Ketamine and fluoxetine exert similar actions on prelimbic and infralimbic responsivity to lateral septal nucleus stimulation in Wistar rats.

Ketamine is a dissociative anesthetic that has been proposed to be a useful alternative in cases of a poor response to other treatments in patients with depression. Remarkably, beneficial clinical actions of ketamine are detected once its psychotropic actions disappear. Therefore, clinical actions may occur independently of dose. Most current studies focus on actions of ketamine on neurotrophic factors, but few studies have investigated actions of ketamine on neural structures for which actions of antidepressants have been previously explored. Lateral septal nucleus (LSN) stimulation reduces neural activity in the prelimbic cortex (PL) and infralimbic cortex (IL) subregions of the medial prefrontal cortex (mPFC). Fluoxetine increases inhibitory responsivity of the LSN-IL connection. In the present study, actions of an anesthetic dose of ketamine were compared with a high dose of fluoxetine on behavior and neural responsivity 24 h after drug administration. Fluoxetine reduced immobility in the forced swim test without changing locomotor activity in the open field test. Ketamine strongly decreased locomotor activity and did not produce changes in immobility. In another set of Wistar rats that received similar drug treatment regimens, the results indicated that LSN stimulation in saline-treated animals produced a long-lasting inhibitory afterdischarge in these mPFC subregions. Actions of ketamine on the LSN-mPFC connection reproduced actions of fluoxetine, consisting of accentuated inhibition of the LSN action on the mPFC. These findings suggest that independent of different actions on neurotransmission, the common final pathway of antidepressants lies in their actions on forebrain structures that are related to emotional regulation.

Functional changes in sleep-related arousal after ketamine administration in individuals with treatment-resistant depression.

The glutamatergic modulator ketamine is associated with changes in sleep, depression, and suicidal ideation (SI). This study sought to evaluate differences in arousal-related sleep metrics between 36 individuals with treatment-resistant major depression (TRD) and 25 healthy volunteers (HVs). It also sought to determine whether ketamine normalizes arousal in individuals with TRD and whether ketamine's effects on arousal mediate its antidepressant and anti-SI effects. This was a secondary analysis of a biomarker-focused, randomized, double-blind, crossover trial of ketamine (0.5 mg/kg) compared to saline placebo. Polysomnography (PSG) studies were conducted one day before and one day after ketamine/placebo infusions. Sleep arousal was measured using spectral power functions over time including alpha (quiet wakefulness), beta (alert wakefulness), and delta (deep sleep) power, as well as macroarchitecture variables, including wakefulness after sleep onset (WASO), total sleep time (TST), rapid eye movement (REM) latency, and Post-Sleep Onset Sleep Efficiency (PSOSE). At baseline, diagnostic differences in sleep macroarchitecture included lower TST (p = 0.006) and shorter REM latency (p = 0.04) in the TRD versus HV group. Ketamine's temporal dynamic effects (relative to placebo) in TRD included increased delta power earlier in the night and increased alpha and delta power later in the night. However, there were no significant diagnostic differences in temporal patterns of alpha, beta, or delta power, no ketamine effects on sleep macroarchitecture arousal metrics, and no mediation effects of sleep variables on ketamine's antidepressant or anti-SI effects. These results highlight the role of sleep-related variables as part of the systemic neurobiological changes initiated after ketamine administration. Clinical Trials Identifier: NCT00088699.

The N-methyl-d-aspartate receptor hypothesis of ketamine's antidepressant action: evidence and controversies.

Substantial clinical evidence has unravelled the superior antidepressant efficacy of ketamine: in comparison to traditional antidepressants targeting the monoamine systems, ketamine, as an N-methyl-d-aspartate receptor (NMDAR) antagonist, acts much faster and more potently. Surrounding the antidepressant mechanisms of ketamine, there is ample evidence supporting an NMDAR-antagonism-based hypothesis. However, alternative arguments also exist, mostly derived from the controversial clinical results of other NMDAR inhibitors. In this article, we first summarize the historical development of the NMDAR-centred hypothesis of rapid antidepressants. We then classify different NMDAR inhibitors based on their mechanisms of inhibition and evaluate preclinical as well as clinical evidence of their antidepressant effects. Finally, we critically analyse controversies and arguments surrounding ketamine's NMDAR-dependent and NMDAR-independent antidepressant action. A better understanding of ketamine's molecular targets and antidepressant mechanisms should shed light on the future development of better treatment for depression. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.

