Stress response dysregulation and stress-induced analgesia in nicotine dependent men and women

Pain sensitivity as a state marker and predictor for adolescent non-suicidal self-injury

BACKGROUND

The pain analgesia hypothesis suggests that reduced pain sensitivity (PS) is a specific risk factor for the engagement in non-suicidal self-injury (NSSI). Consistent with this, several studies found reduced PS in adults as well as adolescents with NSSI. Cross-sectional studies in adults with borderline personality disorder (BPD) suggest that PS may (partially) normalize after remission or reduction of BPD symptoms. The objective of the present study was to investigate the development of PS over 1 year in a sample of adolescents with NSSI and to investigate whether PS at baseline predicts longitudinal change in NSSI.

METHODS

N = 66 adolescents who underwent specialized treatment for NSSI disorder participated in baseline and 1-year follow-up assessments, including heat pain stimulation for the measurement of pain threshold and tolerance. Associations between PS and NSSI as well as BPD and depressive symptoms were examined using negative binomial, logistic, and linear regression analyses.

RESULTS

We found that a decrease in pain threshold over time was associated with reduced NSSI (incident rate ratio = 2.04, p = 0.047) and that higher pain tolerance at baseline predicted lower probability for NSSI (odds ratio = 0.42, p = 0.016) 1 year later. However, the latter effect did not survive Holm correction (p = 0.059). No associations between PS and BPD or depressive symptoms were observed.

CONCLUSION

Our findings suggest that pain threshold might normalize with a decrease in NSSI frequency and could thus serve as a state marker for NSSI.

Neurobiology of Stress-Induced Nicotine Relapse

Tobacco smoking is the leading cause of preventable death and disease. Although there are some FAD-approved medicines for controlling smoking, the relapse rate remains very high. Among the factors that could induce nicotine relapse, stress might be the most important one. In the last decades, preclinical studies have generated many new findings that lead to a better understanding of stress-induced relapse of nicotine-seeking. Several molecules such as α3β4 nicotinic acetylcholine receptor, α2-adrenergic receptors, cannabinoid receptor 1, trace amine-associated receptor 1, and neuropeptide systems (corticotropin-releasing factor and its receptors, dynorphine and kappa opioid receptor) have been linked to stress-induced nicotine relapse. In this review, we discuss recent advances in the neurobiology, treatment targets, and potential therapeutics of stress-induced nicotine relapse. We also discuss some factors that may influence stress-induced nicotine relapse and that should be considered in future studies. In the final section, a perspective on some research directions is provided. Further investigation on the neurobiology of stress-induced nicotine relapse will shed light on the development of new medicines for controlling smoking and will help us understand the interactions between the stress and reward systems in the brain.

Nociception related biomolecules in the adult human saliva: A scoping review with additional quantitative focus on cortisol

Nociception related salivary biomolecules can be useful patients who are not able to self-report pain. We present the existing evidence on this topic using the PRISMA-ScR guidelines and a more focused analysis of cortisol change after cold pain induction using the direction of effect analysis combined with risk of bias analysis using ROBINS-I. Five data bases were searched systematically for articles on adults with acute pain secondary to disease, injury, or experimentally induced pain. Forty three articles met the inclusion criteria for the general review and 11 of these were included in the cortisol-cold pain analysis. Salivary melatonin, kallikreins, pro-inflammatory cytokines, soluable TNF-α receptor II, secretory IgA, testosterone, salivary α-amylase (sAA) and, most commonly, cortisol have been studied in relation to acute pain. There is greatest information about cortisol and sAA which both rise after cold pain when compared with other modalities. Where participants have been subjected to both pain and stress, stress is consistently a more reliable predictor of salivary biomarker change than pain. There remain considerable challenges in identifying biomarkers that can be used in clinical practice to guide the measurement of nociception and treatment of pain. Standardization of methodology and researchers' greater awareness of the factors that affect salivary biomolecule concentrations are needed to improve our understanding of this field towards creating a clinically relevant body of evidence.

Sex effects in the interaction of acute stress and pain perception

ABSTRACT

A reciprocity between the stress and the pain system is recognized; however, the manner by which sex affects this reciprocity is unclear. Understanding the interactions of stress, pain, and sex may shed light on the apparent women's vulnerability to chronic pain, which often coexists with increased distress, and to affective disorders, which often coexist with chronic pain. The study's aim was to examine the effect of acute, validated, psychosocial stress on pain perception and modulation of women and men in a controlled manner. Participants were 82 women and 66 men. Heat-pain threshold, heat-pain tolerance, and pain modulation by temporal summation of pain (TSP), and pain adaptation were measured before and after exposure to the Montreal Imaging Stress Task (MIST) or to a sham task. The stress response was verified by perceived ratings of stress and anxiety, autonomic variables, and salivary cortisol. A significant stress response was obtained by the MIST among both sexes; however, women displayed a greater increase in perceived distress, and men displayed a greater increase in cortisol. Among women, TSP decreased and pain adaptation increased following the MIST, responses that were predicted by perceived distress levels. Among men, TSP increased following the MIST but was not predicted by the stress variables. In conclusion, acute stress manipulation seems to differentially affect both stress and pain responses of women and men: women exhibited stress-induced antinociception and men exhibited stress-induced pronociception. Higher perceived stress levels among women may trigger a temporary increase in pain inhibition mechanisms to serve evolutionary purposes.

Respiration rate during a stress task moderates neuroticism and perceived stress in older adults

BACKGROUND

Research suggests that respiration rate is related to psychological factors such as neuroticism and perceived stress in addition to physiological factors. However, it is unclear how respiration rate during a laboratory stress task relates to the relationship between neuroticism and perceived stress.

PARTICIPANTS AND PROCEDURE

This cross-sectional secondary analysis examined respiration rate during a stress task in moderating the relationship between neuroticism and perceived stress in a sample of generally healthy older adults (n = 64). Respiration data were collected during an auditory oddball paradigm and the Portland Arithmetic Stress Task (PAST), a laboratory-based cognitive stressor.

