[Melatonin alleviates autophagy in cortical neurons of neonatal rats with hypoxic- ischemic brain damage via the PI3K/AKT pathway]. / è¤ªé»‘ç´ é€šè¿‡PI3K/AKTé€šè·¯å‡è½»ç¼ºæ°§ç¼ºè¡€æ€§è„‘æŸä¼¤æ–°ç”Ÿå¤§é¼ å¤§è„‘çš®å±‚ç¥žç»ç»†èƒžè‡ªå™¬çš„ç ”ç©¶.

OBJECTIVES: To observe the effects of melatonin on autophagy in cortical neurons of neonatal rats with hypoxic-ischemic brain damage (HIBD) and to explore its mechanisms via the PI3K/AKT signaling pathway, aiming to provide a basis for the clinical application of melatonin. METHODS: Seven-day-old Sprague-Dawley neonatal rats were randomly divided into a sham operation group, an HIBD group, and a melatonin group (n=9 each). The neonatal rat HIBD model was established using the classic Rice-Vannucci method. Neuronal morphology in the neonatal rat cerebral cortex was observed with hematoxylin-eosin staining and Nissl staining. Autophagy-related protein levels of microtubule-associated protein 1 light chain 3 (LC3) and Beclin-1 were detected by immunofluorescence staining and Western blot analysis. Phosphorylated phosphoinositide 3-kinase (p-PI3K) and phosphorylated protein kinase B (p-AKT) protein expression levels were measured by immunohistochemistry and Western blot. The correlation between autophagy and the PI3K pathway in the melatonin group and the HIBD group was analyzed using Pearson correlation analysis. RESULTS: Twenty-four hours post-modeling, neurons in the sham operation group displayed normal size and orderly arrangement. In contrast, neurons in the HIBD group showed swelling and disorderly arrangement, while those in the melatonin group had relatively normal morphology and more orderly arrangement. Nissl bodies were normal in the sham operation group but distorted in the HIBD group; however, they remained relatively intact in the melatonin group. The average fluorescence intensity of LC3 and Beclin-1 was higher in the HIBD group compared to the sham operation group, but was reduced in the melatonin group compared to the HIBD group (P<0.05). The number of p-PI3K+ and p-AKT+ cells decreased in the HIBD group compared to the sham operation group but increased in the melatonin group compared to the HIBD group (P<0.05). LC3 and Beclin-1 protein expression levels were higher, and p-PI3K and p-AKT levels were lower in the HIBD group compared to the sham operation group (P<0.05); however, in the melatonin group, LC3 and Beclin-1 levels decreased, and p-PI3K and p-AKT increased compared to the HIBD group (P<0.05). The correlation analysis results showed that the difference of the mean fluorescence intensity of LC3 and Beclin-1 protein in the injured cerebral cortex between the melatonin and HIBD groups was negatively correlated with the difference of the number of p-PI3K+ and p-AKT+ cells between the two groups (P<0.05). CONCLUSIONS: Melatonin can inhibit excessive autophagy in cortical neurons of neonatal rats with HIBD, thereby alleviating HIBD. This mechanism is associated with the PI3K/AKT pathway.

[The TXNIP/Trx-1/GPX4 pathway promotes ferroptosis in hippocampal neurons after hypoxia-ischemia in neonatal rats]. / TXNIP/Trx-1/GPX4é€šè·¯ä¿ƒè¿›æ–°ç”Ÿå¤§é¼ ç¼ºæ°§ç¼ºè¡€åŽæµ·é©¬ç¥žç»å ƒé“æ­»äº¡çš„ä½œç”¨æœºåˆ¶.

