Influence of beta-Endorphin on anxious behavior in mice: interaction with EtOH

Associations of physical activity and mental health in pregnant women: A cross-sectional isotemporal substitution analysis

BACKGROUND

Prenatal mental health is an increasing public concern. At present, it has been shown that increasing physical activity (PA) is effective in promoting mental health of pregnant women. However, mental health may depend not only on the amount of time spent on a specific activity, but also on the intensity and type of the activity that it replaces. This study is aimed to explore the impact of replacing 60 min of one health behavior with another on the mental health of pregnant women.

METHODS

The cross-sectional study recruited 983 pregnant women from Chongqing, China between June and December 2021. The pregnant women self-reported their movement behaviors using the Pregnancy Physical Activity Questionnaire-Chinese version (PPAQ-C). Participants also completed three measures of mental health: Childbirth Attitudes Questionnaire (CAQ), 9-item Patient Health Questionnaire (PHQ-9) and the Positive affect sub-scale. An Isotemporal Substitution Model was used to evaluate mental health after replacing one movement behavior.

RESULTS

The analysis showed that replacing 60 min of sedentary behavior (SB) with moderate-to-vigorous intensity PA (MVPA) promoted positive emotions, and replacing SB with light intensity PA (LPA) reduced childbirth fear. Regarding PA types, replacing inactivity with household, occupational, or transport PA could reduce fear, and replacing inactivity, occupational, household or transport PA with sport PA could improve positive emotions and alleviate depression.

CONCLUSION

An active pregnancy lifestyle with higher levels of moderate-to-vigorous physical activity and light physical activity and less sedentary behavior time and other inactive states may improve mental health. Future health promotion for pregnant women should consider the flexibility of physical activity types and intensities.

β-Endorphin influences sedative and ataxic effects of alcohol

Beta-endorphin (β-E) is an opioid peptide linked to the behavioral effects of ethanol. For example, β-E provides negative feedback to inhibit the hypothalamic-pituitary-adrenal (HPA) stress axis, and neuroadaptation of this system to ethanol may facilitate sex differences in disordered drinking. Locomotor sensitivity to ethanol may also influence the risk for addiction; however, the role of β-E in psychomotor effects of ethanol is not fully understood. We examined the role of β-E and sex on locomotor effects of ethanol using adult male and female wild-type C57BL/6J and β-E deficient B6.129S2-Pomctm1Low/J mice in a parallel rod floor apparatus following 0.75 or 2.0 g/kg ethanol. Beginning 15 min after intraperitoneal injection, we recorded foot slips, distance traveled, slips per meter, first instance of immobility, and total time spent off-balance (lying on the floor) over 15 min, and collected blood for analysis of ethanol concentration 60 min after injection. Overall, β-E deficient mice were more sedated and ataxic following ethanol; at the lower dose they slipped more frequently and had a higher rate of slips per meter traveled. At the higher dose, β-E deficient mice were predominantly sedated, slipping less frequently, and traveling less, as well as spending more time off-balance and becoming immobile sooner. Genotype interacted with sex in that male β-E deficient mice slipped more frequently than their female counterparts, suggesting that β-E may elicit sex-dependent effects of ethanol-induced ataxia. Blood ethanol concentration did not differ between any group, suggesting that behavioral differences result from altered sensitivity to ethanol. Our data support the contention that β-E modulates the locomotor effects of ethanol and may influence ataxia in a sex-dependent manner. These findings help elucidate the role of β-E in diverging behavioral responses to ethanol and may aid the development of targeted treatments for alcohol use disorders.

β-Endorphin (an endogenous opioid) inhibits inflammation, oxidative stress and apoptosis via Nrf-2 in asthmatic murine model

Asthma, a chronic respiratory disease is characterized by airway inflammation, remodelling, airflow limitation and hyperresponsiveness. At present, it is considered as an umbrella diagnosis consisting several variable clinical presentations (phenotypes) and distinct pathophysiological mechanisms (endotypes). Recent evidence suggests that oxidative stress participates in airway inflammation and remodelling in chronic asthma. Opioids resembled by group of regulatory peptides have proven to act as an immunomodulator. β-Endorphin a natural and potent endogenous morphine produced in the anterior pituitary gland play role in pain modulation. Therapeutic strategy of many opioids including β-Endorphin as an anti‑inflammatory and antioxidative agent has not been yet explored despite its promising analgesic effects. This is the first study to reveal the role of β-Endorphin in regulating airway inflammation, cellular apoptosis, and oxidative stress via Nrf-2 in an experimental asthmatic model. Asthma was generated in balb/c mice by sensitizing with 1% Toulene Diisocyanate on day 0, 7, 14 and 21 and challenging with 2.5% Toulene Diisocyanate from day 22 to 51 (on every alternate day) through intranasal route. β-Endorphin (5 µg/kg) was administered through the nasal route 1 h prior to sensitization and challenge. The effect of β-Endorphin on pulmonary inflammation and redox status along with parameters of oxidative stress were evaluated. We found that pre-treatment of β-Endorphin significantly reduced inflammatory infiltration in lung tissue and cell counts in bronchoalveolar lavage fluid. Also, pre-treatment of β-Endorphin reduced reactive oxygen species, Myeloperoxidase, Nitric Oxide, Protein and protein carbonylation, Glutathione Reductase, Malondialdehyde, IFN-γ, and TNF-α. Reversely, β-Endorphin significantly increased Superoxide dismutase, Catalase, glutathione, Glutathione-S-Transferase, and activation of NF-E2-related factor 2 (Nrf-2) via Kelch-like ECH-associated protein 1 (Keap1), independent pathway in the lung restoring architectural alveolar and bronchial changes. The present findings reveal the therapeutic potency of β-END in regulating asthma by Keap-1 independent regulation of Nrf-2 activity. The present findings reveal the therapeutic potency of β-Endorphin in regulating asthma.

Age, β-endorphin, and sex dependent effects of maternal separation on locomotor activity, anxiety-like behavior, and alcohol reward

Introduction

Childhood adversity is pervasive and linked to numerous disadvantages in adulthood, including physical health problems, mental illness, and substance use disorders. Initial sensitivity to the rewarding effects of alcohol predicts the risk of developing an alcohol use disorder, and may be linked to developmental stress. The opioid peptide β-endorphin (β-E) regulates the stress response and is also implicated in the risk for excessive alcohol consumption.