Total intravenous anesthesia with Ketofol in rabbits: a comparison of the effects of constant rate infusion of midazolam, fentanyl or dexmedetomidine.

BACKGROUND: When inhalant anesthetic equipment is not available or during upper airway surgery, intravenous infusion of one or more drugs are commonly used to induce and/or maintain general anesthesia. Total intravenous anesthesia (TIVA) does not require endotracheal intubation, which may be more difficult to achieve in rabbits. A range of different injectable drug combinations have been used as continuous infusion rate in animals. Recently, a combination of ketamine and propofol (ketofol) has been used for TIVA in both human patients and animals. The purpose of this prospective, blinded, randomized, crossover study was to evaluate anesthetic and cardiopulmonary effects of ketofol total intravenous anesthesia (TIVA) in combination with constant rate infusion (CRI) of midazolam, fentanyl or dexmedetomidine in eight New Zealand White rabbits. Following IV induction with ketofol and endotracheal intubation, anesthesia was maintained with ketofol infusion in combination with CRIs of midazolam (loading dose [LD]: 0.3 mg/kg; CRI: 0.3 mg/kg/hr; KPM), fentanyl (LD: 6 µg/kg; CRI: 6 µg/kg/hr; KPF) or dexmedetomidine (LD: 3 µg/kg; CRI: 3 µg/kg/hr; KPD). Rabbits in the control treatment (KPS) were administered the same volume of saline for LD and CRI. Ketofol infusion rate (initially 0.6 mg kg- 1 minute- 1 [0.3 mg kg- 1 minute- 1 of each drug]) was adjusted to suppress the pedal withdrawal reflex. Ketofol dose and physiologic variables were recorded every 5 min. RESULTS: Ketofol induction doses were 14.9 ± 1.8 (KPM), 15.0 ± 1.9 (KPF), 15.5 ± 2.4 (KPD) and 14.7 ± 3.4 (KPS) mg kg- 1 and did not differ among treatments (p > 0.05). Ketofol infusion rate decreased significantly in rabbits in treatments KPM and KPD as compared with saline. Ketofol maintenance dose in rabbits in treatments KPM (1.0 ± 0.1 mg/kg/min) and KPD (1.0 ± 0.1 mg/kg/min) was significantly lower as compared to KPS (1.3 ± 0.1 mg/kg/min) treatment (p < 0.05). Ketofol maintenance dose did not differ significantly between treatments KPF (1.1 ± 0.3 mg/kg/min) and KPS (1.3 ± 0.1 mg/kg/min). Cardiovascular variables remained at clinically acceptable values but ketofol infusion in combination with fentanyl CRI was associated with severe respiratory depression. CONCLUSIONS: At the studied doses, CRIs of midazolam and dexmedetomidine, but not fentanyl, produced ketofol-sparing effect in rabbits. Mechanical ventilation should be considered during ketofol anesthesia, particularly when fentanyl CRI is used.

Substance specific EEG patterns in mice undergoing slow anesthesia induction.

The exact mechanisms and the neural circuits involved in anesthesia induced unconsciousness are still not fully understood. To elucidate them valid animal models are necessary. Since the most commonly used species in neuroscience are mice, we established a murine model for commonly used anesthetics/sedatives and evaluated the epidural electroencephalographic (EEG) patterns during slow anesthesia induction and emergence. Forty-four mice underwent surgery in which we inserted a central venous catheter and implanted nine intracranial electrodes above the prefrontal, motor, sensory, and visual cortex. After at least one week of recovery, mice were anesthetized either by inhalational sevoflurane or intravenous propofol, ketamine, or dexmedetomidine. We evaluated the loss and return of righting reflex (LORR/RORR) and recorded the electrocorticogram. For spectral analysis we focused on the prefrontal and visual cortex. In addition to analyzing the power spectral density at specific time points we evaluated the changes in the spectral power distribution longitudinally. The median time to LORR after start anesthesia ranged from 1080 [1st quartile: 960; 3rd quartile: 1080]s under sevoflurane anesthesia to 1541 [1455; 1890]s with ketamine. Around LORR sevoflurane as well as propofol induced a decrease in the theta/alpha band and an increase in the beta/gamma band. Dexmedetomidine infusion resulted in a shift towards lower frequencies with an increase in the delta range. Ketamine induced stronger activity in the higher frequencies. Our results showed substance-specific changes in EEG patterns during slow anesthesia induction. These patterns were partially identical to previous observations in humans, but also included significant differences, especially in the low frequencies. Our study emphasizes strengths and limitations of murine models in neuroscience and provides an important basis for future studies investigating complex neurophysiological mechanisms.

