Hypothalamic POMC neuron-specific knockout of MC4R affects insulin sensitivity by regulating Kir2.1

BACKGROUND

Imbalance in energy regulation is a major cause of insulin resistance and diabetes. Melanocortin-4 receptor (MC4R) signaling at specific sites in the central nervous system has synergistic but non-overlapping functions. However, the mechanism by which MC4R in the arcuate nucleus (ARC) region regulates energy balance and insulin resistance remains unclear.

METHODS

The MC4Rflox/flox mice with proopiomelanocortin (POMC) -Cre mice were crossed to generate the POMC-MC4Rflox/+ mice. Then POMC-MC4Rflox/+ mice were further mated with MC4Rflox/flox mice to generate the POMC-MC4Rflox/flox mice in which MC4R is selectively deleted in POMC neurons. Bilateral injections of 200 nl of AAV-sh-Kir2.1 (AAV-sh-NC was used as control) were made into the ARC of the hypothalamus. Oxygen consumption, carbon dioxide production, respiratory exchange ratio and energy expenditure were measured by using the CLAMS; Total, visceral and subcutaneous fat was analyzed using micro-CT. Co-immunoprecipitation assays (Co-IP) were used to analyze the interaction between MC4R and Kir2.1 in GT1-7 cells.

RESULTS

POMC neuron-specific ablation of MC4R in the ARC region promoted food intake, impaired energy expenditure, leading to increased weight gain and impaired systemic glucose homeostasis. Additionally, MC4R ablation reduced the activation of POMC neuron, and is not tissue-specific for peripheral regulation, suggesting the importance of its central regulation. Mechanistically, sequencing analysis and Co-IP assay demonstrated a direct interaction of MC4R with Kir2.1. Knockdown of Kir2.1 in POMC neuron-specific ablation of MC4R restored the effect of MC4R ablation on energy expenditure and systemic glucose homeostasis, indicating by reduced body weight and ameliorated insulin resistance.

CONCLUSION

Hypothalamic POMC neuron-specific knockout of MC4R affects energy balance and insulin sensitivity by regulating Kir2.1. Kir2.1 represents a new target and pathway that could be targeted in obesity.

The Relevance of Serum Macrophage Migration Inhibitory Factor Level and Executive Function in Patients with White Matter Hyperintensity in Cerebral Small Vessel Disease

(1) Objective: To investigate the relationship between serum macrophage migration inhibitory factor (MIF) level and white matter hyperintensity (WMH) and executive function (EF) in cerebral small vascular disease (CSVD), and assess the impact and predictive value of MIF level and Fazekas scores in CSVD-related cognitive impairment (CI) (CSVD-CI); (2) Methods: A total of 117 patients with WMH admitted to the First Affiliated Hospital of Xinxiang Medical College from January 2022 to August 2022 were enrolled. According to the Montreal cognitive assessment (MoCA) scale, subjects were divided into a normal cognitive group and an impaired group. All subjects required serum MIF level, 3.0 T MRI, and neuropsychological evaluation to investigate the risk factors for CDVD-CI, analyze the correlation between MIF level, WMH, and EF, and to analyze the diagnostic value of MIF and WMH degree in predicting CSVD-CI; (3) Results: 1. Fazekas score and MIF level were the risk factors of CSVD-CI. 2. The Fazekas score was negatively correlated with MoCA score, positively correlated with Stroop C-Time, Stroop C-Mistake, Stroop interference effects (SIE)-Time, SIE-Mistake, and color trails test (CTT) interference effects (CIE) (B-A). 3. The MIF level was positively correlated with Fazekas score, Stroop C-Time, SIE-Time, CTT B-Time, and CIE (B-A), and negatively correlated with MoCA score. 4. Fazekas score and MIF level were significant factors for diagnosing CSVD-CI; (4) Conclusion: The Fazekas score and MIF level may be the risk factors of CSVD-CI, and they are closely correlated to CI, especially the EF, and they have diagnostic value for CSVD-CI.