OBJECTIVES: To observe the change in ferroptosis in hippocampal neurons after hypoxia-ischemia (HI) in neonatal rats and investigate the related mechanism based on the TXNIP/Trx-1/GPX4 signaling pathway. METHODS: Healthy neonatal Sprague-Dawley rats, aged 7 days, were randomly divided into three groups: sham-operation (n=30), hypoxic-ischemic brain damage (HIBD) (n=30) and siRNA (TXNIP siRNA) (n=12). The classic Rice-Vannucci method was used to establish a neonatal rat model of HIBD. At 6 hours, 24 hours, 72 hours, and 7 days after modeling, Western blot was used to measure the protein expression of GPX4 in the hippocampal tissue at the injured side; at 24 hours after modeling, laser speckle imaging combined with hematoxylin-eosin staining was used to determine whether the model was established successfully; NeuN/GPX4 and GFAP/GPX4 immunofluorescence staining combined with Western blot and other methods was used to measure the protein expression of GPX4 and the signal molecules TXNIP and Trx-1 in the hippocampal tissue at the injured side; the kits for determining the content of serum iron and tissue iron were used to measure the change in iron content; quantitative real-time PCR was used to measure the mRNA expression of TXNIP, Trx-1, and GPX4. RESULTS: At 6 hours, 24 hours, 72 hours, and 7 days after modeling, the HIBD group had a significantly lower protein expression level of GPX4 than the sham-operation group (P<0.05). At 24 hours after modeling, the HIBD group had a significantly lower cerebral blood flow of the injured side than the sham-operation group (P<0.05), with loose and disordered arrangement and irregular morphology of hippocampal CA1 neurons at the injured side. Compared with the sham-operation group, the HIBD group had a significantly higher number of TXNIP+ cells and significantly lower numbers of Trx-1+ cells and NeuN+GPX4+/NeuN+ cells in the hippocampal CA1 region at the injured side (P<0.05), with almost no GFAP+GPX4+ cells in the hippocampal CA1 region. Compared with the sham-operation group, the HIBD group and the siRNA group had significantly higher levels of serum iron and tissue iron in the hippocampus at the injured side (P<0.05). Compared with the HIBD group, the siRNA group had significantly lower levels of serum iron and tissue iron in the hippocampus at the injured side (P<0.05). The HIBD group and the siRNA group had significantly higher mRNA and protein expression levels of TXNIP than the sham-operation group (P<0.05), and the siRNA group had significantly lower expression levels than the HIBD group (P<0.05). The HIBD group and the siRNA group had significantly lower mRNA and protein expression levels of Trx-1 and GPX4 in the hippocampus at the injured side than the sham-operation group (P<0.05), and the siRNA group had significantly higher expression levels than the HIBD group (P<0.05). CONCLUSIONS: HI induces ferroptosis of hippocampal neurons in neonatal rats by activating the TXNIP/Trx-1/GPX4 pathway, thereby resulting in HIBD.

[The Research on Measurement System and Method of Tissue Optical Parameters with Wide Spectra Based on Double-Integrating-Spheres].

The measurement of tissue optical parameters is the focusing research content of Biomedical Photonics. The optical properties of human tissue are closely related to the physiological and pathological state. In recent years, the tissue imaging diagnosis and non-invasive detection of componentsbecome the hot research topics, applying the tissue optical properties especially the absorption and scattering properties. These provide the basis for the study of optical imaging and the spectrum detection of body composition etc. The Double-Integrating-Spheres (DIS) method can measure the absorption coefficient, scattering coefficient and so on in vitro tissuesimultaneously. It has the advantages of accurate, rapid, large applicable scope. The method applya standard method for measuring the optical parameters. This paper build the wide spectrum measurement system of optical parameters based on DIS and super continuum lasers. Then we analyze the transfer function, error sources and the best measuring conditions of the system. Finally we establish the correction forward model based on BP-MCML and the inverse algorithm of the optical parameters based on L-M algorithm. The optical parameters of intralipid solution in the wavelength range of 1,100~1,400 nm are measured. The experiment results show that the improved inverse algorithm is accurate. The multiple measurements standard deviation is within 3%. Compared the results of scattering coefficient and absorption coefficient at different wavelengths to the results of other research groups, the deviation is less than 3.4%.