Role of Ketamine in the Treatment of Psychiatric Disorders

Microdosing ketamine in Drosophila does not block serotonin reuptake, but causes complex behavioral changes mediated by glutamate and serotonin receptors

Microdosing ketamine is a novel antidepressant for treatment-resistant depression. Traditional antidepressants, like selective serotonin reuptake inhibitors (SSRIs), inhibit serotonin reuptake, but it is not clear if ketamine shows a similar mechanism. Here, we tested the effects of feeding ketamine and SSRIs to Drosophila melanogaster larvae, which has a similar serotonin system to mammals and is a good model to track depressive behaviors, such as locomotion and feeding. Fast-scan cyclic voltammetry (FSCV) was used to measure optogenetically stimulated serotonin changes, and locomotion tracking software and blue dye feeding to monitor behavior. We fed larvae various doses (1-100 mM) of antidepressants for 24 h and found that 1 mM ketamine did not affect serotonin, but increased locomotion and feeding. Low doses (≤10 mM) of escitalopram and fluoxetine inhibited dSERT and also increased feeding and locomotion behaviors. At 100 mM, ketamine inhibited dSERT and increased serotonin concentrations, but decreased locomotion and feeding because of its anesthetic properties. Since microdosing ketamine causes behavioral effects, we further investigated behavioral changes with a SERT16 mutant and low doses of other NMDA receptor antagonists and 5-HT1A and 2 agonists. Feeding and locomotion changes were similar to ketamine in the mutant, and we found NMDA receptor antagonism increased feeding, while serotonin receptor agonism increased locomotion, which could explain these effects with ketamine. Ultimately, this work shows that Drosophila is a good model to discern antidepressant mechanisms, and that ketamine does not work on dSERT like SSRIs, but effects behavior with other mechanisms that should be investigated further.

Esketamine enhances memory reconsolidation in the novel object recognition task

Esketamine, the right-handed optical isomer of racemic ketamine, is a rapidly acting antidepressant approved by the FDA for treatment-resistant depression in 2019. However, few studies have investigated esketamine's role in learning and memory, particularly in the context of memory reconsolidation. Herein, we evaluated esketamine's role in memory reconsolidation in 7-week-old male Institute of Cancer Research mice subjected to the novel object recognition (NOR) memory task. The NOR reconsolidation procedure comprised three phases: sampling, reactivation, and testing. Esketamine-enhanced NOR memory performance when injected into mice 0 h after reactivation rather than following a 6 h delay. Conversely, administering esketamine 24 h after sampling without reactivation did not enhance NOR memory performance. Notably, esketamine exhibited no discernible effects on nonspecific responses, such as locomotor activity and exploratory behavior. Furthermore, the α-amino-3‑hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type receptor antagonist NBQX effectively blocked the esketamine-induced enhancement of memory reconsolidation. In conclusion, esketamine treatment markedly improves memory reconsolidation in NOR tasks, and this effect is linked to AMPA receptor activity.

A Pilot Study Comparing a Community of Practice Program with and without Concurrent Ketamine-Assisted Therapy

The prevalence of depression, anxiety, and post-traumatic stress disorder (PTSD) has increased among healthcare providers, while the effectiveness of conventional treatments remains limited. Ketamine-assisted therapy offers a promising alternative; however, few have integrated ketamine with a group-based therapeutic modality. We report a retrospective, secondary analysis of a 12-week pilot of a Community of Practice (CoP) oriented group therapy program with optional, adjunct ketamine for depression, anxiety, and PTSD in a sample of 57 healthcare providers. All participants moved through the treatment as one group, with 38 electing to also receive three adjunct ketamine sessions in addition to the weekly CoP. Symptoms were assessed at baseline and pilot completion with the PHQ-9 for depression, GAD-7 for anxiety, and PCL-5 for PTSD. We observed significant reductions in the mean change among all participants, suggesting that benefit was derived from the CoP component, with or without ketamine as an adjunct. PHQ-9 scores decreased by 6.79 (95% CI: 5.09-8.49, p < .001), GAD-7 scores decreased by 5.57 (CI: 4.12-7.00, p < .001), and PCL-5 scores decreased by 14.83 (CI: 10.27-19.38, p < .001). Reductions were larger, but statistically nonsignificant, among those receiving ketamine. Further research is required to assess the impact of ketamine as an adjunct in group-based therapies.

