Arginine vasopressin altered the expression of monocarboxylate transporters in cultured astrocytes isolated from stroke-prone spontaneously hypertensive rats and congenic SHRpch1_18 rats

Expression of TNFR1, VEGFA, CD147 and MCT1 as early biomarkers of diabetes complications and the impact of aging on this profile

Hyperglycemia leads to microvascular lesions in various tissues. In diabetic nephropathy-DN, alterations in usual markers reflect an already installed disease. The study of new biomarkers for the early detection of diabetic complications can bring new prevention perspectives. Rats were divided into diabetic adult-DMA-or elderly-DME and control sham adult-CSA-or control sham elderly-CSE. Blood and urine samples were collected for biochemical analysis. Bulbar region, cardiac, hepatic and renal tissues were collected for target gene expression studies. As result, DMA showed decreased TNFR1, MCT1 and CD147 expression in the bulbar region, TNFR1 in the heart, VEGFA and CD147 in the kidney and TNFR1 in blood. Positive correlations were found between TNFR1 and MCT1 in the bulbar region and HbA1c and plasma creatinine, respectively. DME showed positive correlation in the bulbar region between TNFR1 and glycemia, in addition to negative correlations between CD147 in the heart versus glycemia and urea. We concluded that the initial hyperglycemic stimulus already promotes changes in the expression of genes involved in the inflammatory and metabolic pathways, and aging alters this profile. These changes prior to the onset of diseases such as DN, show that they have potential for early biomarkers studies.

Lactate Supply from Astrocytes to Neurons and its Role in Ischemic Stroke-induced Neurodegeneration

Glucose transported to the brain is metabolized to lactate in astrocytes and supplied to neuronal cells via a monocarboxylic acid transporter (MCT). Lactate is used in neuronal cells for various functions, including learning and memory formation. Furthermore, lactate can block stroke-induced neurodegeneration. We aimed to clarify the effect of astrocyte-produced lactate on stroke-induced neurodegeneration. Previously published in vivo and in vitro animal and cell studies, respectively, were searched in PubMed, ScienceDirect, and Web of Science. Under physiological conditions, lactate production and release by astrocytes are regulated by changes in lactate dehydrogenase (LDH) and MCT expression. Moreover, considering stroke, lactate production and supply are regulated through hypoxia-inducible factor (HIF)-1α expression, especially with hypoxic stimulation, which may promote neuronal apoptosis; contrastingly, neuronal survival may be promoted via HIF-1α. Stroke stimulation could prevent neurodegeneration through the strong enhancement of lactate production, as well as upregulation of MCT4 expression to accelerate lactate supply. However, studies using astrocytes derived from animal stroke models revealed significantly reduced lactate production and MCT expression. These findings suggest that the lack of lactate supply may strongly contribute to hypoxia-induced neurodegeneration. Furthermore, diminished lactate supply from astrocytes could facilitate stroke-induced neurodegeneration. Therefore, astrocyte-derived lactate may contribute to stroke prevention.

Effect of lemon seed flavonoids on the anti-fatigue and antioxidant effects of exhausted running exercise mice

In this research, mice were gavaged with different doses of lemon seed flavonoids (LSF) for 4 weeks, and vitamin C was used as a positive control to investigate its effects on anti-fatigue and antioxidant capacity in exhaustively exercised mice. The results obtained from the study indicated that both vitamin C and LSF could significantly increase the running exhaustion time of mice, and the exhaustion time of mice was prolonged with increasing LSF concentration. LSF can increase hepatic glycogen and the free fatty acid content and reduce the lactate and urea nitrogen contents in a dose-dependent manner in mice. Serum CK, AST, and ALT levels in mice decreased gradually with increasing LSF concentration. LSF increased SOD and CAT levels and decreased MDA levels in mice in a dose-dependent manner. LSF could also enhance nNOS, eNOS, and ASCT1 mRNA expression and decrease syncytin-1, iNOS and TNF-α expression in the skeletal muscle of mice. By HPLC analysis, LSF was found to contain epigallocatechin, caffeic acid, epicatechin, vitexin, quercetin, and hesperidin, which are common flavonoids of this species. Thus, it was observed that LSF has good anti-fatigue and antioxidant capacities, and its anti-fatigue effect is related to improving the hepatic glycogen reserve capacity, increasing fat mobilization, and reducing lactate accumulation and protein decomposition. The antioxidant capacity of LSF is related to scavenging free radicals and reducing lipid peroxidation, and its antioxidant effect comes from its five antioxidant flavonoids. In conclusion, LSF has high development and application prospects in nutritional supplements. PRACTICAL APPLICATIONS: Lemon seed is the waste of lemon processing, which contains abundant flavonoids. The flavonoids in lemon seed can be used to exert its antioxidant effect and recover from exhausted exercise. Therefore, it can be concluded that lemon seed flavonoids are functional components that can be used as exercise recovery substances.

