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dunng the day and persist overnight. Thus, daily tobacco users are 

 exposed to the effects of nicotine for 24 hours each day. 



3. Nicotine that enters the blood is rapidly distnbuted to the brain. As a 

 result, effects of nscotme on the central nervous system occur rapidly 

 after a puff of cigarette smoke or after absorption of nicotine from 

 other routes of administration. 



4. Acute and chronic tolerance develops to many effects of nicotine. 

 Such tolerance is consistent with reports that initial use of tobacco 

 products, such as in adolescents first beginning to smoke, is usually 

 accompanied by a number of unpleasant symptoms which disappear 

 following chronic tobacco use. 



2. Nicotine: Sites and Mechanisms of Actions 



1 . Nicotine is a powerful pharmacologic agent that acts in the brain and 

 throughout the body. Actions include electrocortical activation, 

 skeletal muscle relaxation, and cardiovascular and endocrine effects. 

 The many biochemical and electrocortical effects of nicotine may act 

 in concert to reinforce tobacco use 



2. Nicotine acts on specific binding sites or receptors throughout the 

 nervous system. Nicotine readily crosses the blood-brain bamer and 

 accumulates in the brain shortly after it enters the body. Once in the 

 brain, it interacts with specific receptors and alters brain energy 

 metatx)lism m a pattern consistent with the distribution of specific 

 binding sites for the drug. 



3. Nicotine and smoking exert effects on nearly all components of the 

 endocrine and neuroendocrine systems (including catecholamines, 

 serotionin, corticosteroids, pituitary hormones). Some of these 

 endocrine effects are mediated by actions of nicotine on brain 

 neurotransminer systems (e.g. hypothalamic-pituitajry axis) In 

 addition, nicotine has direct peripherally mediated effects (e.g.. on the 

 adrenal medulla and the adrenal conex). 



3. Tobacco Use as Drug Dependence 



1 . Cigarettes and other forms of tobacco are addicting. Patterns of 

 tobacco use are regular and compulsive, and a withdrawal syndrome 

 usually accompanies tobacco abstinence. 



2. Nicotine is the drug in tobacco that causes addiction. Specifically, 

 nicotine is psychoactive ("mood altering") and can provide pleasurable 

 effects. Nicotine can serve as a reinforcer to motivate tobacco- 

 seeking and tobacco-using behavior. Tolerance develops to actions of 

 nicotine such that repeats! use results in diminished effects and can 

 be accompanied by increased intake. Nicotine also causes physical 

 dependence characterized by a withdrawal syndrome that usually 

 accompanies nicotine abstinence. 



3. The physical characteristics of nicotine delivery systems can affect 

 their toxicity and addictiveness. Therefore, new nicotine delivery 

 systems should be evaluated for their toxic and addictive effects. 



4. Tobacco Use Compared to Other Dnig Dependencies 



1. The pharmacologic and behavioral processes that determine tobacco 

 addiction are similar to those that determine addiction to drugs such 

 as heroin and cocaine. 



