Objective: As a high-level nerve center that regulates visceral and endocrine activity, the hypothalamus plays an important role in regulating the body’s stress response. Previous studies have shown that stress can cause damage to hypothalamic neurons. The present study aimed to further clarify the mechanism of endoplasmic reticulum stress (ERS) involvement in hypothalamic neuronal injury. Methods: A 7-day stressed rat model was established with daily restraining for 8 h and forced ice-water swimming for 5 min. The rats were randomly divided into control, stress, stress + GSK2606414 (PERK phosphorylation inhibitor), stress + KIRA6 (IRE1 phosphokinase activity inhibitor), GSK2606414, and KIRA6 groups. The pathological changes of hypothalamic neurons were observed by thionine staining. Expression of ERS proteins GRP78, ATF4, ASK1, JNK, and CHOP in the hypothalamic neurons were observed by immunohistochemical staining. The expression of JNK and CHOP mRNA in the hypothalamic neurons were observed by RNA in situ hybridization (RNA Scope) and the expression of related proteins and mRNA was semiquantitatively analyzed by microscopy-based multicolor tissue cytometry (MMTC). Results: Thionine staining revealed that stress exposure resulted in edema, a lack of Nissl bodies, and pyknosis in hypothalamic neurons. Immunohistochemistry and RNA Scope showed that stress exposure significantly increased the expression of GRP78, ATF4, ASK1, CHOP, JNK, JNK mRNA, and CHOP mRNA. Treatment with PERK and IRE1 inhibitors attenuated pathological damage and downregulated the expression of ATF4, ASK1, JNK, CHOP, JNK mRNA, and CHOP mRNA. Conclusion: Stress caused pathological changes in rat hypothalamic neurons. ERS PERK-ATF4-CHOP and IRE1-ASK1-JNK pathways were involved in the injury process.

Metformin is of great focus because of its high safety, low side effects, and various effects other than lowering blood sugar, such as anti-inflammation, anti-tumor, and anti-aging. Studies have shown that metformin has a modulating effect on the composition and function of the intestinal microbiota other than acting on the liver. However, the composition of microbiota is complex and varies to some extent between species and individuals, and the experimental design of each study is also different. Multiple factors present a major obstacle to better comprehending the effects of metformin on the gut microbiota. This paper reviews the regulatory effects of metformin on the gut microbiota, such as increasing the abundance of genus Akkermansia, enriching short-chain fatty acids (SCFAs)-producing bacterial genus, and regulating gene expression of certain genera. The intestinal microbiota is a large and vital ecosystem in the human body and is considered to be the equivalent of an “organ” of the human body, which is highly relevant to human health and disease status. There are a lot of evidences that the gut microbiota is responsible for metformin’s widespread effects. However, there are only a few systematic studies on this mechanism, and the specific mechanism is still unclear. This paper aims to summarize the possible mechanism of metformin in relation to gut microbiota.

Nanoparticle-based drug delivery system remains a significant challenge in the current treatment of solid tumors, primarily due to their limited penetration capabilities. Herein, we successfully engineer photodynamic gel-bombs (DCM@OPR) capable of penetrating deeply into tumor tissues utilizing the photodynamic-triggered explosive energy and receptor-mediated transcytosis, significantly enhancing the therapeutic efficacy of breast cancer. The photodynamic gel-bombs were fabricated by loading powerful components of chlorin e6 and MnO₂ nanoparticles, as well as Doxorubicin, into a crosslinked Ca²⁺-gel. Upon exposure to laser irradiation, the obtained photodynamic gel-bombs are capable of generating explosive energy, resulting in their fragmentation into numerous nanofragments. The photodynamic-triggered explosive energy subsequently drives these nanofragments to deeply penetrate into tumor tissues through gap leakage among tumor cells. In addition, the photodynamic-triggered explosive energy also promotes the escape of those therapeutic components (including chlorin e6, MnO₂ nanoparticles, and doxorubicin) and nanofragments from lysosomes. In the subsequent stages, these nanofragments also exhibit excellent transcytosis capacity, facilitating deep penetration into tumor tissues. As expected, the enhanced penetration and accumulation of therapeutic components into tumor tissues can be achieved, significantly enhancing the anti-proliferation capacity against breast cancer.

