Venous plasma nicotine correlates of hormonal effects of tobacco smoking

Abstract

The present study resolves some of the discrepancies in the literature by correlating the effects of tobacco smoking on hormone release with venous plasma nicotine levels. Cortisol, prolactin, and beta-endorphin concentrations were measured. Habitual male tobacco users smoked denicotinized (very low nicotine) and average nicotine cigarettes in the morning after overnight tobacco abstinence. Several venous blood samples were withdrawn before and during the smoking sessions for subsequent analyses. The increases in plasma nicotine correlated well with plasma cortisol and prolactin levels (correlation coefficients r=0.66 and 0.53, respectively, p<0.05). This study quantifies the well known increase in plasma cortisol and prolactin after nicotine postsmoking for about 1h with peak plasma levels up to 35 ng/ml. Contrary to most abused drugs which release dopamine and decrease prolactin, nicotine concentration correlated with increased prolactin release. Increases in maximal plasma beta-endorphin levels following tobacco smoking were barely statistically significant with insufficient data to obtain a correlation coefficient.

Figure 1

Effects of smoking tobacco cigarettes on plasma cortisol. In this and subsequent figures, the A.M. data from day 1 (open circles) and day 2 (closed circles) sessions (usually within one week or so) in overnight abstinent tobacco smokers are illustrated from about 8:00 a.m. Time −5 min is when the first venous blood samples were drawn and 195 min when the last samples were drawn. A total of 16–23 subjects’ data were included. Note that day 1 cortisol levels are statistically significant and consistently slightly higher than on day 2 from −5 to 115 min in the PET scanner. In this and in Fig. 3 significant time differences are noted by **p < .01, ***p < .001.

Figure 2

Correlation of plasma nicotine and cortisol levels. Note that day 1 and day 2 data are very similar. Plasma nicotine and cortisol levels after denic and avnic cigarette smoking were combined. A total of 16–23 subjects with complete data were studied. The delta increase in nicotine and cortisol levels were both calculated by using the peak value after smoking minus the value just before smoking. The correlation coefficient r = 0.66. Time 0 in this and Fig. 4 is immediately after smoking.

Figure 3

Effects of tobacco cigarette smoking on plasma prolactin. A total of 16 subjects were included with complete data. Note that there is a trend for a slight increase after smoking denic and a greater increase after avnic cigarettes on the two different days.

Figure 4

Correlation of plasma nicotine and prolactin levels. Plasma nicotine and prolactin levels after denic and avnic cigarette smoking are correlated (r = 0.53) but less than with plasma cortisol.