Esketamine alleviates hypoxia/reoxygenation injury of cardiomyocytes by regulating TRPV1 expression and inhibiting intracellular Ca2+ concentration.

OBJECTIVE: This study aimed to investigate the effect of Esketamine (ESK) on the Hypoxia/Reoxygenation (H/R) injury of cardiomyocytes by regulating TRPV1 and inhibiting the concentration of intracellular Ca2+. METHODS: The H/R injury model of H9c2 cardiomyocytes was established after 4h hypoxia and 6h reoxygenation. H9c2 cells were treated with different concentrations of ESK or TRPV1 agonist capsaicin (10 µM) or TRPV1 inhibitor capsazepine (1 µM). Cell viability was detected by CCK-8 method, and apoptosis by flow cytometry. Intracellular Ca2+ concentration was evaluated by Fluo-4 AM. LDH, MDA, SOD, and GSH-Px were detected with corresponding commercial kits. TRPV1 and p-TRPV1 proteins were detected by Western blot. RESULTS: After H/R, H9c2 cell viability decreased, apoptosis increased, intracellular Ca2+ concentration increased, LDH and MDA levels increased, SOD and GSH-Px levels decreased, and p-TRPV1 expression increased. ESK treatment rescued these changes induced by H/R. After up-regulating TRPV1, the protective effect of ESK on H/R injury of H9c2 cells was weakened, while down-regulating TRPV1 could further protect against H/R injury. CONCLUSION: ESK alleviates H/R injury of cardiomyocytes by regulating TRPV1 expression and inhibiting intracellular Ca2+ concentration.

O-GlcNAcylation levels remain stable regardless of the anaesthesia in healthy rats.

Anaesthetics are used daily in human and veterinary medicine as well as in scientific research. Anaesthetics have an impact on cell homeostasis especially through modulation of protein post-translational modifications. O-GlcNAcylation, a ubiquitous post-translational modification, plays a role in many biological processes. The aims of this study were to evaluate whether (1) anaesthesia influences O-GlcNAcylation and (2) its stimulation affects physiological parameters. Male Wistar rats (n = 38) were anaesthetized with ketamine-xylazine or isoflurane. They randomly received either an intravenous injection of Ringer's lactate or NButGT (10mg/kg) in order to increase O-GlcNAcylation levels. One hour after induction of anaesthesia, haemodynamic parameters and plasmatic markers were evaluated. Heart, brain and lungs were harvested and O-GlcNAcylation levels and O-GlcNAc-related enzymes were evaluated by western blot. Cardiac and pulmonary O-GlcNAcylation levels and cardiac, cerebral and pulmonary O-GlcNAc associated enzyme expression were not impacted with anaesthesia. Compared with ketamine-xylazine, isoflurane had a lower impact on blood pressure, heart rate and glycaemia. Pharmacological stimulation of O-GlcNAcylation by NButGT did not affect the physiological parameters. This study offers unprecedented insights into the regulation of O-GlcNAcylation and O-GlcNAc related enzymes during anaesthesia. Pharmacological stimulation of O-GlcNAcylation over a 1-h period did not disrupt the physiological balance in healthy anaesthetized rats.

Therapeutic doses of ketamine acutely attenuate the aversive effect of losses during decision-making.