RESULTS

The results indicated that respiration rate during the PAST significantly moderated the relationship between neuroticism and perceived stress (p = .031), such that participants who exhibited a very low (-1.78 SD) respiration rate showed a non-significant relationship between neuroticism and perceived stress, whereas participants with average (mean; p < .001) and elevated respiration rates (+1 SD; p < .001) exhibited a significant positive relationship between neuroticism and perceived stress.

CONCLUSIONS

These findings add to a body of literature suggesting that stress reactivity is an important link between personality factors and negative outcomes. However, this is the first study to our knowledge to examine the role of physiological stress reactivity in buffering this relationship. The results suggest that individuals higher in neuroticism may attenuate the relationship between stress vulnerability and perceived stress through decreased physiological stress reactivity, particularly by exhibiting slow breathing during a stressor.

Stress-induced analgesia: an evaluation of effects on temporal summation of pain and the role of endogenous opioid mechanisms

Acute stress reduced the initial pain rating in a temporal summation protocol via nonopioid mechanisms but did not affect temporal summation slope, an indicator of central sensitization.

Introduction:

Objectives:

Methods:

Results:

Conclusions:

Blunted opioid regulation of the HPA stress response during nicotine withdrawal: therapeutic implications

Endogenous opioids regulate pain, drug reward, and stress responses. We have previously shown reduced hypothalamic-pituitary-adrenal (HPA) responses to psychological stress and to opioid blockade among dependent smokers. In this study, we examined the extent to which biologically confirmed nicotine withdrawal alters endogenous opioid regulation of HPA axis functioning during rest and in response to acute stress. Smokers were randomly assigned to one of two conditions; 24 h withdrawal from all nicotine-containing products (n = 62) or smoking ad libitum (n = 44). A nonsmoking comparison group (n = 43) was also included. Participants (85 males and 64 females) completed two acute stress sessions during which a placebo or 50 mg of naltrexone (opioid antagonist) were administered using a double-blind design. Blood and saliva samples (assayed for cortisol and adrenocorticotropic hormone, i.e. ACTH) and mood measures were obtained during a resting absorption period, after acute stress (public speaking, mental arithmetic, and cold pressor tasks), and during an extended recovery period. Results indicated that opioid blockade (naltrexone) was associated with increased ACTH and cortisol responses to stress, and tobacco withdrawal was associated with blunted hormonal responses. A pattern of sex differences also emerged, with women exhibiting reduced ACTH responses to stress and higher ACTH and plasma cortisol responses to opioid blockade. These results indicated that compared to ad libitum smoking, nicotine withdrawal is associated with blunted opioid modulation of the HPA axis. Sex may modulate these effects. Blunted endogenous opioid regulation may underlie an incentive process that reinforces smoking behavior and may warrant therapeutic attention.

Stress and pain: modality-specific opioid mediation of stress-induced analgesia

Preclinical research has demonstrated that exposure to acute stress is associated with attenuated pain perception, so called stress-induced analgesia (SIA). Mechanisms of SIA in humans have not been reliably demonstrated. This study examined the role of the endogenous opioid system in the impact of combined interpersonal and mental stressors on evoked pain responses in 84 participants (34 women). Using a within-subject, double-blinded, counterbalanced design, participants were administered either oral placebo or the opioid antagonist naltrexone (50 mg) across two testing sessions. In each session, they experienced two evoked pain stimuli (cold pressor test [CPT], heat pain) after an extended rest period (rest condition) and after exposure to an acute stressor (a combination of public speaking and mental arithmetic challenge; stress condition). Results showed that both stress and opioid blockade produced significant changes in hormonal and cardiovascular measures, consistent with successful induction of acute stress. Stress was associated with attenuated pain perception (SIA) as indicated by significantly increased CPT tolerance. These effects were particularly pronounced in individuals experiencing the stress condition first. More importantly, SIA effects on CPT tolerance were abolished by opioid blockade. There were no significant SIA effects on heat pain responses. This study demonstrates that the endogenous opioid system may mediate effects of acute stress on pain perception, although this effect seems to be qualified by the type of evoked pain stimuli experienced.

Effects of Mindfulness-Based Stress Reduction on Experimental Pain Sensitivity and Cortisol Responses in Women With Early Life Abuse: A Randomized Controlled Trial

OBJECTIVE

Early life abuse (ELAb) initiates pathophysiological cascades resulting in long-term maladaptive stress responsivity, hyperalgesia, and an increased risk of psychopathology. Mindfulness-based stress reduction (MBSR) is effective in modifying psychological and somatic symptoms; thus, we predicted that MBSR would be particularly efficacious for women with ELAb.

METHOD

Medically healthy women (mean age = 31 years) with or without a history of early (≤13 years) physical or sexual abuse provided self-report measures and were tested in the laboratory before and after randomization to standard MBSR (n = 52) or social support (SSG) (n = 60) for 8 weeks. The laboratory procedure involved pain testing using the cold pressor and temporal summation of heat pain (indexing central sensitization) procedures, and exposure to the Trier Social Stress Test. Plasma cortisol in response to the experimental protocol was assessed as area under the curve (AUC).

RESULTS

The interventions differentially impacted pain sensitivity and cortisol AUC for women with ELAb, as MBSR increased the temporal summation of heat pain intensity ratings (p = .024) and reduced cortisol AUC (p = .004). For women without ELAb, MBSR decreased cold pressor tolerance (p = .045) and decreased the temporal summation of heat pain intensity ratings relative to SSG (p = .024). Both MBSR and SSG improved depression symptoms and emotion regulation abilities (p values < .001); however, MBSR was associated with greater benefits in describing emotions (p = .008) and impulse control (p = .017) for women with ELAb.

CONCLUSIONS

Women with ELAb benefited from MBSR-specific improvements in central sensitization, mindfulness skills, and emotion regulation abilities. This is the first study to examine the efficacy of MBSR in modifying affective and somatic symptoms based on ELAb status and provides evidence for considering ELAb in tailoring treatment approaches.Trial Registration: ClinicalTrials.gov Identifier: NCT01995916; https://clinicaltrials.gov/ct2/show/NCT01995916.