Methods

We explored the influence of β-E in an animal model of early life adversity using controlled maternal separation by evaluating changes in locomotor activity, anxiety-like behavior, and the initial rewarding effects of alcohol in a single exposure conditioned place preference paradigm in control C57BL/6J and β-E deficient β-E +/+ 0.129S2-Pomc tm1Low/J; β-E −/− mice. Maternal separation (MS) occurred for 3 h each day from post-natal days (PND) 5–18 in approximately half the subjects.

Results

Maternal interactions increased following the separation protocol equally in both genotypes. MS and control subjects were tested as adolescents (PND 26–32) or adults (PND 58–72); the effects of MS were generally more pronounced in older subjects. Adults were more active than adolescents in the open field, and MS decreased activity in adolescent mice but increased it in adults. The increase in adult activity as a result of early life stress depended on both β-E and sex. β-E also influenced the effect of maternal separation on anxiety-like behavior in the Elevated Plus Maze. MS promoted rewarding effects of alcohol in male β-E deficient mice of either age, but had no effect in other groups.

Discussion

Taken together, these results suggest that the effects of MS develop over time and are β-E and sex dependent and may aid understanding of how individual differences influence the impact of adverse childhood experiences.

Depression, Anxiety and Antidepressants and Anxiolytics Use in Spanish Informal Caregivers according to the Physical Activity Frequency: EHSS 2014–2020

Depression and anxiety are two of the most common mental diseases both in formal and nonformal caregivers. Physical activity during leisure time seems to have benefits on their practitioner’s mental health. This study aimed to analyze the associations between physical activity frequency (PAF) and depression and anxiety status, as well as antidepressant and anxiolytic use in Spanish nonformal caregivers. A cross-sectional study with data from the 2014 and 2020 European Health Interview Surveys in Spain (EHSS) including 4520 Spanish nonformal caregivers was carried out. The PAF was found to be related to depression and anxiety, as well as antidepressants and anxiolytics use (p < 0.001), with the highest proportions of these variables found in the inactive population (p < 0.05), while the active and very active populations showed the lowest proportions (p < 0.05). Weak but statistically significant correlations were found between all variables of interest (p < 0.001). Being female, older, and dedicating more hours per week to caregiving and caring for nonfamily members were found to have increased risks of depression, anxiety and antidepressants or anxiolytics use. Nonformal caregivers who were not physically active during their leisure time had higher mental disorders and psychotropic drug use proportions than the active and very active caregivers. Thus, increasing nonformal caregivers’ PAF could be a protective tool.

Protective Role and Functional Engineering of Neuropeptides in Depression and Anxiety: An Overview

Behavioral disorders, such as anxiety and depression, are prevalent globally and touch children and adults on a regular basis. Therefore, it is critical to comprehend how these disorders are affected. It has been demonstrated that neuropeptides can influence behavior, emotional reactions, and behavioral disorders. This review highlights the majority of the findings demonstrating neuropeptides' behavioral role and functional engineering in depression and anxiety. Gut-brain peptides, hypothalamic releasing hormone peptides, opioid peptides, and pituitary hormone peptides are the four major groups of neuropeptides discussed. Some neuropeptides appear to promote depression and anxiety-like symptoms, whereas others seem to reduce it, all depending on the receptors they are acting on and on the brain region they are localized in. The data supplied here are an excellent starting point for future therapy interventions aimed at treating anxiety and depression.

Nonpharmacological interventions for subthreshold depression in adults: A systematic review and network meta-analysis

Subthreshold depression (StD) is very common, with an estimated global incidence of 25%, and is associated with other clinical conditions. Nonpharmacological interventions have been demonstrated to be effective, but which one is best should be further investigated. This study aims to compare and rank the efficacy of nonpharmacological interventions in adults with StD. Ten databases were searched, and comparisons were made using a random-effects network meta-analysis using the frequentist framework. The assumption of local consistency was assessed by using the node-splitting method. The surface under the cumulative ranking curve (SUCRA) was used to separately rank each intervention. A total of 32 randomized controlled trials (RCTs) were included. The results showed that psychotherapy, as an intervention class, had significantly positive effects compared to control groups (SMD = -0.78, 95% CI: -1.06, -0.49) and had the highest rank (SUCRA, 79.0%; mean rank, 1.6). Cognitive behavioral therapy (CBT), as an individual intervention, had significantly positive effects relative to all control groups and had the highest rank (SUCRA, 82.5%; mean rank, 3.1). We speculate that psychotherapy, especially CBT, may be the most effective nonpharmacological intervention to improve StD in adults. More RCTs examining the efficacy of different nonpharmacological interventions are needed.

Evidence of alterations of Beta-endorphin levels and Mu-opioid receptor gene expression in bipolar disorder

Despite the well-recognized effects of endogenous opioids on mood and behavior, research on its role in bipolar disorder (BD) is still limited to small or anecdotal reports. Considering that Beta-endorphins (β-END) and Mu-opioid receptors (MOR), in particular, have a crucial activity in affective modulation, we hypothesized their alteration in BD. A cross-sectional study was conducted. We compared: (1) BD type I (BD-I) patients (n = 50) vs healthy controls (n = 27), (2) two BD-I subject subgroups: manic (MAN; n = 25) vs depressed (DEP; n = 25) subjects. Plasma levels of β-END and MOR gene expression in peripheral blood mononuclear cells were analyzed using ELISA Immunoassay qRT-PCR. We found that subjects with BD exhibited a significant upregulation of MOR gene expression and a decrease of β-END (p<0.0001 for both). MAN display higher MOR levels than DEP (p<0.001) and HC (p<0.0001). Plasma levels of β-END were lower in DEP compared to MAN (p<0.05) and HC (p<0.0001). The main limitations are the cross-sectional design and the lack of a group of euthymic subjects. Although preliminary, our results suggest a dysregulation of the endogenous opioid systems in BD. In particular, both MAN and DEP showed a reduction of β-END levels, whereas MAN was associated with MOR gene overexpression.

The Interaction Between POMC rs2071345 Polymorphism and Alcohol Dependence in Anxiety Symptoms Among Chinese Male Problem Drinkers

OBJECTIVE

Alcohol dependence can increase the level of anxiety. A growing body of research has identified a link between anxiety symptoms of problem drinkers and their genetic or environment factors, respectively. However, to date few studies have directly examined gene-environment (G × E) interaction on their anxiety symptoms during the acute alcohol withdrawal. The present study aims to examine the interaction between the proopiomelanocortin (POMC) rs2071345 polymorphism and alcohol dependence on anxiety symptoms of male problem drinkers, and further test the exact form of interaction on two competing models: the diathesis-stress model vs. the differential susceptibility model.