The discovery of rapid-acting antidepressant, ketamine has opened a pathway to a new generation of treatments for depression, and inspired neuroscientific investigation based on a new perspective that non-adaptive changes in the intrinsic excitatory and inhibitory circuitry might underlie the pathophysiology of depression. Nevertheless, it still remains largely unknown how the hypothesized molecular and synaptic levels of changes in the circuitry might mediate behavioral and neuropsychological changes underlying depression, and how ketamine might restore adaptive behavior. Here, we used computational models to analyze behavioral changes induced by therapeutic doses of ketamine, while rhesus macaques were iteratively making decisions based on gains and losses of tokens. When administered intramuscularly or intranasally, ketamine reduced the aversiveness of undesirable outcomes such as losses of tokens without significantly affecting the evaluation of gains, behavioral perseveration, motivation, and other cognitive aspects of learning such as temporal credit assignment and time scales of choice and outcome memory. Ketamine's potentially antidepressant effect was separable from other side effects such as fixation errors, which unlike outcome evaluation, was readily countered with strong motivation to avoid errors. We discuss how the acute effect of ketamine to reduce the initial impact of negative events could potentially mediate longer-term antidepressant effects through mitigating the cumulative effect of those events produced by slowly decaying memory, and how the disruption-resistant affective memory might pose challenges in treating depression. Our study also invites future investigations on ketamine's antidepressant action over diverse mood states and with affective events exerting their impacts at diverse time scales.

A Randomized, Double-Blind, Placebo-Controlled Pilot Trial of the Acute Antisuicidal and Antidepressant Effects of Intranasal (R,S)-Ketamine in Severe Unipolar and Bipolar Depression With and Without Comorbid Alcohol Use Disorder.

Objective: Although individuals with a family history of alcohol use disorder (AUD) have a superior antidepressant response to ketamine, outcomes in patients with current AUD remain unclear. This study sought to investigate whether intranasal (IN) racemic (R,S)-ketamine had antisuicidal and antidepressant effects in unipolar and bipolar depression and whether comorbid AUD conferred superior antisuicidal outcomes for patients.Methods: This was a double-blind, randomized, placebo-controlled trial (May 2018 to January 2022) of single administration, fixed-dose (50 mg) IN (R,S)-ketamine (or saline comparator) in unmedicated inpatients meeting Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, criteria for a current major depressive episode (bipolar or unipolar), with current suicidal ideation (SI) and past attempt. Patients with and without comorbid AUD were enrolled. Change in Scale for Suicide Ideation score was the primary outcome measure, and change in Montgomery-Åsberg Depression Rating Scale score was the secondary outcome measure.Results: No significant group × time effect was noted for SI (F = 1.1, P = .36). A statistical trend toward superior improvement in suicidality was observed in participants with comorbid AUD. The group × time interaction was significant for improvements in depression (F = 3.06, P = .03) and largely unaffected by comorbid AUD or primary mood disorder type. Within the ketamine group, a significant correlation was observed between improvement in depressive symptoms and SI for patients without comorbid AUD (r =0.927, P = .023) that was absent in patients with AUD (r = 0.39, P = .44).Conclusion: IN ketamine induced rapid antidepressant effects compared to placebo but did not significantly alter SI scores. The treatment was well tolerated. Continued investigation with IN ketamine as a practical alternative to current formulations is warranted.Trial Registration: ClinicalTrials.gov identifier: NCT03539887.

Esketamine induces tripartite motif-containing protein 24 to improve cognitive dysfunction in Alzheimer's disease.

Esketamine has been revealed to improve cognitive impairments under different conditions, while its function in Alzheimer's disease (AD) has not been well characterized. We expounded the effects and detailed mechanism of esketamine in triple transgenic AD (3xTg-AD) mice in the present study. The impaired spatial learning and memory retention of 3xTg-AD mice were ameliorated by esketamine, whereas tripartite motif-containing protein 24 (TRIM24) depletion reversed the ameliorative effects of esketamine in 3xTg-AD mice. Esketamine elevated the extent of PI3K and AKT phosphorylation in the hippocampus by promoting TRIM24 expression, and knockdown of TRIM24 impaired the PI3K/AKT pathway. AD-like mice had increased expression of pro-inflammatory molecules and elevated expression of GFAP and p-Tau. Esketamine reduced inflammation, but its therapeutic effect was reversed by TRIM24 knockdown. The PI3K/AKT pathway blockage exacerbated cognitive deficits and neuroinflammatory responses in mice. Thus, esketamine has the potential to improve the cognitive and memory functions of 3xTg-AD mice by repressing neuroinflammation by activating TRIM24 and the downstream PI3K/AKT pathway.

Subanesthetic S-ketamine does not acutely alter striatal dopamine transporter binding in healthy Sprague Dawley female rats.

