Endogenous opioids inhibit ambulatory blood pressure during naturally occurring stress

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.

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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.

Current Options for the Pharmacotherapy of Obesity

650 millions of adults are obese worldwide - in the US alone, forty percent of the adults are obese. Although the obesity pandemic is constantly expanding at very high costs for health care systems, the currently available options of pharmacotherapy for obesity are rather limited. Despite intensive research efforts, the vast majority of the anti-obesity drugs developed up to now have a rather limited efficacy and/or safety profile. In the last fifty years, various drugs reached advanced states of clinical development but were either never marketed or were initially approved but withdrawn later due to safety issues. However, the understanding of the pathophysiology of obesity has been steadily improving and new, promising drugs targeting various selective obesityassociated and energy-homeostasis-related pathways are now available. When lifestyle changes alone fail to combat, then additional pharmacotherapy with an acceptable efficacy and safety profile could provide a useful therapeutic option.

Stress and drug-cue-induced craving in opioid-dependent individuals in naltrexone treatment

BACKGROUND

Naltrexone is a nonaddictive medication that blocks the euphoric effects of opioids. However, naltrexone treatment is associated with high rates of noncompliance and opioid relapse, possibly because it does not reduce stress and protracted withdrawal symptoms during early recovery. Prior clinical and preclinical research has indicated that both stress and drug-cue-related arousal response is associated with craving and vulnerability to relapse in a range of drug-using populations.

AIMS

To examine opioid craving and the subjective and cardiovascular response to stress and drug cues in naltrexone-treated opioid abusers.

METHOD

Eleven men and three women engaged in naltrexone treatment for opioid dependence. They were exposed to personalized stress, drug-cue, and neutral-relaxing imagery in a single laboratory session. Subjective (craving, emotion) and cardiovascular (heart rate, systolic blood pressure, and diastolic blood pressure) measures were assessed.

RESULTS

Stress and drug-cue-related imagery significantly increased opioid craving, anxiety, and negative emotions and significantly decreased positive emotions compared to neutral imagery. Selective emotional responses were greater in the stress condition than in the drug-cue condition. Only stress-related imagery was associated with an increased cardiovascular response.

CONCLUSIONS

Naltrexone-treated opioid abusers demonstrate vulnerability to stress and drug-cue-induced craving and arousal responses that may contribute to the high rates of noncompliance and relapse among opioid-dependent individuals undergoing naltrexone treatment. Pharmacological and behavioral interventions that specifically target the negative affectivity that co-occurs with drug-cue and stress-induced craving could be of benefit in improving naltrexone treatment outcomes in opioid dependence.

Trait anger and blood pressure recovery following acute pain: evidence for opioid-mediated effects

Previous work has suggested that positive associations between trait anger (TRANG) and pain sensitivity are due to dysfunctional endogenous opioid analgesic systems. In this study, we examined whether TRANG is associated with impaired opioid modulation of blood pressure (BP) recovery. A total of 46 pain-free normotensive controls and 69 normotensive chronic low back pain (LBP) sufferers received opioid blockade (8 mg naloxone i.v.) or placebo in randomized, counterbalanced order in separate sessions. During each, participants underwent a 1-min finger pressure pain task followed by an ischemic forearm pain task. Opioid blockade impaired post-pain BP recovery in controls but not LBP participants (ps < .001). In controls, low TRANG was associated with blockade-induced recovery impairments, with no blockade effect in high TRANG participants. In LBP participants, blockade did not alter recovery regardless of TRANG (interaction ps < .05). Results support dysfunctional opioid modulation of BP recovery in healthy high TRANG controls and further suggest chronic pain-related impairments in opioid-mediated cardiovascular recovery.

Opioid analgesia in persons at risk for hypertension

OBJECTIVE

Acute pain sensitivity is reduced in clinical hypertension, but the precise relationship between pain perception and altered blood pressure control is not well-characterized. A negative correlation between resting blood pressure and pain sensitivity is observed throughout the normotensive range, suggesting links between basic mechanisms of blood pressure control and pain regulation. The opioid peptides are important endogenous analgesic mechanisms, but their role in the hypoalgesia of blood pressure elevations has not been well-established. The current study sought to examine the effects of endogenous opioids on blood pressure-associated hypoalgesia in young adults at risk for hypertension development.

