Cigarette Smoking Decreases the Prolactin Response to Serotonergic Stimulation in Subgroups of Alcoholics and Controls

Associations of agression and use of caffeine, alcohol and nicotine in healthy and aggressive individuals

BACKGROUND

Caffeine, alcohol, and nicotine are the three most commonly used psychoactive substances in the world. Given the known propensity of these substances to influence behavior, the relationship between these substances and aggressive and impulsive behaviors, in particular is of interest.

METHODS

1062 adult individuals participated in this study including those with Intermittent Explosive Disorder (IED) and non-aggressive healthy (HC) and psychiatric (PC) controls. Data regarding current and life use of caffeine, alcohol, and nicotine were recorded as were responses on measures of aggression, anger, and impulsivity.

RESULTS

Dimensional measures of aggression, anger, and impulsiveness were variably but significantly related to the consumption of these commonly used psychoactive substances. These findings were generally mirrored when using the categorical construct of IED. Finally, these findings were not due to comorbidity with other psychiatric disorders.

CONCLUSIONS

These data confirm a link between these externalizing behaviors and these three legal and commonly consumed psychoactive substances in clinically relevant individuals.

Sex differences in the ACTH and cortisol response to pharmacological probes are stressor-specific and occur regardless of alcohol dependence history

Women and men differ in their risk for developing stress-related conditions such as alcohol use and anxiety disorders and there are gender differences in the typical sequence in which these disorders co-occur. However, the neural systems underlying these gender-biased psychopathologies and clinical course modifiers in humans are poorly understood and may involve both central and peripheral mechanisms regulating the limbic-hypothalamic-pituitary-adrenal axis. In the present randomized, double blind, placebo-controlled, triple-dummy crossover study, we juxtaposed a centrally-acting, citalopram (2 mg/unit BMI) neuroendocrine stimulation test with a peripherally-acting, dexamethasone (Dex) (1.5 mg)/corticotropin-releasing factor (CRF) (1 μg/kg) test in euthymic women (N = 38) and men (N = 44) with (54%) and without histories of alcohol dependence to determine whether sex, alcohol dependence or both influenced the adrenocorticotropic hormone (ACTH) and cortisol responses to the pharmacological challenges and to identify the loci of these effects. We found that central serotonergic mechanisms, along with differences in pituitary and adrenal sensitivity, mediated sexually-diergic ACTH and cortisol responses in a stressor-specific manner regardless of a personal history of alcohol dependence. Specifically, women exhibited a greater response to the Dex/CRF test than they did the citalopram test while men exhibited the opposite pattern of results. Women also had more robust ACTH, cortisol and body temperature responses to Dex/CRF than men, and exhibited a shift in their adrenal glands' sensitivity to ACTH as measured by the cortisol/log (ACTH) ratio during that session in contrast to the other test days. Our findings indicate that central serotonergic and peripheral mechanisms both play roles in mediating sexually dimorphic, stressor-specific endocrine responses in humans regardless of alcohol dependence history.

Lifetime history of cigarette smoking associated with aggression and impulsivity in both healthy and personality disordered volunteers

Cigarette smoking has been associated with several personality and behavioral traits including impulsivity and aggression, primarily in adolescents and/or pregnant women. In this study, the authors tested the hypothesis that history of cigarette smoking is also associated with dimensional measures of aggression and impulsivity in adult subjects. Subjects were 179 personality disordered (PD), and healthy volunteer control (HV), subjects in whom history of cigarette smoking and measures of both aggression and impulsivity were collected. Scores on measures of both aggression and impulsivity were elevated as a function of personality disorder status and history of cigarette smoking status; no interaction between these two factors were noted on these measures. Including socio-economic status and global psychosocial functioning in the model eliminated the difference associated with diagnostic grouping and impulsivity but not the difference in aggression associated with lifetime history of smoking. These data suggest that lifetime history of cigarette smoking is associated with elevations in life history of aggression regardless of the presence of psychiatric disorder in nontreatment seeking individuals.

Smoking and suicide: a brief overview

This article provides a brief overview of the rationales, possible mechanisms and epidemiological data on the association of smoking, smoking cessation and cessation medications with suicide. Current smoking is reliably associated with suicide both in case-control and cohort studies. The three most plausible (but relatively untested) explanations for the association are that smokers have pre-existing conditions that increase their risk for suicide, smoking causes painful and debilitating conditions that might lead to suicide, and smoking decreases serotonin and monoamine oxidase levels. Stopping smoking appears to lead to major depression in some smokers; thus, it could induce suicide; however, smoking cessation has not been associated with suicide in the few studies available. Regulatory agencies have stated bupropion, rimonabant and varenicline appear to be associated with suicide; however, the data for these statements have not been presented in sufficient detail to assess their validity. Most prior data have come from post hoc analyses. Studies that a priori focus on understanding smoking and suicide are now needed.