METHODS

A total of 440 male problem drinkers (M age = 44.5 years, SD = 9.45) were recruited from nine main psychiatric hospitals of northern China during acute alcohol withdrawal. Blood samples were collected for genotyping, self-reported anxiety symptoms, and levels of alcohol dependence were assessed.

RESULTS

Results indicated that the POMC rs2071345 polymorphism significantly moderated anxiety symptoms associated with alcohol dependence. A region of significance (RoS) test showed that male problem drinkers with T allele were more likely to experience more anxiety symptoms than those with CC homozygote when the standardized score of concurrent alcohol dependence was above 0.31. Confirmatory model evaluation indicated that the interaction effect involving POMC gene polymorphism conformed to the diathesis-stress model rather than differential-susceptibility model of person × environment interaction.

CONCLUSIONS

This study suggested that the SNP in POMC rs2071345 was associated with alcohol dependence in anxiety symptoms of male problem drinkers and further provided evidence in support of the diathesis-stress hypothesis of alcohol dependence in terms of anxiety symptoms.

Effects of exercise training on depression and anxiety with changing neurotransmitters in methamphetamine long term abusers: A narrative review

Study aim: It is generally accepted that methamphetamine (MA) is a highly addictive psychostimulant which copies functions of certain neurotransmitters in the brain, and emits dopamine and serotonin in the brain. Frequent abuse of methamphetamine damages dopaminergic and serotonergic nerve endings at different sites of brain and also increases the anxiety and depression. Exercise seems to reverse physiological and neurological damages due to previous MA dependents and help to reduce anxiety and depression in this population. The aim is to determine the effect of exercise training on neurotransmitters and rate of depression and anxiety in chronic methamphetamine abusers based on a literature review.

Materials and methods: The present study investigated published articles in five computerized databases including Magiran, Google scholars, SID, PubMed and Scopus from 2011 until 2020. The searched keywords included sports, neurotransmitter, methamphetamine, depression, anxiety and treatment. The obtained results were described using texts, table and figure.

Results: According to the results, physical activity and exercise significantly increased blood serotonin and dopamine levels and significantly decreased the depression and anxiety.

Conclusion: Different evidences suggested that physical activity and exercise as positive responses and adaptations might influence on circulatory levels of two neurotransmitters (serotonin and dopamine) in methamphetamine addicts, decrease anxiety and depression, and improve preparation in previous MA dependents. In the rehabilitation period, the overall improvement in previous MA dependents might significantly increase. Exercise training can improve the physical and mental state of people addicted to methamphetamine as a non-drug therapy to promote health. However, more research is necessary to support this conclusion.

Effects of Compost-Bedded Pack Barn on Circulating Cortisol and Beta-Endorphins in Dairy Cows: A Case Study

Simple Summary

Management and housing conditions have been reported to significantly affect the health and welfare of livestock species. Therefore, the adoption of novel, alternative housing systems (such as the compost-bedded pack barn, developed in the USA) requires extensive research to assess the implications for animal welfare. From a general point of view, animal welfare is typically assessed by means of animal-based (such as blood biochemical markers) and resource-based (such as management practices) indicators. Based on such considerations, the present study evaluated the fluctuation of circulating cortisol and beta-endorphins in dairy cows housed in a conventional freestall barn (FB) and in the alternative compost-bedded pack barn (CB). The results obtained suggest that the CB housing system did not elicit significant changes in either blood cortisol or beta-endorphins.

Abstract

The up-to-date literature suggests that the compost-bedded pack barn housing system is capable of remarkably improving productive and reproductive performance, as well as health status and welfare, in dairy cattle. However, there is currently limited knowledge available on the endocrine and biochemical changes in animals housed in such alternative systems. Therefore, this study aimed to measure blood cortisol (COR) and beta-endorphins (BE) in 22 two-year-old primiparae Fleckvieh cows, who were randomly allotted to the following two different housing systems: CB (n = 11) and FB (n = 11). Blood samples were collected at the beginning of the experiment (T0) and every two months thereafter (T1, T2, and T3). The COR and BE were measured through an immunoenzymatic kit. With the only exception being T0, no differences were observed over time between the two groups, neither for COR nor for BE. However, the blood cortisol levels of the CB cows decreased over time, while a T1 peak was identified in the FB group. On the contrary, both the housing systems displayed numerically higher BE at T3 than at the other experimental times. Therefore, the overall data suggest that the compost-bedded pack barn did not significantly affect the studied parameters. Accordingly, cow welfare should be assessed using a wider panel of animal-based indicators.

Potential for Kappa-Opioid Receptor Agonists to Engineer Nonaddictive Analgesics: A Narrative Review

A serious adverse effect of prescription opioid analgesics is addiction, both to these analgesics and to illicit drugs like heroin that also activate the µ-opioid receptor (MOR). Opioid use disorder (OUD) and opioid overdose deaths represent a current American health crisis, and the prescription of opioid analgesics has contributed significantly to this crisis. While prescription opioids are highly effective analgesics, there currently exists no facile way to use them for extended periods without the risk of addiction. If addiction caused by MOR-targeting analgesics could be blocked by blending in a new "antiaddiction" ingredient that does not diminish analgesia and does not introduce its own therapeutically limiting side effects, then continued clinical use of prescription opioids for treating pain could be maintained (or even enhanced) instead of curtailed. In this narrative review, we contextualize this hypothesis, first with a brief overview of the current American opioid addiction crisis. The neurobiology of 2 key receptors in OUD development, MOR and the κ-opioid receptor (KOR), is then discussed to highlight the neuroanatomical features and circuitry in which signal transduction from these receptors lie in opposition-creating opportunities for pharmacological intervention in curtailing the addictive potential of MOR agonism. Prior findings with mixed MOR/KOR agonists are considered before exploring new potential avenues such as biased KOR agonists. New preclinical data are highlighted, demonstrating that the G protein-biased KOR agonist nalfurafine reduces the rewarding properties of MOR-targeting analgesics and enhances MOR-targeting analgesic-induced antinociception. Finally, we discuss the recent discovery that a regulator of G protein signaling (namely, RGS12) is a key component of signaling bias at KOR, presenting another drug discovery target toward identifying a single agent or adjuvant to be added to traditional opioid analgesics that could reduce or eliminate the addictive potential of the latter drug.

