Advances in the Management of Treatment-Resistant Depression

QRFP and GPR103 in the paraventricular nucleus play a role in chronic stress-induced depressive-like symptomatology by enhancing the hypothalamic-pituitary-adrenal axis

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis during chronic stress is essential for depression neurobiology. As the latest member of the RFamide peptide family in mammals, pyroglutamylated RFamide peptide (QRFP) is closely implicated in neuroendocrine maintenance by activating G-protein-coupled receptor 103 (GPR103). We hypothesized that QRFP and GPR103 might contribute to chronic stress-induced depression by promoting corticotropin-releasing hormone (CRH) release from neurons in the paraventricular nucleus (PVN), and various methods were employed in this study, with male C57BL/6J mice adopted as the experimental subjects. Chronic stress induced not only depression-like behaviors but also significant enhancement in QRFP and GPR103 in the PVN. Genetic overexpression of QRFP/GPR103 and stereotactic infusion of QRFP-26/QRFP-43 peptide in the PVN all mimicked chronic stress that induced various depression-like phenotypes in naïve mice, and this was mediated by promoting CRH biosynthesis and HPA activity. In contrast, genetic knockdown of QRFP/GPR103 in the PVN produced notable antidepressant-like effects in mice exposed to chronic stress. Furthermore, genetic knockout of QRFP also protected against chronic stress in mice. In addition, both the C-terminal biological region of QRFP and the downstream PKA/PKC-CREB signaling coupled to GPR103 stimulation underlie the role of QRFP and GPR103 in depression. Collectively, QRFP and GPR103 in PVN neurons could be viable targets for novel antidepressants.

The salt-inducible kinases inhibitor HG-9-91-01 exhibits antidepressant-like actions in mice exposed to chronic unpredictable mild stress

Major depressive disorder is a frequently occurring neuropsychiatric disorder throughout the world. However, the limited and delayed therapeutic efficacy of monoaminergic medications has led to intensive research efforts to develop novel antidepressants. We have previously demonstrated that hippocampal salt-inducible kinase 2 (SIK2) plays a role in the pathogenesis of depression via regulating the downstream CREB-regulated transcription coactivator 1 (CRTC1)-cAMP response element-binding protein (CREB)-brain derived neurotrophic factor (BDNF) pathway. HG-9-91-01 is a potent and selective inhibitor of salt-inducible kinases (SIKs). The present study aims to explore whether HG-9-91-01 has antidepressant-like actions in male C57BL/6J mice. The chronic unpredictable mild stress (CUMS) model of depression, various behavioral tests, western blotting, co-immunoprecipitation, immunofluorescence, stereotactic infusion, and viral-mediated genetic knockdown were used together. It was found that hippocampal infusion of HG-9-91-01 induced significant antidepressant-like effects in the CUMS model, accompanied with preventing the enhancement of CUMS on the hippocampal SIK2 expression and cytoplasmic translocation of CRTC1. HG-9-91-01 treatment also reversed the decreasing effects of CUMS on the BDNF signaling cascade and adult neurogenesis in the hippocampus. Moreover, the antidepressant-like actions of HG-9-91-01 in mice required the hippocampal CRTC1-CREB-BDNF pathway. In conclusion, HG-9-91-01 has potential of being a novel antidepressant candidate.

Medicinal Applications of Cannabinoids Extracted from Cannabis sativa (L.): A New Route in the Fight Against COVID-19?

Cannabis sativa is a well-known plant that has been recognized for its benefits since ancient times by several medicinal systems, including those of China, India, Greece, and Egypt. Although C. sativa is one of the most investigated medicinal plants in the world, it faces some of the greatest controversies surrounding its legalization and use as a medication. C. sativa contains several hundred phytoconstituents, including the infamous "cannabinoids". It is necessary to properly understand the medicinal importance of these phytochemicals and spread awareness among the countries where cannabis is still facing legal obstacles. The current review focuses on the most recent literature pertaining to various applications of cannabinoids, with a special focus on the medicinal aspect of these phytochemicals. Peer-reviewed articles focusing on the importance of cannabis and cannabinoids are the target of this review. Articles were selected based on the relevance to the general scope of the work, i.e., application of cannabinoids. Cannabinoids can truly be regarded as wonder drugs, considering their immense diversity of usage. Unfortunately, however, many of the mares have never been researched biologically or pharmacologically due to their low yield in the plant. However, the approval of some cannabinoids by the FDA (along with other recognized national medical health systems) has opened the horizon for the use of these natural drugs in medicines such as Epidiolex® (cannabidiol, used for the treatment of severe forms of epilepsy) and Sativex®(Δ⁹-tetrahydrocannabinol and cannabidiol, used for the treatment of spasticity caused by multiple sclerosis). Many pharmacological properties of C. sativa are attributed to cannabidiol (CBD), a non-psychoactive component, along with Δ9-tetrahydrocannabinol (Δ⁹-THC), a psychoactive component. This review addresses the most important applications or current utilization of cannabinoids in a variety of treatments such as chronic pain, cancer, emesis, anorexia, irritable bowel syndrome, communicable diseases, glaucoma, and central nervous system disorders. The biosynthetic pathway of cannabinoids is also discussed. In short, cannabis has a myriad of bioactive compounds that have the potential to increase the list of approved cannabinoids suitable for therapy.

