Oxytocin ameliorates cognitive impairments by attenuating excitation/inhibition imbalance of neurotransmitters acting on parvalbumin interneurons in a mouse model of sepsis-associated encephalopathy.

Inflammation plays a crucial role in the initiation and progression of sepsis, and it also induces alterations in brain neurotransmission, thereby contributing to the development of sepsis-associated encephalopathy (SAE). Parvalbumin (PV) interneurons are pivotal contributors to cognitive processes in various central dysfunctions including SAE. Oxytocin, known for its ability to augment the firing rate of gamma-aminobutyric acid (GABA)ergic interneurons and directly stimulate inhibitory interneurons to enhance the tonic inhibition of pyramidal neurons, has prompted an investigation into its potential effects on cognitive dysfunction in SAE. In the current study, we administered intranasal oxytocin to the SAE mice induced by lipopolysaccharide (LPS). Behavioral assessments, including open field, Y-maze, and fear conditioning, were used to evaluate cognitive performance. Golgi staining revealed hippocampal synaptic deterioration, local field potential recordings showed weakened gamma oscillations, and immunofluorescence analysis demonstrated decreased PV expression in the cornu ammonis 1 (CA1) region of the hippocampus following LPS treatment, which was alleviated by oxytocin. Furthermore, immunofluorescence staining of PV co-localization with vesicular glutamate transporter 1 or vesicular GABA transporter indicated a balanced excitation/inhibition effect of neurotransmitters on PV interneurons after oxytocin administration in the SAE mice, leading to improved cognitive function. In conclusion, cognitive function improved after oxytocin treatment. The number of PV neurons in the hippocampal CA1 region and the balance of excitatory/inhibitory synaptic transmission on PV interneurons, as well as changes in local field potential gamma oscillations in the hippocampal CA1 region, may represent its specific mechanisms.

Hydrogen attenuates postoperative pain through Trx1/ASK1/MMP9 signaling pathway.

BACKGROUND: Postoperative pain is a serious clinical problem with a poorly understood mechanism, and lacks effective treatment. Hydrogen (H2) can reduce neuroinflammation; therefore, we hypothesize that H2 may alleviate postoperative pain, and aimed to investigate the underlying mechanism. METHODS: Mice were used to establish a postoperative pain model using plantar incision surgery. Mechanical allodynia was measured using the von Frey test. Cell signaling was assayed using gelatin zymography, western blotting, immunohistochemistry, and immunofluorescence staining. Animals or BV-2 cells were received with/without ASK1 and Trx1 inhibitors to investigate the effects of H2 on microglia. RESULTS: Plantar incision surgery increased MMP-9 activity and ASK1 phosphorylation in the spinal cord of mice. MMP-9 knockout and the ASK1 inhibitor, NQDI-1, attenuated postoperative pain. H2 increased the expression of Trx1 in the spinal cord and in BV-2 cells. H2 treatment mimicked NQDI1 in decreasing the phosphorylation of ASK1, p38 and JNK. It also reduced MMP-9 activity, downregulated pro-IL-1ß maturation and IBA-1 expression in the spinal cord of mice, and ameliorated postoperative pain. The protective effects of H2 were abolished by the Trx1 inhibitor, PX12. In vitro, in BV-2 cells, H2 also mimicked NQDI1 in inhibiting the phosphorylation of ASK1, p38, and JNK, and also reduced MMP-9 activity and decreased IBA-1 expression induced by LPS. The Trx1 inhibitor, PX12, abolished the protective effects of H2 in BV-2 cells. CONCLUSIONS: For the first time, the results of our study confirm that H2 can be used as a therapeutic agent to alleviate postoperative pain through the Trx1/ASK1/MMP9 signaling pathway. MMP-9 and ASK1 may be the target molecules for relieving postoperative pain.

Therapeutic Hypothermia Enhances Cold-Inducible RNA-Binding Protein Expression and Inhibits Mitochondrial Apoptosis in a Rat Model of Cardiac Arrest.

