Increased HPA Axis Activity and Serum Tryptophan in Naswar (Dipping Tobacco) Users: A Case-Control Study

Nicotine is the principal addictive agent present in Naswar, a smokeless dipping tobacco product. 5-Hydroxytryptamine (5-HT) has been implicated in the reinforcement properties of nicotine. Also, the hypothalamic-pituitary-adrenal (HPA) axis is of vital importance in evaluating the response to stress and nicotine addiction. The study aimed to evaluate serum tryptophan and cortisol levels in Naswar users in relation to addiction. Additionally, serum cotinine levels were also determined to assess daily nicotine exposure. The study comprised 90 healthy Naswar users and 68 non-tobacco users. Estimation of serum cortisol, tryptophan and albumin was carried out. From the Naswar user group, 20 were selected for the estimation of serum cotinine for which blood was drawn twice first in the morning and then in the evening. Serum tryptophan and cortisol levels in Naswar users were significantly raised compared to the control group. However, no difference in the levels of albumin between Naswar users and the control group were found. The mean cotinine values rose from the morning value of 366.0 ± 40.69 ng/ml (mean ± SEM) to an evening value of 503.1 ± 42.96 ng/ml that in turn is equivalent to consumption of 40 cigarettes. Elevated cortisol levels might constitute an important aspect of Naswar addiction. Additionally, raised levels of serum tryptophan in Naswar users could lead to raised concentration of 5-HT which also might be a significant factor contributing to Naswar addiction. Also, serum cotinine concentrations equivalent to an intake of about 40 cigarettes per day is quite alarming.