(R,S)-Ketamine Promotes Striatal Neurogenesis and Sensorimotor Recovery Through Improving Poststroke Depression–Mediated Decrease in Atrial Natriuretic Peptide

S-ketamine ameliorates post-stroke depression in mice via attenuation of neuroinflammation, synaptic restoration, and BDNF pathway activation

The available therapeutic options for post-stroke depression patients are limited. Although SSRIs are the most commonly prescribed antidepressants, their slow onset of action and the higher risk of adverse effects or contraindications have led to an urgent need to develop fast-acting and highly specific antidepressants tailored to the needs of PSD patients. Therefore, ketamine has drawn attention. While ketamine has been shown to exert rapid antidepressant effects in numerous studies, whether it can ameliorate PSD remains unclear, and the molecular and cellular mechanisms underlying its therapeutic action in PSD are largely elusive. In this study, we used a PSD preclinical model induced by photothrombosis and chronic restraint stress to investigate the effects of S-ketamine. The present study demonstrates that a single acute intraperitoneal injection of 10 mg/kg S-ketamine on the first day after PSD significantly alleviates depressive-like behaviours in PSD mice. In addition, this improvement was maintained for at least five consecutive days. Mechanistically, S-ketamine reduced pro-inflammatory cytokines in the medial prefrontal cortex (mPFC), mitigated synaptic damage (evidenced by increased dendritic spine density, SYP, and PSD-95 expression). Furthermore, S-ketamine treatment upregulated the expression of brain-derived neurotrophic factor (BDNF), tropomyosin related kinase B (TrkB), phosphorylated serine/threonine-specific protein kinase B (p-Akt), phosphorylated extracellular signal-regulated kinase (p-Erk), phosphorylated calcium/calmodulin-dependent protein kinase II (p-CaMKII), and phosphorylated cAMP response element binding protein (p-CREB). Overall, S-ketamine shows promise for PSD treatment through its anti-inflammatory, synaptic enhancing, and BDNF pathway modulating effects. This research enhances our understanding of the pathological mechanisms underlying PSD and provides new therapeutic insights for its treatment.

Foxq1 activates CB2R with oleamide to alleviate POCD

Postoperative cognitive dysfunction (POCD) is a major concern, particularly among older adults. This study used social isolation (ISO) and multiomics analyses in aged mice to investigate potential mechanisms underlying POCD development. Aged mice were divided into two groups: ISO and paired housing (PH). Oleamide and the cannabinoid receptor type 2 (CB2R) antagonist AM630 were administered intraperitoneally, while Foxq1 adeno-associated viral (AAV) vector was injected directly into the hippocampus. Intramedullary tibial surgeries were subsequently performed to establish the POCD models. Behavioral tests comprising the Y-maze, open field test, and novel object recognition were conducted 2 days after surgery. Hippocampal and serum inflammatory cytokines were assessed. Following surgery, ISO mice demonstrated intensified cognitive impairments and escalated inflammatory markers. Integrative transcriptomic and metabolomic analysis revealed elevated oleamide concentrations in the hippocampus and serum of PH mice, with associative investigations indicating a close relationship between the Foxq1 gene and oleamide levels. While oleamide administration and Foxq1 gene overexpression substantially ameliorated postoperative cognitive performance and systemic inflammation in mice, CB2R antagonist AM630 impeded these enhancements. The Foxq1 gene and oleamide may be crucial in alleviating POCD. While potentially acting through CB2R-mediated pathways, these factors may modulate neuroinflammation and attenuate proinflammatory cytokine levels within the hippocampus, substantially improving cognitive performance postsurgery. This study lays the groundwork for future research into therapeutic approaches targeting the Foxq1-oleamide-CB2R axis, with the ultimate goal of preventing or mitigating POCD.

Reversal of the detrimental effects of social isolation on ischemic cerebral injury and stroke-associated pneumonia by inhibiting small intestinal T-cell migration into the brain and lung

Social isolation (ISO) is associated with an increased risk and poor outcomes of ischemic stroke. However, the roles and mechanisms of ISO in stroke-associated pneumonia (SAP) remain unclear. Adult male mice were single- or pair-housed with an ovariectomized female mouse and then subjected to transient middle cerebral artery occlusion. Isolated mice were treated with the natriuretic peptide receptor A antagonist A71915 or anti-gamma-delta (γδ) TCR monoclonal antibody, whereas pair-housed mice were treated with recombinant human atrial natriuretic peptide (rhANP). Subdiaphragmatic vagotomy (SDV) was performed 14 days before single- or pair-housed conditions. We found that ISO significantly worsened brain and lung injuries relative to pair housing, which was partially mediated by elevated interleukin (IL)-17A levels and the migration of small intestine-derived inflammatory γδ T-cells into the brain and lung. However, rhANP treatment or SDV could ameliorate ISO-exacerbated post-stroke brain and lung damage by reducing IL-17A levels and inhibiting the migration of inflammatory γδ T-cells into the brain and lung. Our results suggest that rhANP mitigated ISO-induced exacerbation of SAP and ischemic cerebral injury by inhibiting small intestine-derived γδ T-cell migration into the lung and brain, which could be mediated by the subdiaphragmatic vagus nerve.