Astrocytic nutritional dysfunction associated with hypoxia-induced neuronal vulnerability in stroke-prone spontaneously hypertensive rats

Stroke-prone spontaneously hypertensive rats (SHRSP) is a valuable animal model to investigate human strokes. SHRSP Izumo strain (Izm) neurons are highly sensitive to blood supply changes. Furthermore, SHRSP/Izm astrocytes show various abnormalities upon hypoxic stimulation compared to control Wistar Kyoto (WKY/Izm) rats. This study aimed to describe stroke-related characteristics of SHRSP/Izm-derived neurons and astrocytes. In addition, we discuss the role of astrocytes in the development of stroke in SHRSP/Izm model. In SHRSP/Izm, neuronal death is induced upon reoxygenation after hypoxia. Furthermore, it was shown that SHRSP/Izm astrocytes show significantly reduced lactate production and supply ability to nerve cells when subjected to hypoxic stimulation. In particular, decreased lactate production and monocarboxylic acid transporter (MCT) expression in SHRSP/Izm astrocytes are factors that induce neuronal cell death. Remarkable differences in glial cell line-derived neurotrophic factor (GDNF) expression and L-serine production were also observed in SHRSP/Izm-derived astrocytes compared to WKY/Izm. Reduced production of both GDNF and L-serine contributes to diminished neuronal survival. The differences between SHRSP/Izm and WKY/Izm astrocyte cellular properties may contribute to compromised neuronal nutrition and induction of neuronal death. These properties are likely to be the factors that enhance stroke in SHRSP/Izm.

Astrocytes in neuroendocrine systems: An overview

A class of glial cell, astrocytes, is highly abundant in the central nervous system (CNS). In addition to maintaining tissue homeostasis, astrocytes regulate neuronal communication and synaptic plasticity. There is an ever-increasing appreciation that astrocytes are involved in the regulation of physiology and behaviour in normal and pathological states, including within neuroendocrine systems. Indeed, astrocytes are direct targets of hormone action in the CNS, via receptors expressed on their surface, and are also a source of regulatory neuropeptides, neurotransmitters and gliotransmitters. Furthermore, as part of the neurovascular unit, astrocytes can regulate hormone entry into the CNS. This review is intended to provide an overview of how astrocytes are impacted by and contribute to the regulation of a diverse range of neuroendocrine systems: energy homeostasis and metabolism, reproduction, fluid homeostasis, the stress response and circadian rhythms.

Salidroside alleviates ischemic brain injury in mice with ischemic stroke through regulating BDNK mediated PI3K/Akt pathway

There is evidence suggesting that inhibition of apoptosis plays a critical role in preventing neurons from damage and even death, after brain ischemia/reperfusion, which shows therapeutic potential for clinical treatment of brain injury. In this study, We preformed MCAO model in C57BL/6J wild-type (BDNK+/+) and BDNK knockout (BDNF-/-) mice respectively, and investigated the neuroprotective effect of Salidroside (Sal) and its underlying mechanisms. The results showed that Sal reversed brain infarct size, reduced cerebral edema, decreased the neurological deficit score and diminished TUNEL positive cells significantly. However, BDNK deficiency inhibited the neuroprotective effect of Sal. In addition, Sal increased cell viability, ameliorated neuron cell injury by decreasing LDH activity, and inhibited cell apoptotic rate. Sal suppressed apoptotic signaling via DNA-binding-dependent and -independent mechanisms. Furthermore, the neuroprotective effect of Sal on BDNK was mediated by PI3K/Akt pathway, which was proved by the use of PI3K knockout (PI3K-/-) mice and siRNA-PI3K. In summary, these data strongly suggested that Sal could be used as an effective neuroprotective agent to protect against ischemic stroke after cerebral I/R injury through regulating BDNK-mediated PI3K/Akt apoptotic pathway in DNA-binding-dependent and -independent manners.