Chapter 6: Drugs and Hormones Flashcards
Where is the blood-brain barrier?
capillaries in the brain consisting of astrocytes and endothelial cells (tight junctions)
What parts of the brain do not have a blood brain barrier?
- area postrema: allows toxic substances in the blood to trigger a vomiting response
- pineal gland: enables hormones to reach it and modulate the day-night cycles controlled by this structure
- pituitary gland: secretes hormones into the bloodstream so there is an opening so these hormones can get through the body
What is the blood brain barrier?
specialized system of brain microvascular endothelial cells (BMVEC) that shields the brain from toxic substances in the blood, supplies brain tissues with nutrients, and filters harmful compounds from the brain back to the bloodstream.
Agonists vs Antagonists
Agonist: Substance that enhances the function of a synapse
Antagonist: Substance that blocks or decreases the function of a synapse
Affects ANY of the stages of the neural impulse
Agonists and antagonists of the acetylcholine synapse
Agonists
- Choline-rich diet increases ACh
- Black widow spider venom promotes release of ACh
- Nicotine stimulates receptors (similar shape to ACh so it fits)
- Physostigmine and organophosphates block inactivation, anti-alzheimer’s drugs
Antagonists
- Botulism poisoning toxin blocks release
- Curare (poison darts) blocks receptors
What differentiates your body between having a sensitization response vs habituation response?
Primed based on life experience and genotype
Sensitization
- The occasional drug taker may have an increased responsiveness to successive equal doses
- Much more likely to develop with periodic use
Tolerance
Tolerance: a learned behavior results when a response to a stimulus weakens with repeated presentations
Results in: increased enzymes, fewer receptors, and learned tolerance
What underlies the behavioral effects of drugs that affect the GABA synapse?
widespread reduction of neuronal firing
What binds with the GABA receptor?
alcohol and benzodiazepines
What binds with the Opioid receptor?
Any endogenous (naturally occurred) or exogenous (taken) compound that binds to opioid receptors to produce morphine-like effects (sleeping and pain-relief)
Naloxone binds with the receptor to block opioids from binding on the synapse
Dopaminergic antagonists
medically prescribed for schizophrenia and drug-induced psychosis (thorazine, abilify, clozaril)
Opiodergic antagonists
ex: naltrexone and naloxone.
What is the brain pathway associated with addiction?
begins in the ventral tegmental area (VTA) and continues on to the mesolimbic dopamine pathway
What causes addiction and dependence?
- Wanting-liking theory (mesolimbic dopamine vs opioid neurons)
- Pleasure and dependence: habitual drug users initially experience pleasure but then endure psychological and physiological withdrawal symptoms as the drug wears off
- Dopamine overloads your brain
What are risk factors in addiction?
- Environmental factors and ACEs are associated with an increase risk of drug initiation and addiction
These factors changes the structure of the brain - Females are twice as sensitive to drugs as males
- Women are more likely than men to abuse nicotine, alcohol, cocaine, amphetamine, opioids, cannabinoids, caffeine, and PCP
Adenosinergic antagonist
ex: caffeine
- Binds to adenosine receptors without activating them
- Adenosine increases throughout the day
- Inhibits an enzyme that ordinarily breaks down the second messenger, cyclic adenosine monophosphate (cAMP)
Cholinergic agonist
ex: nicotine and cognex
GABAergic agonists
ex: alcohol + valium, xanax, klonopin
Glutamatergic antagonists
Ex: PCP and Ketamine + Namenda
Dopaminergic agonists
ex: cocaine, amphetamine, methamphetamine + Adderral, Ritalin, L-dopa
Serotonergic agonists
ex: Peyote, LSD, DMT, MDMA + Zoloft, Prozac
Opiodergic agonists
ex: Opium, Morphine, Heroin + morphine, codeine, oxycodone (Percocet), fentanyl, methadone
Cannabinergic agonists
Ex: THC + Sativex
Classes of hormones
Steroids, Peptide, Homeostatic, Gonadal, Glucocorticoids
Two types of stress responses and hormones involved
Fast acting: primes the body immediately for fight or flight (epinephrine)
Slow-acting: both mobilizes the body’s resources to confront a stressor and repairs stress-related damage (cortisol)
Ending a stress response
Hippocampus is well suited to detecting cortisol in the blood and instructing the hypothalamus to reduce blood cortisol levels
Prolonged stress reduces the hippocampal ability to reduce cortisol levels
Steroid Hormone
Fat-soluble chemical messenger synthesized from cholesterol. Can result in gene transcription, DNA activation
Anabolic-androgenic steroids
Synthetic hormones related to the male sex hormone testerone that have both muscle-building (anabolic) and masculinizing (androgenic) effects
Peptide Hormone
- affects the target cell’s physiology
Ex: insulin, growth hormone
Homeostatic hormones
Maintain internal metabolic balance and regulation of physiological systems - mineralocorticoids such as aldosterone (blood volume)
ex: leptin and gherlin (done eating vs hunger)
Gonadal Hormone
Control reproductive functions, sexual development, behavior
ex: Estrogen, testosterone, progesterone
Glucocorticoid Hormone
- Secreted in times of stress, important in protein and carbohydrate metabolism
ex: Cortisol, corticosterone
