Nicotine:
Historical background:
• 1950’s 70% of adults smoked
• 1960’s Surgeon general’s warning
• Government attempts to cut down rate of smokers but cant get it below 25%
• Smoking tied to lower socioeconomic groups
• Tobacco companies emphasize smoking is just a habbit
Tobacco company research
• Health and government scientist focused otn the health risks of smoking
• Tobacco companies research focused on nicotine
o Found that rats would IVSA nicotine
o Responding would go up when ½ dose given
o In humans when given cigarettes with less nicotine IPI goes down puff rate goes up
o When given cigarettes with more tobacco IPI goes up Puff rate goes down
ACh: Acetyl Choline
• ACh synthesized by taking choline and Acetyl CoA andvia an enzyme combining them
• ACh is an excitatory Neurotransmitter
• ACh acts on Cholinergic receptors
o Nicotinic
o Muscarinic
• ACh is broken down by Acetyl cholinesterase (AChe)
o Metabolites resulting are choline and acetic acid
Cholinergic transmission
• Anti-cholinesterase drugs
o Block the breakdown of ACh
By blocking the effects of acetyl cholinesterase
o Increase ACh transmission
• Anticholinergic drugs
o Decreases Ach transmission via competitive binding
Anticholinergic Drugs
• Drugs that block ACh so that it cant bind
o Nicotinic Anticholinergic
o Muscarinic Anticholinergic
• Anticholinergic drugs & Smoking
o If you five a nicotinic anticholinergic to a smoker
Low dose: The IPI would go up to compensate for the blocked receptors
High Dose: The person would quit smoking due to no reward
Nicotinic cholinergic receptors nAChRs
• Located on the projections from the PPT that release Glu onto the VTA
o There’d be another neuron releasing ACh onto the nAChRs
• They control the release of Glutemate onto the VTA which releases DA on the NaC
• In the end the reward of nicotine is the same as cocaine: Meso Accumbens
• Nicotine facilitates Glu release on receptors on the VTA= LTP
Nicotine and LTP
• Rats given nicotine and 2 weeks later given cocaine have behavioral responses that show sensitization
o Future responsivity to psychostimulants increased
• If a person smokes it neurochemically sets them up for cocaine and sensitization to other drugs
• Nicotine the best gateway drug
• Stress of poverty sensitizes the brain to nicotine
Smoking and the PPT
• If you destroyed the PPT a rat would not IVSA Nicotine
o It would also have additional behavioral effects such as mood response to rewarding stimuli
o 90% of schizophrenics smoke
