Chapter 6: Drugs and Hormones Flashcards
Attention-Deficit/Hyperactivity Disorder (ADHD)
developmental disorder characterized by core behavioral symptoms including impulsivity, hyperactivity, and/or inattention
Psychopharmacology
study of how drugs affect the nervous system and behavior
Psychoactive Drug
substance that acts to alter mood, thought or behavior
is used to manage neuropsychological illness, and may be taken recreationally
Agonist
substance that enhances neurotransmitter function
Antagonist
substance that blocks neurotransmitter function
Tolerance
decrease in response to a drug with passage of time
Fetal Alcohol Spectrum Disorder (FASD)
range of physical and intellectual impairments observed in some children born to alcoholic parents
Amphetamine
synthetic compound that increases the neurotransmitter dopamine in the synaptic cleft by reversing the dopamine transporter
Dopamine Hypothesis of Schizophrenia?
idea that excess dopamine activity causes symptoms of schizophrenia
Major Depression
mood disorder characterized by prolonged feelings of worthlessness and guilt, disruption of normal eating habits, insomnia, a general slowing of behavior, and frequent thoughts of suicide
Monoamine Oxidase (MAO) Inhibitor
drug that blocks the enzyme monoamine oxidase from degrading such neurotransmitters as 5-HT, NE and DA
Tricyclic
drug, characterized by its three-ring chemical structure, that blocks 5-HT reuptake transporter proteins
Selective Serotonin Reuptake Inhibitor (SSRI)
drug that blocks 5-HT reuptake into the presynaptic terminal and most commonly used to treat depression
Competitive Inhibitor
drug used to treat overdoses and opioid addiction, an example is naloxone, which acts quickly to block opioid action by competing with the opioid for binding sites
How do drugs and hormones influence brain and behavior?
principles of psychopharmacology
psychoactive drugs
factors influencing individual responses to drugs
explaining and treating drug abuse
hormones
What is psychopharmacology?
study of the ways drugs affect the nervous system and behavior
What are drugs?
chemical compounds administered to produce a desired change
improvement of physical/mental symptomatology
What are psychoactive drugs?
substance that acts to alter moods, thought, or behavior, used to manage neuropsychological illness
often used recreationally
What are the routes of drug administration?
the way a drug enters/passes through the body to reach target
a psychoactive drug has to reach it’s target to work
can be administered: orally or inhaled, absorbed through skin or mucous membranes, injected into the bloodstream, into a muscle, or even into the brain
What is the effect of injecting a drug directly into the brain?
allows it to act quickly in low doses because it encounters fewer barriers
What is the effect of ingesting a drug orally?
safest, easiest, and most convenient way to administer them
drugs that are weak acids pass from the stomach into the bloodstream
drugs that are weak bases pass from the intestines to the bloodstream
has the most barriers to the brain
ingestion>absorption by stomach/small intestine
What is the effect of injecting a drug in muscles?
encounter more barriers than do drugs inhaled
What is the effect of inhaling drugs into the lungs?
encounter few barriers en route to the brain
gases or aerosols penetrate the cell linings of respiratory tract easily
absorbed by membranes into bloodstream almost immediately after inhalation
What is the effect of injecting drugs into the bloodstream?
encounter the fewest barriers to the brain but must be hydrophilic
when injected into bloodstream a drug passes through less obstacles
with each obstacle eliminated en route to the brain, a drug’s dosage can be reduced by a factor of 10
How do drugs enter the bloodstream in the stomach?
drug must be water-soluble
diluted over the body through blood to reach target
What is the effect of drugs being absorbed by the skin?
drugs contained in adhesive patches are absorbed through the skin and into the bloodstream
the skin is made out of protective layers
small molecule drugs can penetrate the skin barrier
What is the factor of 10 rule?