Therapeutic hypothermia is well known for its protective effect against brain injury after cardiac arrest, but the exact mechanism remains unclear. Cold-inducible RNA-binding protein (CIRP), a member of cold shock protein, enables mammalian cells to withstand decreased temperature by regulating gene translation. However, the role of CIRP in global cerebral ischemia after therapeutic hypothermia has not been clearly elucidated. In the present study, rats resuscitated from 4 min of cardiac arrest were separately treated with therapeutic hypothermia (immediately after return of spontaneous circulation (ROSC); targeted temperature at 33 °C) and therapeutic normothermia (targeted temperature at 36.8 °C) for 6 h. The hippocampus was harvested at 0 h (baseline), 6 h, 12 h, 1 day, 3 days, and 7 days after ROSC. The expression of CIRP messenger RNA (mRNA) was assessed by real-time PCR. CIRP and mitochondrial apoptosis-associated proteins were tested by Western blot. The histological changes and neurological function were respectively evaluated by hematoxylin-eosin staining and neurological deficit score (NDS). Compared with baseline, rats resuscitated from cardiac arrest showed increased expression of CIRP, Bax, Caspase 9, and Caspase 3 and decreased expression of Bcl-2 in hippocampus (P < 0.05). However, therapeutic hypothermia after ROSC alleviated the alterations of Bax, Caspase 9, Caspase 3, and Bcl-2, while further increased the hippocampal expression of CIRP mRNA and protein, when compared with the normothermia rats (P < 0.05). In addition, compared with the therapeutic normothermia rats, histopathological damage in CA1 zone and NDS were respectively decreased and increased in the hypothermia rats (P < 0.05). Our findings suggest that 32 °C therapeutic hypothermia exerts an important neuroprotective effects by up-regulating CIRP expression and inhibiting mitochondrial apoptosis factor production in the cardiac arrest rat model.

Mild Hypothermia Combined with Hydrogen Sulfide Treatment During Resuscitation Reduces Hippocampal Neuron Apoptosis Via NR2A, NR2B, and PI3K-Akt Signaling in a Rat Model of Cerebral Ischemia-Reperfusion Injury.

We investigated whether mild hypothermia combined with sodium hydrosulfide treatment during resuscitation improves neuron survival following cerebral ischemia-reperfusion injury beyond that observed for the individual treatments. Male Sprague-Dawley rats were divided into seven groups (n = 20 for each group). All rats underwent Pulsinelli 4-vessel occlusion. Ischemia was induced for 15 min using ligatures around the common carotid arteries, except for the sham group. Immediately after initiating reperfusion, the mild hypothermia (MH), sodium hydrosulfide (NaHS), hydroxylamine (HA), MH + NaHS, MH + HA, and ischemia-reperfusion (I/R) control groups received an intraperitoneal injection of saline, sodium hydrosulfide, hydroxylamine, sodium hydrosulfide, hydroxylamine, and saline, respectively, and mild hypothermia (32 to 33 °C) was induced in the MH, MH + NaHS, and MH + HA groups for 6 h. The levels of NR2A, NR2B, p-Akt, and p-Gsk-3ß in the hippocampus of the MH, NaHS, and MH + NaHS groups were higher than those in the I/R control group, with the highest levels observed in the MH + NaHS group (P < 0.05). Treatment with hydroxylamine reduced the levels of these proteins in the HA and MH + HA groups, compared with the I/R control and MH groups, respectively. The apoptotic index of the CA1 region of the hippocampus was 45.2, 66.5, 63.5, and 84.8 % in the MH + NaHS, MH, NaHS, and I/R control groups, respectively (P < 0.05), indicating that the combination treatment shifted the NR2A/NR2B balance in favor of synaptic neuron stimulation and phosphatidylinositol 3'-kinase (PI3K)/Akt signaling. The combination of mild hypothermia and sodium hydrosulfide treatment for resuscitation following ischemia-reperfusion injury was more beneficial for reducing hippocampal apoptosis and pathology than that of mild hypothermia or hydrogen sulfide treatment alone.

Hydrogen sulphide and mild hypothermia activate the CREB signaling pathway and prevent ischemia-reperfusion injury.

