Propofol-induced deep sedation reduces emotional episodic memory reconsolidation in humans

Post-retrieval noradrenergic activation impairs subsequent memory depending on cortico-hippocampal reactivation

When retrieved, seemingly stable memories can become sensitive to significant events, such as acute stress. The mechanisms underlying these memory dynamics remain poorly understood. Here, we show that noradrenergic stimulation after memory retrieval impairs subsequent remembering, depending on hippocampal and cortical signals emerging during retrieval. In a three-day study, we measured brain activity using fMRI during initial encoding, 24 hr-delayed memory cueing followed by pharmacological elevations of glucocorticoid or noradrenergic activity, and final recall. While post-retrieval glucocorticoids did not affect subsequent memory, the impairing effect of noradrenergic arousal on final recall depended on hippocampal reactivation and category-level reinstatement in the ventral temporal cortex during memory cueing. These effects did not require a reactivation of the original memory trace and did not interact with offline reinstatement during rest. Our findings demonstrate that, depending on the retrieval-related neural reactivation of memories, noradrenergic arousal after retrieval can alter the future accessibility of consolidated memories.

Early Cognitive Function after Deep Sedation Using Different Anesthetic Agents in Pediatric Patients: A Prospective, Randomized Controlled Trial

Background and Objectives: The impact of anesthetic agents on memory and cognitive function following general anesthesia is of great interest, particularly regarding their effects on the developing pediatric brain. While numerous studies have examined the relationship between anesthetic drugs and brain function, research focusing on early cognitive function following sedation remains limited. Materials and Methods: This study was a prospective, randomized controlled trial involving 148 pediatric patients scheduled for hematological procedures, specifically bone marrow aspiration (BMA) and intrathecal chemotherapy (ITC). Patients were divided into two groups based on the primary anesthetic used: the inhalational sedation group (IHG), in which sevoflurane was used, and the intravenous sedation group (IVG), which received propofol infusion. Apart from the main anesthetic agent, all sedation methods were consistent across both groups. A cognitive function test administered before sedation involved memorizing four distinct images, each associated with a different number. Then, the patients were asked to identify the omitted image upon awakening in the recovery room. Herein, this pre- vs. post-sedation test is called the early recognition assessment (ERA) tool. The primary outcome was the correct response rate after sedation for the two groups. Secondary outcomes included the sedation score, the behavior response score, and the correct response rates according to the number of sedation procedures. Results: This study included 130 patients in the final analysis, with 74 originally assigned to each group. The initial cognitive assessment revealed no significant difference in performance between the anesthetic agents. In addition, no differences were observed in the rates of correct responses or post-sedation scores after repeated procedures. However, the IVG demonstrated higher behavior response scores compared to the IHG. Conclusions: There were no significant differences in the rates of correct responses using the ERA tool between the two groups, irrespective of the number of sedation procedures performed. While some differences were noted in preoperative, intraoperative, and post-anesthesia care, these did not significantly impact the cognitive outcomes measured.

Repurposing General Anesthetic Drugs to Treat Depression: A New Frontier for Anesthesiologists in Neuropsychiatric Care

During the last 100 years, the role of anesthesiologists in psychiatry has focused primarily on facilitating electroconvulsive therapy and mitigating postoperative delirium and other perioperative neurocognitive disorders. The discovery of the rapid and sustained antidepressant properties of ketamine, and early results suggesting that other general anesthetic drugs (including nitrous oxide, propofol, and isoflurane) have antidepressant properties, has positioned anesthesiologists at a new frontier in the treatment of neuropsychiatric disorders. Moreover, shared interest in understanding the biologic underpinnings of anesthetic drugs as psychotropic agents is eroding traditional academic boundaries between anesthesiology and psychiatry. This article presents a brief overview of anesthetic drugs as novel antidepressants and identifies promising future candidates for the treatment of depression. The authors issue a call to action and outline strategies to foster collaborations between anesthesiologists and psychiatrists as they work toward the common goals of repurposing anesthetic drugs as antidepressants and addressing mood disorders in surgical patients.

