Morphine Reward Promotes Cue-Sensitive Learning: Implication of Dorsal Striatal CREB Activity

Chronic alcohol consumption shifts learning strategies and synaptic plasticity from hippocampus to striatum-dependent pathways

Introduction

The hippocampus and striatum have dissociable roles in memory and are necessary for spatial and procedural/cued learning, respectively. Emotionally charged, stressful events promote the use of striatal- over hippocampus-dependent learning through the activation of the amygdala. An emerging hypothesis suggests that chronic consumption of addictive drugs similarly disrupt spatial/declarative memory while facilitating striatum-dependent associative learning. This cognitive imbalance could contribute to maintain addictive behaviors and increase the risk of relapse.

Methods

We first examined, in C57BL/6 J male mice, whether chronic alcohol consumption (CAC) and alcohol withdrawal (AW) might modulate the respective use of spatial vs. single cue-based learning strategies, using a competition protocol in the Barnes maze task. We then performed in vivo electrophysiological studies in freely moving mice to assess learning-induced synaptic plasticity in both the basolateral amygdala (BLA) to dorsal hippocampus (dCA1) and BLA to dorsolateral striatum (DLS) pathways.

Results

We found that both CAC and early AW promote the use of cue-dependent learning strategies, and potentiate plasticity in the BLA → DLS pathway while reducing the use of spatial memory and depressing BLA → dCA1 neurotransmission.

Discussion

These results support the view that CAC disrupt normal hippocampo-striatal interactions, and suggest that targeting this cognitive imbalance through spatial/declarative task training could be of great help to maintain protracted abstinence in alcoholic patients.

Protection against Morphine-Induced Inhibitory Avoidance Memory Impairment in Rat by Curcumin: Possible Role of Nitric Oxide/ cAMP-Response Element Binding Protein Pathway

BACKGROUND

Although a substantial body of research suggests curcumin (CUR) has the preventive potential in memory impairment, the mechanism by which CUR prevents memory loss is still being investigated. This study employs an inhibitory avoidance (IA) model to investigate whether CUR can prevent morphine (Mor)-induced memory impairment as well as the possible role of cAMP-response element binding (CREB) protein, and nitric oxide (NO) signaling in this mechanism.

METHODS

This experimental study was conducted at the Animal Lab of the Physiology Research Center, Kashan University of Medical Sciences (Kashan, Iran) in 2018. Forty rats were randomly divided into four groups: control, CUR (pretreatment gavage of CUR [10 mg/Kg] for 35 days), Mor (7.5 mg/Kg, i.p.), and CUR+Mor (n=10 per group). Following the evaluation of the IA memory and locomotor activity of the animals, the CREB protein expression in the hippocampus and NO metabolites (NOx) level in the brain tissue were also investigated. The data were analyzed using Sigmaplot software (version 14.0) by using the ANOVA, Kruskal-Wallis, Holm-Sidak, and Dunn's post hoc tests. P<0.05 was considered to be statistically significant.

RESULTS

In the Mor group, the IA memory of the rats was significantly impaired (P=0.001). CUR prevented the Mor-induced IA memory impairment (P=0.075). While the Mor treatment decreased the phosphorylated CREB (p-CREB) expression, the CUR+Mor cotreatment increased p-CREB expression (P=0.010). Nevertheless, the Mor treatment increased the total CREB expression (P=0.010). The NOx concentration in the brain tissue was decreased following the Mor treatment (P=0.500) but increased after the CUR+Mor cotreatment (P=0.001).

CONCLUSION

The present findings suggest that CUR prevents the memory impairment of rats, possibly through NO and its downstream CREB signaling.

Social-capital determinants of the women with diabetes: a population-based study

Introduction

Social-capital level contributes to clinical factors and health outcomes of patients suffering from diabetes. Considering the social determinants of type 2 diabetes patients could benefit to prevention of diabetes complications especially in women population. This study aims to determine social capital determinants in women with diabetes.