BACKGROUND: Both hydrogen sulphide (H2S) and mild hypothermia have been reported to prevent brain damage caused by reperfusion assault through regulating the N-methyl-D-aspartate receptor (NMDAR). However, the relationship between the two treatments and how they exert neuro-protective effects through NMDARs remain to be elucidated. METHODS: Transient cerebral ischemia was induced using the Pulsinelli four-vessel occlusion method. We used sodium hydrosulphide (NaHS) as the H2S donor. We randomly divided 100 Sprague-Dawley rats into five groups of 20: Sham operation group (Sh), normothermic (36-37 °C) ischemia group (NT), mild hypothermic (32-33 °C) ischemia group (mHT), normothermic ischemia combined with NaHS treatment group (NT + NaHS), and mild hypothermic ischemia combined with NaHS treatment group (mHT + NaHS). After 6 hrs of reperfusion, rats were decapitated and hippocampus samples were immediately collected. We measured NR2A (GluN1), NR2B (GluN2) and p-CREB protein levels using western blotting. We further analyzed BDNF mRNA expression by real-time PCR. Hematoxylin and eosin (HE) staining was used to examine pyramidal cell histology at the CA1 region. All statistical analyses were carried out by ANOVA and LSD t-test as implemented by the SPSS 13.0 software. RESULTS: In the four test groups with ischemia-reperfusion, hippocampal H2S concentration increased following treatment, and administration of NaHS further increased H2S levels. Moreover, administration of both NaHS and mild hypothermia resulted in up-regulation of NR2A and NR2B protein expressions, as well as p-CREB protein and BDNF mRNA levels. At the cellular level, NaHS and mild hypothermia groups exhibited lower damage caused by ischemia-reperfusion in the CA1 region of the hippocampus. The strongest protective effect was observed in rats treated with combined NaHS and mild hypothermia, suggesting their effects were additive. CONCLUSION: Our results support previous findings that hydrogen sulphide and mild hypothermia can prevent ischemia-reperfusion injury. Both treatments caused an up-regulation of NMDA receptors, as well as an elevation in p-CREB protein and BDNF mRNA levels. Thus, hydrogen sulphide and mild hypothermia may provide neuro-protective effect through activating the pro-survival CREB signaling pathway.

Efficacy of mild hypothermia for the treatment of patients with cardiac arrest.

BACKGROUND: Therapeutic hypothermia has been recommended for the treatment of cardiac arrest patients who remain comatose after the return of spontaneous circulation. The aim of this study was to evaluate the effectiveness and safety of mild hypothermia on patients with cardiac arrest by conducting a meta-analysis. METHODS: The relevant trials were searched in Cochrane Library, PubMed, Web of Science, Embase, CNKI and Wan Fang Data from the date of their establishment to October 2014. Thereafter, the studies retrieved were screened based on predefined inclusion and exclusion criteria. Data were extracted, and the quality of the included studies was evaluated. A meta-analysis was conducted using the Cochrane Collaboration Review Manager 5.2 software. RESULTS: Six randomized controlled trials involving 531 cases were included, among which 273 cases were assigned to the treatment group and the other 258 cases to the control group. The meta-analysis indicated that mild hypothermia therapy after cardiac arrest produced significant differences in survival rate (relative risk [RR] =1.23, 95% confidence interval [CI]: 1.02-1.48, P = 0.03) and neurological function (RR = 1.33, 95% CI: 1.08-1.65, P = 0.007) after 6 months compared with normothermia therapy. However, no significant differences were observed in the survival to the hospital discharge (RR = 1.35, 95% CI: 0.87-2.10, P = 0.18), favorable neurological outcome at hospital discharge (RR = 1.53, 95% CI: 0.95-2.45, P = 0.08) and adverse events. CONCLUSIONS: The meta-analysis demonstrated that mild hypothermia can improve the survival rate and neurological function of patients with cardiac arrest after 6 months. On the other hand, regarding the survival to hospital discharge, favorable neurological outcome at hospital discharge, and adverse events, our meta-analysis produced nonsignificant results.

Use of hypophysin in hypotensive patients with low systemic vascular resistance following cardiopulmonary bypass.

OBJECTIVE: This study aimed to test the effects of hypophysin on hemodynamics and coronary artery caliber of patients with hypotension and decreased systemic vascular resistance (SVR) following cardiopulmonary bypass (CPB). METHODS: Twenty-four patients with mean arterial pressure (MAP) < 60 mmHg, mean aorta pressure < 70 mmHg, SVR < 800 dynes.sec.cm-5, cardiac index (CI) > 2.5 l.min-1.m-2, central venous pressure > 8 mmHg and refractory to dopamine, norepinephrine, and fluid resuscitation were treated with hypophysin at an initial dose of 0.6 IU and a continuous infusion rate of 1 - 4 IU/h till the end of operation. The hemodynamics and the diameter of proximal left main coronary artery were evaluated before incision, before hypophysin administration, 5 min after hypophysin administration, and at the end of operation. RESULTS: MAP, SVR, and the diameter of proximal left main coronary artery increased whereas heart rate, CI, stroke volume index, and mean pulmonary artery pressure had no significant changes after hypophysin administration compared with before hypophysin administration. All hypophysin-treated patients successfully recovered. CONCLUSION: Hypophysin may improve the hemodynamics and dilate the proximal left main coronary artery in hypotensive patients with low SVR following CPB.

[Effect of mild hypothermia on the expression of acid-sensing ion channels 1a and 2a following global cerebral ischemia-reperfusion in rats].