Use of ketamine for depression and suicidality in cancer and terminal patients: Review of current data

Depression and suicidality are significant challenges faced by cancer patients, particularly those in advanced stages of the disease or nearing the end of life. Conventional antidepressant therapies often have limited effectiveness or delayed onset of action, making the exploration of alternative treatments crucial. The use of ketamine as a potential treatment for depression and suicidality in cancer and terminal patients has gained considerable attention in recent years. This review article aims to provide a comprehensive analysis of the current data regarding the efficacy and safety of ketamine in this specific population. This review presents an overview of clinical trials and case studies investigating the use of ketamine in this population. It explores the effectiveness of ketamine as a standalone treatment or in combination with other interventions. Furthermore, the article addresses the limitations and future directions of research in this field. It highlights the need for larger, well-controlled studies with long-term follow-up to establish the efficacy, safety and optimal treatment parameters of ketamine for depression and suicidality in palliative care.

Effects of Antidepressant Medication on Brain-derived Neurotrophic Factor Concentration and Neuroplasticity in Depression: A Review of Preclinical and Clinical Studies

Depression is the most prevalent and debilitating disease with great impact on societies. Evidence suggests Brain-Derived Neurotrophic Factor (BDNF) plays an important role in pathophysiology of depression. Depression is associated with altered synaptic plasticity and neurogenesis. BDNF is the main regulatory protein that affects neuronal plasticity in the hippocampus. A wealth of evidence shows decreased levels of BDNF in depressed patients. Important literature demonstrated that BDNF-TrkB signaling plays a key role in therapeutic action of antidepressants. Numerous studies have reported anti-depressant effects on serum/plasma levels of BDNF and neuroplasticity which may be related to improvement of depressive symptoms. Most of the evidence suggested increased levels of BDNF after antidepressant treatment. This review will summarize recent findings on the association between BDNF, neuroplasticity, and antidepressant response in depression. Also, we will review recent studies that evaluate the association between postpartum depression as a subtype of depression and BDNF levels in postpartum women.

P2X7 receptor-mediated depression-like reactions arising in the mouse medial prefrontal cortex

Major depressive disorder is a frequent and debilitating psychiatric disease. We have shown in some of the acute animal models of major depressive disorder (tail suspension test and forced swim test) that depression-like behavior can be aggravated in mice by the microinjection into the medial prefrontal cortex of the P2X7R agonistic adenosine 5'-triphosphate or its structural analog dibenzoyl-ATP, and these effects can be reversed by the P2X7R antagonistic JNJ-47965567. When measuring tail suspension test, the prolongation of immobility time by the P2YR agonist adenosine 5'-[β-thio]diphosphate and the reduction of the adenosine 5'-(γ-thio)triphosphate effect by P2Y1R (MRS 2179) or P2Y12R (PSB 0739) antagonists, but not by JNJ-47965567, all suggest the involvement of P2YRs. In order to elucidate the localization of the modulatory P2X7Rs in the brain, we recorded current responses to dibenzoyl-ATP in layer V astrocytes and pyramidal neurons of medial prefrontal cortex brain slices by the whole-cell patch-clamp procedure; the current amplitudes were not altered in preparations taken from tail suspension test or foot shock-treated mice. The release of adenosine 5'-triphosphate was decreased by foot shock, although not by tail suspension test both in the hippocampus and PFC. In conclusion, we suggest, that in the medial prefrontal cortex, acute stressful stimuli cause supersensitivity of P2X7Rs facilitating the learned helplessness reaction.

Key Characteristics and Development of Psychoceuticals: A Review

Psychoceuticals have brought benefits to the pharmacotherapeutic management of central nervous system (CNS) illnesses since the 19th century. However, these drugs have potential side effects or lack high response rates. This review covers twenty drugs' biochemical mechanisms, benefits, risks, and clinical trial reports. For this study, medications from seven psychoceutical organizations were reviewed and evaluated. Nineteen drugs were chosen from the organizations, and one was selected from the literature. The databases used for the search were Pubmed, Google Scholar, and NIH clinical trials. In addition, information from the organizations' websites and other sources, such as news reports, were also used. From the list of drugs, the most common targets were serotonergic, opioid, and N-methyl-D-aspartate (NMDA) receptors. These drugs have shown promise in psychiatric illnesses such as substance abuse, post-traumatic stress disorder (PTSD), anxiety, depression, and neurological conditions, such as Parkinson's disease, traumatic brain injury, and neuroinflammation. Some of these drugs, however, are still early in development, so their therapeutic significance cannot be determined. These twenty drugs have promising benefits, but their clinical usage and efficacy must still be explored.