Impact of Nicotine Exposure and Withdrawal on Plasma Glucose, Insulin and Glycated Haemoglobin in High-fat Diet Fed Wistar Rats
Abstract:
Background to the Study: Nicotine, which is the most abundant constituent of tobacco cigarette is one of the most commonly abused drugs. The duo of obesity and tobacco smoking increases the risk of cardiometabolic disorders.
Methodology: The experiment involved 48 male waster rats separated into 4 groups of 8 rats each. All the animals were placed on high-fat diet (Margarine; blue band) in addition to the different doses of nicotine in the experimental groups. Group 1 served as control and received distilled water, Groups 2, 3 and 4 received 200µg/kg, 400µg/kg and 800µg/kg of nicotine oral solution respectively. The experimental groups were placed on their respective doses of nicotine solution for an initial four weeks. Thereafter, four animals in each group were sacrificed and blood samples collected to determine their nicotine exposure plasma levels of glucose, insulin and glycated hemoglobin. The remaining four animals in each group continued without nicotine for another four weeks after which they were sacrificed and blood samples collected to determine their nicotine withdrawal plasma levels of glucose, insulin and glycated hemoglobin.
Results: The results showed that exposure to the three concentrations of nicotine (200, 400 and 800µg/kg respectively) significantly caused a rise in plasma insulin levels but dose-dependent reduction in both glucose and glycated haemoglobin compared to their control groups. Four weeks after withdrawal of initial 200µg/kg nicotine there were no significant changes in the levels of plasma glucose, insulin and glycated haemoglobin compared to the nicotine exposed groups. Withdrawal, after initial exposure to 400µg/kg of nicotine was associated with significant rise in both the plasma glucose and glycated haemoglobin but no significant change in insulin compared to their respective nicotine exposed groups. Cessation, after initial exposure 800µg/kg of nicotine resulted in significant rise in plasma levels of glucose, glycated haemoglobin and insulin compared to their nicotine exposed groups.
Conclusion: The possible reduction in food consumption and increased physical activity together with the increased levels of insulin in the plasma could contribute to the lowered plasma glucose shown in this study. The reduction in the levels of glycated haemoglobin following exposure to nicotine may be potentially beneficial in diabetic management. Therefore, reversal of plasma glucose and glycated haemoglobin levels could be achieved four weeks after cessation of 800µg/kg of nicotine. This result could suggest a possible association of nicotine cessation with decreased insulin sensitivity
