Anesthetic Sevoflurane Induces Enlargement of Dendritic Spine Heads in Mouse Neurons via Tau-Dependent Mechanisms.

BACKGROUND: Sevoflurane induces neuronal dysfunction and cognitive impairment. However, the underlying mechanism remains largely to be determined. Tau, cyclophilin D, and dendritic spine contribute to cognitive function. But whether changes in dendritic spines are involved in the effects of sevoflurane and the potential association with tau and cyclophilin D is not clear. METHODS: We harvested hippocampal neurons from wild-type mice, tau knockout mice, and cyclophilin D knockout mice. We treated these neurons with sevoflurane at day in vitro 7 and measured the diameter of dendritic spine head and the number of dendritic spines. Moreover, we determined the effects of sevoflurane on the expression of excitatory amino acid transporter 3 (EAAT3), extracellular glutamate levels, and miniature excitatory postsynaptic currents (mEPSCs). Finally, we used lithium, cyclosporine A, and overexpression of EAAT3 in the interaction studies. RESULTS: Sevoflurane-induced tau phosphgorylation increased the diameter of dendritic spine head and decreased the number of dendritic spines in neurons harvested from wild-type and cyclophilin D knockout mice, but not tau knockout mice. Sevoflurane decreased the expression of EAAT3, increased extracellular glutamate levels, and decreased the frequency of mEPSCs in the neurons. Overexpression of EAAT3 mitigated the effects of sevoflurane on dendritic spines. Lithium, but not cyclosporine A, attenuated the effects of sevoflurane on dendritic spines. Lithium also inhibited the effects of sevoflurane on EAAT3 expression and mEPSCs. CONCLUSIONS: These data suggest that sevoflurane induces a tau phosphorylation-dependent demtrimental effect on dendritic spine via decreasing EAAT3 expression and increasing extracellular glutamate levels, leading to neuronal dysfunction.

Transmission of Alzheimer's disease-associated microbiota dysbiosis and its impact on cognitive function: evidence from mice and patients.

Spouses of Alzheimer's disease (AD) patients are at a higher risk of developing incidental dementia. However, the causes and underlying mechanism of this clinical observation remain largely unknown. One possible explanation is linked to microbiota dysbiosis, a condition that has been associated with AD. However, it remains unclear whether gut microbiota dysbiosis can be transmitted from AD individuals to non-AD individuals and contribute to the development of AD pathogenesis and cognitive impairment. We, therefore, set out to perform both animal studies and clinical investigation by co-housing wild-type mice and AD transgenic mice, analyzing microbiota via 16S rRNA gene sequencing, measuring short-chain fatty acid amounts, and employing behavioral test, mass spectrometry, site-mutations and other methods. The present study revealed that co-housing between wild-type mice and AD transgenic mice or administrating feces of AD transgenic mice to wild-type mice resulted in AD-associated gut microbiota dysbiosis, Tau phosphorylation, and cognitive impairment in the wild-type mice. Gavage with Lactobacillus and Bifidobacterium restored these changes in the wild-type mice. The oral and gut microbiota of AD patient partners resembled that of AD patients but differed from healthy controls, indicating the transmission of microbiota. The underlying mechanism of these findings includes that the butyric acid-mediated acetylation of GSK3ß at lysine 15 regulated its phosphorylation at serine 9, consequently impacting Tau phosphorylation. Pending confirmative studies, these results provide insight into a potential link between the transmission of AD-associated microbiota dysbiosis and development of cognitive impairment, which underscore the need for further research in this area.

Sevoflurane anaesthesia induces cognitive impairment in young mice through sequential tau phosphorylation.