Major depressive disorder is one of the most prevalent mental health disorders, posing a global socioeconomic burden. Conventional antidepressant treatments have a slow onset of action, and 30% of patients show no clinically significant treatment response. The recently approved fast-acting antidepressant S-ketamine, an N-methyl-D-aspartate receptor antagonist, provides a new approach for treatment-resistant patients. However, knowledge of S-ketamine's mechanism of action is still being established. Depressed human subjects have lower striatal dopamine transporter (DAT) availability compared to healthy controls. Rodent studies report increased striatal dopamine concentration in response to acute ketamine administration. In vivo [18F]FE-PE2I ([18F]-(E)-N-(3-iodoprop-2-enyl)-2ß-carbofluoroethoxy-3ß-(4'-methyl-phenyl) nortropane) positron emission tomography (PET) imaging of the DAT has not previously been applied to assess the effect of acute subanesthetic S-ketamine administration on DAT availability. We applied translational in vivo [18F]FE-PE2I PET imaging of the DAT in healthy female rats to evaluate whether an acute subanesthetic intraperitoneal dose of 15 mg/kg S-ketamine alters DAT availability. We also performed [3H]GBR-12935 autoradiography on postmortem brain sections. We found no effect of acute S-ketamine administration on striatal DAT binding using [18F]FE-PE2I PET or [3H]GBR-12935 autoradiography. This negative result does not support the hypothesis that DAT changes are associated with S-ketamine's rapid antidepressant effects, but additional studies are warranted.

Environmental enrichment enhances the antidepressant effect of ketamine and ameliorates spatial memory deficits in adult rats.

Ketamine is a rapid-acting antidepressant associated with various cognitive side effects. To mitigate these side effects while enhancing efficacy, it can be co-administered with other antidepressants. In our study, we adopted a similar strategy by combining ketamine with environmental enrichment, a potent sensory-motor paradigm, in adult male Wistar rats. We divided the animals into four groups based on a combination of housing conditions and ketamine versus vehicle injections. The groups included those housed in standard cages or an enriched environment for 50 days, which encompassed a 13-day-long behavioral testing period. Each group received either two doses of ketamine (20 mg/kg, IP) or saline as a vehicle. We tested the animals in the novel object recognition test (NORT), forced swim test (FST), open field test (OFT), elevated plus maze (EPM), and Morris water maze (MWM), which was followed by ex vivo c-Fos immunohistochemistry. We observed that combining environmental enrichment with ketamine led to a synergistic antidepressant effect. Environmental enrichment also ameliorated the spatial memory deficits caused by ketamine in the MWM. There was enhanced neuronal activity in the habenula of the enrichment only group following the probe trial of the MWM. In contrast, no differential activity was observed in enriched animals that received ketamine injections. The present study showed how environmental enrichment can enhance the antidepressant properties of ketamine while reducing some of its side effects, highlighting the potential of combining pharmacological and sensory-motor manipulations in the treatment of mood disorders.

Exploring the impact of music on response to ketamine/esketamine: A scoping review.

Music and ketamine are both known to affect therapeutic outcomes, but few studies have investigated their co-administration. This scoping review describes the existing literature on the joint use of music and ketamine-or esketamine (the S(+) enantiomer of ketamine)-in humans. The review considers that extant studies have explored the intersection of ketamine/esketamine and music in healthy volunteers and in patients of various age groups, at different dosages, through different treatment processes, and have varied the sequence of playing music relative to ketamine/esketamine administration. Studies investigating the use of music during ketamine anesthesia are also included in the review because anesthesia and sedation were the early drivers of ketamine use. Studies pertaining to recreational ketamine use were omitted. The review was limited to articles published in the English language but not restricted by publication year. To the best of our knowledge, this scoping review is the first comprehensive exploration of the interplay between music and ketamine/esketamine and offers valuable insights to researchers interested in designing future studies.

Ketamine-induced prevention of SD-associated late infarct progression in experimental ischemia.