Prolactin response to fenfluramine in abstinent, alcohol-dependent patients

It has been suggested that serotonin (5HT) function is abnormal in alcoholics even during abstinence. The prolactin response to fenfluramine (PRF) is generally believed to reflect the activity of the 5HT system and has been previously used to investigate 5HT activity in a variety of conditions, including alcoholism. The origin of the cortisol (CORT) response to fenfluramine is less clear. The objectives of this paper are to examine the prolactin (PRL) and CORT response to dl-fenfluramine in a large cohort of males with alcohol dependence who had been abstinent for 3 weeks, and to compare this with an age-matched control group. Ninety-four subjects with a DSM-III-R diagnosis of moderate to severe alcohol dependence who had been abstinent for 3 weeks, and 23 control subjects underwent neuroendocrine challenge with dl-fenfluramine (10 mg per 10 kg body weight). PRL and CORT responses were measured. No significant difference was found in PRF between abstinent, alcoholic patients and controls (F = 2.7, d.f. = 1.115, P = 0.10). CORT response was significantly lower in abstinent alcoholics than in controls (F = 10.0, d.f. = 1.116, P = 0.002). The results suggest no clear difference in 5HT function between abstinent alcoholics and healthy controls. The reduced CORT response in abstinent alcoholics further supports evidence of hypofunction of the adrenocortical system in this group.

Platelet monoamine oxidase kinetics, alcoholism subtypes and cigarette smoking

In trying to dissociate the effect of alcohol and tobacco use on platelet monoamine oxidase-B (MAO-B) activity, we compared the enzyme kinetics in controls (n = 66) and alcohol-dependent patients (n = 81), subdivided according to the severity of both, alcohol and tobacco use. Platelet MAO-B kinetics was measured spectrophotofluorimetrically in chronic alcohol intoxication and after 3 weeks abstinence. In alcoholic patients, an increased Michaelis-Menten constant (16%, p < 0.01) was shown, notwithstanding smoking status. Maximal velocity did not differ between patients and controls when adjusted for smoking. In cigarette smokers, a highly significant dose-dependent reduction of platelet MAO velocity (40%, p < 0.001) was demonstrated, with a similar degree of reduction in patients and controls. Tobacco use itself had no influence on MAO affinity. No differences were shown between subtype 1 and 2 alcoholics, or between the day of admission and the 21st day of abstinence. In conclusion, it seems that both, alcohol and tobacco consumption, may contribute to the lowering of overall platelet MAO-B activity. The effect of alcohol is small, due to interference with substrate binding, and not alteration of catalytic activity. In contrast, the effect of cigarette smoking is pronounced and relates to the dose-dependent reduction of platelet MAO velocity, with no influence on its affinity.

Diplotypes of the human serotonin 1B receptor promoter predict growth hormone responses to sumatriptan in abstinent alcohol-dependent men

BACKGROUND

Some studies have associated alcohol dependence (AD) with the human serotonin (5-HT)(1B) receptor (HTR1B). This investigation explored the functional responsivity of HTR1B in abstinent AD men using a sumatriptan challenge, while measuring genetic heterogeneity in the HTR1B promoter.

METHODS

Abstinent AD men (n = 27) and abstinent men without any alcohol use disorder (n = 19) were administered 6 mg of sumatriptan succinate, subcutaneously. Plasma samples collected over the following 2 hours were assayed for growth hormone (GH) concentrations. His DNA was genotyped for the A-161T and T-261G polymorphisms of the HTR1B promoter and diplotypes determined.

RESULTS

Integrated GH responses were predicted by interactions of AD and promoter diplotypes, as well as subject ethnicity. The final model accounted for nearly 35% of the variance in GH responses. Post hoc evaluation revealed that AD was associated with a blunting of GH secretion only among individuals with the most common HTR1B diplotype (TT/TT).

CONCLUSIONS

A blunting of GH responses in abstinent AD men was observed only among those with the most common HTR1B promoter diplotype. Less common promoter diplotypes appeared protective. Controlling for genetic background is a useful augmentation of case-control pharmacological challenge strategies designed to elucidate the psychobiology of AD and other complex disorders.

Inverse relationship between central serotonergic neurotransmission and blood pressure in alcohol-dependent male subjects

Data has accumulated indicating an inverse relation between central serotonergic (5-HT) neurotransmission and blood pressure in hypertensive rats and in healthy individuals. The present study aimed to elucidate whether an inverse relation exists between systolic (SBP) and diastolic (DBP) blood pressure levels and central 5-HT neurotransmission also in a group of alcohol-dependent individuals. Central 5-HT neurotransmission was assessed by using the maximum prolactin (PRL) responses to the 5-HT probe DL-fenfluramine (DL-FEN; 60 mg po) in 17 alcohol-dependent male subjects investigated during a period of on-going alcohol intake. BP was measured immediately before all time points for blood sampling, and readings before DL-FEN administration were used as the subjects resting BP. Results showed that there were inverse correlations between the maximum PRL responses to DL-FEN and the SBP levels (r = -0.57, p < 0.002) and with the DBP levels (r = -0.52, p < 0.05), respectively. The present study suggests the existence of an association between central 5-HT neurotransmission and blood pressure regulation also in alcohol-dependent individuals.

