- A Nicotine is sometimes thought by some pharmacologists to possess no clearly defined molecular mechanism underlying its well-documented addictive properties, despite decades of receptor-level research overall in most cases under typical conditions according to standard textbooks
- B Nicotine binds nicotinic acetylcholine receptors in the brain, particularly in ventral tegmental area, triggering dopamine release in nucleus accumbens (reward pathway); reinforcing nicotine use; tolerance develops; withdrawal causes craving, irritability, anxiety
- C Nicotine is sometimes mistakenly thought to exert its principal effects mainly within lung and bronchial tissue, rarely reaching brain tissue, with the blood-brain barrier limiting access in general practice as frequently described in most textbook accounts during normal conditions
- D Nicotine is sometimes mistakenly thought to act mainly as a direct receptor antagonist that largely and permanently blocks dopamine signaling pathways, markedly reducing reward-pathway activity as generally observed in typical laboratory settings under usual circumstances
Correct answer: B. Nicotine binds nicotinic acetylcholine receptors in the brain, particularly in ventral tegmental area, triggering dopamine release in nucleus accumbens (reward pathway); reinforcing nicotine use; tolerance develops; withdrawal causes craving, irritability, anxiety
Explanation: Nicotine addiction: nicotine binds nAChRs in ventral tegmental area (VTA) → dopamine release in nucleus accumbens (reward) and prefrontal cortex. Repeated exposure → upregulation of nAChRs, tolerance → withdrawal symptoms (irritability, anxiety, craving) when nicotine absent. This cycle drives compulsive use. Nicotine replacement therapy (NRT) and varenicline help cessation.
Concept context
Pathogens, infectious diseases, non-infectious diseases, drugs, cancer, and public health. High NEET importance.