Effects of Rapastinel (Formerly GLYX-13) on Serum Brain-Derived Neurotrophic Factor in Obsessive-Compulsive Disorder

ERK/mTOR signaling may underlying the antidepressant actions of rapastinel in mice

Rapastinel as the allosteric modulator of N-methyl-D-aspartate receptor (NMDAR) produces rapid antidepressant-like effects dependent on brain-derived neurotrophic factor (BDNF) and VGF (nonacryonimic) release. Herein, we further explore the molecular mechanisms of the antidepressant effects of repeated administration with rapastinel in mice. Our results showed that continuous 3-day rapastinel (5 and 10 mg/kg, i.v.) produced antidepressant-like actions dependent on the increase in extracellular regulated protein kinase (ERK)/mammalian target of rapamycin (mTOR) signaling and downstream substrates p70S6 kinase (p70S6k) and the eukaryotic initiation factor 4E-binding protein 1 (4E-BP1), which may induce the expression of VGF and BDNF in the hippocampus and prefrontal cortex of mice. Furthermore, compared with a single treatment, our data indicated that 3-day repeated rapastinel treatment produced antidepressant-like actions accompanied by potentiation of ERK/mTOR/VGF/BDNF/tropomyosin-related kinase receptor B (TrkB) signaling. Based on previous and our supplementary data that showed the pivotal role of on α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) in the rapid release of VGF and BDNF and activation of TrkB by a single dose of rapastinel, we postulate that the antidepressant-like effects of single or repeated administration of rapastinel may result in the rapid release of VGF and BDNF or ERK/mTOR signaling pathway-mediated VGF/BDNF/TrkB autoregulatory feedback loop respectively. Our current work adds new knowledge to the molecular mechanisms that underlie the antidepressant-like actions of rapastinel in mice.

Brain-derived neurotrophic factor as a biomarker for obsessive-compulsive disorder: A meta-analysis

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is a growth factor that plays many critical functions in the central nervous system (CNS) and may be involved in the development of a range of psychopathologies, including depression, dementia, and neurodegenerative disorders.

METHODS

In the present study, we performed the first systematic review with a meta-analysis to quantitatively compare the peripheral blood BDNF levels between patients with obsessive-compulsive disorder (OCD) and healthy controls (HCs). A systematic search was conducted using PubMed and Web of Science databases to identify the relevant articles.

RESULTS

Nine studies encompassing 474 adults with OCD and 436 HCs were included in this meta-analysis. A random-effects meta-analysis showed that patients with OCD had significantly decreased peripheral blood levels of Brain-derived neurotrophic factor (BDNF) when compared with the HCs (Hedges' g = -0.722, 95% confidence interval [CI] = -1.152 to -0.292, P = 0.001). Subgroup analyses revealed decreased BDNF levels in plasma of patients (Hedges' g = -1.137, 95% CI = -1.463 to -0.810, P = 0.000) and drug-free patients (Hedges' g = -1.269, 95% CI = -1.974 to -0.564, P = 0.000) as compared to patients on active drug therapy and HCs. Meta-regression analyses showed that age, sex, sample size, Y-BOS total score, and publication year had no moderating effects on the outcome.

CONCLUSION

Although the relationship between our findings and the pathophysiology of OCD and the role BDNF plays in the development of the disease remains to be determined, the outcomes suggest that BDNF may serve as a potential biomarker of OCD.

Investigational and Experimental Drugs to Treat Obsessive-Compulsive Disorder

Treatment-resistance is a frequent condition for obsessive-compulsive disorder (OCD). Over the past decades, a lot of effort has been made to address this issue, and several augmentation strategies of serotonergic drugs have been investigated. Antidopaminergic drugs are considered the first choice as augmentation strategy for treatment-resistant OCD patients, but they seem to work only for a subset of patients, and none of them have been officially approved for OCD. Recently, the role of glutamate and inflammation in OCD pathophysiology clearly emerged, and this has led to several investigations on glutamatergic and anti-inflammatory agents. Results seem promising but still inconclusive. Probiotic interventions (considered to modulate the immune systems and the brain activity) are gaining attention in several psychiatric fields but are still at their early stages in the OCD field. Research on new treatment approaches for OCD is moving forward, and more than one hundred interventional trials are ongoing around the world. While the vast majority of these trials involve neuromodulation and psychotherapeutic approaches, only a small proportion (around 20%) involve the investigation of new pharmacological approaches (tolcapone, nabilone, psilocybin, troriluzole, nitrous oxide, rituximab, naproxen, and immunoglobulins). Here, we provide a comprehensive review of investigational and experimental drugs to treat OCD.

Current and up-and-coming pharmacotherapy for obsessive-compulsive disorder in adults

INTRODUCTION

Only 40-60% of obsessive-compulsive patients respond to first line treatments, such as selective serotonin reuptake inhibitors (SSRIs) and cognitive-behavioral therapy. Several second-line treatments have been investigated in the last two decades, and most of them seem to work, at least in a subset of patients. However, since there is still a lack of treatment predictors, the treatment of obsessive-compulsive disorder (OCD) is still empirical and non-evidence based.

AREAS COVERED

In this paper, we review current and up-and-coming pharmacotherapy for OCD in adults, focusing on two emerging fields of research, inflammation and glutamate systems, since they have attracted the greatest attention in recent years in OCD pharmacological research.

EXPERT OPINION

Most of the investigated second-line agents seem to work at least in a subset of patients with OCD. These results raise an open question: what works for who? In our opinion, this question should be answered in a precision medicine perspective or, in other words, individualizing diagnostic processes and treatment approaches. In a precision medicine approach, OCD treatment should be sub-type specific, phase specific, multimodal and sequential, and, more importantly, dimensional.