Methods

Four hundred and thirty-five women with diabetes take-part in this cross-sectional, multi-centric study. The data was completed by a demographic questionnaire and the Social Capital instrument (SC-IQ). This study is investigating demographic (age, gender, BMI, marital, educational and social-economic status), and lifestyle factors (physical activity, nutrition), Diabetes status (HbA1c Level, medications, complications, duration of diabetes), general health status (life satisfaction, self-rated health, physical activity, and depression) and Social capital items (Value of life, Tolerance of Diversity, Neighborhood network, Family and Friends Connections, Work connections, Community participation, Feeling of trust and Safety and Proactivity). The descriptive statistics and linear regression models were used to assess the associations between social capital and determinants.

Results

The mean age of participants was 50 (SD: 7.7), range 28-71 year. The mean social capital score was 77.8 (SD: 15.8). In linear regression analysis, results showed that women who had the greater score in total social-capital (ß: 3.7, SE: 1.5) and Feeling of trust and Safety (ß: 0.87, SE: 0.42) had vigorous physical activity and also women who had greater score in Neighborhood Connections had moderate physical activity in comparison with patients who had low physical activity. (ß: 0.67, SE: 0.26 and ß: 0.61, SE: 0.26).Also, the findings showed that women who had had a lower score in total social-capital (ß: 6, SE: 1.47), Community participation (ß: 1.44, SE: 0.37), Value of life (ß: 1.71, SE: 0.24), Family and Friends Connections (ß: 0.88, SE: 0.25) and proactivity (ß: 0.71, SE: 0.25) had depression in comparison with patients who had no depression. The findings revealed that instead of each year increase in the duration of diabetes, the total social-capital score had decreased about the half score (ß: 0.48, SE: 0.21).

Conclusions

Important social factors that make diabetes control are alterable to health interventions. The results of the current study suggest that social capital status may determine how effectively the women with diabetes have been managed. This initial finding permits subsequent experimental investigations to identify social strategies that can be valuable to improve diabetes control.

Early Life Stress Increases Brain Glutamate and Induces Neurobehavioral Manifestations in Rats

Early life stress (ELS) is associated with an increased risk of developing depression and anxiety disorders. Disturbances of the neurobiological glutamatergic system are implicated in depression; however, the long-term effects of ELS on glutamate (Glu) metabolites remain unclear. Our study used 7T proton magnetic resonance spectroscopy (7T ¹H MRS) to detect metabolic Glu in a rat model to investigate maternal deprivation (MD)-induced ELS. MD was established in Sprague-Dawley rats by periodic separation from mothers and peers. Changes in the hippocampal volume and Glu metabolism were detected by 7T ¹H MRS after testing for depression-like behavior via open field, sucrose preference, and Morris water maze tests. Adult MD offspring exhibited depression-like behavior. Compared to the control, the MD group exhibited reduced ratio of central activity time to total time and decreased sucrose consumption (p < 0.05). MD rats spent less time in the fourth quadrant, where the platform was originally placed, in the Morris water maze test. According to 7T ¹H MRS, hippocampus of MD rats had elevated Glu and glutamate + glutamine (Glu+Gln) levels compared with the control group hippocampi, but Gln, γ-aminobutyric acid (GABA), and glutamate + glutamine (Glu+Gln) in the prefrontal cortex of MD rats showed a downward trend. Depression-like behavior and cognition deficits related to ELS may induce region-specific changes in Glu metabolism in the prefrontal cortex and hippocampus. The novel, noninvasive 7T ¹H MRS-identified associations between Glu levels and ELS may guide future clinical studies.

Injection of minocycline into the periaqueductal gray attenuates morphine withdrawal signs

This study investigated the effects of minocycline microinjections, into the midbrain periaqueductal gray (PAG), on morphine withdrawal and the expression of pannexin-1 (panx1), phosphorylated mammalian target of rapamycin (p-mTOR), protein kinase A (PKA), and cAMP response element-binding protein (CREB). Rats were injected with morphine, intraperitoneally, at increasing doses, twice per day, to establish animal models of morphine exposure. Minocycline was administered into the PAG before the first intraperitoneal (i.p.) injection of morphine each day, on days 1-4. On the last day of the experiment, all rats were injected with naloxone, and morphine withdrawal was observed, and then changes in the expression levels of ionized calcium-binding adaptor molecule 1 (Iba1) and its downstream factors, panx1, p-mTOR, PKA, and CREB were evaluated by western blot and immunohistochemistry analyses. Morphine withdrawal increased microglial activation, whereas minocycline could inhibit microglial activation and withdrawal and the downregulation of panx1, p-mTOR, PKA, and CREB expression, reducing the effects of morphine withdrawal.