BACKGROUND: The volatile anaesthetic sevoflurane induces time (single or multiple exposures)-dependent effects on tau phosphorylation and cognitive function in young mice. The underlying mechanism for this remains largely undetermined. METHODS: Mice received 3% sevoflurane for 0.5 h or 2 h daily for 3 days on postnatal day (P) 6, 9, and 12. Another group of mice received 3% sevoflurane for 0.5 h or 1.5 h (3 × 0.5) on P6. We investigated effects of sevoflurane anaesthesia on tau phosphorylation on P6 or P12 mice, on cognitive function from P31 to P37, and on protein interactions, using in vivo studies, in vitro phosphorylation assays, and nanobeam single-molecule level interactions in vitro. RESULTS: An initial sevoflurane exposure induced CaMKIIα phosphorylation (132 [11]% vs 100 [6]%, P<0.01), leading to tau phosphorylation at serine 262 (164 [7]% vs 100 [26]%, P<0.01) and tau detachment from microtubules. Subsequent exposures to the sevoflurane induced GSK3ß activation, which phosphorylated detached or free tau (tau phosphorylated at serine 262) at serine 202 and threonine 205, resulting in cognitive impairment in young mice. In vitro phosphorylation assays also demonstrated sequential tau phosphorylation. Nanobeam analysis of molecular interactions showed different interactions between tau or free tau and CaMKIIα or GSK3ß, and between tau and tubulin at a single-molecule level. CONCLUSIONS: Multiple exposures to sevoflurane can induce sequential tau phosphorylation, leading to cognitive impairment in young mice, highlighting the need to investigate the underlying mechanisms of anaesthesia-induced tau phosphorylation in developing brain.

Impact of adrenomedullin on mitochondrial respiratory capacity in human adipocyte.

Mitochondrial function in adipocyte is an important aspect in maintaining metabolic homeostasis. Our previous observation showed that circulating levels of adrenomedullin (ADM) and mRNA and protein for ADM in omental adipose tissue were higher in patients with gestational diabetes mellitus (GDM), and these alterations are accompanied by glucose and lipid metabolic dysregulation, but the impact of ADM on mitochondrial biogenesis and respiration in human adipocyte remain elusive. The present study demonstrated that: (1) Increasing doses of glucose and ADM inhibit human adipocyte mRNA expressions of mitochondrial DNA (mtDNA)-encoded subunits of electron transport chain, including nicotinamide adenine dinucleotide dehydrogenase (ND) 1 and 2, cytochrome (CYT) b, as well as ATPase 6; (2) ADM significantly increases human adipocyte mitochondrial reactive oxygen species generation and this increase is reversed by ADM antagonist, ADM22-52, but treatment with ADM does not significantly affect mitochondrial contents in the adipocytes; (3) Adipocyte basal and maximal oxygen consumption rate are dose-dependently suppressed by ADM, thus results in impaired mitochondrial respiratory capacity. We conclude that elevated ADM observed in diabetic pregnancy may be involved in glucose and lipid dysregulation through compromising adipocyte mitochondrial function, and blockade of ADM action may improve GDM-related glucose and adipose tissue dysfunction.

The association between gut microbiota and postoperative delirium in patients.

Postoperative delirium is a common postoperative complication in older patients, and its pathogenesis and biomarkers remain largely undetermined. The gut microbiota has been shown to regulate brain function, and therefore, it is vital to explore the association between gut microbiota and postoperative delirium. Of 220 patients (65 years old or older) who had a knee replacement, hip replacement, or laminectomy under general or spinal anesthesia, 86 participants were included in the data analysis. The incidence (primary outcome) and severity of postoperative delirium were assessed for two days. Fecal swabs were collected from participants immediately after surgery. The 16S rRNA gene sequencing was used to assess gut microbiota. Principal component analyses along with a literature review were used to identify plausible gut microbiota, and three gut bacteria were further studied for their associations with postoperative delirium. Of the 86 participants [age 71.0 (69.0-76.0, 25-75% percentile of quartile), 53% female], 10 (12%) developed postoperative delirium. Postoperative gut bacteria Parabacteroides distasonis was associated with postoperative delirium after adjusting for age and sex (Odds Ratio [OR] 2.13, 95% Confidence Interval (CI): 1.09-4.17, P = 0.026). The association between delirium and both Prevotella (OR: 0.59, 95% CI: 0.33-1.04, P = 0.067) and Collinsella (OR: 0.57, 95% CI: 0.27-1.24, P = 0.158) did not meet statistical significance. These findings suggest that there may be an association between postoperative gut microbiota, specifically Parabacteroides distasonis, and postoperative delirium. However, further research is needed to confirm these findings and better understand the gut-brain axis's role in postoperative outcomes.

