Alpha2C-adrenoceptor Del322-325 polymorphism and risk of psychiatric disorders: significant association with opiate abuse and dependence

The involvement of the adrenergic system in feeding and eating disorders. A systematic review

BACKGROUND

Adrenergic dysregulation has been proposed as a possible underlying mechanism in feeding and eating disorders (FED). This review aims to synthesise the current evidence on the role of adrenergic dysregulation in the pathogenesis and management of FED.

METHODS

A systematic review was conducted in MEDLINE, Cochrane Library, and Clinicaltrials.gov. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was adopted. Preclinical, clinical, and pharmacological studies assessing the adrenergic system in FED were included.

RESULTS

Thirty-one out of 1415 recognised studies were included. Preclinically, studies on adrenaline's anorectic impact, receptor subtypes, and effects on hepatic function in rats show that catecholamine anorexia is primarily alpha-adrenergic, whereas beta-adrenergic anorexia can be obtained only after puberty, implying an impact of sexual hormones. Clinically, catecholamine levels may be higher in FED patients than in healthy controls (HC). Individuals with anorexia nervosa (AN) may show higher epinephrine-induced platelet aggregability response than HC. Pharmacological trials suggest that the alpha-2-adrenergic medication clonidine may not lower AN symptoms, but agents regulating the adrenaline-noradrenaline neurotransmission (bupropion, reboxetine, duloxetine, sibutramine) have been found to improve binge eating symptoms.

CONCLUSION

Adrenergic dysregulation may be involved in the pathophysiology of FED. More research is needed to comprehend underlying mechanisms and treatment implications.

2,3-Dihydrobenzo-dioxine piperidine derivatives as potent and selective α2c antagonists

In this manuscript, we report a series of benzodioxine methyl piperidine derivatives as highly potent and selective α2C antagonists by ligand design to improve the pharmacokinetics of a previous candidate molecule.

The potential anti-depressant properties of dexmedetomidine infusion: a review of mechanistic, preclinical, and clinical evidence

Major depressive disorder (MDD) is a highly prevalent and disabling condition for which the currently available treatments are not fully effective. Existing unmet needs include rapid onset of action and optimal management of concurrent agitation. Dexmedetomidine (DEX) is a selective and potent α2-adrenergic receptor (α2-AR) agonist, with unique pharmacokinetic and pharmacodynamic properties. In this review, we discuss pre-clinical and clinical studies which focused on DEX in the context of its putative antidepressant effects for the management of MDD. Preliminary data support DEX as an antidepressant with fast onset of action, which would be especially helpful for patients experiencing treatment resistant depression, and agitation. We further explore the mechanistic and clinical implications of considering DEX as a putative antidepressant agent, and the next steps to explore the efficacy of low dose DEX infusion among patients with treatment resistant depression.

Dexmedetomidine Alleviates Postpartum Depressive Symptoms following Cesarean Section in Chinese Women: A Randomized Placebo-Controlled Study

OBJECTIVES

Few studies have investigated the prophylactic efficacy of dexmedetomidine (DEX) in postpartum depressive symptoms (PDS). A randomized double-blind placebo-controlled trial was conducted to investigate whether the administration of DEX, immediately after delivery and for patient-controlled intravenous analgesia (PCIA), can attenuate PDS.

METHODS

A total of 600 parturients scheduled for elective cesarean delivery under spinal anesthesia were randomly allocated into the control group (infusion with 0.9% normal saline after delivery and PCIA with sufentanil) and the DEX group (DEX infusion 0.5 μg/kg after delivery and PCIA with DEX plus sufentanil). The prevalence of postpartum depressive disorders was indicated by the Edinburgh Postnatal Depression Scale (EPDS). Postoperative analgesia, sedation, and sleep quality of parturients were also assessed.

RESULTS

Postpartum blues and PDS prevalence in the DEX, versus control, group were significantly lower (5.0% vs 14.1%, p<0.001; 5.7% vs 16.3%, p<0.001, respectively), especially in parturients with antenatal depression or moderate stress during pregnancy. Compared with the control group, the EPDS score at postpartum days 7 and 42 in the DEX group was significantly lower (4.23 ± 4.37 vs 1.93 ± 3.36, p<0.001; 4.68 ± 4.78 vs 1.99 ± 3.18, p<0.001, respectively), as was the incidence of postpartum self-harm ideation at postpartum days 7 and 42 in the DEX group versus the control group (1.1% vs 4.0%, p=0.03; 0.4% vs 2.9%, p=0.04, respectively). The pain score and the sleep quality in the DEX group were better than that in the control group (p<0.001).

CONCLUSION

The application of DEX in the early postpartum period can significantly attenuate the incidence of postpartum depressive disorders.

Endogenous Opiates and Behavior: 2016

This paper is the thirty-ninth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2016 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, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

Therapeutic Potential of Selectively Targeting the α2C-Adrenoceptor in Cognition, Depression, and Schizophrenia-New Developments and Future Perspective

α_2A- and α_2C-adrenoceptors (ARs) are the primary α₂-AR subtypes involved in central nervous system (CNS) function. These receptors are implicated in the pathophysiology of psychiatric illness, particularly those associated with affective, psychotic, and cognitive symptoms. Indeed, non-selective α₂-AR blockade is proposed to contribute toward antidepressant (e.g., mirtazapine) and atypical antipsychotic (e.g., clozapine) drug action. Both α_2C- and α_2A-AR share autoreceptor functions to exert negative feedback control on noradrenaline (NA) release, with α_2C-AR heteroreceptors regulating non-noradrenergic transmission (e.g., serotonin, dopamine). While the α_2A-AR is widely distributed throughout the CNS, α_2C-AR expression is more restricted, suggesting the possibility of significant differences in how these two receptor subtypes modulate regional neurotransmission. However, the α_2C-AR plays a more prominent role during states of low endogenous NA activity, while the α_2A-AR is relatively more engaged during states of high noradrenergic tone. Although augmentation of conventional antidepressant and antipsychotic therapy with non-selective α₂-AR antagonists may improve therapeutic outcome, animal studies report distinct yet often opposing roles for the α_2A- and α_2C-ARs on behavioral markers of mood and cognition, implying that non-selective α₂-AR antagonism may compromise therapeutic utility both in terms of efficacy and side-effect liability. Recently, several highly selective α_2C-AR antagonists have been identified that have allowed deeper investigation into the function and utility of the α_2C-AR. ORM-13070 is a useful positron emission tomography ligand, ORM-10921 has demonstrated antipsychotic, antidepressant, and pro-cognitive actions in animals, while ORM-12741 is in clinical development for the treatment of cognitive dysfunction and neuropsychiatric symptoms in Alzheimer's disease. This review will emphasize the importance and relevance of the α_2C-AR as a neuropsychiatric drug target in major depression, schizophrenia, and associated cognitive deficits. In addition, we will present new prospects and future directions of investigation.