
Second-generation antipsychotics
Affect both dopamine AND serotonin receptors
Helps with negative (withdrawl or lack of something that would normally be there) symptoms, like blunted emotional responses
Antidepressants
Reduce chronic mood disturbances
Accumulating monoamines and prolonging their activity is a major feature of antidepressants
Monoamine oxidase inhibitors
Prevents breakdown of monoamines
Accumulation of these in synaptic cleft for longer
Tricyclic antidepressants
Increase norepinephrine and serotonin by blocking reuptake
Reuptake
When neurons reabsorb neurotransmitters after they have been used to transmit signals
Anxiolytics (tranquilizers)
Reduce nervous system activity
Barbiturates
One of the OG anxiolytics
Are addictive
Benzodiazepine agonists
Anxiolytic
More selective
More frequently prescribed
Act on GABA A receptors to enhance inhibitory effects of GABA
Goal is to recude exitability in the nervous system (anxiety, etc.)
Opiates
Potently relieve pain
Extracted from poppyseed flowers
Morphine
Heroin
Oxycodone and fentanyl
Endogenous opioids
Peptides produced in the body that bind to opioid receptors and relieve pain:
Enkephalins
Endorphins
Dynorphins
Three main kinds of opioid receptors
delta, kappa, mu
Naloxone and naltrexone
Drugs that block opioid receptors, can rapidly reverse effects in case of overdose
Opiate antagonists
Can block rewarding effects of drugs like heroin, so can be useful in treating addiction
Buprenorphine
Partial agonist, can bind to receptor, helpful for withdrawal in opioid use disorder
Cannabinoids
Cannabis
Two main active ingredients:
THC
CBD
Effects include relaxation and mood alteration, but can also cause stimulation and paranoia
Occasional use seems harmless, but heavy use linked to respiratory issues, neuropsychiatric disorders, cognitive decline, etc.
Two kinds of cannabinoid receptors
CB1 receptors: only found in CNS
CB2 receptors: prominent in the immune system
Endocannabinoids
Endogenous ligand to cannabinoid receptors
Can act as retrograde messengers and may influence neurotransmitter release from the presynaptic neuron
Example of an endocannabinoid
Ex: Anandamide
Diverse functions, like altering memory formation, etc.
Can combat nausea and lower eye pressure from glaucoma
Stimulants
Increase nervous system activity
Many naturally occurring, some synthetic
Some act by increasing excitatory synaptic potentials, others block inhibitory processes
Examples of stimulants
Nicotine, amphetamine, caffeine, cocaine
Nicotine
From tobacco
Increases heart pressure, blood pressure, acid secretion from stomach, and intestinal activity
Short-term effects are pleasurable, but long-term effects can be harmful
Nicotine receptors
Acts as an agonist on nicotinic ACh receptors in the body and brain
Rewarding effects are mediated by receptors in the ventral tegmental area
Cocaine
Purified extract from the coca shrub
All forms are highly addictive and many negative side effects
Blocks monoamine transporters– especially dopamine– slowing reuptake of neurotransmitters
Also increases the amount of dopamine released
Amphetamine and methamphetamine
Synthetic stimulants
Short-term effects: alertness, euphoria, increased stamina
Long-term effects: weight loss, sleeplessness, deterioration of mental and physical condition (may lead to symptoms similar to schizophrenia)
How amphetamine and methamphetamine work
Induce release of transmitters from presynaptic terminals (cause exocytosis without getting neuron to fire)
Increase release of NT when neurons do fire
Block reuptake of NT into presynaptic cell
Provide an alternative target for breakdown enzymes
Alcohol
Biphasic
Can act as both a stimulant and a depressant
Initial stimulant followed by prolonged depressant phase
Alcohol’s action at GABA A receptors
Increases inhibitory effects
Social disinhibition, impaired motor coordination, and sensory disturbances
Also stimulates some dopamine pathways, causing slightly euphoric effects
Alcohol abuse
Damages nerve cells, in particular: superior frontal cortex, Purkinje cells of cerebellum, and hippocampal pyramidal cells
Periodic overconsumption, or bingeing, may cause brain damage and reduce neurogenesis
Hallucinogens (psychedelics)
Alter sensory perception
LSD (acid), mescaline (peyote), and psylocybin (mushrooms)
LSD
Acts as serotonin agonist or partial agonist
Psilocybin
Shrooms
Serotonin agonist
Reduce activity in medial prefrontal cortex and anterior cingulate cortex – brain regions that inhibit limbic emotion and processing
Ketamine
Potent analgesic and anesthetic
NDMA receptor antagonist in prefrontal cortex
MDMA
Ecstacy
Hallucinogenic amphetamine derivative
Increases serotonin levels and changes in dopamine, oxytocin, and prolactin levels
Addiction
A chronic, relapsing brain disease that is characterized by compulsive drug seeking and use despite harmful or adverse consequences
The pursuit of rewarding experiences drives behavior
Early in life, behavior is driven by immediate rewards (ex: food and water)
When you get older, more value is placed on long-term rewards (ex: grades)
Reward-seeking behavior helps to guide our motivations so we can put in effort that’s required to obtain them
Can start to be maladaptive and lead to neural changes in circuitry
Where do drugs act in the brain?
Reward pathway
Many addictive drugs cause dopamine release in nucleus accumbens from neurons that originate in the ventral tegmental area
Biological factors of addiction
Women more likely to self-medicate and can become addicted much more quickly
Men more likely to take drugs in groups
Personality, genetics, heritability
Social factors of addiction
Amount of support you have, knowing dangers of drug use
Environmental effects of addiction
Availability
Medical interventions for substance abuse
Partial agonists and benzodiazepines can be used for withdrawal
Altering the body’s response to the abuse drug
Blocking the brain’s reward system
What if you keep taking drugs?
Can downregulate amount of receptors in postsynaptic cell
Alters reward circuitry, and individual’s ability to experience pleasure is reduced
Eventually, addicts need to take it to elevate dopamine levels to feel normal
