Prolonged exposure to transdermal nicotine improves memory in male mice, but impairs biochemical parameters in male and female mice

Abstract

Introduction. Nicotine is an alkaloid that affects the functioning of the central nervous system and produces dependence. In low doses, it acts as a stimulant and relaxant. Nicotine was reported to have pro-cognitive effects in humans and animals. However, high doses of nicotine are harmful for many organs.The aim of the study was to check whether a 30-day exposure to transdermal nicotine affects memory and biochemical parameters in mice. Materials and method. A total of 32 mice (16 males and 16 females) were used in the experiment. Mice were divided into 4 groups of 8 animals each: I control-females receiving placebo patches for 30 days, II females receiving nicotine patches for 30 days, III control-males receiving placebo patches, IV males receiving nicotine patches. Spontaneous alternation and locomotor activity were examined weekly in a Y-maze. Body mass was recorded daily. On day 30, venous blood samples were obtained and the animals were anaesthetized with CO2. Their blood was used to measure alanine transaminase (ALT), asparagine transaminase (AST), cholesterol, creatinine and glycosylated haemoglobin (HbA1C). Results. Nicotine significantly improved memory in male mice on day 8. It increased ALT and AST activities in males and females, as well as the concentration of cholesterol in their blood sera. Conclusions. In conclusion, transdermal nicotine may produce transient improvement in fresh spatial memory in male mice, but it is not a long-term effect and therefore nicotine does not seem to be appropriate for use in the treatment of neurodegenerative disorders. It elevates blood cholesterol level and thus may increase the risk of atherosclerosis and cardiovascular events; moreover, it negatively affects liver enzymes. Nicotine use is therefore not recommended.