Self-reported review of the value of esketamine in patients with treatment-resistant depression: Understanding the patient experience in the STRIVE Study

Esketamine nasal spray (ESK) is indicated, in conjunction with an oral antidepressant (OAD), for the management of treatment-resistant depression (TRD) in adults. Select US-based patients from an open-label, long-term extension safety study of ESK (NCT02782104) participated in this study through semi-structured interviews. The study evaluated patient-reported early health changes related to emotional health, daily functioning, and social functioning in adults with TRD treated with ESK plus OAD. Eligible patients were responders to ESK who had begun initial ESK treatment ≤30 months before enrollment and were currently receiving ESK plus OAD. Results from 23 patients (9 men, 14 women; mean age, 46 years) were analyzed. Patients described the degree to which ESK treatment changed the effects of depression on aspects of health as either being much improved or improved (91.8%, 156/170). Key characteristics noted regarding treatment with ESK plus OAD included degree of effectiveness (n = 11), rapid onset of action (n = 7), and side-effect profile (n = 5). All patients reported being either satisfied (52%) or very satisfied (48%) with ESK plus OAD treatment. Adverse events were consistent with the known safety profile of ESK. Study insights may help prepare patients with TRD and their clinicians to anticipate potential health changes experienced with ESK.

Benefit-Risk Assessment of Esketamine Nasal Spray vs. Placebo in Treatment-Resistant Depression

This post hoc analysis assessed the benefit–risk profile of esketamine nasal spray + oral antidepressant (AD) induction and maintenance treatment in patients with treatment‐resistant depression (TRD). The Benefit–Risk Action Team framework was utilized to assess the benefit–risk profile using data from three induction studies and one maintenance study. Benefits were proportion of remitters or responders in induction studies and proportion of stable remitters or stable responders who remained relapse‐free in the maintenance study. Risks were death, suicidal ideation, most common adverse events (AEs), and potential long‐term risks. Per 100 patients on esketamine + AD vs. AD + placebo in induction therapy, 5–21 additional patients would remit and 14–17 additional patients would respond. In maintenance therapy, 19–32 fewer relapses would occur with esketamine. In both cases, there was little difference in serious or severe common AEs (primarily dissociation, vertigo, and dizziness). These findings support a positive benefit–risk balance for esketamine + AD as induction and maintenance treatment in patients with TRD.

Toolbox: Psychotropic medications for augmentation or combination in treatment-resistant depression

This toolbox compares pharmacologic options for treatment-resistant depression (TRD) that may be considered if the patient fails to experience adequate response or remission despite optimizing antidepressant therapy.

Emerging therapies for treatment resistant depression

Despite new insights and evidence-based treatment options for clinical depression in the recent years, the current choices of safe and effective therapies are still inadequate to sustain a long-term response in the depressed patient. Many do not improve, improve partially or are classified as ‘treatment resistant’ with poor compliance and marked functional impairment. The aim of this article is to review future therapeutic options and advances in treatments available for this cohort of patients. Several innovative and promising studies are underway to explore the role of ketamine, a glutamate N-methyl-d-aspartate (NMDA) antagonist in treating treatment-resistant depression and acute suicidal ideation. Furthermore, new research reveals that depression is associated with a significant drop in neurotrophic factors such as brain derived neurotrophic factor (BDNF) and increasing BDNF may be a new strategy for developing new antidepressants. Neuromodulation interventions by stimulating specific brain regions including deep brain stimulation (DBS), magnetic seizure therapy (MST), and transcranial direct current stimulation (tDCS), still in experimental stages, are also discussed.