Influences of Fasting on Stress Response and Withdrawal Symptoms in Habitual Khat Users

BACKGROUND

Fasting changes mood and physiological states. Substance use, such as khat use, is prohibited during fasting during Ramadan, a traditional practice among Muslims. Habitual khat use is associated with increased negative affect and altered psychobiological stress responses. Effects of fasting on stress responses, mood, and withdrawal symptoms among khat users have not been examined.

METHODS

In this study, 80 individuals completed an ambulatory monitoring period and a laboratory assessment session. Participants who completed the study while fasting during Ramadan were matched by gender and khat use status with participants who completed the study while not fasting. This resulted in 40 participants (12 females and 28 males; 25 khat users and 15 nonusers) in each fasting group. Cardiovascular (blood pressure and heart rate) and subjective measures were collected throughout the laboratory stress session. A mental arithmetic challenge was used to induce stress. In addition, self-reported mood and withdrawal measures were collected multiple times during the ambulatory assessment.

RESULTS

Khat users reported greater negative affect than nonusers. Results from the ambulatory study indicated that withdrawal symptoms were lower during evening hours in the fasting group than in the no-fasting group. Stress-related changes in positive and negative affects were flattened in the fasting group relative to the no-fasting group. Khat users reported reduced blood pressure responses relative to nonusers.

CONCLUSION

These preliminary results demonstrate that fasting is associated with reduced negative affect and withdrawal symptoms in khat users. Khat use was related to blunted blood pressure stress responses, but this was independent of fasting. Due to the small sample size, these results should be replicated with a large sample and comprehensive stress tasks.

Effects of tobacco addiction on links between early life adversities, sleep disturbance, and depression: A moderated mediation approach

Despite the well-established relationship between early life adversities (ELA) and depression, the underlying mechanisms for this link remain less clear and need to be developed. The aim of this study was to advance our understanding of this link by testing the mediating role of sleep disturbances and the moderating role of tobacco use in this mediation. A total of 579 smokers and non-smokers were recruited in two US communities (Duluth and Minneapolis, MN). Simple and moderated mediation analyses were performed using the PROCESS macro for SPSS, with the number of ELA as an independent variable, depression symptoms assessed by the Patient Health Questionnaire-9 (PHQ-9) as a dependent variable, sleep quality assessed by the Pittsburgh Sleep Quality Index (PSQI) as a mediator, and smoking status as a moderator variable. The study demonstrated that ELA and depressive symptoms were positively correlated; and sleep quality fully mediated this relationship. This mediation was moderated by tobacco use (index of moderated mediation = 0.10, 95%CI [0.03; 0.19]) and was more pronounced among smokers (b = 0.14, 95%CI [0.07; 0.23]) than non-smokers (b = 0.04, 95%CI [0.0002; 0.10]). Subsequent mediation analyses run separately for each component of the PSQI suggested that individuals who experienced ELA and who were smokers had greater delays in sleep onset and were more likely to sleep for a shorter duration, both of which predicted greater depressive symptoms. Sleep quality is therefore a promising ELA-related target for preventive and therapeutic interventions as well as for further research in depression and tobacco addiction.

Regular cannabis use is associated with blunted affective, but not cardiovascular, stress responses

AIMS

To examine the potential impact of regular cannabis use on cardiovascular and subjective responses to acute stress.

DESIGN

We used a quasi-experimental design in which subjective states and cardiovascular measures were obtained during rest and in response to acute stress challenges in a sample of regular cannabis users and non-users.

PARTICIPANTS

Seventy-nine adults (forty-five cannabis users and thirty-four non-users).

MEASUREMENTS

We measured subjective states (positive affect, state stress, state anxiety, cannabis craving) and cardiovascular indicators (blood pressure, heart rate, mean arterial pressure) during baseline rest and in response to public speaking, mental arithmetic, and cold-pressor challenges. Regular cannabis use was established via self-report and was confirmed with a positive urine drug test.

FINDINGS

Regular cannabis use was associated with blunted positive affect (F = 5.67, p = .002), state stress (F = 6.05, p = .002), and state anxiety (F = 6.48, p < .001) in response to acute stress challenges. There was no evidence of an association between cannabis use and cardiovascular responses (Fs ≤ 1.54; Ps ≥ 0.21). Contrary to expectations, cannabis craving decreased in response to stress challenges (F = 8.44, p < .001).

CONCLUSION

Chronic cannabis use is associated with blunted positive and negative (stress, anxiety) affective responses to acute stress, indicating emotional dysregulation in this population.

Neuropeptide and cytokine regulation of pain in the context of substance use disorders

Substance use disorders (SUDs) are frequently accompanied by affective symptoms that promote negative reinforcement mechanisms contributing to SUD maintenance or progression. Despite their widespread use as analgesics, chronic or excessive exposure to alcohol, opioids, and nicotine produces heightened nociceptive sensitivity, termed hyperalgesia. This review focuses on the contributions of neuropeptide (CRF, melanocortin, opioid peptide) and cytokine (IL-1β, TNF-α, chemokine) systems in the development and maintenance of substance-induced hyperalgesia. Few effective therapies exist for either chronic pain or SUD, and the common interaction of these disease states likely complicates their effective treatment. Here we highlight promising new discoveries as well as identify gaps in research that could lead to more effective and even simultaneous treatment of SUDs and co-morbid hyperalgesia symptoms.

Stress Allostasis in Substance Use Disorders: Promise, Progress, and Emerging Priorities in Clinical Research

Clinicians and researchers alike have long believed that stressors play a pivotal etiologic role in risk, maintenance, and/or relapse of alcohol and other substance use disorders (SUDs). Numerous seminal and contemporary theories on SUD etiology posit that stressors may motivate drug use and that individuals who use drugs chronically may display altered responses to stressors. We use foundational basic stress biology research as a lens through which to evaluate critically the available evidence to support these key stress-SUD theses in humans. Additionally, we examine the field's success to date in targeting stressors and stress allostasis in treatments for SUDs. We conclude with our recommendations for how best to advance our understanding of the relationship between stressors and drug use, and we discuss clinical implications for treatment development.