Spreading depolarizations (SDs) occur frequently in patients with malignant hemispheric stroke. In animal-based experiments, SDs have been shown to cause secondary neuronal damage and infarct expansion during the initial period of infarct progression. In contrast, the influence of SDs during the delayed period is not well characterized yet. Here, we analyzed the impact of SDs in the delayed phase after cerebral ischemia and the potential protective effect of ketamine. Focal ischemia was induced by distal occlusion of the left middle cerebral artery in C57BL6/J mice. 24 h after occlusion, SDs were measured using electrocorticography and laser-speckle imaging in three different study groups: control group without SD induction, SD induction with potassium chloride, and SD induction with potassium chloride and ketamine administration. Infarct progression was evaluated by sequential MRI scans. 24 h after occlusion, we observed spontaneous SDs with a rate of 0.33 SDs/hour which increased during potassium chloride application (3.37 SDs/hour). The analysis of the neurovascular coupling revealed prolonged hypoemic and hyperemic responses in this group. Stroke volume increased even 24 h after stroke onset in the SD-group. Ketamine treatment caused a lesser pronounced hypoemic response and prevented infarct growth in the delayed phase after experimental ischemia. Induction of SDs with potassium chloride was significantly associated with stroke progression even 24 h after stroke onset. Therefore, SD might be a significant contributor to delayed stroke progression. Ketamine might be a possible drug to prevent SD-induced delayed stroke progression.

Ketamine administration causes cognitive impairment by destroying the circulation function of the glymphatic system.

BACKGROUND: Ketamine, as a non-competitive antagonist of N-methyl-D-aspartate (NMDA) receptors, was originally used in general anesthesia. Epidemiological data show that ketamine has become one of the most commonly abused drugs in China. Ketamine administration might cause cognitive impairment; however, its molecular mechanism remains unclear. The glymphatic system is a lymphoid system that plays a key role in metabolic waste removal and cognitive regulation in the central nervous system. METHODS: Focusing on the glymphatic system, this study evaluated the behavioral performance and circulatory function of the glymphatic system by building a short-term ketamine administration model in mice, and detected the expression levels of the 5-HT2c receptor, ΔFosb, Pten, Akt, and Aqp4 in the hippocampus. Primary astrocytes were cultured to verify the regulatory relationships among related indexes using a 5-HT2c receptor antagonist, a 5-HT2c receptor short interfering RNA (siRNA), and a ΔFosb siRNA. RESULTS: Ketamine administration induced ΔFosb accumulation by increasing 5-HT2c receptor expression in mouse hippocampal astrocytes and primary astrocytes. ΔFosb acted as a transcription factor to recognize the AATGATTAAT bases in the 5' regulatory region of the Aqp4 gene (-1096 bp to -1087 bp), which inhibited Aqp4 expression, thus causing the circulatory dysfunction of the glymphatic system, leading to cognitive impairment. CONCLUSIONS: Although this regulatory mechanism does not involve the Pten/Akt pathway, this study revealed a new mechanism of ketamine-induced cognitive impairment in non-neuronal systems, and provided a theoretical basis for the safety of clinical treatment and the effectiveness of withdrawal.

Effects of ketamine on penile tissues in an experimental priapism model in rats.

BACKGROUND: This study aimed to evaluate the histopathological and biochemical effects of ketamine on penile tissues following ischemia-reperfusion injury induced by priapism. METHODS: Twenty-four male rats were randomized into three groups. Group 1 served as the control group. Group 2 underwent the priapism model to induce ischemia-reperfusion injury. Group 3, the treatment group, experienced a similar ischemia-reperfusion model as Group 2; additionally, 50 mg/kg of ketamine was administered intraperitoneally just before reperfusion. Blood biochemical analyses and penile histopathological evaluations were performed. RESULTS: In Group 3, significant improvements were observed in all histopathological scores, including desquamation, edema, inflammation, and vasocongestion compared to Group 2 (p<0.001). Blood biochemical analyses showed that the malondialdehyde (MDA) levels were recorded as 10 in Group 2, with a significant decrease in Group 3 (p=0.013). Similarly, proinflammatory cytokine levels, including interleukin-1 beta (IL-1ß), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α), were found to be suppressed in Group 3 compared to Group 2 (p=0.003, p=0.022, and p=0.028, respectively). Antioxidant enzyme activities, such as glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD), were higher in Group 3 compared to Group 2 (p=0.016 and p=0.024, respec-tively). CONCLUSION: Ketamine is an effective anesthetic agent in alleviating the effects of penile ischemia-reperfusion injury.