Lowered endogenous mu-opioid receptor availability in subclinical depression and anxiety

Major depressive disorder is associated with lowered mood, anxiety, anhedonia, sleep problems, and cognitive impairments. Many of these functions are regulated by μ-opioid receptor (MOR) system. Preclinical, in vivo, and post-mortem studies have however yielded inconclusive results regarding the role of the MOR in depression and anxiety. Moreover, it is not known whether alterations in MOR are already present in subclinical depression and anxiety. In a large-scale retrospective cross-sectional study we pooled data from 135 (113 males and 22 females) healthy subjects whose brain's MOR availability was measured with positron emission tomography (PET) using an agonist radioligand [11C]carfentanil that has high affinity for MORs. Depressive and anxious symptomology was addressed with BDI-II and STAI-X questionnaires, respectively. Both anxiety and depression scores in the subclinical range were negatively associated with MOR availability in cortical and subcortical areas, notably in amygdala, hippocampus, ventral striatum, and orbitofrontal and cingulate cortices. We conclude that dysregulated MOR availability is involved in altered mood and pathophysiology of depression and anxiety disorders.

Ketamine Blocks Morphine-Induced Conditioned Place Preference and Anxiety-Like Behaviors in Mice

Patients suffering from opioid use disorder often relapse during periods of abstinence, which is posited to be caused by negative affective states that drive motivated behaviors. Here, we explored whether conditioning mice with morphine in a conditioned place preference (CPP) training paradigm evoked anxiety-like behavior during morphine abstinence. To do this, mice were conditioned with morphine (10 mg/kg, i.p.) for 5 days. Twenty-four hours following conditioning, anxiety levels were tested by measuring time in the open arms of the elevated plus-maze. The next day, mice were placed in the three-compartment chamber to measure morphine-induced CPP. Our results show that following morphine conditioning, mice spent significantly less time in the open arm of the elevated plus-maze and expressed robust morphine CPP on CPP test day. Furthermore, we found that an acute treatment with (R,S)-ketamine (10 mg/kg, i.p.), a medication demonstrating promise for preventing anxiety-related phenotypes, 30 min before testing on post-conditioning day 1, increased time spent in the open arm of the elevated plus-maze in saline- and morphine-conditioned mice. Additionally, we found that the second injection of ketamine 30 min before CPP tests on post-conditioning day 2 prevented morphine-induced CPP, which lasted for up to 28 days post-conditioning. Furthermore, we found that conditioning mice with 10% (w/v) sucrose using an oral self-administration procedure did not evoke anxiety-like behavior, but elicited robust CPP, which was attenuated by ketamine treatment 30 min before CPP tests. Overall, our results suggest that the ketamine-induced block of morphine CPP may not be attributed solely to alleviating negative affective states, but potentially through impaired memory of morphine-context associations.

Experimental alcoholism primes structural and functional impairment of the glymphatic pathway

Alcoholism is a risk factor for the development of cognitive decline and dementia. Here we demonstrated that the glymphatic function in the brain was impaired by alcohol administration. Acute moderate alcohol administration substantially retarded and reduced the entry of subarachnoid cerebrospinal fluid (CSF) via the paravascular space into the cerebral parenchyma, thus impaired CSF-interstitial fluid (ISF) exchange and parenchymal amyloid β (Aβ) peptide clearance. The elevated release of β-endorphin and reduced cerebrovascular pulsatility after acute alcohol administration may account for the impairment of the glymphatic function. Chronic moderate alcohol consumption led to pronounced activation of astrocytes and a widespread loss of perivascular AQP4 polarization in the brain, which results in an irreversible impairment of the glymphatic function. The results of the study suggest that impaired glymphatic functions and reduced parenchymal Aβ clearance found in both acute and chronic alcohol treatment may contribute to the development of cognitive decline and dementia in alcoholism.

Impact of problematic mobile phone use and insufficient physical activity on depression symptoms: a college-based follow-up study

Background

Insufficient physical activity (IPA) and mobile phone dependence are common coexisting behaviors among college students. However, the impact of the synergies between the two behaviors on depression has yet to be validated. Therefore, this study evaluated independent and interactive associations of problematic mobile phone use (PMPU) and IPA with depression symptoms and increased depressive symptoms among Chinese college students.

Methods

In total, 2134 college students participated in this follow-up study, which was conducted between June 2014 (wave 1) and December 2014 (wave 2) at Anhui Medical University. The Self-rating Questionnaire for Adolescent Problematic Mobile Phone Use and the Center for Epidemiologic Studies Depression Scale were used to assess PMPU and depression symptoms, respectively. Physical activity (PA) was assessed with a reliable question from the Youth Risk Behavior Survey. Joint effects of PMPU and PA were calculated, and increased depressive symptoms were assessed. We used multivariable-adjusted odds ratios (OR) with 95% confidence intervals (CI) to evaluate associations between depression symptoms and PMPU, IPA, and the PMPU/IPA joint effect, estimated by binary logistic regression models.

Results

PMPU and high PMPU/IPA joint effect scores were significantly associated with depression symptoms in waves 1 (OR 7.36, 95% CI: 5.09, 10.66) and 2 (OR 3.74, 95% CI: 2.56, 5.48). IPA was significantly associated with depression symptoms in wave 1 (OR 1.40, 95% CI: 1.09, 1.79) but not wave 2 (OR 1.24, 95% CI: 0.95, 1.62). PMPU and high PMPU/IPA joint effect scores were also significantly associated with increased depressive symptoms (OR 2.36, 95% CI: 1.55, 3.60).

Conclusions

These results suggest that PMPU is an important factor for depression in college students, and IPA may be a synergistic factor.

Effect of walking on depression prevalence for diabetes using information communication technology: Prospective study

AIM

This study aimed to evaluate the prevention of diabetic depression and its impact on medical costs through the implementation of a step count monitoring system using information and communication technology.

METHODS

This study carried out a longitudinal analysis of a prospective cohort. A total of 296 participants were enrolled in the intervention group and 882 participants in the control group. The participants in the intervention group were provided with pedometers, which each participant was asked to scan using devices stationed throughout the city. Activity data were stored in real time by a cloud system. The experiment lasted 30 months.

RESULTS

None of the diabetes patients in the intervention group was diagnosed with depression during the study period, compared with 4.09% in the control group. Thus, the intervention suppressed the increase in medical costs for the people who did not develop depression in the diabetic group.

CONCLUSIONS

The prevalence rate of depression among the participants with diabetes was lowered significantly. The medical costs of the participants who did not have diabetes were also reduced by implementing the step count monitoring system with information and communication technology. This shows that the use of an information and communication technology pedometer system can have favorable effects in terms of preventing depression in diabetes patients and further benefits for non-diabetic people. Geriatr Gerontol Int 2019; 19: 1147-1152.