Influences of the Menstrual Phase on Cortisol Response to Stress in Nicotine Dependent Women: A Preliminary Examination

INTRODUCTION

Evidence indicates that menstrual cycle phase plays a role in smoking withdrawal symptoms and craving. Stress increases these symptoms. Whether the stress regulatory mechanism is associated with menstrual phase and withdrawal symptoms is not well understood.

METHODS

Thirty-seven female smokers and 16 female nonsmokers were asked to complete a laboratory session. In each group, approximately half of the participants were tested when they were in the follicular phase and the other half was tested in the luteal phase. The session included resting baseline, stress, and recovery periods. Saliva samples for the measurement of cortisol and subjective measures of craving and withdrawal symptoms were collected at the end of each period.

RESULTS

A series of repeated measures analysis of covariance found a significant smoking group × menstrual phase × sampling time interaction in cortisol levels (p < .05). Follow-up analyses indicated a reduced cortisol stress response in the luteal group relative to the follicular group in smokers (p < .02). This difference was not found in nonsmokers.

CONCLUSIONS

Menstrual cycle phase is related to hormonal stress response and smoking withdrawal symptomatology.

IMPLICATIONS

We show influences of the menstrual cycle phase on stress response among smokers. This is demonstrated by a reduced cortisol response to stress in the luteal group relative to the follicular group among smokers. This menstrual phase difference was not found in nonsmokers.

Maternal deprivation alters nociceptive response in a gender-dependent manner in rats

The present study aimed at investigating both the early and long-term effects of maternal deprivation as well as gender on neuromotor reflexes, anxiety behavior and thermal nociceptive responses. A total of 64 Wistar rats pups (32 males, 32 females) were utilized and were deprived of their mother for 3 h/daily, from postnatal day 1 (P1) until P10. Successively, animals were divided into 2 groups: control group (C) - pups no subjected to intervention; and the maternal-deprived group (MD): pups subjected to maternal deprivation. The neuromotor reflexes were evaluated through the righting reflex and negative geotaxis tests; the exploratory behavior by open field test (OFT); the anxiety-like behavior by elevated plus-maze test (EPM); the thermal nociceptive responses byhot plate (HP) and tail-flick (TFL) tests. All the animals subjected to maternal deprivation showed a delayed reflex response at P8 in the negative geotaxis test. In contrast, the OFT at P20 identified an effect of gender on the outer crossings and grooming as well as an interaction between gender and maternal deprivation on latency. Additionally, effect of maternal deprivation in the open and closed arms as well as gender effect in the protected head-dipping (PHD) and non-protected head-dipping (NPHD) were observed at P20 (EPM). In contrast, there were a gender effect on latency and an interaction between gender and maternal deprivation on rearing at P42. Moreover, in nociceptive tests was observed an analgesic effect induced by maternal deprivation; however, in the TFL test, only deprived females showed this effect. Surprisingly, only control animals presented an ontogeny nociceptive effect in the HP testat P21 and P43, which may be related to an increase in the inhibitory nociceptive pathways throughout life. In this way, we suggest maternal deprivation to be able to anticipate the maturation of the inhibitory nociceptive pathway. In conclusion, maternal deprivation induced a delayed reflex response at P8 and altered the anxiety and nociceptive behaviors according to the time after exposure to this stressor, in a gender-specific manner.

Substance-related disorders: A review of prevalence and correlates among patients with chronic pain

Over the past few decades, research has revealed high rates of substance-related disorders among patients with chronic pain. In addition to their potentially deleterious health consequences, substance-related disorders have consistently been associated with negative pain-related outcomes among patients with chronic pain. The goal of this narrative review was to provide an overview of studies that have examined the prevalence and correlates of substance-related disorders among patients with chronic pain. A particular focus was placed on opioids, sedatives/hypnotics, cannabis, tobacco, and alcohol given that these substances have received the bulk of research attention among patients with pain. Research conducted to date suggests that a host of biological and psychological factors are likely to contribute to the elevated rates of substance-related disorders among patients with chronic pain. In this review, in addition to reviewing the prevalence and correlates of substance-related disorders among patients with pain, we briefly discussed the changes that were recently made from the DSM-4 to the DSM-5 in the diagnostic criteria for substance-related disorders, and the implications of these changes for the assessment of patients with chronic pain. We also provided a brief overview of instruments that can be used for the assessment of these disorders in clinical and research settings.

Impact of early life adversity on the stress biobehavioral response during nicotine withdrawal

Exposure to early life adversity (ELA) is associated with increased subsequent risk for addiction and relapse. We examined changes in psychobiological responses to stress in dependent smokers and nonsmoking controls and evaluated how history of early adversity may exacerbate acute changes during nicotine withdrawal and acute stress. Smokers were randomly assigned to one of two conditions; 24 h withdrawal (66 smokers) from smoking and all nicotine-containing products or smoking ad libitum (46 smokers) prior to an acute laboratory stress induction session; and 44 nonsmokers provided normal referencing. The laboratory session included a baseline rest, stress and recovery periods. Plasma and saliva samples for the measurement stress hormones and cardiovascular and self-report mood measures were collected multiple times during the session. Multivariate analysis confirmed that all groups showed stress-related increases in negative mood, cardiovascular measures and stress hormones, particularly smokers in the withdrawal condition. Individuals with high ELA showed greater adrenocorticotropic hormone (ACTH), but lower plasma and salivary cortisol levels, than those with low ELA. Cortisol differences were abolished during tobacco withdrawal. These findings demonstrate that ELA moderates the effects of withdrawal on stress-related biobehavioral changes.

The effect of passive heat stress on distress andself-control in male smokers and non-smokers

In the current study, we tested the effects of core body temperature increases (e.g. heat stress) on affect, self-reported physical discomfort, and subsequent self-control in male smokers and nonsmokers using a novel passive heat stress paradigm, within a distress tolerance framework. Twenty-eight men (14 smokers), completed both heat stress and control sessions in randomized order. Results revealed that increases in core body temperature were associated with increased anxiety, irritability, and body discomfort as well as decreased happiness, with stronger effects for smokers. Smokers and nonsmokers both evidenced less self-control during the heat session and did not differ on this measure, nor on a measure of interoceptive sensitivity. The current study indicates that heat stress is a viable method for studying distress tolerance in men, and suggests the value in examining dynamic changes in self-control as a function of distress. Implications will be discussed for distress tolerance in general and smokers in specific.

