636 



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. 



Chapter III: 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 

 barrier and accumulates in the brain shortly after it enters the 

 body. Once in the brain, it interacts with specific receptors and 

 alters brain energy metabolism in 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 catechol- 

 amines, serotonin, corticosteroids, pituitary hormones). Some 

 of these endocrine effects are mediated by actions of nicotine 

 on brain neurotransmitter systems (e.g., hypothalam- 

 ic-pituitary axis). In addition, nicotine has direct peripherally 

 mediated effects (e.g., on the adrenal medulla and the adrenal 

 cortex). 



Chapter IV: 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. Specifi- 

 cally, nicotine is psychoactive ("mood altering") and can 

 provide pleasurable effects. Nicotine can serve as a reinforcer 

 to motivate tobacco-seeking and tobacco-using behavior. Toler- 

 ance develops to actions of nicotine such that repeated use 

 results in diminished effects and can be accompanied by 

 increased intake. Nicotine also causes physical dependence 

 characterizes .jy a withdrawal syndrome that usually accompa- 

 nies 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. 



14 



