Regenerative potential of the brain: Composition and forming of regulatory microenvironment in neurogenic niches

An important mechanism of neuronal plasticity is neurogenesis, which occurs during the embryonic period, forming the brain and its structure, and in the postnatal period, providing repair processes and participating in the mechanisms of memory consolidation. Adult neurogenesis in mammals, including humans, is limited in two specific brain areas, the lateral walls of the lateral ventricles (subventricular zone) and the granular layer of the dentate gyrus of the hippocampus (subgranular zone). Neural stem cells (NSC), self-renewing, multipotent progenitor cells, are formed in these zones. Neural stem cells are capable of differentiating into the basic cell types of the nervous system. In addition, NSC may have neurogenic features and non-specific non-neurogenic functions aimed at maintaining the homeostasis of the brain. The microenvironment formed in neurogenic niches has importance maintaining populations of NSC and regulating differentiation into neural or glial cells via cell-to-cell interactions and microenvironmental signals. The vascular microenvironment in neurogenic niches are integrated by signaling molecules secreted from endothelial cells in the blood vessels of the brain or by direct contact with these cells. Accumulation of astrocytes in neurogenic niches if also of importance and leads to activation of neurogenesis. Dysregulation of neurogenesis contributes to the formation of neurological deficits observed in neurodegenerative diseases. Targeting regulation of neurogenesis could be the basis of new protocols of neuroregeneration.     

Blood–Brain Barrier Breakdown in Stress and Neurodegeneration: Biochemical Mechanisms and New Models for Translational Research

Biochemistry (Moscow) - Blood-brain barrier (BBB) is a structural and functional element of the neurovascular unit (NVU), which includes cells of neuronal, glial, and endothelial nature. The main...     

Use of HepG2 cell line for evaluation of toxic and metabolic antipsychotic action

The toxic and metabolic effects of antipsychotics on cells of hepatic origin have been studied in vitro using human hepatoblastoma cell line HepG2. The cells were cultured in the presence of two first- and second-generation antipsychotics, haloperidol and olanzapine, respectively, at concentrations that can exist in the blood, liver and other tissues with high lipid content when the drugs are used for therapeutic purposes. During cultivation in several periods, the products of carbohydrate and lipid metabolism were quantified, the activities of several enzymes in the culture medium were measured, and viability (proliferation) of cells was assessed with MTS assay. Both drugs were toxic to HepG2 cells, which was manifested in inhibition of proliferation and an increased alkaline phosphatase activity in the culture medium. The toxic action of olanzapine in the doses used was less significant than that of haloperidol. According to literature data, antipsychotics increase the expression of lipogenesis genes in cells of the central nervous system, adipose tissue and liver, which can lead to hyperlipidemia. However, we have not observed increased levels of total cholesterol, cholesterol of low and high density lipoproteins, and triglycerides in the culture medium of HepG2 cells in the presence of haloperidol and olanzapine. This may be associated with the fact that both drugs, which are cationic amphiphiles, are able to inhibit intracellular lipid trafficking. Moreover, both drugs had no effect on the activity of aspartate aminotransferase and gamma-glutamyltransferase in the culture medium, but contributed to a decrease in the activity of alanine aminotransferase. Overall, our work has confirmed that HepG2 cells may serve as a useful model to obtain new data on drug effects on the metabolism of cells of hepatic origin and to assess the risk of hepatotoxicity in preclinical studies.