[Study of 2,6-di(propan-2-yl)phenol detection features and localization nature in warm-blooded after intragastric administration]

OBJECTIVE

Study of 2.6-di(propan-2-yl)phenol (2.6-di(P-2-yl)F) distribution nature in warm-blooded in case of fatal poisoning due to intragastric administration of the substance.

MATERIAL AND METHODS

The warm-blooded model consisted of Wistar male rats aged about 4 months, administered 1.800 mg 2.6-di(P-2-yl)F per 1 kg of animal body weight (≈3 LD50). After the rats died, 2.6-di(P-2-yl)F was isolated from their corpses' biomatrices by infusing an ethyl acetate-acetone mixture (7:3), purified by extraction (distribution in the systems trichloromethane-aqueous solution (pH 11.0-11.5) and aqueous solution (pH 2-4) - ethyl acetate), and normal pressure chromatography in a silica gel column L 40×100 µm (eluent hexane-acetone (7:3). The analyte was identified using gas chromatography with mass spectrometry (capillary (0.2 mm) column, stationary phase - polysiloxane with a ratio (in %) of methyl and phenyl substituents of 95:5), thin layer chromatography (Sorbfil plates, dynamic phase hexane-diethyl ether (9:1)), and electronic spectrophotometry (solvent - ethanol). The analyte content was quantified by spectrophotometry.

RESULTS

In the study, 2.6-di(P-2-yl)F mainly accumulated in the stomach contents (378.94±41.51) and tissues (175.20±17.12). Among other biomatrices obtained from poisoned rat corpses, a significant amount of the investigated toxic compound was found in the heart (142.79±13.08) and spleen (117.83±16.23), a bit smaller amounts - in the lungs (112.32±29.54) and small intestine (97.10±11.66).

CONCLUSIONS

A scheme for determining 2.6-di(propan-2-yl)phenol in biomaterial has been developed and applied to study the analyte localization in the body of animals poisoned by it. The highest amount of the toxicant (mg/100 g) was found in the stomach contents (378.94±41.51), its tissues (175.20±17.12), heart (142.79±13.08) and spleen (117.83±16.23).

Rapid thalamocortical network switching mediated by cortical synchronization underlies propofol-induced EEG signatures: a biophysical model

Propofol-mediated unconsciousness elicits strong alpha/low-beta and slow oscillations in the electroencephalogram (EEG) of patients. As anesthetic dose increases, the EEG signal changes in ways that give clues to the level of unconsciousness; the network mechanisms of these changes are only partially understood. Here, we construct a biophysical thalamocortical network involving brain stem influences that reproduces transitions in dynamics seen in the EEG involving the evolution of the power and frequency of alpha/low-beta and slow rhythm, as well as their interactions. Our model suggests that propofol engages thalamic spindle and cortical sleep mechanisms to elicit persistent alpha/low-beta and slow rhythms, respectively. The thalamocortical network fluctuates between two mutually exclusive states on the timescale of seconds. One state is characterized by continuous alpha/low-beta-frequency spiking in thalamus (C-state), whereas in the other, thalamic alpha spiking is interrupted by periods of co-occurring thalamic and cortical silence (I-state). In the I-state, alpha colocalizes to the peak of the slow oscillation; in the C-state, there is a variable relationship between an alpha/beta rhythm and the slow oscillation. The C-state predominates near loss of consciousness; with increasing dose, the proportion of time spent in the I-state increases, recapitulating EEG phenomenology. Cortical synchrony drives the switch to the I-state by changing the nature of the thalamocortical feedback. Brain stem influence on the strength of thalamocortical feedback mediates the amount of cortical synchrony. Our model implicates loss of low-beta, cortical synchrony, and coordinated thalamocortical silent periods as contributing to the unconscious state.NEW & NOTEWORTHY GABAergic anesthetics induce alpha/low-beta and slow oscillations in the EEG, which interact in dose-dependent ways. We constructed a thalamocortical model to investigate how these interdependent oscillations change with propofol dose. We find two dynamic states of thalamocortical coordination, which change on the timescale of seconds and dose-dependently mirror known changes in EEG. Thalamocortical feedback determines the oscillatory coupling and power seen in each state, and this is primarily driven by cortical synchrony and brain stem neuromodulation.

