Different physiological and behavioural effects of e cigarette vapour and cigarette smoke in mice
Nicotine is the primary addictive substance in tobacco smoke and electronic cigarette (e cig) vapour. Methodological limitations have made it difficult to compare the role of the nicotine and non nicotine constituents of tobacco smoke. The aim of this study was to compare the effects of traditional cigarette smoke and e cig vapour containing the same amount of nicotine in male BALB/c mice exposed to the smoke of 21 cigarettes or e cig vapour containing 16.8 mg of nicotine delivered by means of a mechanical ventilator for three 30 min sessions/day for seven weeks. One hour after the last session, half of the animals were sacrificed for neurochemical analysis, and the others underwent mecamylamine precipitated or spontaneous withdrawal for the purposes of behavioural analysis. Chronic intermittent non contingent, second hand exposure to cigarette smoke or e cig vapour led to similar brain cotinine and nicotine levels, similar urine cotinine levels and the similar up regulation of a4b2 nicotinic acetylcholine receptors in different brain areas, but had different effects on body weight, food intake, and the signs of mecamylamine precipitated and spontaneous withdrawal episodic memory and emotional responses. The findings of this study demonstrate for the first time that e cig vapour induces addiction related neurochemical, physiological and behavioural alterations. The fact that inhaled cigarette smoke and e cig vapour have partially different dependence related effects indicates that compounds other than nicotine contribute to tobacco dependence.
European Neuropsychopharmacology