1 milligram (1000 micrograms) of amphetamine produces a noticeable behavioral change orally
if inhaled into the lungs or injected into the blood, circumventing the stomach, a dose of just 100ug yields the same results
if amphetamine is injected into the cerebrospinal fluid, bypassing both the stomach and the blood, 10ug us enough to produce an identical outcome
1ug if the drug is applied directly to target neurons
What is the blood brain barrier?
the body presents a number of barriers to the internal movement of drugs: cell membranes, capillary walls, and the placenta
the blood-brain barrier prevents most substances from entering the brain via the bloodstream
protects the brain’s ionic balance
denies neurochemicals that can disrupt neural communication
protects the brain from circulating hormones and form toxins/infectious diseases
What are endothelial cells in the blood-brain barrier?
endothelial cells form a layer that lines the blood vessels, regulate exchanges between bloodstream and surrounding tissues
endothelial cells in capillaries throughout the body are not tightly joined
it’s easy for substances to move out and into the bloodstream
endothelial cell walls in the brain are fused to form tight junctions, so most substances cannot squeeze between them
What are astrocytes in the blood-brain barrier?
astrocytes provide a route for the exchange of food and waste between capillaries and the brain’s extracellular fluid, as well as from there to other cells
What are barrier free brain sites?
the pineal gland
pituitary
area postrema
How do molecules gain access to the brain?
to carry out it’s work the brain needs oxygen and glucose for fuel and amino acids to build proteins
fuel molecules reach brain cells from the blood, carbon dioxide and other waste products are excreted from brain cells and are carried away by the blood
molecules of these vital substances cross the blood-brain barrier in two ways
How do molecules cross the brain barrier to promote brain function?
small, uncharged molecules (oxygen and carbon dioxide) are fat soluble and can freely pass through the endothelial membranes
complex molecules of glucose, amino acids, and other food components are carried across the membrane by active transport systems or ion pumps
transporter proteins specialized to convey a particular substance
some psychoactive drugs (must be sufficiently small or have the correct chemical structure) do gain access to the CNS
How does the body eliminate drugs?
some substances that cannot be removed may build up in the body and become toxic
drugs are broken down (catabolized) in the kidneys, liver, and intestines
drugs are excreted in urine, feces, sweat, breast milk, and exhaled air
the liver is active in catabolizing drugs, houses a family of enzymes involved in drug catabolism
the cytochrome P450 enzyme family is involved in drug catabolism, some of which are also present in the gastrointestinal tract microbiome
the liver is capable of catabolizing many drugs into forms that are more easily excreted from the body
waste management is necessary
What is drug action at the synapses?
most psychoactive drugs exert their effects by influencing synaptic chemical signaling
agonist: drugs that increase neurotransmission
antagonist: drugs that block decrease neurotransmission
What is tolerance?
decreased response to a drug with repeated exposure
different types of tolerance
each likely to develop with increased drug exposure
What is metabolic tolerance?
increase in number of enzymes in liver, blood, or brain used to break down a substance
metabolized faster = blood levels decrease
What is cellular tolerance?
activities of brain cells adjust to minimize effects of substance
accounts for low signs of intoxication with high blood alcohol levels
What is learned tolerance?
people learn to cope with being intoxicated
person may no longer appear intoxicated
What is sensitization?
the occasional drug taker may have an increased responsiveness to successive equal doses
whereas tolerance generally develops with repeated use of a drug, sensitization is much more likely to develop with periodic use
What is the relevance of sensitization?
many drug therapies (e.g. schizophrenia) must be taken for several weeks before they produce beneficial effects
sensitization is related to dependence, before a person becomes dependent, the person must be sensitized by numerous experiences with the drug
life experiences, especially stressful ones, can produce effects resembling sensitization that prime the nervous system for addiction
What are psychoactive drugs?
people have been using drugs for therapeutic and recreational reasons throughout history
the DSM offers a classification system for diagnosing neurological and behavioral disorders
psychoactive drugs can be grouped based on the primary neurotransmitter system that they are known to affect
What are adenosinergic drugs?
the most widely consumed psychoactive drug, caffeine, is adenosinergic
binds to adenosine receptors without activating them (adenosine antagonist)
endogenous adenosine induces drowsiness
leads to alertness
also inhibits an enzyme that ordinarily breaks down the second messenger, cyclic adenosine monophosphate (cAMP), the resulting increase in cAMP leads to increased glucose production, making more energy available and allowing higher rates of cellular activity
promotes the release of dopamine and acetylcholine, stimulant effect > improved RT, focus, etc.
repeated daily intake of caffeine produces a mild form of drug dependence
fade within a week of abstinence
What are cholinergic drugs?