OBJECTIVE: To investigate the effects of mild hypothermia on the expression of ASIC1a and ASIC2a in the rat hippocampus following global cerebral ischemia-reperfusion, so as to speculate the underlying mechanisms of neuroresuscitation. METHODS: Ninety five male SD rats were randomly divided into five groups (n = 19): sham operation group (I), model group (II), mild hypothermia group (III), PcTX1 group (IV), mild hypothermia combined PcTX1 group (V). Transient (15 min) global cerebral ischemia was induced by the four-vessel occlusion. PcTX1 (500 ng/ml) 6 µl were injected into lateral cerebral ventricle immediately after reperfusion in group IV and V, while the equal volume of normal saline was injected into lateral cerebral ventricle immediately after reperfusion in the other three groups. At the same time, mild hypothermia after reperfusion was performed and lasted for 6 hours in group III and V, the rectal temperature was reduced to 32 - 33°C within 15 min, while it was maintained at 36 - 37°C by lamp in other three groups. Determination the expression of ASIC1a and ASIC2a protein at 6 h and 24 h of reperfusion, and the expression of ASIC1a and ASIC2a mRNA at 24 h of reperfusion. Observe the pathomorphological changes of hippocampal CA1 neurons at 24 h of reperfusion. Detect the brain water content at 72 h of reperfusion. RESULTS: The difference in the expression of ASIC1a mRNA and protein among the groups was not changed significantly (P > 0.05). Compared with group I, the expression of ASIC2a mRNA and ASIC2a protein was up-regulated in other groups (P < 0.05). It was significantly higher in group III and V than in group II and IV (P < 0.05). Compared to 6 h of reperfusion, the expression of ASIC2a protein was higher in group II, III, IV and V respectively after 24 h of reperfusion. Compared to group I, the number of pyramidal cells in CA1 region of hippocampus in group II, III, IV and V were decreased at 24 h of reperfusion (P < 0.01). Compared to group II, the number of pyramidal cells in CA1 region of hippocampus in group III, IV and V were increased at 24 h of reperfusion (P < 0.01); and compared to group III and IV, the number of pyramidal cells at 24 h of reperfusion in group V was significantly higher (P < 0.01). Compared to group I, the content of brain water in II, III and IV group were increased at 72 h of reperfusion (P < 0.01). Compared to group II, the content of brain water in group III, IV and V were decreased at 72 h of reperfusion (P < 0.01). Giving mild hypothermia or PcTX1 could alleviate the damage in CA1 region of hippocampus, with the best effect in group V, which administers PcTX1 combined mild hypothermia. CONCLUSION: Mild hypothermia attenuates global cerebral ischemia-reperfusion of rat, which may up-regulate the expression of ASIC2a mRNA and protein. Mild hypothermia combined by PcTX1 could induce neuroresuscitation.

[Effects of gabapentin on high-voltage-activated calcium current in dorsal root ganglion neurons in rats].

OBJECTIVE: To compare the effects of gabapentin on high-voltage-activated calcium (HVA) current in dorsal root ganglion (DRG) neurons in normal and nerve-injured rats and understand the reasons of their differences. METHODS: Pathogen-free male SD rats (weight 180 - 220 mg) aged 4 - 6 weeks were used. The animals were anesthetized with intraperitoneal pentobarbital sodium 50 mg/kg. L(5) spinal nerve was ligated between DRG and sciatic nerve and cut distal to the ligature. The animals were decapitated at Day 14 post-operation. L(5) (SNL-L(5) group) and L(4) DRGs (SNL-L(4) group) were respectively isolated and the ganglionic neurons enzymatically dissociated. The control group of rats was not operated. The lumbar DRG neurons of normal rats were treated similarly. The HVA-Ca(2+) current was recorded by the technique of whole cell patch clamp. RESULTS: Compared with the SNL-L(4) group [(16.0 ± 1.9)%, (26.9 ± 2.0)%, (27.4 ± 2.3)%] and the control group, gabapentin inhibited the peak calcium current highlier at 10, 100 and 300 µmol/L in the SNL-L(5) group [(18.5 ± 1.7)%, (32.0 ± 2.6)%, (32.7 ± 2.8)%] (P < 0.05). The steady-state inactivation curves shifted to more hyperpolarized potentials in the SNL-L(5) group. The N-type relative contribution to the gabapentin-sensitive HVA-Ca(2+) current was markedly elevated in the SNL-L(5) group compared with that in other two groups (P < 0.05). CONCLUSION: Gabapentin enhances the inhibition of HVA-Ca(2+) current in injured DRG neurons following spinal nerve ligation in rats. The alteration in the activation of electrophysiological properties and the increase of N-type relative contribution to the total HVA-Ca(2+) current may be involved in the mechanism.