Evaluation of β-endorphin concentration, mood, and pain intensity in men with idiopathic hip osteoarthritis treated with variable magnetic field

Osteoarthritis is the most frequently diagnosed disease of the musculoskeletal system. Growing number of patients waiting for surgical treatment and the possible negative consequences resulting from long-term pharmacological therapy lead to the search for non-pharmacological methods aimed at alleviating pain and reducing doses of analgesics, among them physical therapy with use of magnetic fields.The study involved 30 men aged 49 to 76 (mean age, 61.7 years) treated for idiopathic osteoarthritis of the hip joint. The subjects were divided into 2 groups (15 patients each) and underwent a cycle of magnetostimulation and magnetoledtherapy procedures, respectively. During the exposure cycle concentrations of β-endorphin were assessed 3 times and the mood was assessed 2 times. In addition, the assessment of pain intensity and the dose of analgesic drugs was performed before and after the end of therapy.Statistically significant increase in plasma β-endorphins concentration was observed in both groups of patients (magnetostimulation-P < .01 vs magnetoledtherapy-P < .001). In the assessment of mood of respondents, no statistically significant differences were found. Significant reduction in intensity of perceived pain was observed in both groups of patients (P < .05). In the group of patients who underwent magnetoledtherapy cycle, the analgesic drug use was significantly lower by 13% (P < .05) as compared with initial values, which was not noted in group of patients who underwent magnetostimulation procedures.The use of magnetic field therapy in the treatment of men with idiopathic osteoarthritis of hip joints causes a statistically significant increase in the concentration of plasma β-endorphins resulting in statistically significant analgesic effect in both magnetostimulation and magnetoledtherapy treated groups of patients, with accompanying decrease of need for analgetic drugs in magnetoledtherapy group, but without any significant changes regarding the patient's mood.

Sex differences in binge-like EtOH drinking, corticotropin-releasing hormone and corticosterone: effects of β-endorphin

Binge drinking is an increasingly common pattern of risky use associated with numerous health problems, including alcohol use disorders. Because low basal plasma levels of β-endorphin (β-E) and an increased β-E response to alcohol are evident in genetically at-risk human populations, this peptide is thought to contribute to the susceptibility for disordered drinking. Animal models suggest that the effect of β-E on consumption may be sex-dependent. Here, we studied binge-like EtOH consumption in transgenic mice possessing varying levels of β-E: wild-type controls with 100% of the peptide (β-E +/+), heterozygous mice constitutively modified to possess 50% of wild-type levels (β-E +/-) and mice entirely lacking the capacity to synthesize β-E (-/-). These three genotypes and both sexes were evaluated in a 4-day, two-bottle choice, drinking in the dark paradigm with limited access to 20% EtOH. β-E deficiency determined sexually divergent patterns of drinking in that β-E -/- female mice drank more than their wild-type counterparts, an effect not observed in male mice. β-E -/- female mice also displayed elevated basal anxiety, plasma corticosterone and corticotropin-releasing hormone mRNA in the extended amygdala, and all of these were normalized by EtOH self-administration. These data suggest that a heightened risk for excessive EtOH consumption in female mice is related to the drug's ability to ameliorate an overactive anxiety/stress-like state. Taken together, our study highlights a critical impact of sex on neuropeptide regulation of EtOH consumption.

Sex and β-Endorphin Influence the Effects of Ethanol on Limbic Gabra2 Expression in a Mouse Binge Drinking Model

Binge drinking is a widespread problem linked to increased risk for alcohol-related complications, including development of alcohol use disorders. In the last decade, binge drinking has increased significantly, specifically in women. Clinically, sexually dimorphic effects of alcohol are well-characterized, however, the underlying mechanisms for these dimorphisms in the physiological and behavioral effects of alcohol are poorly understood. Among its many effects, alcohol consumption reduces anxiety via the inhibitory neurotransmitter GABA, most likely acting upon receptors containing the α-2 subunit (Gabra2). Previous research from our laboratory indicates that female mice lacking the endogenous opioid peptide β-endorphin (βE) have an overactive stress axis and enhanced anxiety-like phenotype, coupled with increased binge-like alcohol consumption. Because βE works via GABA signaling to reduce anxiety, we sought to determine whether sexually dimorphic binge drinking behavior in βE deficient mice is coupled with differences in CNS Gabra2 expression. To test this hypothesis, we used βE knock-out mice in a "drinking in the dark" model where adult male and female C57BL/6J controls (βE +/+) and βE deficient (βE -/-; B6.129S2-Pomc^tm1Low/J) mice were provided with one bottle of 20% ethanol (EtOH) and one of water (EtOH drinkers) or two bottles of water (water drinkers) 3 h into the dark cycle for four consecutive days. Following a binge test on day 4, limbic tissue was collected and frozen for subsequent qRT-PCR analysis of Gabra2 mRNA expression. Water-drinking βE +/+ females expressed more Gabra2 in central nucleus of the amygdala and the bed nucleus of the stria terminalis than males, but this sex difference was absent in the βE -/- mice. Genotype alone had no effect on alcohol consumption or drug-induced increase in Gabra2 expression. In contrast, βE expression had bi-directional effects in females: in wildtypes, Gabra2 mRNA was reduced by binge EtOH consumption, while EtOH increased expression in βE -/- females to levels commensurate with drug-naïve βE +/+ females. These results support the contention that βE plays a role in sexually dimorphic binge-like EtOH consumption, perhaps through differential expression of GABA_A α2 subunits in limbic structures known to play key roles in the regulation of stress and anxiety.

Opioidergic Regulation of Emotional Arousal: A Combined PET–fMRI Study

Emotions can be characterized by dimensions of arousal and valence (pleasantness). While the functional brain bases of emotional arousal and valence have been actively investigated, the neuromolecular underpinnings remain poorly understood. We tested whether the opioid and dopamine systems involved in reward and motivational processes would be associated with emotional arousal and valence. We used in vivo positron emission tomography to quantify μ-opioid receptor and type 2 dopamine receptor (MOR and D2R, respectively) availability in brains of 35 healthy adult females. During subsequent functional magnetic resonance imaging carried out to monitor hemodynamic activity, the subjects viewed movie scenes of varying emotional content. Arousal and valence were associated with hemodynamic activity in brain regions involved in emotional processing, including amygdala, thalamus, and superior temporal sulcus. Cerebral MOR availability correlated negatively with the hemodynamic responses to arousing scenes in amygdala, hippocampus, thalamus, and hypothalamus, whereas no positive correlations were observed in any brain region. D2R availability—here reliably quantified only in striatum—was not associated with either arousal or valence. These results suggest that emotional arousal is regulated by the MOR system, and that cerebral MOR availability influences brain activity elicited by arousing stimuli.