Transmission of Alzheimer's Disease-Associated Microbiota Dysbiosis and its Impact on Cognitive Function: Evidence from Mouse Models and Human Patients.

Spouses of Alzheimer's disease (AD) patients are at higher risk of developing AD dementia, but the reasons and underlying mechanism are unknown. One potential factor is gut microbiota dysbiosis, which has been associated with AD. However, it remains unclear whether the gut microbiota dysbiosis can be transmitted to non-AD individuals and contribute to the development of AD pathogenesis and cognitive impairment. The present study found that co-housing wild-type mice with AD transgenic mice or giving them AD transgenic mice feces caused AD-associated gut microbiota dysbiosis, Tau phosphorylation, and cognitive impairment. Gavage with Lactobacillus and Bifidobacterium restored these changes. The oral and gut microbiota of AD patient partners resembled that of AD patients but differed from healthy controls, indicating the transmission of oral and gut microbiota and its impact on cognitive function. The underlying mechanism of these findings includes that the butyric acid-mediated acetylation of GSK3ß at lysine 15 regulated its phosphorylation at serine 9, consequently impacting Tau phosphorylation. These results provide insight into a potential link between gut microbiota dysbiosis and AD and underscore the need for further research in this area.

Blood tau-PT217 contributes to the anesthesia/surgery-induced delirium-like behavior in aged mice.

INTRODUCTION: Blood phosphorylated tau at threonine 217 (tau-PT217) is a newly established biomarker for Alzheimer's disease and postoperative delirium in patients. However, the mechanisms and consequences of acute changes in blood tau-PT217 remain largely unknown. METHODS: We investigated the effects of anesthesia/surgery on blood tau-PT217 in aged mice, and evaluated the associated changes in B cell populations, neuronal excitability in anterior cingulate cortex, and delirium-like behavior using positron emission tomography imaging, nanoneedle technology, flow cytometry, electrophysiology, and behavioral tests. RESULTS: Anesthesia/surgery induced acute increases in blood tau-PT217 via enhanced generation in the lungs and release from B cells. Tau-PT217 might cross the blood-brain barrier, increasing neuronal excitability and inducing delirium-like behavior. B cell transfer and WS635, a mitochondrial function enhancer, mitigated the anesthesia/surgery-induced changes. DISCUSSION: Acute increases in blood tau-PT217 may contribute to brain dysfunction and postoperative delirium. Targeting B cells or mitochondrial function may have therapeutic potential for preventing or treating these conditions.

Oestrous cycle affects emergence from anaesthesia with dexmedetomidine, but not propofol, isoflurane, or sevoflurane, in female rats.

BACKGROUND: Although sex differences in anaesthetic sensitivity have been reported, what underlies these differences is unknown. In rodents, one source of variability in females is the oestrous cycle. Here we test the hypothesis that the oestrous cycle impacts emergence from general anaesthesia. METHODS: Time to emergence was measured after isoflurane (2 vol% for 1 h), sevoflurane (3 vol% for 20 min), dexmedetomidine (50 µg kg-1 i.v., infused over 10 min), or propofol (10 mg kg-1 i.v. bolus) during proestrus, oestrus, early dioestrus, and late dioestrus in female Sprague-Dawley rats (n=24). EEG recordings were taken during each test for power spectral analysis. Serum was analysed for 17ß-oestradiol and progesterone concentrations. The effect of oestrous cycle stage on return of righting latency was assessed using a mixed model. The association between righting latency and serum hormone concentration was tested by linear regression. Mean arterial blood pressure and arterial blood gases were assessed in a subset of rats after dexmedetomidine and compared in a mixed model. RESULTS: Oestrous cycle did not affect righting latency after isoflurane, sevoflurane, or propofol. When in the early dioestrus stage, rats emerged more rapidly from dexmedetomidine than in the proestrus (P=0.0042) or late dioestrus (P=0.0230) stage and showed reduced overall power in frontal EEG spectra 30 min after dexmedetomidine (P=0.0049). 17ß-Oestradiol and progesterone serum concentrations did not correlate with righting latency. Oestrous cycle did not affect mean arterial blood pressure or blood gases during dexmedetomidine. CONCLUSIONS: In female rats, the oestrous cycle significantly impacts emergence from dexmedetomidine-induced unconsciousness. However, 17ß-oestradiol and progesterone serum concentrations do not correlate with the observed changes.