[Study of 2,6-di(propan-2-yl)phenol stability in biomaterial]

The aim of this study is to research the stability of 2.6-di(propan-2-yl)phenol in biomaterial. GC-MS (column DB-5MS EVIDEX (25 m×0.2 mm); stationary liquid phase of 5%-phenyl-95% dimethylpolysiloxane), TLC (Sorbfil plates, mobile phase of hexane-diethyl ether (9:1) and spectrophotometry (solvent medium - 95% ethanol) were used as methods of analysis. 2.6-di(propan-2-yl)phenol was isolated from the biomatrix (liver tissue) by infusion with a mixture of ethyl acetate-acetone (7:3). The analyte was purified by combining extraction (water-ethyl acetate system) and semi-preparative chromatography on a column of silica gel L 40/100 µm, eluent - hexane-acetone (7:3). It was found that at -22 °C, 0 °C, 12 °C, 20 °C and 30 °C 2.6-di(propan-2-yl)phenol can be present in the liver tissue for 119, 98, 70, 56 and 42 days, respectively. The possibility of mathematical description of analyte decomposition dynamics in biomaterial (liver tissue) at the considered temperatures on the basis of hyperbola equation has been studied. The experimentally calculated coefficients in the hyperbola equation (k_m) for temperatures -22 °C, 0 °C, 12 °C, 20 °C and 30 °C are equal to 1823, 1130, 697, 510, and 255, respectively. The dependence k_m on the conserving temperature (t^о) was educed. The equation for the description of dependence is offered: k_m=30.61∙(50-t^o)-402.39. It is shown that this equation can be the basis for prediction of 2.6-di(propan-2-yl)phenol stability in biomaterial (liver tissue) in the temperature range from -22 °C to 30 °C.

The potential of ketamine for posttraumatic stress disorder: a review of clinical evidence

Posttraumatic stress disorder (PTSD) is a devastating condition, for which there are few pharmacological agents, often with a delayed onset of action and poor efficacy. Trauma-focused psychotherapies are further limited by few trained providers and low patient engagement. This frequently results in disease chronicity as well as psychiatric and medical comorbidity, with considerable negative impact on quality of life. As such, off-label interventions are commonly used for PTSD, particularly in chronic refractory cases. Ketamine, an N-methyl-D-aspartate (NDMA) receptor antagonist, has recently been indicated for major depression, exhibiting rapid and robust antidepressant effects. It also shows transdiagnostic potential for an array of psychiatric disorders. Here, we synthesize clinical evidence on ketamine in PTSD, spanning case reports, chart reviews, open-label studies, and randomized trials. Overall, there is high heterogeneity in clinical presentation and pharmacological approach, yet encouraging signals of therapeutic safety, efficacy, and durability. Avenues for future research are discussed.

A narrative review of the epigenetics of post-traumatic stress disorder and post-traumatic stress disorder treatment

Epigenetic research in post-traumatic stress disorder (PTSD) is essential, given that environmental stressors and fear play such a crucial role in its development. As such, it may provide a framework for understanding individual differences in the prevalence of the disorder and in treatment response. This paper reviews the epigenetic markers associated with PTSD and its treatment, including candidate genes and epigenome-wide studies. Because the etiopathogenesis of PTSD rests heavily on learning and memory, we also draw upon animal neuroepigenetic research on the acquisition, update and erasure of fear memory, focusing on the mechanisms associated with memory reconsolidation. Reconsolidation blockade (or impairment) treatment in PTSD has been studied in clinical trials and, from a neurological perspective, may hold promise for identifying epigenetic markers of successful therapy. We conclude this paper by discussing several key considerations and challenges in epigenetic research on PTSD in humans.