Hemodynamic effects of an intravenous bolus of epinephrine in healthy rats: A randomized, open-label, controlled pilot study.

BACKGROUND: IV epinephrine is widely used in the treatment of shock to increase blood pressure (BP). However, whether it may also induce hypotension remains unknown. OBJECTIVE: The aim of this randomized, open-label, controlled pilot study was to observe hemodynamic changes after an IV bolus of epinephrine in healthy rats. METHODS: Healthy male Sprague-Dawley rats were randomized to 1 of 5 groups to receive IV epinephrine in doses of 0.5 µg/kg (group 1); 1 µg/kg (group 2); 2 µg/kg (group 3); 4 µg/kg (group 4); or 8 µg/kg (group 5). A sixth group received placebo (0.3 mL of normal saline) and served as the control. BP was monitored continuously. Mean arterial pressure (MAP) and heart rate (HR) were recorded at 0, 5, 15, and 30 seconds and 1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18, and 20 minutes after administration. The highest mean (SD) systolic BP (SBP) and the lowest mean (SD) diastolic BP (DBP) during this period were also recorded. Hypertension and hypotension were defined as BP increased or decreased > 10% from baseline. RESULTS: Forty-two Sprague-Dawley rats were included in the study. The initial hypertension occurred at ~18 seconds in all epinephrine-treated groups (all, P < 0.01), and the subsequent hypotension occurred at mean (SD) 1.3 (0.5), 2.2 (0.4), 3.0 (0.6), and 3.4 (1.1) minutes in groups 2, 3, 4, and 5, respectively (all, P < 0.01). The highest mean (SD) SBP and the lowest mean (SD) DBP in groups 1, 2, 3, 4, 5, and the control group were 184 (12)/78 (11), 208 (14)/78 (10), 219 (18)/69 (14), 232 (17)/55 (11), 243 (16)/56 (15), and 148 (12)/91 (7) mm Hg, respectively, compared with baseline. HR decreased significantly at 15 seconds in groups 2 and 3, and at 5, 15, and 30 seconds in groups 4 and 5 (all, P < 0.01). One rat in group 4 and 1 rat in group 5 died due to treatment-related cerebral hemorrhage. The control group had no significant hemodynamic changes from baseline. Compared with the control group, MAP increased significantly at 5, 15, and 30 seconds and 1 minute in the epinephrine-treated groups and decreased significantly at 2, 3, and 4 minutes in group 3 and at 2, 3, 4, and 6 minutes in groups 4 and 5 (all, P < 0.05). CONCLUSIONS: An IV bolus of epinephrine > 1 µg/kg was associated with biphasic changes in BP, including initial hypertension and subsequent hypotension, in these healthy rats. Future blinded and larger studies using lower doses are needed.

Lighter general anesthesia causes less decrease in arterial pressure induced by epinephrine scalp infiltration during neurosurgery.

Scalp infiltration with epinephrine-containing lidocaine solution can elicit significant hypotension before craniotomy under general anesthesia. A prospective randomized controlled study was designed to observe whether a lighter depth of general anesthesia could prevent the unintentional hypotension induced by the epinephrine scalp infiltration during neurosurgery or not. Fifty patients undergoing scheduled neurosurgery involving craniotomy were randomly allocated into 2 groups. After anesthesia induction, anesthesia was maintained with propofol 2 mug/mL and rimifentanil 2 ng/mL by target-controlled infusion in group 1, and propofol 4 microg/mL and rimifentanil 4 ng/mL in group 2 (control group), respectively. All the patients received epinephrine scalp infiltration with 1% lidocaine 16 mL containing epinephrine 5 microg/mL. Mean arterial pressure (MAP) and heart rate were recorded at 30-second interval from the baseline to 5 minutes after the beginning of local infiltration. Bispectral index readings indicated group 1 had the lighter general anesthesia than group 2 (P<0.05). MAP was higher (P<0.05) and heart rate was lower (P<0.05) at 1.5 minutes time point in group 1 than group 2. The mean percentage of maximal decrease in MAP was group 1 (13%) group 2 (4%) without significant difference (P>0.05). The results implied that keeping a lighter general anesthesia caused less decrease in arterial blood pressure and was a relative effective method to prevent hypotension episode induced by epinephrine scalp infiltration.