Sevoflurane Induces a Cyclophilin D-Dependent Decrease of Neural Progenitor Cells Migration.

Clinical studies have suggested that repeated exposure to anesthesia and surgery at a young age may increase the risk of cognitive impairment. Our previous research has shown that sevoflurane can affect neurogenesis and cognitive function in young animals by altering cyclophilin D (CypD) levels and mitochondrial function. Neural progenitor cells (NPCs) migration is associated with cognitive function in developing brains. However, it is unclear whether sevoflurane can regulate NPCs migration via changes in CypD. To address this question, we treated NPCs harvested from wild-type (WT) and CypD knockout (KO) mice and young WT and CypD KO mice with sevoflurane. We used immunofluorescence staining, wound healing assay, transwell assay, mass spectrometry, and Western blot to assess the effects of sevoflurane on CypD, reactive oxygen species (ROS), doublecortin levels, and NPCs migration. We showed that sevoflurane increased levels of CypD and ROS, decreased levels of doublecortin, and reduced migration of NPCs harvested from WT mice in vitro and in WT young mice. KO of CypD attenuated these effects, suggesting that a sevoflurane-induced decrease in NPCs migration is dependent on CypD. Our findings have established a system for future studies aimed at exploring the impacts of sevoflurane anesthesia on the impairment of NPCs migration.

Impact of Adrenomedullin on Mitochondrial Respiratory Capacity in Human Adipocyte.

For metabolic homeostasis adequate mitochondrial function in adipocytes is essential. Our previous observation showed that circulating levels of adrenomedullin (ADM) and mRNA and protein for ADM in omental adipose tissue were higher in patients with gestational diabetes mellitus (GDM) compared with normal pregnancy, and these alterations are accompanied by glucose and lipid metabolic dysregulation, but the impact of ADM on mitochondrial biogenesis and respiration in human adipocyte remain elusive. In this study we demonstrated that: (1) Increasing doses of glucose and ADM inhibit human adipocyte mRNA expressions of mitochondrial DNA (mtDNA)-encoded subunits of electron transport chain (ETC), including nicotinamide adenine dinucleotide dehydrogenase (ND) 1 and 2, cytochrome (CYT) b, as well as ATPase 6; (2) ADM significantly increases human adipocyte mitochondrial reactive oxygen species (ROS) generation and this increase is reversed by ADM antagonist, ADM22-52, but does not significantly affect adipocyte mitochondrial contents; (3) Adipocyte basal and maximal oxygen consumption rate (OCR) are dose-dependently suppressed by ADM, and results in impaired mitochondrial respiratory capacity. We conclude that elevatedADM observed in diabetic pregnancy may be involved in glucose and lipid dysregulation through compromising adipocyte mitochondrial function, and blockade of ADM actions in adipocytes may improve GDM-related metabolic complications.

The association between gut microbiota and postoperative delirium in patients.