[Effects and mechanism of astragalus polysaccharide on wound healing of deep partial-thickness burns in rats]

Objective: To investigate the effects and mechanism of astragalus polysaccharide (APS) on wound healing of deep partial-thickness burns in rats. Methods: The experimental study method was used. Fifty 7-week-old male Sprague-Dawley rats were divided into normal group, simple burn group, APS group, inhibitor group, and inhibitor+APS group according to the random number table, with 10 rats in each group. Except for normal group, rats in the other 4 groups were inflicted with a deep partial-thickness burn wound on the back. Rats in normal group and simple burn group were intraperitoneally injected with normal saline, and rats in the other three groups were injected with APS and/or integrin-linked kinase (ILK) inhibitor, respectively. After 7 days of injection, the wound healing rate of rats with burns in the four groups was calculated, and the serum content of interferon-γ, interleukin-2 (IL-2), and tumor necrosis factor α (TNF-α) in rats in 5 groups was determined by enzyme-linked immunosorbent assay (ELISA). The normal skin tissue of rats in normal group and wound tissue of rats with burns in the four groups were taken, the water content was determined and the water ratio was calculated, the content of interferon-γ, IL-2, and TNF-α was detected by ELISA, the mRNA expressions of epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), and ILK were detected by real-time fluorescence quantitative reverse transcription polymerase chain reaction, and the protein expressions of ILK, protein kinase B (Akt), phosphorylated Akt (p-Akt), glycogen synthetic kinase-3β (GSK-3β), and phosphorylated GSK-3β (p-GSK-3β) were detected by Western blotting. Data were statistically analyzed with one-way analysis of variance and least significant difference test. Results: After 7 days of injection, the wound healing rate of rats in APS group was (67±5)%, which was significantly higher than (52±4)% in simple burn group and (59±5)% in inhibitor+APS group (with all the P values <0.05). The wound healing rate of rats in inhibitor+APS group was significantly higher than (48±4)% in inhibitor group (P<0.05). After 7 days of injection, compared with those in serum or normal skin tissue of rats in normal group, the serum content of interferon-γ, TNF-α, IL-2 and the water ratio of wound tissue of rats in simple burn group were significantly increased (P<0.05); compared with those in APS group, the serum content of interferon-γ, TNF-α, IL-2 and the water ratio of wound tissue of rats in simple burn group and inhibitor+APS group were significantly increased (P<0.05); compared with those in inhibitor group, the serum content of interferon-γ, TNF-α, IL-2 and the water ratio of wound tissue of rats in inhibitor+APS group were significantly decreased (P<0.05). After 7 days of injection, compared with that in normal skin tissue of rats in normal group, the content of interferon-γ, TNF-α, and IL-2 in wound tissue of rats in simple burn group was significantly increased (P<0.05); compared with that in APS group, the content of interferon-γ, TNF-α, and IL-2 in wound tissue of rats in simple burn group and inhibitor+APS group was significantly increased (P<0.05); compared with that in inhibitor group, the content of interferon-γ, TNF-α, and IL-2 in wound tissue of rats in inhibitor+APS group was significantly decreased (P<0.05). After 7 days of injection, compared with those in normal skin tissue of rats in normal group, the mRNA expressions of EGF, bFGF, ILK and protein expressions of ILK, p-Akt, p-GSK-3β in wound tissue of rats in simple burn group were significantly increased (P<0.05); compared with those in APS group, the mRNA expressions of EGF, bFGF, ILK and protein expressions of ILK, p-Akt, p-GSK-3β in wound tissue of rats in simple burn group and inhibitor+APS group were significantly decreased (P<0.05); compared with those in inhibitor group, the mRNA expressions of EGF, bFGF, ILK and protein expressions of ILK, p-Akt, p-GSK-3β in wound tissue of rats in inhibitor+APS group were significantly increased (P<0.05). There were no statistically significant differences in the protein expressions of Akt and GSK-3β in normal skin tissue of rats in normal group and wound tissue of rats with burns in the four groups (P>0.05). Conclusions: APS can alleviate systemic and local inflammation, alleviate tissue edema, and promote the expressions of healing factors in rats with deep partial-thickness burns, thus to promote the wound healing, possibly by activating ILK/Akt/GSK-3β signaling pathway.

Role of narrative medicine-based education in cultivating empathy in residents

OBJECTIVE

To explore the role of narrative medicine-based education in standardized empathy training for residents.

METHODS

Among the 2018-2020 residents at the First Affiliated Hospital of Xinxiang Medical University, 230 receiving neurology training were enrolled in this study and randomly divided into study and control groups. The study group received narrative medicine-based education and standardized routine resident training. The Jefferson Scale of Empathy-Medical Student version (JSE-MS) was used to evaluate empathy in the study group, and the neurological professional knowledge test scores of the two groups were also compared.

RESULTS

In the study group, the empathy score was higher than the preteaching score (P < 0.01). The neurological professional knowledge examination score was higher in the study group than in the control group, albeit not significantly.

CONCLUSION

The addition of narrative medicine-based education in standardized training improved empathy and may have improved the professional knowledge of neurology residents.