Endogenous opiates and behavior: 2017

This paper is the fortieth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2017 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Genesis of the Heroin-Induced Addictive Process: Articulation Between Psychodynamic and Neurobiological Theories

Psychotherapeutic consultations of drug addict's patients in a Care, Support and Prevention Center in Addictology led us to propose several hypotheses on the genesis of addiction and its articulation with currently available neurobiological data. This care center dispenses both pharmacological maintenance medications for heroin dependence, such as methadone or buprenorphine, and psychological support. Our first hypothesis posits that the addictive process is driven by the narcissistic vulnerability of these patients, its neurobiological foundations being mainly mediated by the activation of endogenous opioid systems. Drug use/abuse could be a way to make arise the "True Self," therefore overcoming the defensive system's set up to protect oneself from early traumas. The neurobiological impact of traumas is also developed and articulated with psychodynamic concepts, particularly those of Winnicott. Additionally, functions of addiction such as defensive, anti-depressant roles and emotional regulation are discussed in relationship with their currently known neuroscientific bases. Although the experience in the psychodynamic clinic is at a level of complexity much higher than what is currently accessible to the neurosciences, most of the research in this domain stays in line with our psychological understanding of the addictive process. Finally, we outline some critically sensitive points regarding the therapeutic support.

Correlations Between Mutant Huntingtin Aggregates and Behavioral Changes in R6/1 Mice

BACKGROUND

Huntington's disease (HD) is a neurodegenerative disorder caused by the expansion of the trinucleotide CAG in the HD gene. While the presence of nuclear aggregates of mutant huntingtin (mHtt) in neurons is a hallmark of HD, the reason behind its toxicity remains elusive.

OBJECTIVE

The present study was conducted to assess a correlation between the number of mHtt aggregates and the severity of HD symptoms in R6/1 mice.

METHODS

We investigated correlations between behavioral deficits and the level of nuclear mHtt aggregates in different neuroanatomical regions in 3-month-old R6/1 mice, the age at which a large variability of symptom severity between animals has been observed.

RESULTS

R6/1 mice were deficient in instinctive and anxiety related behaviors as well as long-term memory capabilities. Significant differences were also found between the sexes; female transgenic mice displayed less severe deficits than males. While the level of mHtt aggregates was correlated with the severity of HD phenotypes in most regions of interest, an opposite relationship also was found for some other regions examined.

CONCLUSIONS

The obtained results suggest harmful and region-specific roles of mHtt aggregates in HD symptoms.

Altered Activity of SK Channel Underpins Morphine Withdrawal Relevant Psychiatric Deficiency in Infralimbic to Accumbens Shell Pathway

Drug addiction can be viewed as a chronic psychiatric disorder that is related to dysfunction of neural circuits, including reward deficits, stress surfeits, craving changes, and compromised executive function. The nucleus accumbens (NAc) plays a crucial role in regulating craving and relapse, while the medial prefrontal cortex (mPFC) represents a higher cortex projecting into the NAc that is active in the management of executive function. In this study, we investigated the role of the small conductance calcium-activated potassium channels (SK channels) in NAc and mPFC after morphine withdrawal. Action potential (AP) firing of neurons in the NAc shell was enhanced via the downregulations of the SK channels after morphine withdrawal. Furthermore, the expression of SK2 and SK3 subunits in the NAc was significantly reduced after 3 weeks of morphine withdrawal, but was not altered in the dorsal striatum. In mPFC, the SK channel subunits were differentially expressed. To be specific, the expression of SK3 was upregulated, while the expression of SK2 was unchanged. Furthermore, the AP firing in layer 5 pyramidal neurons of the infralimbic (IL) cortex was decreased via the upregulations of the SK channel-related tail current after 3 weeks of morphine withdrawal. These results suggest that the SK channel plays a specific role in reward circuits following morphine exposure and a period of drug withdrawal, making it a potential target for the prevention of relapse.