Indoor tanning bed use and risk of food addiction based on the modified Yale Food Addiction Scale

The popularity of indoor tanning may be partly attributed to the addictive characteristics of tanning for some individuals. We aimed to determine the association between frequent indoor tanning, which we view as a surrogate for tanning addiction, and food addiction. A total of 67,910 women were included from the Nurses’ Health Study II. In 2005, we collected information on indoor tanning during high school/college and age 25-35 years, and calculated the average use of indoor tanning during these periods. Food addiction was defined as ≥3 clinically significant symptoms plus clinically significant impairment or distress, assessed in 2009 using a modified version of the Yale Food Addiction Scale. Totally 23.3% (15,822) of the participants reported indoor tanning at high school/college or age 25-35 years. A total of 5,557 (8.2%) women met the criteria for food addiction. We observed a dose–response relationship between frequency of indoor tanning and the likelihood of food addiction (P_trend < 0.0001), independent of depression, BMI, and other confounders. Compared with never indoor tanners, the odds ratio (95% confidence interval) of food addiction was 1.07 (0.99-1.17) for average indoor tanning 1-2 times/year, 1.25 (1.09-1.43) for 3-5 times/year, 1.34 (1.14-1.56) for 6-11 times/year, 1.61 (1.35-1.91) for 12-23 times/year, and 2.98 (1.95-4.57) for 24 or more times/year. Frequent indoor tanning before or at early adulthood is associated with prevalence of food addiction at middle age. Our data support the addictive property of frequent indoor tanning, which may guide intervention strategies to curb indoor tanning and prevent skin cancer.

β-endorphin regulates alcohol consumption induced by exercise restriction in female mice

Animal models have long been used to study the mechanisms underlying the complex association between alcohol and stress. Female mice prevented from running on a home-cage activity wheel increase voluntary ethanol consumption. β-endorphin is an endogenous opioid involved in negatively regulating the stress response and has also been implicated in the risk for excessive drinking. The present study investigates the role of β-endorphin in moderating free-choice consumption of ethanol in response to a blocked activity wheel. Female, transgenic mice with varying levels of the opioid peptide were given daily 2-h access to 20% ethanol with rotations on a running wheel blocked on alternate days. Subjects with low β-endorphin exhibited enhanced stress sensitivity by self-administering larger quantities of ethanol on days when wheel running was prevented. β-endorphin levels did not influence voluntary activity on the running wheel. There were genotypic differences in plasma corticosterone levels as well as corticotropin-releasing hormone mRNA content in multiple brain regions associated with the stress response in these free drinking and running subjects. Susceptibility to stress is enhanced in female mice with low levels of β-endorphin, and better understanding of the role for this opioid in mitigating the response to stressors may aid in the development of interventions and treatments for excessive use of alcohol in women.

β-Endorphin neuronal transplantation into the hypothalamus alters anxiety-like behaviors in prenatal alcohol-exposed rats and alcohol-non-preferring and alcohol-preferring rats

BACKGROUND

Alcohol exposure has adverse effects on stress physiology and behavioral reactivity. This is suggested to be due, in part, to the effect of alcohol on β-endorphin (β-EP)-producing neurons in the hypothalamus. In response to stress, β-EP normally provides negative feedback to the hypothalamic-pituitary-adrenal axis and interacts with other neurotransmitter systems in the amygdala to regulate behavior. We examined whether β-EP neuronal function in the hypothalamus reduces the corticosterone response to acute stress, attenuates anxiety-like behaviors, and modulates alcohol drinking in rats.

METHODS

To determine whether β-EP neuronal transplants modulate the stress response, anxiety behavior, and alcohol drinking, we implanted differentiated β-EP neurons into the paraventricular nucleus (PVN) of the hypothalamus of normal, prenatal alcohol-exposed, and alcohol-preferring (P) and alcohol-non-preferring (NP) rats. We then assessed corticosterone levels in response to acute restraint stress and other markers of stress response in the brain and anxiety-like behaviors in the elevated plus maze and open-field assays.

RESULTS

We showed that β-EP neuronal transplants into the PVN reduced the peripheral corticosterone response to acute stress and attenuated anxiety-like behaviors. Similar transplants completely reduced the hypercorticosterone response and elevated anxiety behaviors in prenatal alcohol-exposed adult rats. Moreover, we showed that β-EP reduced anxiety behavior in P rats with minimal effects on alcohol drinking during and following restraint stress.

CONCLUSIONS

These data further establish a role of β-EP neurons in the hypothalamus for regulating physiological stress response and anxiety behavior and resemble a potential novel therapy for treating stress-related psychiatric disorders in prenatal alcohol-exposed children and those genetically predisposed to increased alcohol consumption.

Ethanol-induced anxiolysis and neuronal activation in the amygdala and bed nucleus of the stria terminalis

High rates of comorbidity for anxiety and alcohol-use disorders suggest a causal relationship between these conditions. Previous work demonstrates basal anxiety levels in outbred Long-Evans rats correlate with differences in voluntary ethanol consumption and that amygdalar Neuropeptide Y (NPY) systems may play a role in this relationship. The present work explores the possibility that differences in sensitivity to ethanol's anxiolytic effects contribute to differential ethanol self-administration in these animals and examines the potential role of central and peripheral NPY in mediating this relationship. Animals were first exposed to the elevated plus maze (EPM) to assess individual differences in anxiety-like behaviors and levels of circulating NPY and corticosterone (CORT). Rats were then tested for anxiety-like behavior in the light-dark box (LD box) following acute ethanol treatment (1 g/kg; intraperitoneally [i.p.]), and neuronal activation in the amygdala and bed nucleus of the stria terminalis (BNST) was assessed using Fos immunohistochemistry. EPM exposure increased plasma CORT levels without altering plasma NPY levels. Acute ethanol treatment significantly increased light-dark transitions and latency to re-enter the light arena, but no differences were seen between high- and low-anxiety groups and no correlations were found between anxiety-like behaviors in the EPM and LD box. Acute ethanol treatment significantly increased Fos immunoreactivity in the BNST and the central amygdala. Although NPY neurons were not significantly activated following ethanol exposure, in saline-treated animals lower levels of anxiety-like behavior in the LD box (more time in the light arena and more transitions) were correlated with higher NPY-positive cell density in the central amygdala. Our results suggest that activation of the CeA and BNST are involved in the behavioral expression of ethanol-induced anxiolysis, and that differences in basal anxiety state may be correlated with NPY systems in the extended amygdala.