METHODS

The effects of the opioid receptor antagonist, naltrexone, on cold pressor pain sensitivity were assessed in young adult men (n = 49) and women (n = 76) with mildly elevated casual blood pressure.

RESULTS

Results indicate interactions between hypertension risk and the effects of opioid blockade on pain sensitivity.

CONCLUSIONS

These findings suggest exaggerated opioid analgesia in persons at enhanced risk for hypertension and point to important links between altered neuropeptide regulation of pain and altered blood pressure control mechanisms in the early stages of hypertension.

Anger management style, blood pressure reactivity, and acute pain sensitivity: evidence for "Trait x Situation" models

BACKGROUND

Anger management style is related to acute and chronic pain, but it is not clear whether anger arousal is needed for these associations to emerge or whether physiological mechanisms mediate these links.

PURPOSE

"Trait x Situation" models were examined to determine whether relationships between anger-out and pain and anger-in and pain depended on anger provocation's preceding pain induction and whether pain sensitivity variance explained by anger management style overlapped with variance in harassment-induced blood pressure reactivity.

METHODS

Healthy individuals (N = 53) underwent either mental arithmetic with harassment and then a cold pressor (MA/CP) or vice versa (CP/MA). The Spielberger Anger Expression Inventory assessed anger-out using the Anger-Out subscale (AOS) and anger-in using the Anger-In subscale (AIS).

RESULTS

AOS x Order and AIS x Order interactions for pain tolerance emerged, such that (a) AOS was related negatively to tolerance among MA/CP participants, whereas AOS and tolerance were not related in CP/MA; (b) AIS was related positively to tolerance in MA/CP, whereas AIS was related negatively to tolerance in CP/MA; and (c) tolerance variance accounted for by AOS in MA/CP overlapped substantially with tolerance variance accounted for by diastolic blood pressure reactivity.

CONCLUSIONS

Findings support the notion that anger management style affects pain and are consistent with evidence that deficient endogenous opioid functioning may be one mechanism through which anger-out is linked to both pain sensitivity and cardiovascular stress reactivity, a connection that appears most reliably when anger is provoked.

Sex differences in pain and hypothalamic-pituitary-adrenocortical responses to opioid blockade

OBJECTIVE

Sex differences in pain sensitivity and stress reactivity have been well documented. Little is known about the role of the endogenous opioid system in these differences. This study was conducted to compare adrenocortical, pain sensitivity, and blood pressure responses to opioid blockade using naltrexone in men and women.

METHODS

Twenty-six participants completed 2 sessions during which placebo or 50 mg of naltrexone was administered, using a double-blind, counterbalanced design. Thermal pain threshold and heat tolerance were assessed. Participants also rated pain during a 90-second cold pressor test (CPT) and completed the McGill Pain Questionnaire (MPQ) after each pain challenge. Blood and saliva samples and cardiovascular and mood measures were obtained throughout the sessions.

RESULTS

Plasma cortisol, adrenocorticotropin, beta endorphin, prolactin, and salivary cortisol levels increased similarly in men and women after naltrexone administration compared with placebo. Women reported more pain during both pain procedures and had lower thermal pain tolerance. In response to naltrexone, women exhibited reduced blood pressure responses and reduced MPQ pain ratings after CPT. No effects of naltrexone on these measures were found in men.

CONCLUSIONS

Although men and women exhibited similar hormonal responses to opioid receptor blockade, women reported less pain and showed smaller blood pressure responses during CPT. Results suggest differential effects of the endogenous opioid system on pain perception and blood pressure in men and women.