Anger, anxiety, and depressive affect as predictors of stress-induced cortisol production in khat and tobacco users

INTRODUCTION

Glucocorticoid activity is disrupted in substance users including khat chewers who also use tobacco. Anger, dysphoria, and anxiety can mediate this relationship. The aim of this study was to contrast emotion dysregulation and substance use variables as predictors of post-stress cortisol output.

MATERIALS AND METHODS

Comparable numbers of males (n = 90) and females (n = 85) including controls, khat only, and concurrent khat and tobacco users participated in a stress study. Depressive affect, anxiety, anger, substance use patterns, and saliva samples were collected following a standardized laboratory stress manipulation.

RESULTS

Regression analysis showed that high depression and low anxiety was associated with high post-stress cortisol, but only in co-users of tobacco and khat. Males, but not females, showed a significant association between co-use of khat and tobacco and cortisol, which appears to be mediated by frequency of use. The link between anxiety and post-stress cortisol in the co-users remained significant after controlling for nicotine dependence and substance use frequency.

CONCLUSION

Anxiety predicted the neuroendocrine consequences of concurrent use of tobacco and khat above and beyond sex, nicotine dependence, anger, and substance use frequency. Sex differences, however, are related to differences in nicotine dependence.

A 90-day OECD TG 413 rat inhalation study with systems toxicology endpoints demonstrates reduced exposure effects of the aerosol from the carbon heated tobacco product version 1.2 (CHTP1.2) compared with cigarette smoke. II. Systems toxicology assessment

Modified risk tobacco products (MRTPs) have the potential to reduce smoking-related health risks. The Carbon Heated Tobacco Product 1.2 (CHTP1.2) is a potential MRTP that uses a pressed carbon heat source to generate an aerosol by heating tobacco. Here, we report the results from the systems toxicology arm of a 90-day rat inhalation study (OECD test guideline 413) to assess the effects of CHTP1.2 aerosol compared with cigarette smoke (CS). Transcriptomics, proteomics, and lipidomics analyses complemented the standard endpoints. In the respiratory nasal epithelium, CS induced an adaptive tissue and inflammatory response, which was much weaker after CHTP1.2 aerosol exposure, mostly limited to the highest CHTP1.2 concentration (at twice the 3R4F CS concentration: 50 vs. 23 μg nicotine/L), in female rats. In the lungs, the effects of CS exposure included inflammatory and cellular stress responses, which were absent or much lower after CHTP1.2 aerosol exposure. Outside of the respiratory tract, CS and CHTP1.2 aerosol induced effects that were previously associated with exposure to any nicotine-containing aerosol, e.g., lower lipid concentrations in serum. Overall, this systems toxicology analysis complements and confirms the results from classical toxicological endpoints and further suggests potentially reduced respiratory health risks of CHTP1.2.

Stress and Addiction: When a Robust Stress Response Indicates Resiliency

OBJECTIVE

Stress reactivity research has traditionally focused on the idea that exaggerated responses to stress may have adverse effects on health. Accumulating evidence suggests that attenuated responses to stress and delayed recovery may also be problematic.

METHODS

This review focuses on the role of the stress response of the hypothalamic-pituitary-adrenocortical axis, the endogenous opioid system, and the cardiovascular system in hypertension, pain perception, and addictive behaviors. Results from multiple methods of assessment and stress paradigms conducted in our laboratory over the past two decades are integrated with research from other investigators and with existing theories.

RESULTS

Research indicates that exaggerated biological and physiological responses to stress and attenuated pain perception are associated with hypertension and risk for cardiovascular diseases. This research complements work linking reduced stress responses with enhanced pain sensitivity and discomfort. Multiple studies have also demonstrated that an attenuated stress response is linked to exacerbation of withdrawal symptoms and relapse in nicotine addiction. Evidence indicates important moderators (i.e., sex, personality traits, and early life adversity) and hypothalamic-pituitary-adrenocortical- and endogenous opioid system-related mechanisms in the altered response to stress. I integrate these findings in a conceptual model emphasizing that robust stress responses in the context of addiction and relapse should be considered as a marker of resiliency.

CONCLUSIONS

A blunted stress response may indicate long-term physiological dysregulation that could usher harmful consequences for cardiovascular disease, pain perception, and addictive disorders. The impact of dysregulation is influenced by multiple individual and situational factors that should be considered in evaluating the clinical significance of stress response dysregulation.

Road traffic noise and determinants of saliva cortisol levels among adolescents

OBJECTIVES

The understanding of determinants for saliva cortisol levels in adolescents is limited. This study investigated the role of road traffic noise exposure, noise annoyance and various other factors for saliva cortisol levels.

METHODS

We collected morning and evening saliva samples from 1751 adolescents from the BAMSE birth cohort based in Stockholm County. Façade noise levels from road traffic were estimated at the residences of the study subjects and repeated questionnaires and medical examinations provided extensive information on various exposures and conditions, including annoyance to noise from different sources. Cortisol was measured using radioimmunoassay. Associations between determinants and saliva cortisol levels were analysed using linear regression.

RESULTS

Morning saliva cortisol levels were significantly higher in females than in males (geometric mean 42.4 and 35.0 nmol/l, respectively) as well as in subjects with allergy related diseases. Height and age were related to saliva cortisol levels as well as sampling season. Road traffic noise exposure was not associated with saliva cortisol, however, annoyance to noise tended to increase the levels. Saliva cortisol levels appeared particularly high among those who were highly annoyed and exposed to road traffic noise levels ≥ 55 dB L_den (50.5 nmol/l, p = 0.02).

CONCLUSION

Our findings suggest that individual perception of noise may be of importance for saliva cortisol levels. The results also point to the complexity of using saliva cortisol as a marker of noise exposure in adolescents.