Effects of propranolol on the modification of trauma memory reconsolidation in PTSD patients: A systematic review and meta-analysis

Post-traumatic stress disorder (PTSD) develops after an exposure to a life-threatening event and is characterized by intrusive memories. According to memory reconsolidation theory retrieval of memory under certain conditions leads to its labilization and subsequent re-storage which could be disrupted by drugs. Propranolol has been the most commonly investigated drug for memory reconsolidation therapy in clinical trials. Intervention with propranolol have shown mixed results in PTSD patients with some studies showing improvement in symptoms while other failing to replicate these findings. We conducted a systematic review and meta-analysis to determine the efficacy of trauma memory disruption by propranolol on PTSD symptoms and physiological responses in PTSD patients. 3224 publications were assessed for eligibility. Seven studies on effects of propranolol on PTSD symptoms and 3 studies on effects of propranolol on physiological responses were incorporated in the meta-analyses. Overall, results indicate that propranolol did not show a beneficial effect on PTSD symptoms (standardized mean difference: 1.29; 95% CI = -2.16 - 0.17). Similarly, propranolol did not influence skin conductance (standardized mean difference: 0.77; 95% CI = -1.85 - 0.31) or EMG response (standardized mean difference: 0.16; 95% CI = -0.65 - 0.33). However, propranolol significantly reduced heart rate after trauma memory recall compared to placebo (standardized mean difference: 0.67; 95% CI = -1.27 to -0.07). This study finds a lack of evidence for the efficacy of propranolol on traumatic memory disruption, in PTSD patients, to recommend its routine clinical use. However, a high level of heterogeneity, variation in propranolol dosage and inadequate sample sizes mean that these findings require cautious interpretation.

Effects of Sevoflurane and Propofol on Posttraumatic Stress Disorder After Emergency Trauma: A Double-Blind Randomized Controlled Trial

OBJECTIVE

Posttraumatic stress disorder (PTSD) is a frequent and disabling consequence of traumatic events. A previous study found that early use of propofol was a potential risk factor for PTSD. This prospective study aimed to investigate the effect of propofol and sevoflurane on PTSD after emergency surgery in trauma patients.

METHODS

A total of 300 trauma patients undergoing emergency surgery were randomly divided into two groups and anesthetized with propofol and/or sevoflurane. Perioperative clinical data were collected. The incidence of PTSD was evaluated with the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5) in the two groups 1 month after the operation. The relevance of the injury time and CAPS-5 scores was assessed by Spearman correlation analysis. Logistic regression analysis was used to analyze the risk factors for PTSD.

RESULTS

The incidence of PTSD in the propofol group was higher than that in the sevoflurane group 1 month postoperatively (23.2 vs. 12.2%, P = 0.014). The injury time was negatively correlated with the CAPS-5 score in the propofol group (r = -0.226, P < 0.001). In the logistic regression analysis, the utilization of propofol was an independent risk factor for PTSD (P = 0.017).

CONCLUSION

Early use of propofol general anesthesia in emergency surgery for trauma patients may increase the risk of PTSD.

CLINICAL TRIAL REGISTRATION

www.chictr.org.cn, identifier: ChiCTR2100050202.

[Propofol: use, toxicology and assay features]

The study objective is to review the literature on the use, pharmacological properties, toxicology, and assay methods for intravenous anesthetic propofol. The scope and forms of propofol use, its pharmacokinetics, biotransformation features, which occurs more than 90% in the liver, and side effects associated with propofol use for anesthesia, are addressed. Propofol infusion syndrome (also known as PrIS) and deaths from propofol overdose due to medical errors, abuse, suicide attempts, and homicide are reported. Propofol identification and assay methods based on high-performance liquid chromatography (HPLC), gas chromatography with mass spectrometry (GC-MS), and liquid chromatography (LC) are described. The features of the methods performance are outlined; biological materials (the study objects) are listed: mainly blood and plasma, as well as urine, bile, hair, etc. The relevance of a comprehensive forensic chemical study of propofol is indicated, though there are few forensic studies of propofol.

Sedation-Led chEmotherapy Evades Pain (S.L.E.E.P.)