Postoperative delirium is one of the most common postoperative complications in older patients. Its pathogenesis and biomarkers, however, remain largely undetermined. Majority of human microbiota is gut microbiota and gut microbiota has been shown to regulate brain function. Therefore, this study aimed to determine the association between gut microbiota and postoperative delirium in patients. Of 220 patients (65 years old or older) who had a knee replacement, hip replacement, or laminectomy under general or spinal anesthesia, 86 participants were included in the data analysis. The incidence (primary outcome) and severity of postoperative delirium was assessed for two days. Fecal swabs were collected from participants immediately after surgery. The 16S rRNA gene sequencing was used to assess gut microbiota. Using principal component analyses along with a literature review to identify biologically plausible mechanisms, and three bacterials were studied for their associations with postoperative delirium. Of the 86 participants [age 71.0 (69.0-76.0, 25%-75% percentile of quartile), 53% female], ten (12%) developed postoperative delirium. Postoperative gut bacteria Parabacteroides distasonis (Odds Ratio [OR] 2.13, 95% Confidence Interval (CI): 1.09-4.17, P = 0.026) was associated with postoperative delirium after adjusting for age and sex. The association between delirium and both Prevotella (OR: 0.59, 95% CI: 0.33-1.04, P = 0.067) and Collinsella (OR: 0.57, 95% CI: 0.27-1.24, P = 0.158) did not meet statistical significance. These findings suggest that postoperative gut microbiota (e.g., Parabacteroides distasonis ) may serve as biomarkers in the pathogenesis of postoperative delirium, pending confirmative studies.

Ketamine Induces Delirium-Like Behavior and Interferes With Endosomal Tau Trafficking.

BACKGROUND: Ketamine is an intravenous anesthetic. However, whether ketamine can induce neurotoxicity and neurobehavioral deficits remains largely unknown. Delirium is a syndrome of acute brain dysfunction associated with anesthesia and surgery in patients, and tau protein may contribute to postoperative delirium. Finally, ketamine may affect the function of the endosome, the key organelle for tau release from neurons. Therefore, we set out to determine the effects of ketamine on delirium-like behavior in mice and on tau trafficking in cultured cells. METHODS: We used the buried-food test, open-field test, and Y-maze test in adult mice to assess the presence of delirium-like behavior in mice. We quantified tau amounts in the serum of mice. We used cell fraction methods to determine the effects of ketamine on tau intracellular trafficking, extracellular release, and endosome trafficking in cultured cells. RESULTS: Ketamine induced delirium-like behavior in mice and increased tau amounts in serum of mice. The ketamine treatments also led to increased accumulation of endosomes, as evidenced by increased endosomal markers Rab5 and Rab7. Moreover, ketamine inhibited endosome maturation, demonstrated by decreased membrane-bound but increased cytoplasm amounts of Rab5 and Rab7. Consequently, ketamine increased tau in the endosomes of cultured cells and the cell culture medium. CONCLUSIONS: These data suggest that ketamine may interfere with intracellular tau trafficking and induce delirium-like behavior, promoting future research regarding the potential neurotoxicity of anesthetics.

Odor Enrichment Attenuates the Anesthesia/Surgery-induced Cognitive Impairment.

OBJECTIVE: To determine the association between olfactory function and cognition in patients and rodents. BACKGROUND: Perioperative neurocognitive disorders include delayed neurocognitive recovery (dNCR). The contribution of olfactory function to dNCR remains undetermined. It is unknown whether odor enrichment could mitigate dNCR. METHODS: We performed a prospective observational cohort study to determine potential association between olfactory impairment and dNCR in patients. We assessed the effects of anesthesia/surgery on olfactory and cognitive function in mice using the block test and Barnes maze. We measured interleukin-6 (IL-6), olfactory mature protein, growth-associated protein 43, mature and premature olfactory neurons, postsynaptic density 95, and synaptophysin in blood, nasal epithelium, and hippocampus of mice. Odor enrichment, IL-6 antibody, and knockout of IL-6 were used in the interaction experiments. RESULTS: Patients with dNCR had worse odor identification than the patients without dNCR [preoperative: 7 (1.25, 9) vs 10 (8, 11), median (interquartile range), P <0.001; postoperative: 8 (2.25, 10) vs 10 (8, 11), P <0.001]. Olfactory impairment associated with dNCR in patients before and after adjusting age, sex, education, preoperative mini-mental state examination score, and days of the neuropsychological tests. Anesthesia/surgery induced olfactory and cognitive impairment, increased levels of IL-6 in blood and nasal epithelium, decreased amounts of olfactory receptor neurons and their markers in the nasal epithelium, and reduced amounts of synapse markers in the hippocampus of mice. These changes were attenuated by odor enrichment and IL-6 antibody. CONCLUSION: The anesthesia/surgery-induced olfactory impairment may contribute to dNCR in patients and postoperative cognitive impairment in mice. Odor enrichment could be a potential intervention.