Toxicity of the main electronic cigarette components, propylene glycol, glycerin, and nicotine, in Sprague-Dawley rats in a 90-day OECD inhalation study complemented by molecular endpoints

While the toxicity of the main constituents of electronic cigarette (ECIG) liquids, nicotine, propylene glycol (PG), and vegetable glycerin (VG), has been assessed individually in separate studies, limited data on the inhalation toxicity of them is available when in mixtures. In this 90-day subchronic inhalation study, Sprague-Dawley rats were nose-only exposed to filtered air, nebulized vehicle (saline), or three concentrations of PG/VG mixtures, with and without nicotine. Standard toxicological endpoints were complemented by molecular analyses using transcriptomics, proteomics, and lipidomics. Compared with vehicle exposure, the PG/VG aerosols showed only very limited biological effects with no signs of toxicity. Addition of nicotine to the PG/VG aerosols resulted in effects in line with nicotine effects observed in previous studies, including up-regulation of xenobiotic enzymes (Cyp1a1/Fmo3) in the lung and metabolic effects, such as reduced serum lipid concentrations and expression changes of hepatic metabolic enzymes. No toxicologically relevant effects of PG/VG aerosols (up to 1.520  mg PG/L + 1.890 mg VG/L) were observed, and no adverse effects for PG/VG/nicotine were observed up to 438/544/6.6 mg/kg/day. This study demonstrates how complementary systems toxicology analyses can reveal, even in the absence of observable adverse effects, subtoxic and adaptive responses to pharmacologically active compounds such as nicotine.

Psychosocial Stress-Induced Analgesia: An Examination of Effects on Heat Pain Threshold and Tolerance and of Neuroendocrine Mediation

Stress-induced analgesia (SIA) is an adaptive response of reduced nociception following demanding acute internal and external stressors. Although a psychobiological understanding of this phenomenon is of importance for stress-related psychiatric and pain conditions, comparably little is known about the psychobiological mechanisms of SIA in humans. The aim of this study was to investigate the effects of acute psychosocial stress on heat pain perception and its possible neuroendocrine mediation by salivary cortisol levels and α-amylase activity in healthy men. Employing an intra-individual assessment of heat pain parameters, acute psychosocial stress did not influence heat pain threshold but significantly, albeit slightly, increased heat pain tolerance. Using linear mixed-model analysis, this effect of psychosocial stress on heat pain tolerance was not mediated by increases of salivary cortisol and state anxiety levels or by the activity of α-amylase. These results show that while psychosocial stress is selectively analgesic for heat pain tolerance, this observed effect is not mediated by stress-induced increases of salivary cortisol and α-amylase activity, as proxies of both the hypothalamus-pituitary-adrenal axis and the autonomic nervous system activation.

Chronic Smoking, Trait Anxiety, and the Physiological Response to Stress

BACKGROUND AND OBJECTIVES

Both chronic smoking and trait anxiety have been associated with dysregulations in psychobiological stress response systems. However, these factors have not been studied in conjunction. We expected trait anxiety and smoking status to attenuate stress reactivity. Furthermore, we expected an allostatic load effect resulting in particularly attenuated stress reactivity in high-anxious smokers. In addition, high-anxious smokers were expected to exhibit increased urges to smoke in response to stress.

METHODS

115 smokers and 37 nonsmokers, aged 18-64 years, completed a laboratory session including mental stressors such as evaluated public speaking and mental arithmetic. Trait anxiety was assessed using Spielberger's State-Trait Anxiety Inventory. Cardiovascular autonomic indices, salivary cortisol, and the desire to smoke were measured at baseline, during stressors, and at recovery.

RESULTS

Regression analyses showed that smokers exhibited attenuated cardiovascular stress responses in comparison to nonsmokers. Higher trait anxiety predicted attenuated systolic blood pressure responses to stress. No interaction effect of smoking status and trait anxiety was found in stress response measures. Higher trait anxiety predicted an increased desire to smoke in response to stress among smokers.

CONCLUSION

Results indicate that both smoking status and trait anxiety are associated with blunted sympatho-adrenal cardiovascular stress reactivity. Elevated urges to smoke in response to stress found among smokers with high trait anxiety suggest an important role of anxiety in smoking propensity and relapse.

Life adversity is associated with smoking relapse after a quit attempt

Multiple cross-sectional studies have linked adverse childhood events and adult adversities to current smoking, lifetime smoking, and former smoking. To date, however, there have been no direct observational studies assessing the influence of adversities on smoking relapse. We prospectively followed 123 participants, 86 of whom were habitual smokers, from pre-quit ad libitum smoking to four weeks post-quit. Thirty-seven non-smokers were also tested in parallel as a comparison group. Subjects provided biological samples for confirmation of abstinence status and self-report history of adversities such as abuse, neglect, family dysfunction, incarceration, and child-parent separation. They also completed mood and smoking withdrawal symptom measures. The results indicated that within non-smokers and smokers who relapsed within the first month of a quit attempt, but not abstainers, females had significantly higher adversity scores than males. Cigarette craving, which was independent from depressive affect, increased for low adversity participants, but not those with no adversity nor high adversity. These results demonstrate that sex and relapse status interact to predict adversity and that craving for nicotine may be an important additional mediator of relapse. These results add further support to the previous cross-sectional evidence of an adversity and smoking relationship. Further studies to clarify how adversity complicates smoking cessation and impacts smoking behaviors are warranted.

Salivary stress biomarkers of recent nicotine use and dependence

BACKGROUND

Although stress plays a critical role in vulnerability to nicotine use and dependence, the stress response factors that contribute to smoking behaviors remain poorly elucidated. To minimize the confounding effects of chronic nicotine use, assessing individuals with relatively short smoking histories is critical for characterizing the neurobiological substrates associated with nicotine dependence early in the course of illness.

