Dysregulation of Regional Endogenous Opioid Function in Borderline Personality Disorder
ABSTRACT Borderline personality disorder is characterized by a lack of effective regulation of emotional responses. The authors investigated the role of the endogenous opioid system and mu-opioid receptors in emotion regulation in borderline personality disorder.
Mu-opioid receptor availability in vivo (nondisplaceable binding potential, or BP(ND)) was measured with positron emission tomography and the selective radiotracer [(11)C]carfentanil during neutral and sustained sadness states in 18 unmedicated female patients with borderline personality disorder and 14 healthy female comparison subjects.
Patients showed greater regional mu-opioid BP(ND) than did comparison subjects at baseline (neutral state) bilaterally in the orbitofrontal cortex, caudate, and nucleus accumbens and in the left amygdala, but lower BP(ND) in the posterior thalamus. Sadness induction was associated with greater reductions in BP(ND) (endogenous opioid system activation) in the patient group than in the comparison group in the pregenual anterior cingulate, left orbitofrontal cortex, left ventral pallidum, left amygdala, and left inferior temporal cortex. Patients showed evidence of endogenous opioid system deactivation in the left nucleus accumbens, the hypothalamus, and the right hippocampus/parahippocampus relative to comparison subjects. Correlations of baseline measures with the Dissociative Experiences Scale and endogenous opioid system activation with the Barratt Impulsiveness Scale did not remain significant after correction for multiple comparisons.
Differences exist between patients with borderline personality disorder and comparison subjects in baseline in vivo mu-opioid receptor concentrations and in the endogenous opioid system response to a negative emotional challenge that can be related to some of the clinical characteristics of patients with borderline personality disorder. The regional network involved is implicated in the representation and regulation of emotion and stress responses.
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ABSTRACT: Relief from emotional pain is a frequently cited reason for engaging in non-suicidal self-injury. The exact mechanism by which self-injury brings about this relief is unknown, but the potential role of endogenous opioids in affective regulation has been posited. Few studies have investigated this and there are a number of methodological challenges to measuring endogenous opioid activity in this population. Furthermore as the majority of research to date has focused on inpatients with borderline personality disorder (BPD), it is uncertain if the findings of previous studies would also apply to those who self-injure but who do not have BPD. Whether or not altered endogenous opioid levels are a cause or a consequence of self-injury is unknown and to this end, comparing self-injury ideators with enactors, may offer a window of insight. Another candidate system, the endocannabinoid system, should also be explored in relation to this research question. The current commentary aims to tease apart the methodological issues in this area of research and stimulate further discussion of this topic.Neuroscience & Biobehavioral Reviews 11/2014; 48. DOI:10.1016/j.neubiorev.2014.11.007 · 10.28 Impact Factor
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ABSTRACT: Positive social interactions are essential for emotional well-being and proper behavioral development of young individuals. Here, we studied the neural underpinnings of social reward by investigating the involvement of opioid neurotransmission in the nucleus accumbens (NAc) in social play behavior, a highly rewarding social interaction in adolescent rats. Intra-NAc infusion of morphine (0.05-0.1 μg) increased pinning and pouncing, characteristic elements of social play behavior in rats, and blockade of NAc opioid receptors with naloxone (0.5 μg) prevented the play-enhancing effects of systemic morphine (1 mg/kg, s.c.) administration. Thus, stimulation of opioid receptors in the NAc was necessary and sufficient for morphine to increase social play. Intra-NAc treatment with the selective μ-opioid receptor agonist [D-Ala(2),N-MePhe(4),Gly(5)-ol]enkephalin (DAMGO) (0.1-10 ng) and the μ-opioid receptor antagonist Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH(2) (CTAP) (0.3-3 μg) increased and decreased social play, respectively. The δ-opioid receptor agonist DPDPE ([D-Pen(2),D-Pen(5)]-enkephalin) (0.3-3 μg) had no effects, whereas the κ-opioid receptor agonist U69593 (N-methyl-2-phenyl-N-[(5R,7S,8S)-7-(pyrrolidin-1-yl)-1-oxaspiro[4.5]dec-8-yl]acetamide) (0.01-1 μg) decreased social play. Intra-NAc treatment with β-endorphin (0.01-1 μg) increased social play, but met-enkephalin (0.1-5 μg) and the enkephalinase inhibitor thiorphan (0.1-1 μg) were ineffective. DAMGO (0.1-10 ng) increased social play after infusion into both the shell and core subregions of the NAc. Last, intra-NAc infusion of CTAP (3 μg) prevented the development of social play-induced conditioned place preference. These findings identify NAc μ-opioid receptor stimulation as an important neural mechanism for the attribution of positive value to social interactions in adolescent rats. Altered NAc μ-opioid receptor function may underlie social impairments in psychiatric disorders such as autism, schizophrenia, or personality disorders.The Journal of Neuroscience : The Official Journal of the Society for Neuroscience 04/2011; 31(17):6362-70. DOI:10.1523/JNEUROSCI.5492-10.2011 · 6.75 Impact Factor
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ABSTRACT: Various approaches to measuring and optimizing molecular diversity of combinatorial libraries are presented. The need for different diversity metrics for libraries consisting of discrete molecules ("cherry picking") vs libraries formed from combinatorial R-group enumeration (array-based selection) is discussed. Ideal requirements for diversity metrics applied to array-based selection are proposed, focusing, in particular, on the concept of incremental diversity, i.e., the change in diversity as redundant or nonredundant molecules are added to a compound collection or combinatorial library. Several distance and cell-based diversity functions are presented and analyzed in terms of their ability to satisfy these requirements. These diversity functions are applied to designing diverse libraries for two test cases, and the performance of the diversity functions is assessed. Issues associated with redundant molecules in the virtual library are discussed and analyzed using one of the test examples. The results are compared to reagent-based diversity optimizations, and it is shown that a product-based diversity protocol can result in significant improvements over a reagent-based scheme based on the diversity obtained for the resulting libraries.Journal of Molecular Graphics and Modelling 08/2000; 18(4-5):412-26, 533-6. DOI:10.1016/S1093-3263(00)00071-1 · 2.02 Impact Factor