Electroacupuncture attenuates surgical pain-induced delirium-like behavior in mice via remodeling gut microbiota and dendritic spine.

Surgical pain is associated with delirium in patients, and acupuncture can treat pain. However, whether electroacupuncture can attenuate the surgical pain-associated delirium via the gut-brain axis remains unknown. Leveraging a mouse model of foot incision-induced surgical pain and delirium-like behavior, we found that electroacupuncture stimulation at specific acupoints (e.g., DU20+KI1) attenuated both surgical pain and delirium-like behavior in mice. Mechanistically, mice with incision-induced surgical pain and delirium-like behavior showed gut microbiota imbalance, microglia activation in the spinal cord, somatosensory cortex, and hippocampus, as well as an enhanced dendritic spine elimination in cortex revealed by two-photon imaging. The electroacupuncture regimen that alleviated surgical pain and delirium-like behavior in mice also effectively restored the gut microbiota balance, prevented the microglia activation, and reversed the dendritic spine elimination. These data demonstrated a potentially important gut-brain interactive mechanism underlying the surgical pain-induced delirium in mice. Pending further studies, these findings revealed a possible therapeutic approach in preventing and/or treating postoperative delirium by using perioperative electroacupuncture stimulation in patients.

Urinary Catheterization Induces Delirium-Like Behavior Through Glucose Metabolism Impairment in Mice.

BACKGROUND: Delirium, an acute confusion status, is associated with adverse effects, including the development of Alzheimer's disease. However, the etiology and underlying mechanisms of delirium remain largely to be determined. Many patients have urinary catheterization (UC), and UC is associated with delirium. However, the cause effects of UC-associated delirium and the underlying mechanisms remain largely unknown. We, therefore, established an animal model of UC, without urinary tract infection, in mice and determined whether UC could induce delirium-like behavior in the mice and the underlying mechanism of these effects. METHODS: Adult female mice (16 weeks old) had UC placement under brief isoflurane anesthesia. The delirium-like behavior was determined using our established mice model at 3, 6, 9, and 24 hours after UC placement. We measured the amounts of glucose in both blood and brain interstitial fluid, adenosine triphosphate (ATP) concentration in the cortex, and glucose transporter 1 in the cortex of mice using western blot, immunohistochemistry imaging, reverse transcriptase-polymerase chain reaction (RT-PCR), and fluorescence at 6 hours after the UC placement. Finally, we used vascular endothelial growth factor (VEGF) in the interaction studies. RESULTS: We found that UC induced delirium-like behavior in mice at 3, 6, 9, but not 24 hours after the UC placement. UC decreased glucose amounts in brain interstitial fluid (86.38% ± 4.99% vs 100% ± 6.26%, P = .003), but not blood of mice and reduced ATP amounts (84.49% ± 8.85% vs 100% ± 10.64%, P = .031) in the cortex of mice. Finally, UC reduced both protein amount (85.49% ± 6.83% vs 100% ± 11.93%, P = .040) and messenger ribonucleic acid (mRNA) expression (41.95% ± 6.48% vs 100% ± 19.80%, P = .017) of glucose transporter 1 in the cortex of mice. VEGF attenuated these UC-induced changes. CONCLUSIONS: These data demonstrated that UC decreased brain glucose and energy amounts via impairing the glucose transport from blood to brain, leading to delirium-like behavior in mice. These findings will promote more research to identify the etiologies and underlying mechanisms of delirium.

Lipid dysfunction and adrenomedullin expression in omental versus subcutaneous adipose tissues in diabetic pregnancies.