nicotine is found in the leaves of the tobacco plant (nicotiana tabacum), feelings of relaxation, sharpness, calmness, and alertness
within a few seconds from inhalation nicotine stimulates acetylcholine nicotinic receptors
at low doses, nicotine is a stimulant, but at very high doses, it dampens neuronal activity
acetylcholine nicotinic receptors causes the release of acetylcholine, norepinephrine, epinephrine, serotonin, endorphins, and dopamine
potentially lethal poison, but tolerance develops rapidly
dependence involves both psychological and physical aspects
smoking cessation leads to heightened anxiety, irritability, craving, anhedonia, and tremors
What is nicotine?
nicotine is a potentially lethal poison
harmful chemicals in cigarettes, lung cancer, respiratory diseases, cancer, etc.
risk factor for Alzheimer’s disease, cholinergic agonist drugs prescribed to treat Alzheimer’s
What are GABAergic drugs?
at low doses, GABAergic agonists reduce anxiety, at medium doses they sedate, at high doses they anesthetic or induce coma
GABA receptor contains a binding site for GABA, one for alcohol and one for benzodiazepines plus a Cl- channel
excitation of the GABA receptor produces an influx of Cl- through its pore
an influx of Cl- increases the concentration of negative charges inside the cell membrane, hyperpolarizing it and making it less likely to propagate an action potential
widespread reduction of neuronal firing underlies the behavioral effects of drugs that affect the GABA synapse
benzodiazepines include diazepam (Valium), alprazolam (Xanax), and clonazepam (Klonopin) and are medically prescribed to reduce anxiety
repeated doses result in increased tolerance
cross tolerance for benzos and alcohol because they act on the NS in similar ways
What are GABAergic receptors?
alcohol consumption has short-term psychological and physiological effects that depend on several factors
alcohol volume, body mass, food intake, etc.
small amounts improve mood, sociability, fine muscle coordination, etc.
long term and frequent consumption of alcohol can lead to increased risk of alcoholism
alcoholism results in damage to the central and peripheral nervous systems, as well as nearly every other system and organ in the body
What are GABA receptors, development, and FASD?
drugs that act on GABA receptors also affect brain development because GAVA is one of the substances that regulate brain development
What are glutamatergic drugs?
the glutamatergic system has several receptors, such as NMDA, AMPA, and kainite
antagonists for the NMDA receptor such as phencyclidine (PCP) and ketamine can produce hallucinations and out-of-body experiences
both PCP and ketamine are also known as dissociative anesthetics
compounds that produce feelings of detachment (dissociation) from the environment and self because they distort perceptions of sight and sound
ketamine is currently medically prescribed for starting and maintaining anesthesia
What are dopaminergic drugs?
dopamine agonists that are used recreationally: cocaine, amphetamine, methamphetamine
dopamine agonists that are medically prescribed: dextroamphetamine (adderall), methylphenidate (ritalin), L-dopa
dopamine antagonists that are medically prescribed for schizophrenia and drug-induced psychosis
What are dopamine agonists?
cocaine is purified from leaves of the coca plant
refined cocaine power can either be sniffed (or snorted) or injected
crack cocaine is chemically altered so that it vaporizes at low temperatures, and the vapors are inhaled
amphetamine increases dopamine in the synaptic cleft by reversing the dopamine transporter
cocaine also blocks the reuptake
but amphetamines also reverse the transporter that packages dopamine in vesicles
takes packaged dopamine and releases it into terminal
What are amphetamines?
a widely used illegal amphetamine derivative is methamphetamine
relatively inexpensive but potent (devastating drug)
amphetamine (adderall) and methylphenidate (ritalin) are medically prescribed to treat ADHD
a recreational dose is 50 times stronger than a clinical dose
dopamine hypothesis of schizophrenia
some forms of the disease may be related to excessive frontal lobe dopamine activity
the use of dopamine antagonist drugs that preferentially bind to D2 receptors has improved the functioning people with schizophrenia
What are serotonergic agonists?
natural recreationally used serotonergic (mescaline, DMT, and psilocybin)
synthetic recreationally used serotonergic (LSD and MDMA/ectasy)
currently, these recreationally used drugs are not medically prescribed and are illegal
some serotonergic agonists are medically prescribed for the treatment of major depression
What are monoamine oxidase (MAO) inhibitors?
drug that blocks the enzyme monoamine oxidase from degrading such neurotransmitters as 5-HT, NE and DA
What are tricyclic receptors?
drug, characterized by its three-ring chemical structure, which blocks 5-HT reuptake transporter protein
What are selective serotonin reuptake inhibitors (SSRIs)?
drug that blocks 5-HT reuptake into the presynaptic terminal and is most commonly used to treat depression
What are the drug effects of 5-HT receptors?
different drugs prescribed to treat depression act on serotonin synapse in different ways to increase its availability
some people can’t tolerate the side effects of antidepressants (increased anxiety, reduced libido, etc.)