Efficacy of addition of the anti-inflammatory, IV glutathione to standard ketamine IV therapy in major depressive disorder.

Ketamine, a N-methyl-D-aspartate (NMDA) antagonist, is used for treatment-resistant depression (TRD). Recent studies have shown that there are increased levels of pro-inflammatory cytokines in individuals with major depressive disorder (MDD) and those with higher levels of oxidative stress markers have a decreased or null response to conventional antidepressants. Glutathione (GSH) as an antioxidant adjuvant to ketamine has not been well studied. This double-blind study with 30 patients divided into 2 groups of 15 each, aimed to determine if GSH, added to standard ketamine infusion (GSH+K), rendered better outcomes in MDD patients versus patients receiving ketamine infusions with a normal saline placebo (K+NS). There were significant drops in BDI-II scores from day 1 to day 14, PHQ- scores from day 1 to day 14 and PHQ-9 scores day 14 to day 28, suggesting the overall treatment was effective. There were no statistically significant differences between the groups over time. However, a sustained improvement in depressive symptoms was observed for 14 days post-infusion in both groups.

Exploring ketamine's reinforcement, cue-induced reinstatement, and nucleus accumbens cFos activation in male and female long evans rats.

Ketamine (KET), a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist, has rapid onset of antidepressant effects in Treatment-Resistant Depression patients and repeated infusions are required to sustain its antidepressant properties. However, KET is an addictive drug, and so more preclinical and clinical research is needed to assess the safety of recurring treatments in both sexes. Thus, the aim of this study was to investigate the reinforcing properties of various doses of KET (0-, 0.125-, 0.25-, 0.5 mg/kg/infusion) and assess KET's cue-induced reinstatement and neuronal activation in both sexes of Long Evans rats. Neuronal activation was assessed using the protein expression of the immediate early gene cFos in the nucleus accumbens (Nac), an important brain area implicated in reward, reinforcement and reinstatement to most drug-related cues. Our findings show that KET has reinforcing effects in both male and female rats, albeit exclusively at the highest two doses (0.25 and 0.5 mg/kg/infusion). Furthermore, we noted sex differences, particularly at the highest dose of ketamine, with female rats displaying a higher rate of self-administration. Interestingly, all groups that self-administered KET reinstated to drug-cues. Following drug cue-induced reinstatement test in rats exposed to KET (0.25 mg/kg/infusion) or saline, there was higher cFos protein expression in KET-treated animals compared to saline controls, and higher cFos expression in the core compared to the shell subregions of the Nac. As for reinstatement, there were no notable sex differences reported for cFos expression in the Nac. These findings reveal some sex and dose dependent effects in KET's reinforcing properties and that KET at all doses induced similar reinstatement in both sexes. This study also demonstrated that cues associated with ketamine induce comparable neuronal activation in the Nac of both male and female rats. This work warrants further research into the potential addictive properties of KET, especially when administered at lower doses which are now being used in the clinic for treating various psychopathologies.

Analysis of the mechanism by which ketamine affects astrocytes in Parkinsonian rats through the PI3K/AKT axis.

Parkinson's disease (PD) remains the most common neurodegenerative disease worldwide, seriously affecting the normal life of patients. Currently, there is no effective clinical cure for PD. In this study, the research team explored the effect of ketamine (KET) on PD, which can lay a reliable foundation for future KET treatment of PD. First, the research team established a PD rat model with 6-hydroxydopamine (6-OHDA). The detection showed that the maximum angle of the inclined plate stay, the number of times of grid crossings and standing, and the ATPase activity in brain tissue were significantly lower in PD rats than in control rats, while the positive rate of α-synuclein in brain tissue was increased, showing typical pathological manifestations of PD. After using KET to intervene in PD rats, the behavioral and brain pathological changes were significantly alleviated, and the inflammation and oxidative stress damage of brain tissue were effectively reduced, suggesting the potential therapeutic effects of KET on PD. Furthermore, the use of KET inhibited the PI3K/AKT axis in the brain tissue of PD rats and promoted autophagy. Moreover, the significant suppression of the PI3K/AKT axis by KET was also demonstrated in the PD cell model established through lipopolysaccharide (LPS) inducement of astrocyte cell line HA1800. It is suggested that the mechanism of KET on PD is related to the inhibition of the PI3K/AKT axis.