Gestational diabetes mellitus (GDM) is one of the most common complications of pregnancy but the underlying mechanism remains obscure. The aims of this study are to examine if omental adipose tissue (OMAT) and subcutaneous AT (SCAT) differentially express proinflammatory and lipid metabolic adipokines, and if so, whether their regional differences have implications on lipid metabolism in GDM. Paired samples of OMAT and SCAT were excised from pregnant women in scheduled Cesarean sections with non-obese (NOBS), obese (OBS) and GDM. The results showed that the mRNA of monocyte chemoattractant protein (MCP)-1, macrophage marker CD68, and cytokines IL-6, IL-8, and TNF-α are increased in OMAT from GDM women compared to that in NOBS and OBS women (P<0.05). Glucose and TNF-α dose-dependently enhanced ADM and its receptor components CRLR and RAMPs in human adipocytes. Immunofluorescence showed that ADM and its receptor components are higher in OMAT from GDM women compared to non-GDM women. Further, basal lipolysis was greater in OMAT than in SCAT and ADM stimulates further glycerol release in OMAT, but not in SCAT, and these increases are reduced by ADM antagonist, ADM22-52. We therefore conclude that elevated ADM and its receptor expressions by OMAT, but not by SCAT appear to contribute to the lipid dysregulation in GDM women, and manipulation of ADM may represent one of the novel approaches in minimizing the risk of GDM-related fetal overgrowth.

Adrenomedullin and its receptors are expressed in mouse pancreatic ß-cells and suppresses insulin synthesis and secretion.

Gestational diabetes mellitus (GDM) is associated with defective pancreatic ß-cell adaptation in pregnancy, but the underlying mechanism remains obscure. Our previous studies demonstrated that GDM women display increased plasma adrenomedullin (ADM) levels, and non-obese GDM mice show decreased serum concentrations of insulin and the number of ß-cells in pancreas islets. The aims of this study is to examine if ADM and its receptors are expressed in female mouse pancreas, and if so, whether insulin secretion is regulated by ADM in mouse ß-cell line, NIT-1 cells and isolated mouse pancreatic islets. Present study shows that ADM and its receptor components CRLR, RAMPs are present in mouse pancreatic islets and co-localized with insulin. The expressions of ADM, CRLR and RAMP2 in islets from pregnant mice are reduced compared to that of non-pregnant mice. NIT-1-ß cells express ADM and its receptor mRNA, and glucose dose-dependently stimulates expressions. Furthermore, ADM inhibits NIT-1-ß cell growth, and this inhibition is reversed by ADM antagonist, ADM22-52. The glucose-induced insulin secretion was suppressed by ADM in NIT-1-ß cells and isolated pancreatic islets from pregnant mice. These inhibitory effects are accompanied by upregulation of endoplasmic reticulum (ER) stress biomarker genes in NIT-1-ß cells. This study unveils that reduced ADM and its receptors may play a role in ß-cell adaptation during pregnancy, while increased plasma ADM in GDM may contribute to the ß-cells dysfunction, and blockade of ADM may reverse ß-cell insulin production.

Testosterone attenuates sevoflurane-induced tau phosphorylation and cognitive impairment in neonatal male mice.