The long-term impact of early life pain on adult responses to anxiety and stress: Historical perspectives and empirical evidence

Approximately 1 in 6 infants are born prematurely each year. Typically, these infants spend 25 days in the Neonatal Intensive Care Unit (NICU) where they experience 10-18 painful and inflammatory procedures each day. Remarkably, pre-emptive analgesics and/or anesthesia are administered less than 25% of the time. Unalleviated pain during the perinatal period is associated with permanent decreases in pain sensitivity, blunted cortisol responses and high rates of neuropsychiatric disorders. To date, the mechanism(s) by which these long-term changes in stress and pain behavior occur, and whether such alterations can be prevented by appropriate analgesia at the time of insult, remains unclear. Work in our lab using a rodent model of early life pain suggests that inflammatory pain experienced on the day of birth blunts adult responses to stress- and pain-provoking stimuli, and dysregulates the hypothalamic pituitary adrenal (HPA) axis in part through a permanent upregulation in central endogenous opioid tone. This review focuses on the long-term impact of neonatal inflammatory pain on adult anxiety- and stress-related responses, and underlying neuroanatomical changes in the context of endogenous pain control and the HPA axis. These two systems are in a state of exaggerated developmental plasticity early in postnatal life, and work in concert to respond to noxious or aversive stimuli. We present empirical evidence from animal and clinical studies, and discuss historical perspectives underlying the lack of analgesia/anesthetic use for early life pain in the modern NICU.

Long-term parental methamphetamine exposure of mice influences behavior and hippocampal DNA methylation of the offspring

The high rate of methamphetamine (METH) abuse among young adults and women of childbearing age makes it imperative to determine the long-term effects of METH exposure on the offspring. We hypothesized that parental METH exposure modulates offspring behavior by disrupting epigenetic programming of gene expression in the brain. To simulate the human pattern of drug use, male and female C57Bl/6J mice were exposed to escalating doses of METH or saline from adolescence through adulthood; following mating, females continue to receive drug or saline through gestational day 17. F1 METH male offspring showed enhanced response to cocaine-conditioned reward and hyperlocomotion. Both F1 METH male and female offspring had reduced response to conditioned fear. Cross-fostering experiments have shown that certain behavioral phenotypes were modulated by maternal care of either METH or saline dams. Analysis of offspring hippocampal DNA methylation showed differentially methylated regions as a result of both METH in utero exposure and maternal care. Our results suggest that behavioral phenotypes and epigenotypes of offspring that were exposed to METH in utero are vulnerable to (a) METH exposure during embryonic development, a period when wide epigenetic reprogramming occurs, and (b) postnatal maternal care.

The effects of beta-endorphin: state change modification

Beta-endorphin (β-END) is an opioid neuropeptide which has an important role in the development of hypotheses concerning the non-synaptic or paracrine communication of brain messages. This kind of communication between neurons has been designated volume transmission (VT) to differentiate it clearly from synaptic communication. VT occurs over short as well as long distances via the extracellular space in the brain, as well as via the cerebrospinal fluid (CSF) flowing through the ventricular spaces inside the brain and the arachnoid space surrounding the central nervous system (CNS). To understand how β-END can have specific behavioral effects, we use the notion behavioral state, inspired by the concept of machine state, coming from Turing (Proc London Math Soc, Series 2,42:230-265, 1937). In section 1.4 the sequential organization of male rat behavior is explained showing that an animal is not free to switch into another state at any given moment. Funneling-constraints restrict the number of possible behavioral transitions in specific phases while at other moments in the sequence the transition to other behavioral states is almost completely open. The effects of β-END on behaviors like food intake and sexual behavior, and the mechanisms involved in reward, meditation and pain control are discussed in detail. The effects on the sequential organization of behavior and on state transitions dominate the description of these effects.

Stress and opioids: role of opioids in modulating stress-related behavior and effect of stress on morphine conditioned place preference

Research studies have defined the important role of endogenous opioids in modulating stress-associated behavior. The release of β-endorphins in the amygdala in response to stress helps to cope with a stressor by inhibiting the over-activation of HPA axis. Administration of mu opioid agonists reduces the risk of developing post-traumatic stress disorder (PTSD) following a traumatic event by inhibiting fear-related memory consolidation. Similarly, the release of endogenous enkephalin and nociceptin in the basolateral amygdala and the nucleus accumbens tends to produce the anti-stress effects. An increase in dynorphin levels during prolonged exposure to stress may produce learned helplessness, dysphoria and depression. Stress also influences morphine-induced conditioned place preference (CPP) depending upon the intensity and duration of the stressor. Acute stress inhibits morphine CPP, while chronic stress potentiates CPP. The development of dysphoria due to increased dynorphin levels may contribute to chronic stress-induced potentiation of morphine CPP. The activation of ERK/cyclic AMP responsive element-binding (CREB) signaling in the mesocorticolimbic area, glucocorticoid receptors in the basolateral amygdala, and norepinephrine and galanin system in the nucleus accumbens may decrease the acute stress-induced inhibition of morphine CPP. The increase in dopamine levels in the nucleus accumbens and augmentation of GABAergic transmission in the median prefrontal cortex may contribute in potentiating morphine CPP. Stress exposure reinstates the extinct morphine CPP by activating the orexin receptors in the nucleus accumbens, decreasing the oxytocin levels in the lateral septum and amygdala, and altering the GABAergic transmission (activation of GABAA and inactivation of GABAB receptors). The present review describes these varied interactions between opioids and stress along with the possible mechanism.

β-endorphin degradation and the individual reactivity to traumatic stress

Reactivity to traumatic stress varies between individuals and only a minority of those exposed to trauma develops stress-induced psychopathologies. Currently extensive effort is made to unravel the specific mechanisms predisposing to vulnerability vs. resilience to stress. We investigated in rats the role of β-endorphin metabolism in vulnerability to acute traumatic stress. Responders (showing extreme anxiety; n=7) and resilient non-responders (not differing from the non-stressed individuals; n=8) to traumatic foot-shock stress were compared for their blood levels of stress hormones as well as brain levels and activity of two opioid-degrading enzymes. β-endorphin is a substrate to insulin degrading enzyme, which also degrades insulin. Therefore, the effects of insulin application on behavioral and hormonal responses and on β-endorphin degradation were tested. Pre- and post-stress levels of serum corticosterone, and post-stress plasma β-endorphin concentration differentiated between the responders and the non-responders. In brain, responders showed enhanced degradation rates of β-endorphin, assessed by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS), in hippocampal and amygdalar slices as compared to non-responders. Application of insulin to the amygdala, prior to exposure to traumatic stress, reduced post-stress anxiety and serum corticosterone levels only in the responders. In parallel, amygdalar β-endorphin degradation rate was also reduced by insulin. These results suggest that slowing down β-endorphin degradation rate may constitute an integral part of the normal stress-response, upon a failure of which an extreme anxiety develops. Modulation of opioid degradation may thus present a potential novel target for interference with extreme anxiety.