Chemotherapy and other invasive therapies are often limited by side effects, pain and negative experiences that can limit adherence to the therapy itself. Such negative components add to the patient's depressive state due to the disease. This research project proposes the use of deep sedation during chemotherapy sessions or other disabling therapies in the treatment of tumors or other severe diseases. The proposed protocol provides for an ad hoc hospitalization which could be during the night, during the day or limited to a few hours. Administration during sleep eliminates the memory and the negative impact the treatment has on the rest of the patient's daily life. This approach also agrees with the evidence of the circadian rhythm of cellular repair processes, which is greater at sunrise and sunset and linked to a good quantity and quality of sleep. In conclusion, this project aims to reduce the negative impact and increase the adherence to and efficacy of the therapy itself.

Neural substrates of propranolol-induced impairments in the reconsolidation of nicotine-associated memories in smokers

The majority of smokers relapse even after successfully quitting because of the craving to smoking after unexpectedly re-exposed to smoking-related cues. This conditioned craving is mediated by reward memories that are frequently experienced and stubbornly resistant to treatment. Reconsolidation theory posits that well-consolidated memories are destabilized after retrieval, and this process renders memories labile and vulnerable to amnestic intervention. This study tests the retrieval reconsolidation procedure to decrease nicotine craving among people who smoke. In this study, 52 male smokers received a single dose of propranolol (n = 27) or placebo (n = 25) before the reactivation of nicotine-associated memories to impair the reconsolidation process. Craving for smoking and neural activity in response to smoking-related cues served as primary outcomes. Functional magnetic resonance imaging was performed during the memory reconsolidation process. The disruption of reconsolidation by propranolol decreased craving for smoking. Reactivity of the postcentral gyrus in response to smoking-related cues also decreased in the propranolol group after the reconsolidation manipulation. Functional connectivity between the hippocampus and striatum was higher during memory reconsolidation in the propranolol group. Furthermore, the increase in coupling between the hippocampus and striatum positively correlated with the decrease in craving after the reconsolidation manipulation in the propranolol group. Propranolol administration before memory reactivation disrupted the reconsolidation of smoking-related memories in smokers by mediating brain regions that are involved in memory and reward processing. These findings demonstrate the noradrenergic regulation of memory reconsolidation in humans and suggest that adjunct propranolol administration can facilitate the treatment of nicotine dependence. The present study was pre-registered at ClinicalTrials.gov (registration no. ChiCTR1900024412).

Effect of etomidate on the reuniens neuronal activity

OBJECTIVES

To explore the effect of etomidate on the neuronal activity of ventral thalamic reuniens nucleus and the underlying mechanisms.

METHODS

Whole-cell patch clamp method was used to explore the effect of etomidate on the activity of ventral thalamic reuniens neurons in the acute brain slices obtained from 4-5 weeks old C57BL/6J mice. The electrophysiological characteristics of ventral thalamic reuniens neurons were recorded in the current clamp mode, and then the effects of etomidate (0.5, 2.0, 8.0 μmol/L etomidate groups) and intralipid (intralipid group) on the discharge frequency and membrane potential of ventral thalamic reuniens neurons were recorded. During the experiment, the ventral thalamic reuniens neuron firing rates (RNFRs) were recorded as FB, FD and Fw before, after administration, and after elution; and the membrane potential was recorded as MPB and MPD before, after administration. The chlorine channel of gamma-amino butyric acid Type A (GABAA) receptor was blocked with 100 μmol/L picrotoxin (PTX). The RNFRs were recorded as FBS, FETO and FETO+PTX before, after perfusing etomidate with sub-anesthesia concentration (0.5 μmol/L) and after perfusing both PTX and etomidate.

RESULTS

In the intralipid group, there was no significant difference among the FB, FD and Fw (P>0.05). But in the etomidate groups (0.5, 2.0, 8.0 μmol/L), the FD was less than the FB, there was significant difference (all P<0.01); the Fw was higher than the FD, there was significant difference (all P<0.05). Moreover, there was significant difference in the inhibitory degree of the RNFRs between the 0.5 μmol/L etomidate group and the 8.0 μmol/L etomidate group (P<0.05). In the experiment to explore the mechanism of etomidate (0.5 μmol/L), the FETO was compared with the FBS, there was significant difference (P<0.01); but when the FETO+PTX was compared with the FBS, there was no significant difference (P>0.05).

