Muscle Injury Induces Postoperative Cognitive Dysfunction

LncRNA-AC020978 Promotes Metabolic Reprogramming in M1 Microglial Cells in Postoperative Cognitive Disorder via PKM2

The present work aimed to explore the role of long non-coding RNA (lncRNA)-AC020978 in postoperative cognitive disorder (POCD) and the underlying mechanism. The POCD mouse model was constructed through isoflurane anesthesia + abbreviated laparotomy. The AC020978 expression in brain tissue was silenced after lentivirus injection, then Morris water maze test was conducted to detect the cognitive disorder level, flow cytometry was performed to analyze M1 macrophage level, ELISA was carried out to measure inflammatory factor levels, H&E, Nissl and immunohistochemical staining was performed to detect the pathological changes in brain tissue, and Western blotting assay was adopted to detect protein expression. In addition, microglial cells were cultured in vitro, after lentivirus infection, the effect of AC020978 on the M1 polarization of microglial cells and glycolysis was observed. AC020978 overexpression promoted POCD progression and aggravated cognitive disorder in mice; in addition, the proportion of peripheral and central M1 cells increased, the inflammatory factor levels were upregulated, and microglial cells were activated. By contrast, AC020978 silencing led to cognitive disorder in mice and suppressed microglial cell activation and M1 polarization. In vitro experimental results indicated that AC020978 promoted the expression and phosphorylation of PKM2, which promoted inflammatory response through enhancing microglial cell glycolysis and M1 polarization. AC020978 interacts with PKM2 to promote the glycolysis and M1 polarization of microglial cells, thus regulating cognitive disorder and central inflammation in POCD.

CTRP6(C1q/Tumor Necrosis Factor (TNF)-related protein-6) alleviated the sevoflurane induced injury of mice central nervous system by promoting the expression of p-Akt (phosphorylated Akt)

Postoperative cognitive impairment and nervous system damage caused by anesthetics seriously affect patient’s postoperative recovery. Recent study has revealed that CTRP6 could alleviate apoptosis, inflammation and oxidative stress of nerve cells, thereby relieving nervous system damage induced by cerebral ischemia reperfusion. However, whether CTRP6 could relieve sevoflurane induced central nervous system injury is unclear. We stimulated C57BL/6 mice with sevoflurane and injected CTRP6 overexpression adenovirus vector. Next, H&E staining and TUNEL assays were performed to examine the effect of CTRP6 on sevoflurane induced injury of central nervous system. Finally, we isolated primary nerve cells of hippocampus. Flow cytometry and commercial kits were used for the detection of apoptosis and ROS levels of these cells. Western blotting was used for the detection of the expression level of p-Akt in central nervous tissues and primary cells. Results showed that sevoflurane induced injury and apoptosis of central nervous tissues. Overexpression of CTRP6 relieved apoptosis and injury of these tissues. CTRP6 inhibited the expression of cleaved caspase-3 and cleaved PARP in these tissues. Sevoflurane promoted apoptosis of primary cells and enhanced the expression of ROS and MDA in these cells. Overexpression of CTRP6 alleviated apoptosis and suppressed production of ROS and MDA in these cells. In addition, CTRP6 also enhanced the expression of p-Akt in primary cells. Taken together, our results suggested that CTRP6 relieved sevoflurane induced injury of central nervous tissues by promoting the expression of p-Akt. Therefore, the targeted drug of CTRP6 should be explored for the remission of these symptoms.

Low Skeletal Muscle Mass Is Associated With Perioperative Neurocognitive Disorder Due To Decreased Neurogenesis in Rats

BACKGROUND

Perioperative neurocognitive disorder (PND) is a postsurgical complication associated with neuroinflammation and impaired hippocampal neurogenesis, in which brain-derived neurotrophic factor (BDNF) plays a key role. Sarcopenia refers to age-related muscle loss that causes cognitive decline, muscle atrophy, and postoperative delirium. Rats with tail suspension (TS) were used to represent a low-activity model, which involves decreased hind limb function by TS. This hind limb unloading by TS can induce sarcopenia in 2 weeks. However, the relationship between PND and muscle atrophy is unclear. In this experiment, we investigated whether preoperative muscle atrophy induced by TS would affect neurogenesis and accelerate PND in rats.

METHODS

Sixty 21-week-old rats were assigned to 4 groups: the TS group, the TS with surgery (TS + S) group, the control group, and the control with surgery (control + S) group. After the abdominal manipulation under 3% sevoflurane anesthesia, cognitive function was assessed using the Morris water maze test and a fear-conditioning test. Neurogenesis was evaluated by checking BDNF secretion and immunohistochemical staining in the hippocampus.

RESULTS

The TS + S group showed impaired swimming latency (difference of means = 12.4 versus control + S; 95% confidence interval [CI], 2.0-22.7; P = .016) (difference of means = 15.2 versus TS; 95% CI, 0.4-30.1; P = .043) and path length (difference of means = 147.8 versus control + S; 95% CI, 20.7-274.9; P = .020) in the maze test and cued fear memory (difference of means = -26.0 versus TS; 95% CI, -46.4 to -5.6; P = .006) (difference of means = -22.3 versus control + S; 95% CI, -42.7 to -1.9; P = .026) in the fear-conditioning test. The postoperative levels of BDNF in the TS + S and TS groups were reduced compared with the other groups (P = .002). The number of neural precursors in the dentate gyrus was significantly lower in the TS + S group (P < .001).

CONCLUSIONS

We observed that preoperative hind limb muscle atrophy, indicated by TS, was associated with an increased occurrence of PND through the reduction in BDNF and neurogenesis after abdominal surgery in young adult rats. Therefore, we concluded that preoperative low skeletal muscle mass can induce PND due to impaired postoperative neurogenesis. Our findings might indicate that low-cost perioperative interventions, such as preoperative exercise, is beneficial to preventing PND.

Venlafaxine Attenuated the Cognitive and Memory Deficit in Mice Exposed to Isoflurane Alone

Post-operative cognitive dysfunction (POCD) is a common complication during the post-operative period. It affects the recovery time of the patient after surgery and the stay time in hospital, which causes a great deal of burden to patients and families emotionally and financially. However, there is no specific and effective treatment available for this disorder. Recent study indicated exposure to general anesthetics contributed to POCD by triggering gamma-amino butyric acid type A (GABA_A) receptors hyperactivities that persisted even the anesthetic compounds have been eliminated. Here, we investigated the antidepressant, venlafaxine (VLX), in a mouse model of POCD and studied whether VLX attenuated the cognitive dysfunction of mice exposed to general anesthetic, isoflurane (ISO). We found that ISO significantly induced an increased surface expression of the GABA_A receptor subunit, α5, in the hippocampus of the mice. However, VLX treatment reduced the increase in α5 subunit expression. Meanwhile, we found the expression levels of interleukin (IL)-1β, tumor necrosis factor alpha (TNF-α), and IL-6 in the brains of mice exposed to ISO were significantly increased. However, VLX could prevent the increase in these cytokines. We also investigated the memory deficit of these mice by using a Y maze behavioral test. Mice with ISO exposure showed decreased alternation performance that could be prevented by the VLX treatment. Collectively, our results here are in line with the previous findings that α5 subunit plays an important role of the formation of POCD, but VLX may be a promising candidate compound for the treatment of POCD.