β-endorphin modulates the effect of stress on novelty-suppressed feeding

Although stress is implicated in the pathophysiology of mood and anxiety disorders, not all individuals who suffer stressful life events develop psychopathology. Differential susceptibility to stress may be influenced by genetically mediated differences in hypothalamic-pituitary-adrenal (HPA) axis activity and moderation of the stress response by the opioid peptide β-endorphin (β-E). The present study investigated genetic contributions to coping behavior by examining anxious behavior of transgenic mice with varying capacities to synthesize β-E [B6.129S2-Pomc^tm1Low/J; regulated by insertion of a premature stop codon into one or both copies of the proopiomelanocortin (POMC) gene], both under normal conditions and following 3 min of forced swim (FS). Ten minutes after this stress exposure or a control manipulation, acutely food-deprived female and male transgenic mice were subjected to a novelty-suppressed feeding (NSF) test, during which their interaction with an almond slice located in the center of an open field box was measured. There was an interaction between genotype and stress for latency to approach the almond and whether or not the almond was approached, such that mice with low or absent β-E displayed a stronger aversion to novelty-feeding after stress exposure than did mice with normal levels. These data provide evidence for a moderating effect of β-E on the behavioral response to stress. Genotypic differences in anxious behavior emerged when mice were stressed prior to behavioral assessment, suggesting that β-E plays a role in coping behavior. These findings indicate that genetic variability in sensitivity of the β-E system to stress may contribute, at least in part, to heritable differences in stress reactivity as well as vulnerability to stress-related psychopathology.

Locomotor sensitization to EtOH: contribution of β-Endorphin

Alcohol use disorders, like all drug addictions, involve a constellation of adaptive changes throughout the brain. Neural activity underlying changes in the rewarding properties of alcohol reflect changes in dopamine transmission in mesolimbic and nigrostriatal pathways and these effects are modulated by endogenous opioids such as β-Endorphin. In order to study the role of β-Endorphin in the development of locomotor sensitization to repeated EtOH exposure, we tested transgenic mice that vary in their capacity to synthesize this peptide as a result of constitutive modification of the Pomc gene. Our results indicate that mice deficient in β-Endorphin show attenuated locomotor activation following an acute injection of EtOH (2.0 g/kg) and, in contrast to wildtype mice, fail to demonstrate locomotor sensitization after 12 days of repeated EtOH injections. These data support the idea that β-Endorphin modulates the locomotor effects of EtOH and contributes to the neuroadaptive changes associated with chronic use.

Extending pharmacological spectrum of opioids beyond analgesia: multifunctional aspects in different pathophysiological states

Opioids are well known to exert potent central analgesic actions. In recent years, the numerous studies have unfolded the critical role of opioids in the pathophysiology of various diseases as well as in biological phenomenon of therapeutic interest. The endogenous ligands of opioid receptors are derived from three independent genes and their appropriate processing yields the major representative opioid peptides beta-endorphin, met-enkephalin, leu-enkephalin and dynorphin, respectively. These peptides and their derivatives exhibit different affinity and selectivity for the mu-, delta- and kappa-receptors located on the central and the peripheral neurons, neuroendocrine, immune, and mucosal cells and on many other organ systems. The present review article highlights the role of these peptides in central nervous system disorders such as depression, anxiety, epilepsy, and stress; gastrointestinal disorders such as diarrhea, postoperative ileus, ulceration, and irritable bowel syndrome; immune system and related inflammatory disorders such as osteoarthritis and rheumatoid arthritis; and others including respiratory, alcoholism and obesity/binge eating. Furthermore, the key role of opioids in different forms of pre- and post-conditioning including ischemic and pharmacological along with in remote preconditioning has also been described.

Effects of exercise and physical activity on depression

INTRODUCTION

Depression is a very prevalent mental disorder affecting 340 million people globally and is projected to become the leading cause of disability and the second leading contributor to the global burden of disease by the year 2020.

AIM

In this paper, we review the evidence published to date in order to determine whether exercise and physical activity can be used as therapeutic means for acute and chronic depression. Topics covered include the definition, classification criteria and treatment of depression, the link between β-endorphin and exercise, the efficacy of exercise and physical activity as treatments for depression, properties of exercise stimuli used in intervention programs, as well as the efficacy of exercise and physical activity for treating depression in diseased individuals.

CONCLUSIONS

The presented evidence suggests that exercise and physical activity have beneficial effects on depression symptoms that are comparable to those of antidepressant treatments.

Beta-endorphin mediates behavioral despair and the effect of ethanol on the tail suspension test in mice

BACKGROUND

The opioid peptide beta-endorphin (beta-E) is synthesized and released in response to stressful stimuli as well as acute alcohol administration. The release of beta-E following exposure to an inescapable aversive situation may mediate behaviors that contribute to allostasis of the stress response. The present study examines the effects of beta-E on immobility in assays involving inescapable stress, both under basal conditions and after acute administration of EtOH.

METHODS

Female and male transgenic mice with varying capacities to translate beta-E were subjected to either the forced swim (FST, Experiment 1) or the tail suspension test (TST, Experiment 2). In Experiment 3, mice were divided into three groups based on hormonal status (male, female-estrous, and female-nonestrous) and injected with either 1 g/kg EtOH or equivolume saline 14 minutes prior to behavioral assessment on the TST.

RESULTS

Experiments 1 and 2 demonstrated a direct relationship between beta-E levels and immobility. There were also sex differences in behavior in these tests, with males displaying more immobility than females. A main effect of genotype in Experiment 3 replicated findings in Experiments 1 and 2. There was also an effect of EtOH (increasing immobility) and a significant interaction reflecting a particularly robust effect of the drug in mice with low beta-E. In addition, there were interactions between beta-E, EtOH effects, and hormonal status.

CONCLUSIONS

These findings support the contention that beta-E moderates behavioral responses to stressful stimuli and suggest a role for this peptide in coping behavior. Furthermore, the effects of EtOH on the response to stress may be mediated by beta-E. Sex differences in this influence may contribute to sex differences in disease susceptibility and expression.

Endogenous opiates and behavior: 2008

This paper is the 31st consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2008 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).