CONCLUSIONS

Etomidate can inhibit the activity of ventral thalamic reuniens neurons in concentration-dependent manner, and which is reversible. Etomidate with sub-anesthetic concentration inhibits the activity of ventral thalamic reuniens neurons via targeting the GABAA receptor.

Detection of Electrophysiological Activity of Amygdala during Anesthesia Using Stereo-EEG: A Preliminary Research in Anesthetized Epileptic Patients

Recent studies of anesthesia mechanisms have focused on neuronal network and functional connectivity. The stereo-electroencephalography (SEEG) recordings provide appropriate temporal and spatial resolution to study whole-brain dynamics; however, the feasibility to detect subcortical signals during anesthesia still needs to be studied with clinical evidence. Here, we focus on the amygdala to investigate if SEEG can be used to detect cortical and subcortical electrophysiological activity in anesthetized epileptic patients. Therefore, we present direct evidence in humans that SEEG indeed can be used to record cortical and subcortical electrophysiological activity during anesthesia. The study was carried out in propofol-anesthetized five epileptic patients. The electrophysiology activity of the amygdala and other cortical areas from anesthesia to the recovery of consciousness was investigated using stereo-EEG (SEEG). Results indicated that with the decrease of propofol concentration, power spectral density (PSD) in the delta band of the amygdala significantly decreased. When it was close to recovery, the correlation between the amygdala and ipsilateral temporal lobe significantly decreased followed by a considerable increase when awake. The findings of the current study suggest SEEG as an effective tool for providing direct evidence of the anesthesia mechanism.

Investigating the efficacy of the reminder-extinction procedure to disrupt contextual threat memories in humans using immersive Virtual Reality

Upon reactivation, consolidated memories can enter a temporary labile state and require restabilisation, known as reconsolidation. Interventions during this reconsolidation period can disrupt the reactivated memory. However, it is unclear whether different kinds of memory that depend on distinct brain regions all undergo reconsolidation. Evidence for reconsolidation originates from studies assessing amygdala-dependent memories using cue-conditioning paradigms in rodents, which were subsequently replicated in humans. Whilst studies providing evidence for reconsolidation of hippocampus-dependent memories in rodents have predominantly used context conditioning paradigms, studies in humans have used completely different paradigms such as tests for wordlists or stories. Here our objective was to bridge this paradigm gap between rodent and human studies probing reconsolidation of hippocampus-dependent memories. We modified a recently developed immersive Virtual Reality paradigm to test in humans whether contextual threat-conditioned memories can be disrupted by a reminder-extinction procedure that putatively targets reconsolidation. In contrast to our hypothesis, we found comparable recovery of contextual conditioned threat responses, and comparable retention of subjective measures of threat memory, episodic memory and exploration behaviour between the reminder-extinction and standard extinction groups. Our result provide no evidence that a reminder before extinction can prevent the return of context conditioned threat memories in humans.

Does deep sedation with analgesia have positive effects on anxiety, pain and compliance in patients before and after prostate biopsy?

AIMS

To investigate whether deep sedation for transrectal prostate biopsy could reduce anxiety and pain and enhance rebiopsy compliance.

METHODS

A two-centre prospective observation study was conducted under two different anaesthetic conditions: deep sedation with analgesia and local anaesthesia with lidocaine. A 12-core prostate biopsy was taken in all patients. Scores on a 0-10 visual analogue scale, the State-Trait Anxiety Inventory-X-1, the Beck Anxiety Inventory and a five-level Likert satisfaction scale were evaluated. Finally, all patients were asked about their willingness to undergo the same procedure again if necessary and whether they wanted to change the anaesthetic method (deep sedation to local anaesthesia or local to sedation) if a repeat procedure was required.

RESULTS

A total of 135 patients were included in this study, including 69 patients in the sedation group and 66 patients in the local group. Lower pain scores (P < .001) and higher satisfaction scores (P = .019) were observed in the sedation group than in the local group after the procedure. Anxiety scores in the sedation group were significantly decreased after the procedure, whereas those were not changed in the local group. The question regarding rebiopsy compliance tended to be more positive in the sedation than in the local group (73.9% vs 62.1%, respectively, P = .099). The proportion of patients who wanted to change their anaesthetic method was much higher in the local than in the sedation group (68.2% vs 11.6%, respectively, P < .001).