The amygdala is an important center of fear learning and memory and plays a critical role in regulating stress disorders. Previous studies have shown that changes in the amygdala caused by stress are an important cause of mental disorders including anxiety, but the specific mechanism remains unclear. Therefore, the purpose of this study was to investigate whether mental disorders induced by stress are related to γ-aminobutyric acid (GABA)ergic neuron damage in the basolateral amygdala (BLA) and whether endoplasmic reticulum stress (ERS) is involved in the injury process. Rat models of different durations of stress were established by restraint and forced ice-water swimming. Behavioral tests and high-performance liquid chromatography (HPLC) were used to detect anxiety in rats and changes in neurotransmitter levels in the BLA. Morphological approaches and microscopy-based multicolor tissue cytometry (MMTC) were used to detect the damage-induced changes in GABAergic neurons in the BLA. Immunofluorescence double labeling was used to detect the expression of ERS-related proteins before and after the inhibition of protein kinase R-like endoplasmic reticulum kinase (PERK) pathway. Stress resulted in damage to GABAergic neurons in the BLA, decreased GABA and increased glutamic acid (GLU) levels, perturbation of the excitation/inhibition (E/I) ratio in the BLA, and obvious anxiety disorders in rats. Moreover, ERS-mediated GABAergic neuron injury was an important cause of neurotransmitter level changes in the BLA. These results suggested that ERS-mediated GABAergic neuron injury in the BLA may be an important cause of stress-induced mental disorders.

Background: Depression is closely associated with stress-induced hippocampal damage and dysfunction. Emerging evidence demonstrates that the gut microbiota and its metabolites, acting as probiotics or prebiotics, can modulate brain structure and function via the gut-brain axis, thereby offering therapeutic potential for ameliorating related neurological and psychiatric disorders. This study delves into the contribution of the gut microbiota and its metabolites to stress-induced ferroptosis of hippocampal neurons and the associated molecular pathways. Methods: This study used time-course stress paradigms combined with ferroptosis inhibitors to identify hippocampal neuronal ferroptosis. Fecal microbiota transplantation were conducted to analyze the role of gut microbiota in this process. Subsequently, 16 S rDNA sequencing and metabolomics techniques were applied to identify key gut microbiota and metabolites. Metabolites intervention were performed to examine their causal relationship with neuronal ferroptosis. Finally, we used histochemical and molecular assays to assess both intestinal and blood-brain barrier integrity as well as inflammation in peripheral blood and hippocampal tissue, along with GPR41/RhoA/Rock1 pathway changes, to preliminarily investigate the molecular mechanisms underlying stress-induced hippocampal neuronal ferroptosis. Results: We demonstrated that stress triggered hippocampal neuronal ferroptosis and subsequent depressive-like behaviors in mice. Fecal microbiota transplantation successfully replicated the ferroptosis phenotype. Butyric acid and valeric acid were identified as key metabolites significantly reduced in the serum of acutely and chronically stressed mice, respectively. Intervention with these metabolites markedly alleviated ferroptosis. Furthermore, valerate intervention increased hippocampal GPR41 expression and significantly suppressed the pro-inflammatory RhoA/Rock1 pathway in chronically stressed mice, thereby reducing neuroinflammation and ameliorating neuronal ferroptosis. However, butyrate intervention showed no significant effect on the GPR41/RhoA/Rock1 pathway. Conclusion: Stress induces ferroptosis in hippocampal neurons, where reduced abundance of short-chain fatty acid-producing bacteria plays a key role. Key metabolites butyric acid and valeric acid alleviate neuroinflammation to improve ferroptosis via the gut-brain axis in acute and chronic stress, respectively. Specifically, valeric acid exerts neuroprotective effect through the GPR41/RhoA/Rock1 pathway, whereas butyric acid-mediated protection likely operates through alternative mechanisms. Graphical

Based on the successful establishment of a rat model of chronic restraint stress, we used multiple algorithms to quantify the morphological changes of rat hypothalamic microglia from various perspectives, providing a pathomorphological basis for the subsequent study of molecular mechanisms of hypothalamic stress injury, such as neuroinflammation. To verify the successful establishment of the chronic stress model, an enzyme-linked immunosorbent assay was performed to detect serum glucocorticoid levels. Microglia labeled with Iba1 in frozen sections of rat hypothalamus were scanned and photographed at multiple levels using confocal microscopy. Subsequently, images were processed for external contouring and skeletonization, and morphological indices of microglia were calculated and analyzed using fractal, skeleton, and Sholl analysis. In addition, the co-expression of CD68 (a marker that can reflect phagocytic activity) and Iba1 was observed by immunofluorescence technique. Compared with the control group, microglia in the chronic stress group displayed reduced fractal dimension and lacunarity, increased density and circularity, enlarged soma areas, and shortened and reduced branches. Sholl analysis confirmed the reduced complexity of microglia following chronic stress. Meanwhile, microglia CD68 increased significantly, indicating that the microglia in the chronic stress group have greater phagocytosis activity. In summary, chronic restraint stress promoted the conversion of microglia in the rat hypothalamus to a less complex form, manifested as larger soma, shorter and fewer branches, more uniform and dense texture, and increased circularity; indeed, the shape of these microglia resembled that of amoeba and they displayed strong phagocytosis activity.