psych 127b lecture 10 Flashcards
what are ways that a drug can act as an agonist?
the drug can act as a precursor/substrate, stimulate NT vesicle release, stimulate postsynaptic receptor opening, block autoreceptors, block reuptake, or inactivate the neurotransmitter breaking enzyme
autoreceptor
ligand gated channel on nerve endings which are closed when ligand (NT) is present and open when not present
ways for a drug to act as an antagonist
prevents storage of NT in vesicles, inhibition of NT vesicle release, blockage of postsynaptic receptors, inhibtion of synthesis reaction enzyme, stimulator of autoreceptors
pharmacokinetics
the process by which drugs are absorbed, distributed within the body, metabolized, and excreted
how can drugs be taken in via absorption
IV injection, oral administration, inhalation, or topical administration
inhalation
quick absorption bc of of closeness between lung and blood membranes, most predictable dosage, fastest onset of effects
injection
-precise dosage, very fast speed of onset through all routes
-direct afferent signals to the brain
-small timeframe to respond to reaction overdose
-must be sterile
topical administration
-direct absorption to the blood stream
-travel via mucus membranes
-includes chewing tobacco, nasal decongestents, sniffing/snorting drugs, or nitroglycerin
when do you experience effects a drug?
after absorption? CHECK IF THIS IS RIGHT
oral administration
-must be stable in stomach fluid, enter intestine, penetrate intestinal lining, then pass into bloodstream
-slow absorption
-non precise dosage
Inactivation and Excretion
-deactivation via enzymes, eventually excreted in the kidneys, skin, lungs, or bile
what causes drug interactions?
overlap in mechanisms of action or competition for metabolic enzymes
what is a mechanism of action
how does CBD demonstrate drug interactions
-CBD is metabolized via the same enzyme (CYP3A4) as many other clinically prescribed medications
-CBD can inhibit the activity of this gene therefore affecting the metabolisms of other medications
where is dopamine released mostly
the striatum of the basal ganglia and the frontal lobe
what is the mesolimbic system
a system containing the ventral tegmental area, nucleus accumbens (ventral striatum), cortex, and hippocampus
-plays a big role in reinforcement and reward
which brain region is implicated in the processing of reward cues and motivation
nucleus accumbens/ventral striatum
how are addictive drugs reinforced by natural reinforcement
-addictive drugs tap into the neural circuitry underlying dopamine release in the nucleus accumbens repeatedly
-drugs tap into this stimulation more reliably and powerfully than natural reinforcers
what are examples of natural reinforcers
food, water, and sex
what are examples of the psychostimulants
cocaine, amphetamines, methamphetamine, nicotine, and caffeine
what are the modern routes of administration for cocaine
-topical/nasal, inhalation, injection
primary effects of low dose short term cocaine
-local anesthesia, vasoconstriction, hypertension, pupillary dilation, motor hyperactivity, euphoria, giddiness
-powerful reinforcement (high addictive potential)
primary effects of long term high dose cocaine
-anxiety, sleep deprivation, hypervigilance, paranoia, impulsivity, altered reality
describe the underlying biological mechanism of cocaine
inhibits reuptake of dopamine in the presynaptic terminal (dopamine agonist)
-also affect 5-HT(seratonin precursor) and norepinephrine reuptake
why does cocaine affect 5HT and NE reuptake
-medicine interaction because they all use the same reuptake channel????
what system does amphetamine act on
-the autonomic nervous system/sympathetic nervous system (mimics the action of adrenaline)
-“sympathomimetic”
what are the physiological effects of amphetamine
-vasoconstriction, hypertension, increased heart rate, restlessness, incresed mo
what is the sympathetic nervous system important for
fight or flight response
what is the underlying neural mechanism for amphetamine
-strongly increases dopamine release, blocks dopamine reuptake, reverses the direction of the reuptake transporter
difference between amphetamine and methamphetamine
-methamphetamine can cross the blood brain barrier much faster because of the added methyl group
-long term toxicity of methamphetamine has similar effects to cocaine
what are the two types of acetylcholine receptors
nicotinic and muscarinic
nicotinic receptors
stimulated by nicotine at the neuromuscular junction
muscarinic
stimulated by muscarine
what is the underlying physiological mechanism of nicotine generally speaking
acts as an agonist of the nicotinic receptor
how does Ach receptor activity affect the CNS
-these receptors modulate levels of other NT
-increased Ach release enhances memory and concentration
how does Ach receptor activity affect the ANS
-the sympathetic nervous system is activated, norepinephrine and epinephrine are released
what behaviors is nicotine an agonist for?
-cardiovascular (tension, constriction, heart rate)
-digestion
what behaviors is nicotine an antagonist for?
-fluid excretion (ex. dry mouth, lack of sweating, urinary retention)
-vasodilation/hypotension
-can affect parasympathetic and sympathetic things
how is caffeine absorbed and what are its effects
-rapid oral absorption
-acts as a slight stimulant (heart rate, peripheral vasodilation, central/neural vasoconstriction)
what is the neural/physiological mechanism for caffeine
-adenosine receptor antagonist in the central nervous system
what does adenosine do
-promotes sedation, regulates oxygen delivery, dilates blood vessels
-decreases the presence of neurotransmitters like DA and 5HT in the synapse