CONCLUSION

Deep sedation with analgesia during transrectal prostate biopsy could reduce pain and postprocedural anxiety and enhance rebiopsy compliance. Considering the psychological and oncological benefits, we strongly recommend inducing deep sedation during transrectal prostate biopsy.

The Effect of Propofol on a Forced Swim Test in Mice at 24 Hours

Background

There are few rapidly acting treatments for acute suicidality or treatment-resistant depression. Propofol (2,6-diisopropylphenol) is an intravenous anesthetic agent used in outpatient settings. It is a gamma-aminobutyric acid type A agonist and has affinity at the N-methyl-D-aspartate receptor. Elevation in mood and sociality in humans has been observed following propofol-induced anesthesia. Other authors reported an open-label study of repeated dosing of propofol in treatment-resistant depression in which several patients experienced sustained improvement. Recently, we reported that in a rodent model of despair, a forced swim test, 45 minutes after administration of 50 mg/kg propofol, immobility time was significantly reduced.

Objective

The objective of the experiment was to determine whether the antidepressant-like effects of a single dose of propofol in mice are sustained for 24 hours.

Methods

The time spent immobile during a forced swim test 24 hours after intraperitoneal administration of a single dose of propofol 50 mg/kg or 0.9% saline was evaluated in 24 adult male mice (C57/BL6). Immobility time was quantified and evaluated with a custom video analysis software program.

Results

Propofol-treated mice were immobile for a mean (SEM) time of 115 (13) seconds, whereas saline-treated mice were immobile for a mean (SEM) time of 94 (14) seconds. A 2-tailed unpaired t test found no significant difference between the treatment groups (t = 1.07, df = 22; P = 0.30).

Conclusions

Twenty-four hours after intraperitoneal administration, the effect of propofol on immobility time was not statistically significantly different from vehicle. However, given our previous report of at least a short-term benefit of propofol on struggling time in the forced swim time and an encouraging pilot study in humans with treatment-resistant depression, further evaluation of propofol's antidepressant potential may be warranted.

Propofol Modulates Early Memory Consolidation in Humans

Maintenance of memory across time is crucial for adaptive behavior. Current theories posit that the underlying consolidation process depends on stabilization of synapses and reorganization of interactions between hippocampus and neocortex. However, the temporal properties of hippocampal-neocortical network reconfiguration during consolidation are still a matter of debate. Translational research on this issue is challenged by the paucity of techniques to transiently interfere with memory in the healthy human brain. Here, we report a neuro-pharmacological approach with the GABA_Aergic anesthetic propofol and a memory task sensitive to hippocampal dysfunction. Patients undergoing minor surgery learned word lists before injection of an anesthetic dose of propofol. Results show that administration of the drug shortly after learning (∼13 min) impairs recall after awakening but spares recognition. By contrast, later administration (∼105 min) has no effect. These findings suggest significant changes in memory networks very early after learning that are decisive for later recall. Propofol general anesthesia provides an experimental tool to modulate the first steps of hippocampus-mediated memory consolidation in humans.

Propofol alleviates cisplatin-related cognitive impairment

Chemotherapy-related cognitive impairment (CRCI) is commonly reported following the administration of chemotherapeutic agents and comprises a wide variety of neurological problems. Many patients after chemotherapy need further surgery under anesthesia. Thus, in this study, we examined whether propofol, one of the most commonly used anesthetics in surgery, could further affect the cognitive abilities in mouse CRCI models. The mice were injected intraperitoneally with cisplatin (2 mg/kg/day) for continuous 10 days and showed significantly reduced body weights. After 10 days reconversion, mice with cisplatin injection showed impaired memory retention in the inhibitory avoidance (IA) task, mimicking the CRCI in patients. Then, we found that a single injection of propofol with the sub-anesthetic dosage (50 mg/kg) but not the anesthetic dosage (250 mg/kg) could significantly alleviate the cisplatin-induced memory impairment. These results imply the possible clinical application of propofol, especially at the sub-anesthetic dosage, in the surgery of patients after chemotherapy.