Intense or prolonged exposure to stress can damage various brain structures, including the amygdala and hippocampus, which are associated with emotional-cognitive functions. Furthermore, this deterioration has been linked to a myriad of neurodegenerative and psychiatric disorders, in particular through disruption of the blood-brain barrier (BBB). However, insights remain scarce concerning the effects and mechanisms associated with stress on the BBB in the amygdala. This study explored the effects of restraint stress on the permeability and integrity of the BBB in the amygdala of male adult SD rats. Serum levels of corticosterone (CORT) and S100B were determined through ELISA. The permeability of the BBB was assessed by measuring Evans Blue (EB) leakage in tissue samples from the rats’ amygdala. These samples were immunostained for markers of tight junctions (Claudin-5, Occludin, ZO-1) and adherens junctions (VE-cadherin), as well as GLUT-1 and AQP-4. Staining was evaluated through confocal microscopy, and the level of expression of these proteins was quantified using the Western Blot (WB) technique. The ultrastructure of brain microvascular endothelial cells was assessed with transmission electron microscopy. Moreover, interleukin-1 beta (IL-1β) content in serum and amygdalar tissues were determined by employing ELISA. Exposure to restraint stress was associated with higher serum levels of S100B and EB leakage in amygdala tissues, especially in days 14 and 21 of the experiment, indicating increased permeability of the BBB. After restraint stress, significant decreases in protein expression were detected for tight junctions, adherens junctions and GLUT-1, while a significant increase was observed for AQP-4. The variation trends of fluorescence intensity generally paralleled these results. Following restraint stress, transmission electron microscopy ascertained enlarged gaps in tight junctions and thickened basal membranes in amygdalar capillaries. In addition, increased IL-1β contents in serum and amygdalar tissues were observed in the restraint-stressed groups. These findings suggest that restraint stress mediates time-dependent alterations in the permeability of the BBB, with modifications in the expression of proteins from tight junctions and adherens junctions, as well as ultrastructural changes in brain microvascular endothelial cells. And it was associated with the inflammation. These alterations may be associated with behavioral and cognitive dysfunctions and neurodegenerative disorders.

Metformin is the initial medication recommended for the treatment of type 2 diabetes mellitus (T2DM). In addition to diabetes treatment, the function of metformin also can be anti-aging, antiviral, and anti-inflammatory. Nevertheless, further exploration is required to fully understand its mode of operation. Historically, the liver has been acknowledged as the main location where metformin reduces glucose levels, however, there is increasing evidence suggesting that the gastrointestinal tract also plays a significant role in its action. In the gastrointestinal tract, metformin effects glucose uptake and absorption, increases glucagon-like peptide-1 (GLP-1) secretion, alters the composition and structure of the gut microbiota, and modulates the immune response. However, the side effects of it cannot be ignored such as gastrointestinal distress in patients. This review outlines the impact of metformin on the digestive system and explores potential explanations for variations in metformin effectiveness and adverse effects like gastrointestinal discomfort.

Methamphetamine (METH) abuse causes serious health problems worldwide, and long-term use of METH disrupts the blood–brain barrier (BBB). Herein, we explored the potential mechanism of endoplasmic reticulum (ER) stress in METH-induced BBB endothelial cell damage in vitro and the therapeutic potential of endoplasmic reticulum stress inhibitors for METH-induced BBB disruption in C57BL/6J mice. Exposure of immortalized BMVEC (bEnd.3) cells to METH significantly decreased cell viability, induced apoptosis, and diminished the tightness of cell monolayers. METH activated ER stress sensor proteins, including PERK, ATF6, and IRE1, and upregulated the pro-apoptotic protein CHOP. The ER stress inhibitors significantly blocked the upregulation of CHOP. Knockdown of CHOP protected bEnd.3 cells from METH-induced cytotoxicity. Furthermore, METH elevated the production of reactive oxygen species (ROS) and induced the dysfunction of mitochondrial characterized by a Bcl2/Bax ratio decrease, mitochondrial membrane potential (MMP) collapse, and cytochrome c. ER stress release was partially reversed by ROS inhibition, and cytochrome c release was partially blocked by knockdown of CHOP. Finally, PBA significantly attenuated METH-induced sodium fluorescein (NaFluo) and Evans Blue leakage, as well as tight junction protein loss, in C57BL/6J mice. These data suggest that BBB endothelial cell damage was caused by METH-induced endoplasmic reticulum stress, which further induced mitochondrial dysfunction, and that PBA was an effective treatment for METH-induced BBB disruption.

The hypothalamus, which is the initial part of the hypothalamic-pituitary-adrenal (HPA) axis, plays a critical role in regulating stress in the central nervous system. The present study aimed to determine whether endoplasmic reticulum stress in hypothalamic neurons is differentially stimulated by varying durations of stress exposure, which ultimately leads to pathological changes in neurons by affecting HPA axis function. There is a need for better morphological evidence of the mechanisms involved in stress-induced neuron injury. A stress model was established in rats by restraining for 8 h and forced ice-water swimming for 5 min each day. The stress-inducing process lasted for 1 day, 3 days, 7 days, 14 days, and 21 days. Enzyme-linked immunosorbent assay (ELISA) was used to assay serum glucocorticoid levels. Thionine staining was used to observe morphological changes in hypothalamic neurons. Immunohistochemistry and microscopy-based multicolor tissue cytometry (MMTC) was used to detect changes in expression of endoplasmic reticulum stress protein GRP78, ATF4, and CHOP. Serum glucocorticoid levels significantly increased after 3 days of stress exposure and the levels peaked by 7 days. By 21 days, however, the levels were significantly decreased. Thionine staining revealed that prolonged stress exposure resulted in hypothalamic neurons with edema, a lack of Nissl bodies, and pyknotic neurons. Immunohistochemistry and MMTC showed that increasing stress periods significantly decreased GRP78 expression, although ATF4 and CHOP protein expression significantly increased. Stress resulted in pathological changes and significant dynamic changes because of endoplasmic reticulum stress in rat hypothalamic neurons. These results suggested that the endoplasmic reticulum stress PERK-ATF4-CHOP pathway may be associated with hypothalamic neuronal injury.