Nicotine

Summary

Nicotine is a naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and Duboisia hopwoodii) and is widely used recreationally as a stimulant and anxiolytic. As a pharmaceutical drug, it is used for smoking cessation to relieve withdrawal symptoms. Nicotine acts as a receptor agonist at most nicotinic acetylcholine receptors (nAChRs), except at two nicotinic receptor subunits (nAChRα9 and nAChRα10) where it acts as a receptor antagonist. Nicotine constitutes approximately 0.6–3.0% of the dry weight of tobacco. Nicotine is also present at ppb-concentrations in edible plants in the family Solanaceae, including potatoes, tomatoes, and eggplants, though sources disagree on whether this has any biological significance to human consumers. It functions as an antiherbivore toxin; consequently, nicotin

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Visual backward masking (VBM) is a potential endophenotype for schizophrenia. Relative VBM deficits were also observed in high as compared to low scorers in one schizotypal subdimension (cognitive disorganisation, CogDis; Cappe et al., 2012). VBM deficits may be related to dysfunctions of the nicotinergic ACh system. Interestingly, nicotine consumption is initiated earlier and higher in people within the schizophrenia spectrum. Here, we investigated whether chronic nicotine consumption relates to the link between VBM deficits and high CogDis scores. We tested 12 early onset smokers (≤ 15 years), 19 late onset smokers (>15 years) and 17 non-smokers. Participants completed the VBM task and the short version of the O-LIFE questionnaire. Indeed, impairments in VBM correlated with increasing CogDis scores in the late smokers and non-smokers, but we found the inverse relationship for early smokers. The other schizotypy dimensions (positive, negative) were unrelated to VBM performance. Hence, our findings support a nicotinic mediation of VBM performance and point to self-medications effects.

2014

Nicotine increases sleep spindle activity

Studies have shown that both nicotine and sleep spindles are associated with enhanced memorisation. Further, a few recent studies have shown how cholinergic input through nicotinic and muscarinic receptors can trigger or modulate sleep processes in general, and sleep spindles in particular. To better understand the interaction between nicotine and sleep spindles, we compared in a single blind randomised study the characteristics of sleep spindles in 10 healthy participants recorded for 2 nights, one with a nicotine patch and one with a sham patch. We investigated differences in sleep spindle duration, amplitude, intra-spindle oscillation frequency and density (i.e. spindles per min). We found that under nicotine, spindles are more numerous (average increase: 0.057 spindles per min; 95% confidence interval: [0.025-0.089]; p = .0004), have higher amplitude (average amplification: 0.260 mu V; confidence interval: [0.119-0.402]; p = .0032) and last longer (average lengthening: 0.025 s; confidence interval: [0.017-0.032]; p = 2.7e-11). These results suggest that nicotine can increase spindle activity by acting on nicotinic acetylcholine receptors, and offer an attractive hypothesis for common mechanisms that may support memorisation improvements previously reported to be associated with nicotine and sleep spindles.

WILEY2019

Nicotine is an important stimulant that is involved in modulating many neuronal processes, including those related to vision. Nicotine is also thought to play a key role in schizophrenia: A genetic variation of the cholinergic nicotine receptor gene, alpha-7 subunit (CHRNA7) has been shown to be associated with stronger backward masking deficits in schizophrenic patients. In this study, we tested visual backward masking in healthy smokers and non-smokers to further understand the effects of nicotine on spatiotemporal vision. In the first study, we tested 48 participants, a group of non-smokers (n=12) and three groups of regular smokers that were either nicotine deprived (n=12), non-deprived (n=12) or deprived but were allowed to smoke a cigarette directly before the start of the experiment (n=12). Performance was similar across groups, except for some small negative effects in nicotine-deprived participants. In the second study, we compared backward masking performance between regular smokers and non-smokers for older (n=37, 13 smokers) and younger (n=67, 21 smokers) adults. Older adults performed generally worse than younger adults but there were no significant differences in performance between smokers and non-smokers. Taken together, these findings indicate that nicotine has no long-term negative effects on visual spatiotemporal processing as determined by visual backward masking.

Nature Publishing Group2014