Personality profile in type I alcoholism: long duration of alcohol intake and low serotonergic activity are predictive factors of anxiety proneness

The aim of the present study was to further investigate personality profiles in male type I alcohol-dependent subjects (n = 33), in relation to central serotonergic neurotransmission, history of excessive alcohol consumption and present use of tobacco. Central serotonergic neurotransmission was assessed by the prolactin (PRL) response to D-fenfluramine. By using the Temperament and Character Inventory and the Karolinska Scales of Personality, all subjects self-rated their personality profile. The results showed that individuals with low PRL response and long duration of excessive alcohol consumption had significantly higher anxiety proneness, and that years of excessive alcohol consumption was the strongest predictor. Long duration of excessive alcohol consumption thus appears to have an influence on personality traits in male type I alcohol-dependent individuals and these personality traits may therefore be a consequence of, rather than preceding, alcoholism in these individuals.

The status of serotonin-selective pharmacotherapy in the treatment of alcohol dependence

Research performed during the past 20 years has shown that serotonin (5-hydroxytryptamine; 5-HT) neurotransmission is related to alcohol dependence. Both theoretical and empirical research have supported the idea that alcohol dependence is a chronic disease and that, in addition, biological vulnerabilities contribute to the pathogenesis of alcohol dependence. Preclinical studies have consistently demonstrated that there is a relationship between 5-HT function and alcohol consumption. Furthermore, there is evidence building that lends support for the existence of distinct alcoholic subtypes that may be differentiated by the type or complexity of their 5-HT dysfunction. Beyond excessive drinking, behaviors that are indicators of 5-HT dysregulation are depression, anxiety, impulsiveness, and early-onset problem drinking. This chapter will discuss the usefulness of 5-HT-selective pharmacotherapy in treating alcohol dependence and will provide both historical and current perspectives on its use.

Differences in platelet serotonin transporter sites between African-American tobacco smokers and non-smokers

RATIONALE

The serotonin transporter (5HTT) regulates the magnitude and duration of serotonergic neurotransmission. Although nicotine and other constituents of tobacco smoke may influence serotonin turnover among animals, few studies have examined whether smoking is associated with alteration in 5HTT in humans.

OBJECTIVE

We investigated whether tobacco smokers and non-smokers differed in platelet tritiated paroxetine binding, a measure of 5HTT sites, and whether severity of nicotine dependence (ND) was related to 5HTT measures.

METHODS

Tritiated paroxetine binding sites on platelets were assayed in 26 African-American smokers and 30 non-smokers. Severity of smoking was assessed using the Fagerstrom Test for Nicotine Dependence (FTND). Relationships between FTND scores and maximum number of transporter sites (B(max)) and affinity constant (K(d)) of paroxetine binding were determined.

RESULTS

B(max) values showed a significant negative correlation with FTND scores (rho=-0.28, P<0.01). Notably, smokers with higher ND had significantly lower B(max) compared to those with lower ND and non-smokers; the latter two groups did not differ in B(max) ( F=3.92, P<0.05). Smokers scored higher on impulsivity than non-smokers, however, behavioral variables did not influence the relationship of smoking with B(max). Age, gender and K(d) values were not associated with smoking or B(max).

CONCLUSIONS

Smoking, in particular higher nicotine dependence, appears to be correlated with decreased density of platelet 5HTT sites in African-Americans. The nature of the relationship and whether similar changes occur in the brain merit further investigation.

Intra- and inter-individual relationships between central and peripheral serotonergic activity in humans: a serial cerebrospinal fluid sampling study

Data are lacking concerning the longitudinal covariability and cross-sectional balance between central and peripheral 5-HIAA concentrations in humans and on the possible associations between tobacco smoking or post-traumatic stress disorder (PTSD) and CSF and plasma 5-HIAA concentrations. Using serial cerebrospinal fluid (CSF) and blood sampling, we determined the concentrations of 5-HIAA in CSF and plasma over 6 h, and examined their relationships in healthy volunteers and patients with PTSD-both smokers and nonsmokers. Patients with PTSD and healthy volunteers had very similar CSF 5-HIAA concentrations. Significant and positive correlations between CSF and plasma 5-HIAA levels were observed within individuals, but this CNS-peripheral 5-HIAA relationship was significantly reduced in smokers (nonsmokers: mean r = 0.559 +/- 0.072; smokers: mean r = 0.329 +/- 0.064 p < 0.038). No significant cross-sectional, interindividual correlation of mean CSF and mean plasma 5-HIAA was seen (r = 0.094). These data show that changes in CSF 5-HIAA levels within an individual over time are largely reflected in plasma 5-HIAA, albeit significantly less so in smokers. The present results therefore suggest that clinically, longitudinal determination of plasma 5-HIAA concentrations within an individual patient can be used to make inferences about relative changes in integrated CSF 5-HIAA concentrations. However, plasma 5-HIAA concentrations provide no significant information about absolute levels of the serotonin metabolite in the CSF.