Emotion induction moderates effects of anger management style on acute pain sensitivity

Anger management style (AMS) is related to both acute and chronic pain intensity. Recent work suggests that an anger expressive AMS in particular may influence acute pain, and that this effect may be most pronounced during anger provocation. The present study examined whether AMS was related to subsequent pain sensitivity without regard to prior emotion induction, only when a strong negative emotion was evoked, or only when anger was provoked. Sixty-four healthy normals partook in semi-structured interviews in which they recalled and verbally described an event in which either anger, sadness, or joy was elicited. They then underwent a cold pressor pain task. Results of hierarchical multiple regressions showed that an anger expressive AMS was related positively to pain threshold only for participants in the anger-recall condition, and that this effect was largely accounted for by their low SBP reactivity during emotion induction. An anger suppressive AMS was related positively to increases in self-reported pain severity, irrespective of emotion-induction condition, and this effect was not accounted for by reactivity in any cardiovascular index. Results extend those of previous studies by illuminating the potential importance of behavioral anger expression for individuals prone to express anger in modulating their reactivity and pain sensitivity. Findings suggest that the detrimental effects of an anger expressive style on pain sensitivity may be ameliorated under conditions in which behavioral anger expression occurs. Results are discussed in terms of recent work suggesting that an expressive AMS is associated with endogenous opioid dysfunction in the absence of behavioral anger expression.

Cardiovascular reactivity: status quo and a research agenda for the new millennium

This article introduces a series of articles that assess the present status of the cardiovascular reactivity construct as well as the progress that has been made since a critical review of the reactivity literature by Pickering and Gerin was published in 1990.

Psychophysiological reactivity in female sexual abuse survivors

This study examined psychophysiological reactivity in 37 female childhood sexual abuse (CSA) survivors. After assessment of posttraumatic stress disorder (PTSD), psychiatric comorbidity, and trauma history, we conducted a psychophysiological assessment of forehead muscle tension, electrodermal activity, and heart rate during a mental arithmetic task and4 script-driven imagery tasks (neutral, consensual sex, pleasant, and trauma). PTSD symptom severity correlated positively with psychophysiologic changes and negative emotions during the trauma imagery task. During mental arithmetic, PTSD symptom severity correlated negatively with autonomic changes and positively with negative emotions. These results extend earlier PTSD research showing trauma-specific increased psychophysiological reactivity related to CSA in women with PTSD. They further suggest a negative association between PTSD severity and autonomic reactions to mental arithmetic.

Endogenous opiates: 1998

This paper is the twenty-first installment of our annual review of research concerning the opiate system. It summarizes papers published during 1998 that studied the behavioral effects of the opiate peptides and antagonists, excluding the purely analgesic effects, although stress-induced analgesia is included. The specific topics covered this year include stress; tolerance and dependence; eating and drinking; alcohol; gastrointestinal, renal, and hepatic function; mental illness and mood; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurologic disorders; electrical-related activity; general activity and locomotion; sex, pregnancy, and development; immunologic responses; and other behaviors.

Ambulatory blood pressure responses and the circumplex model of mood: a 4-day study

BACKGROUND

The relation between mood or emotions and concurrent ambulatory blood pressure responses holds both fundamental and clinical interest.

METHODS

The primary sample consisted of 69 normotensive or borderline hypertensive but otherwise healthy adult males. The validation sample consisted of 85 healthy male undergraduate college students. Both samples underwent half-hourly 24-hour ambulatory blood pressure measurements on four separate workdays, 1 week apart. At each ambulatory measurement, subjects recorded their behavior, environment, and mood. The circular mood scale, a circular visual analogue scale based on the circumplex model of mood, was used to reflect the totality of a participant's affective state space. Longitudinal random effects regression models were applied in the data analysis.

RESULTS

The results for both samples were quite similar. Sleep and posture had the greatest influence on ambulatory blood pressure and heart rate. The effects of the environmental setting, social setting, and consumption were modest but statistically significant. Independent of these covariates, mood exerted a significant effect on blood pressure and heart rate. Relative to the "mellow" default category, blood pressure increased both for "anxious/annoyed" and "elated/happy" and decreased during "disengaged/sleepy" mood. The range of mood-related blood pressure estimates was 6.0/3.7 mm Hg.

CONCLUSIONS

The pattern of blood pressure responses suggests that they were related to the degree of engagement of a mood rather than the degree of unpleasantness. The hypothesis that posits that negative affect-related cardiovascular reactivity mediates the observed correlation between negative affect and disease risk should be reconsidered.