Successful use of ketamine to treat severe depression with suicidality post-COVID-19 - A case report

Every second patient who suffers from COVID-19 experiences is at risk for depression. The treatment of severe depression with suicidal risk is challenging in patients with COVID-19 given the restrictions in access to and safety concerns with the use of electroconvulsive therapy during the COVID pandemic. Although ketamine is effective in treating depression, especially in presence of acute suicidality, to date, there are no reports on ketamine use to treat severe depression in the context of COVID-19. In this case report, we describe the success of ketamine to treat a person with severe depression and suicidality following COVID-19 infection.

Pathophysiology and Current Drug Treatments for Post-Stroke Depression: A Review

Post-stroke depression (PSD) is a biopsychosocial disorder that affects individuals who have suffered a stroke at any point. PSD has a 20 to 60 percent reported prevalence among stroke survivors. Its effects are usually adverse, can lead to disability, and may increase mortality if not managed or treated early. PSD is linked to several other medical conditions, including anxiety, hyper-locomotor activity, and poor functional recovery. Despite significant awareness of its adverse impacts, understanding the pathogenesis of PSD has proved challenging. The exact pathophysiology of PSD is unknown, yet its complexity has been definitively shown, involving mechanisms such as dysfunction of monoamine, the glutamatergic systems, the gut-brain axis, and neuroinflammation. The current effectiveness of PSD treatment is about 30-40 percent of all cases. In this review, we examined different pathophysiological mechanisms and current pharmacological and non-pharmacological approaches for the treatment of PSD.

RhANP attenuates endotoxin-derived cognitive dysfunction through subdiaphragmatic vagus nerve-mediated gut microbiota-brain axis

BACKGROUND

Atrial natriuretic peptide (ANP) secreted from atrial myocytes is shown to possess anti-inflammatory, anti-oxidant and immunomodulatory effects. The aim of this study is to assess the effect of ANP on bacterial lipopolysaccharide (LPS)-induced endotoxemia-derived neuroinflammation and cognitive impairment.

METHODS

LPS (5 mg/kg) was given intraperitoneally to mice. Recombinant human ANP (rhANP) (1.0 mg/kg) was injected intravenously 24 h before and/or 10 min after LPS injection. Subdiaphragmatic vagotomy (SDV) was performed 14 days before LPS injection or 28 days before fecal microbiota transplantation (FMT). ANA-12 (0.5 mg/kg) was administrated intraperitoneally 30 min prior to rhANP treatment.

RESULTS

LPS (5.0 mg/kg) induced remarkable splenomegaly and an increase in the plasma cytokines at 24 h after LPS injection. There were positive correlations between spleen weight and plasma cytokines levels. LPS also led to increased protein levels of ionized calcium-binding adaptor molecule (iba)-1, cytokines and inducible nitric oxide synthase (iNOS) in the hippocampus. LPS impaired the natural and learned behavior, as demonstrated by an increase in the latency to eat the food in the buried food test and a decrease in the number of entries and duration in the novel arm in the Y maze test. Combined prophylactic and therapeutic treatment with rhANP reversed LPS-induced splenomegaly, hippocampal and peripheral inflammation as well as cognitive impairment. However, rhANP could not further enhance the protective effects of SDV on hippocampal and peripheral inflammation. We further found that PGF mice transplanted with fecal bacteria from rhANP-treated endotoxemia mice alleviated the decreased protein levels of hippocampal polyclonal phosphorylated tyrosine kinase receptor B (p-TrkB), brain-derived neurotrophic factor (BDNF) and cognitive impairment, which was abolished by SDV. Moreover, TrkB/BDNF signaling inhibitor ANA-12 abolished the improving effects of rhANP on LPS-induced cognitive impairment.

CONCLUSIONS

Our results suggest that rhANP could mitigate LPS-induced hippocampal inflammation and cognitive dysfunction through subdiaphragmatic vagus nerve-mediated gut microbiota-brain axis.