OBJECTIVES

This pilot study examined sympathetic nervous system (alpha-amylase) and hypothalamic-pituitary-adrenal axis (cortisol, dehydroepiandrosterone) responses to the Trier Social Stress Test (TSST) in young adult smokers. Associations among objective indices of recent smoking (salivary cotinine, carbon monoxide in the breath [CO]), behavioral measures of nicotine dependence and withdrawal, and salivary biomarkers in response to the TSST were investigated.

METHODS

Smokers (N = 64; 28 males, 36 females) provided saliva samples at 30 min intervals for 2 h prior to the TSST and every 10 min for 1 h following the TSST.

RESULTS

Alpha-amylase responses to the TSST were positively associated with salivary cotinine levels but negatively associated with CO levels. Individuals with a lower level of nicotine dependence had increased cortisol responses to the stressor, whereas those with a higher level of nicotine dependence did not show any cortisol changes in response to the stressor.

CONCLUSIONS

These findings indicate that different mechanisms may be involved at different levels of nicotine dependence severity. Recent nicotine use and lower dependence severity may be associated with increased activation of the stress response systems. In contrast, more severe levels of dependence may downregulate stress response systems.

Substance use modulates stress reactivity: Behavioral and physiological outcomes

Drug addiction is a major public health concern in the United States costing taxpayers billions in health care costs, lost productivity and law enforcement. However, the availability of effective treatment options remains limited. The development of novel therapeutics will not be possible without a better understanding of the addicted brain. Studies in both clinical and preclinical models indicate that chronic drug use leads to alterations in the body and brain's response to stress. Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis may shed light on the ability of stress to increase vulnerability to relapse. Further, within both the HPA axis and limbic brain regions, corticotropin-releasing factor (CRF) is critically involved in the brain's response to stress. Alterations in both central and peripheral CRF activity seen following chronic drug use provide a mechanism by which substance use can alter stress reactivity, thus mediating addictive phenotypes. While many reviews have focused on how stress alters drug-mediated changes in physiology and behavior, the goal of this review is to focus on how substance use alters responses to stress.

Changes in circulating leptin levels during the initial stage of cessation are associated with smoking relapse

RATIONALE

Leptin has been linked to tobacco craving and withdrawal-related symptoms. Very few studies have examined leptin prospectively in both male and female nonsmokers and smokers.

OBJECTIVES

We examine leptin concentrations prospectively in both male and female nonsmokers and smokers to assess the associations of leptin with psychological symptoms and smoking relapse during ad libitum smoking, the first 48 h post quit, and 4 weeks post-cessation.

METHODS

Self-report psychological, anthropomorphic, and biological measures (cotinine, carbon monoxide, and plasma leptin) were collected before and after 48 h of smoking abstinence. Smokers were stratified at 28 days post quit as abstinent or relapsed if they had smoked daily for seven consecutive days at any point in the 28 days.

RESULTS

Leptin concentration (square root transformed ng/ml) increased over the 48-h abstinence, but only in female abstainers. In contrast, leptin was very stable across time for nonsmokers, relapsers, and males. Cox regression supported that increased leptin was associated with decreased risk of relapse. Leptin was correlated negatively with withdrawal symptoms for abstainers only. Females produce more leptin than males and this level increases from ad libitum smoking to 48-h post quit.

CONCLUSIONS

The current analysis indicates that a leptin increase early in cessation predicts abstinence. The increase in women, but not men, in response to abstinence provides further evidence of important gender differences. The negative correlation between leptin and withdrawal symptoms indicates a possible protective effect of leptin. Further research is ongoing to elucidate the psychological and biological determinants of this effect.

Sex differences in hormonal responses to stress and smoking relapse: a prospective examination

INTRODUCTION

Dysregulation in the hypothalamic-pituitary-adrenal axis has been shown to be associated with smoking relapse. No study has directly examined the role of sex differences in this relationship.

METHODS

Nicotine dependent men (n = 52) and women (n = 46) interested in cessation completed 2 laboratory stress sessions during ad libitum smoking and after 48 hr of abstinence. The laboratory session included baseline, stress, and recovery periods. Blood and saliva samples were collected at the end of each period for the measurement of cortisol and adrenocorticotropic hormone. Self-report measures of craving and withdrawal symptoms were also collected. Participants attended 4 weekly follow-up sessions for counseling where they provided biological samples and self-report measures including smoking status. Relapse was defined by smoking cigarettes for 7 consecutive days post-cessation.

RESULTS

Results showed that 60 participants relapsed during the 4-week period. Cox regression models from the abstinence session showed that cortisol levels regardless of source were predictive of relapse but the direction of prediction was sex dependent (Sex × Hormone, all ps < .05). Follow-up analyses further revealed that lower cortisol levels predicted relapse in men whereas greater cortisol levels predicted relapse in women (ps < .05). Enhanced craving predicted early smoking relapse in men but not in women (ps < .05). Data from the ad libitum session showed no differences in predicting relapse.

CONCLUSION

These findings highlight that sex differences in the hormonal response to stress and subjective craving during nicotine withdrawal are critical predictors of risk for understanding early relapse.

Circulating leptin and pain perception among tobacco-dependent individuals

Recent preclinical evidence suggests that leptin may modulate the stress response and may increase nociception. In this study, we examined for the first time the extent to which cigarette smoking is associated with leptin levels during an extended rest period and in response to noxious stimuli. Repeated blood samples were collected during a laboratory session from smokers and nonsmokers and assayed for leptin. Pain experiences, as well as neuroendocrine and cardiovascular measures, were collected across cold pressor and thermal heat pain tests. Both analysis of variance and correlations confirmed that smokers demonstrated dysregulations in leptin responsivity and association with pain relative to nonsmokers. The flat pattern of leptin release and the weak associations of this hormone with pain in smokers suggest a long-term effect of tobacco dependence on this regulatory hormone. In light of leptin's influence on reward pathways, further investigation of leptin's involvement in nicotine dependence is warranted.

Family hardships and serum cotinine in children with asthma

BACKGROUND AND OBJECTIVE

A better understanding of how poverty-related hardships affect child health could highlight remediable intervention targets. Tobacco smoke exposure may be 1 such consequence of family hardship. Our objective was to explore the relationship between family hardships and tobacco exposure, as measured by serum cotinine, a tobacco metabolite, among children hospitalized for asthma.