What are opioids?
any endogenous or exogenous compound that binds to opioid receptors to produce morphine-like effects
sleep inducing (narcotic) and pain-relieving (analgesic) properties
What are three sources of opioids?
isolated (morphine, codeine)
altered (heroin, oxycodone)
synthetic (fentanyl and methadone)
What is opium?
opium is a white milky latex extracted from the seed pods of the opium poppy, Papaver somniferum
used for thousands of years
relief from pain, coughing, induce sleep, etc.
What are opioidergic?
natural opioids include codeine and morphine
semi-synthetic opioids include heroin and oxycodone (mu receptors)
heroin more potent than morphine
penetrates blood-brain barrier faster
synthetic opioids include fentanyl (prescribed for pain management)
alter pain perception, relaxation, and lead to euphoria
can lead to respiratory depression (primary cause of death in users)
What are characteristics of opioid addiction?
all opioids are potently addictive, and abuse of medically prescribed opioids is at a crisis point worldwide
repeated opioid use produces tolerance such that within a few weeks, the effective dosage may increase tenfold
brutal withdrawal symptom upon withdrawal
because opioid use results in both tolerance and sensitization, an opioid user is at constant risk of overdosing
What is naloxone?
drugs such as naloxone act as antagonists at opioid receptors
naloxone is a competitive inhibitor, a drug used to treat overdoses and opioid addiction and that acts quickly to block opioid action by competing with the opioid for binding sites
What are cannabinergic drugs?
tetrahydrocannabinol (THC) is one of the 84 cannabinoids and the main psychoactive constituent in cannabis
THC alters mood primarily by interacting with the cannabidiol 1 (CB1) receptor found on neurons, and it also binds with the CB2 receptors found on glial cells and in other body tissues
cannabis has extremely low toxicity, not a single documented cannabis-overdose death in history
evidence points to the usefulness of THC and cannabidiol (CBD), another cannabinoid, as therapeutic agents for a number of disorders
more research is needed to unpack the full effects of cannabis consumption
Disinhibition Theory
explanation holding that alcohol has a selective depressant effect on the brain’s frontal cortex, which controls judgement, while sparing subcortical structures responsible for more instinctual behaviors, such as desire
Behavioral Myopia
“nearsighted” behavior displayed under the influence of alcohol, wherein local and immediate cues become prominent, remote cues and consequences are ignored
Substance Abuse
a pattern of drug use in which people rely on a drug chronically and excessively, allowing it to occupy a central place in their life
Addiction
a complex brain disorder characterized by escalation, compulsive drug taking, and relapse
called substance use disorder per the DSM-5
Withdrawal Symptoms
physical and psychological behavior displayed by a user when drug use ends
Psychomotor Activation
increased behavioral and cognitive activity so that at certain levels of consumption, the drug user feels energetic and in control
Wanting-and-Liking Theory
explanation holding that when a drug is associated with certain cues, the cues themselves elicit desire for the drug, also called incentive sensitization theory
Steroid Hormone
fat-soluble chemical messenger synthesized from cholesterol
Peptide Hormone
chemical messenger synthesized by cellular DNA that acts to affect the target cell’s physiology
Homeostatic Hormone
one of a group of hormones that maintain internal metabolic balance and regulate physiological systems in an organism
Gonadal (Sex) Hormone
one of a group of hormones, such as testosterone, that control reproductive functions and bestow sexual appearance and identity as male or female
Glucocorticoid
one of a group of steroid hormones, such as cortisol, secreted in times of stress, important in protein and carbohydrate metabolism
Anabolic Steroid
class of synthetic hormones related to testosterone that have both muscle-building (anabolic) and masculinizing (androgenic) effects
