Nicotine acute effects

The composition of tobacco smoke is complex (about 500 compounds have been identified) and varies with the type of tobacco and the way it is smoked. The chief pharmacologically active ingredients are nicotine (acute effects) and tars (chronic effects). 

Memory impairments produced by choiine deprivation in rats are improved by nicotine (Sasaki et ai. 1991). It reduces memory deficits due to septohippocampai iesions or aged animais (Levin 1992). Nicotine s effect on memory not oniy appears after acute administration, but may persist for at least 4 weeks after the end of chronic administration (Levin et ai. 1992). 

Stein E, Pankiewicz J, Harsch HH, Cho JK, Fuller SA, Hoffmann RG, Hawkins M, Rao S, Bandettini PA, Bloom AS (1998) Nicotine-induced limbic cortical activation in the human brain a functional MRI smdy. Am J Psychiatry 155 1009-1015 Sziraki I, Lipovac MN, Hashim A, Sershen H, Allen D, Cooper T, Czobor P, Lajtha A (2001) Differences in nicotine-induced dopamine release and nicotine pharmacokinetics between Lewis and Fischer 344 rats, Neurochem Res 26 609-617 Terborg C, Birkner T, Schack B, Witte OW (2002) Acute effects of cigarette smoking on cerebral oxygenation and hemodynamics a combined study with near-infrared spectroscopy and transcranial Doppler sonography, J Neurol Sci 205 71-75 Thompson JC, WUby G, Stough C (2002) The effects of transdermal nicotine on inspection time. Hum Psychopharmacol 17 157-161... 

Rose JE, Behm FM, Westman EC, Johnson M (2000) Dissociating nicotine and nonnicotine components of cigarette smoking. Pharmacol Biochem Behav 67 71-81 Rose JE, Behm FM, Westman EC (2001) Acute effects of nicotine and mecamylamine on tobacco withdrawal symptoms, cigarette reward and ad lib smoking. Pharmacol Biochem Behav 68 187-197... 

Chang Q, Fischbach GD. 2006. An acute effect of neuregulin 1 beta to suppress alpha 7-containing nicotinic acetylcholine receptors in hippocampal intemeurons. J Neurosci 26 11295-11303. 

As we noted, nicotine s effects arc pervasive and complex. Table 7.5 is a summary of nicotine s acute pharmacological effects at normal doses, < r do.scs that arc typically ingested by everyday smokers, tobacco chewers, or snuff users, for example. Because of nicotine s biphasic effects, its effects at higher doses would tend to be more depressant than are the effects listed in Table 7.5. 

Nicotine is classified as a stimulant drug, but people who use it often report decreased arousal. That is, the perception is that nicotine has a calming effect, and nicotine users find this effeet reinforcing (Todd, 2004). The reasons for this perception of lowered arousal are complex. One factor may be nicotine s acute effect of relaxing the skeletal muscles (see Table 7.5 also see Jones, 1987b). Another pharmacological reason is nicotine s biphasic action at higher doses its effects are more depressant. 

In reviewing nicotine s acute effects, you saw how easily a person might acquire and keep the habit of tobacco use. In reviewing the health consequences of chronic tobacco use, you may have wondered why anyone would continue to use tobacco products. Yet, of couree, many people do continue despite wanting to quit others find quitting easier. 

Nicotine s acute effects involve the CNS and ANS. It tends to have stimulant effects at lower doses but more depressant effects at higher doses. 

Kouri Em, McCarthy EM, Faust AH, Lukas SE. Pretreatment with transder-mal nicotine enhances some of ethanol s acute effects in men. Drug Alcohol Depend2004 75(1) 55—65. 

DeIpNnIum barbeyi (larkspur) is a major cause of cattle loss. The toxic principle, a diter-pene alkaloid, is a neuromuscular blocking agent that acutely affects postsynaptic cholinergic and nicotinic receptors. Effects irKlude muscle tremors, excitemenL disorientation, bloat, arrhythmia, prostration, and death. 

It is known that human exposure to organophosphorus compounds can result in a variety of acute toxic effects. These arise primarily as a result of the inhibition of acetylcholinesterase. Signs of acute toxicity are due to effects on the central nervous system (anxiety, ataxia, hypotension), to muscarinic effects (wheezing, cough, rhinitis) and to nicotinic effects (muscle weakness, mydriasis and tachycardia). Other acute effects include chest tightness, abdominal cramps, confusion and convulsions. With some organophosphorus compounds, a specific syndrome may develop. This is delayed peripheral neuropathy or OP-induced delayed neuropathy (OPIDN). (For a more detailed discussion on the toxicity of organophosphorus compounds see Chapter 10.)... 

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