METHODS

We prospectively enrolled a cohort of 774 children, aged 1 to 16 years, admitted for asthma or bronchodilator-responsive wheezing. The primary outcome was detectable serum cotinine. We assessed family hardships, including 11 financial and social variables, through a survey of the child's caregiver. We used logistic regression to evaluate associations between family hardship and detectable cotinine.

RESULTS

We had complete study data for 675 children; 57% were African American, and 74% were enrolled in Medicaid. In total, 56% of children had detectable cotinine. More than 80% of families reported ≥ 1 hardship, and 41% reported ≥ 4 hardships. Greater numbers of hardships were associated with greater odds of having detectable cotinine. Compared with children in families with no hardships, those in families with ≥ 4 hardships had 3.7-fold (95% confidence interval, 2.0-7.0) greater odds of having detectable serum cotinine in adjusted analyses. Lower parental income and educational attainment were also independently associated with detectable serum cotinine.

CONCLUSIONS

Family hardships are prevalent and associated with detectable serum cotinine level among children with asthma. Family hardships and tobacco smoke exposure may be possible targets for interventions to reduce health disparities.

Peptide YY and ghrelin predict craving and risk for relapse in abstinent smokers

Appetite hormones are directly involved in regulating satiety, energy expenditure, and food intake, and accumulating evidence suggests their involvement in regulating reward and craving for drugs. This study investigated the ability of peptide YY (PYY) and ghrelin during the initial 24-48 h of a smoking cessation attempt to predict smoking relapse at 4 weeks. Multiple regression analysis indicated that increased PYY was associated with decreased reported craving and increased positive affect. Cox proportional hazard models showed that higher ghrelin levels predicted increased risk of smoking relapse (hazard ratio=2.06, 95% CI=1.30-3.27). These results indicate that circulating PYY may have buffering effects during the early stages of cessation while ghrelin may confer increased risk of smoking relapse. Further investigation of the links between these hormones and nicotine dependence is warranted.

Nicotine withdrawal and stress-induced changes in pain sensitivity: a cross-sectional investigation between abstinent smokers and nonsmokers

Chronic smoking has been linked with alterations in endogenous pain regulation. These alterations may be pronounced when individuals quit smoking because nicotine withdrawal produces a variety of psychological and physiological symptoms. Smokers interested in quitting (n = 98) and nonsmokers (n = 37) completed a laboratory session including cold pressor test (CPT) and heat thermal pain. Smokers set a quit date and completed the session after 48 h of abstinence. Participants completed the pain assessments once after rest and once after stress. Cardiovascular and nicotine withdrawal measures were collected. Smokers showed blunted cardiovascular responses to stress relative to nonsmokers. Only nonsmokers had greater pain tolerance to CPT after stress than after rest. Lower systolic blood pressure was related to lower pain tolerance. These findings suggest that smoking withdrawal is associated with blunted stress response and increased pain sensitivity.

Changes in biochemical markers of pain perception and stress response after spinal manipulation

STUDY DESIGN

Controlled, repeated-measures, single-blind randomized study.

OBJECTIVES

To determine the effect of cervical or thoracic manipulation on neurotensin, oxytocin, orexin A, and cortisol levels.

BACKGROUND

Previous studies have researched the effect of spinal manipulation on pain modulation and/or range of movement. However, there is little knowledge of the biochemical process that supports the antinociceptive effect of spinal manipulation.

METHODS

Thirty asymptomatic subjects were randomly divided into 3 groups: cervical manipulation (n = 10), thoracic manipulation (n = 10), and nonmanipulation (control) (n = 10). Blood samples were extracted before, immediately after, and 2 hours after each intervention. Neurotensin, oxytocin, and orexin A were determined in plasma using enzyme-linked immuno assay. Cortisol was measured by microparticulate enzyme immuno assay in serum samples.

RESULTS

Immediately after the intervention, significantly higher values of neurotensin (P<.05) and oxytocin (P<.001) levels were observed with both cervical and thoracic manipulation, whereas cortisol concentration was increased only in the cervical manipulation group (P<.05). No changes were detected for orexin A levels. Two hours after the intervention, no significant differences were observed in between-group analysis.

CONCLUSION

The mechanical stimulus provided by spinal manipulation triggers an increase in neurotensin, oxytocin, and cortisol blood levels. Data suggest that the initial capability of the tissues to tolerate mechanical deformation affects the capacity of these tissues to produce an induction of neuropeptide expression. J

Stress modulates illness-course of substance use disorders: a translational review

Childhood trauma and post-childhood chronic/repeated stress could increase the risk of a substance use disorder by affecting five stages of addiction illness-course: (a) initial experimentation with substances; (b) shifting from experimental to regular use; (c) escalation from regular use to abuse or dependence; (d) motivation to quit; and (e) risk of (re-)lapse. We reviewed the human literature on relationships between stress and addiction illness-course. We explored per illness-course stage: (i) whether childhood trauma and post-childhood chronic/repeated stress have comparable effects and (ii) whether effects cut across classes of substances of abuse. We further discuss potential underlying mechanisms by which stressors may affect illness-course stages for which we relied on evidence from studies in animals and humans. Stress and substances of abuse both activate stress and dopaminergic motivation systems, and childhood trauma and post-childhood stressful events are more chronic and occur more frequently in people who use substances. Stressors increase risk to initiate early use potentially by affecting trait-like factors of risk-taking, decision making, and behavioral control. Stressors also accelerate transition to regular use potentially due to prior effects of stress on sensitization of dopaminergic motivation systems, cross-sensitizing with substances of abuse, especially in people with high trait impulsivity who are more prone to sensitization. Finally, stressors increase risk for abuse and dependence, attenuate motivation to quit, and increase relapse risk potentially by intensified sensitization of motivational systems, by a shift from positive to negative reinforcement due to sensitization of the amygdala by corticotropin releasing factor, and by increased sensitization of noradrenergic systems. Stress generally affects addiction illness-course across stressor types and across classes of substances of abuse.