BACKGROUND: Sevoflurane anaesthesia induces phosphorylation of the microtubule-associated protein tau and cognitive impairment in neonatal, but not adult, mice. The underlying mechanisms remain largely to be determined. Sex hormones can be neuroprotective, but little is known about the influence of testosterone on age-dependent anaesthesia effects. METHODS: Six- and 60-day-old male mice received anaesthesia with sevoflurane 3% for 2 h daily for 3 days. Morris water maze, immunoassay, immunoblotting, co-immunoprecipitation, nanobeam technology, and electrophysiology were used to assess cognition; testosterone concentrations; tau phosphorylation; glycogen synthase kinase-3ß (GSK3ß) activation; binding or interaction between tau and GSK3ß; and neuronal activation in mice, cells, and neurones. RESULTS: Compared with 60-day-old male mice, 6-day-old male mice had lower testosterone concentrations (3.03 [0.29] vs 0.44 [0.12] ng ml-1; P<0.01), higher sevoflurane-induced tau phosphorylation in brain (133 [20]% vs 100 [6]% in 6-day-old mice, P<0.01; 103 [8]% vs 100 [13]% in 60-day-old mice, P=0.77), and sevoflurane-induced cognitive impairment. Testosterone treatment increased brain testosterone concentrations (1.76 [0.10] vs 0.39 [0.05] ng ml-1; P<0.01) and attenuated the sevoflurane-induced tau phosphorylation and cognitive impairment in neonatal male mice. Testosterone inhibited the interaction between tau and GSK3ß, and attenuated sevoflurane-induced inhibition of excitatory postsynaptic currents in hippocampal neurones. CONCLUSIONS: Lower brain testosterone concentrations in neonatal compared with adult male mice contributed to age-dependent tau phosphorylation and cognitive impairment after sevoflurane anaesthesia. Testosterone might attenuate the sevoflurane-induced tau phosphorylation and cognitive impairment by inhibiting the interaction between tau and GSK3ß.

WS635 Attenuates the Anesthesia/Surgery-Induced Cognitive Impairment in Mice.

Anesthesia/surgery has been reported to be associated with perioperative neurocognitive disorder (PND) in patients and induces cognitive impairment in mice. Previous studies demonstrate cyclosporine A (CsA) attenuates the anesthesia/surgery-induced cognitive impairment in mice. However, CsA has immunosuppressive effects and may not be routinely used to prevent or treat PND in patients. WS635 is a nonimmunosuppressive CsA analog. We, therefore, set out to determine whether WS635 could mitigate the anesthesia/surgery-induced cognitive impairment in mice. We performed abdominal surgery under 1.4% isoflurane anesthesia (anesthesia/surgery) for 2 h in 9 month-old wild-type (WT) mice. We treated the mice with CsA (10 mg/kg) or different doses (13.2 mg/kg, 26.4 mg/kg and 52.8 mg/kg) of WS635 before and after the anesthesia/surgery. Barnes maze and fear conditioning system (FCS) were employed to evaluate the cognitive function in mice. We measured the amounts of postsynaptic density (PSD)-95, synaptophysin, and ATP in the hippocampus and cortex of the mice using western blot and ATP Colorimetric/Fluorometric Assay, respectively. We found that the treatment with 52.8 mg/kg, but not 13.2 mg/kg or 26.4 mg/kg, of WS635 attenuated the anesthesia/surgery-induced cognitive impairment in mice and the reductions in the amounts of PSD-95, synaptophysin, and ATP in the mice brain tissues. These results have established a system to study WS635 further and suggest that we need to perform more experiments to determine whether WS635 can ultimately be used as one of the interventions for PND in patients.

Isoflurane impairs oogenesis through germ cell apoptosis in C. elegans.

Anesthetic isoflurane has been reported to induce toxicity. However, the effects of isoflurane on fecundity remain largely unknown. We established a system in C. elegans to investigate the effects of isoflurane on oogenesis. Synchronized L4 stage C. elegans were treated with 7% isoflurane for 4 h. Dead cells, ROS, embryos, and unfertilized eggs laid by hermaphrodites were measured by fluorescence imaging and counting. The C. elegans with losses of ced-3, cep-1, abl-1, male C. elegans, and oxidative stress inhibitor N-acetyl-cysteine were used in the interaction studies. We found that isoflurane decreased the numbers of embryos and unfertilized eggs and increased the levels of dead cells and ROS in C. elegans. The isoflurane-induced impairment of oogenesis was associated with abl-1, ced-3, but not cep-1. N-acetyl-cysteine attenuated the isoflurane-induced impairment of oogenesis in C. elegans. Mating with male C. elegans did not attenuate the isoflurane-induced changes in oogenesis. These findings suggest that isoflurane may impair oogenesis through abl-1- and ced-3-associated, but not cep-1-associated, germ cell apoptosis and oxidative stress, pending further investigation. These studies will promote more research to determine the potential effects of anesthesia on fecundity.