Stimulants 3 Nicotine Flashcards
Along with caffeine and alcohol, one of the most widely
used psychoactives in the world and routinely rated by addicts as the toughest substance to stop using
Nicotine
Nicotine is who’s neurotoxic defense against
insects, works like other ACh-agonist toxins, paralyzing insects that eat the leaves
Tobacco plant
Nicotine is a what agonist
ACh
admin of nicotine is customarily
inhalation or mucous membrane
nicotine can also be absorbed through what (ie transdermal patches)
skin
leads to good absorption from intestines
(nicotine is basic)
oral administration
this admin is not useful because nicotine undergoes extensive (90%) first pass metabolism
PO
passively slips through this with ease
BBB
elimination is
fairly quick (T1/2 ~ 2± hours)
the most important metabolizing
enzyme, converting nicotine mostly to cotinine
Cytochrome P450 CYP2A6
stress accelerates
nicotine metabolism
tobacco farmers who handle the leaves (wet) without gloves can have nicotine seep into the skin/clothing, causing them to get sick
green tobacco sickness
What does this mean for smokers’ reports that smoking helps them feel less stressed?
nicotine gets metabolized quicker, sends them into a state of nicotine withdrawal, smoking makes the withdrawal go away
main route for metabolite elimination
urine
Nicotine acts mainly as a direct agonist at what, causing Na+ influx = EPSP
nicotinic Ach receptors
The key effect is activation of these excitatory nicotinic receptors located on
VTA dopamine neurons
activation of these excitatory nicotinic receptors located on VTA dopamine neurons leads to
increased activity in mesolimbic “reward” circuitry (but not nearly to the extent that cocaine or amphetamines can increase it)
activation of these excitatory nicotinic receptors located on VTA dopamine neurons ends up also activating
endogenous opioid systems
Curiously, at very high doses, nicotine begins to have what effects on ACh activity (tolerance???)
antagonist
among the estimated 4700 chemicals in tobacco smoke,
something appears to work as an MAOI (i.e., slowing the
breakdown of DA, NE, 5-HT), not nicotine itself, but most likely
beta carbolines
mesocortical nicotinic receptor activation can lead to
more dopamine activity and attention in frontal lobe
Like caffeine, increased alertness, attention/concentration, working memory (overall sharpening of mental functioning), reduced hunger
psychoactive effects of nicotine
Many persons have inadvertently discovered it as “self-
medication” for
ADHD
Smoking rates are extremely high among
schizophrenic persons