Epigenetic Mechanisms of Methamphetamine Addiction / 生物化学与生物物理进展

Methamphetamine (METH) is a powerful stimulant drug that can cause addiction and serious health problems. It is one of the most widely abused drugs in the world. However, the mechanisms of how METH affects the brain and leads to addiction are still unclear, and there are no effective treatments for METH addiction in clinical practice. Therefore, it is important to explore the new addiction mechanisms and treatment strategies of METH. METH addiction is a complex and chronic brain disorder that involves multiple brain regions and neurotransmitter systems. Neurotransmitters are chemical messengers that transmit signals between neurons (nerve cells) in the brain. Some of the main neurotransmitters involved in METH addiction are dopamine (DA), glutamate (Glu), norepinephrine (NE), and serotonin (SNRIS). These neurotransmitters regulate various aspects of brain function, such as reward, reinforcement, motivation, cognition, emotion, and behavior. When a person takes METH, it causes a surge of these neurotransmitters in the brain, especially in the prefrontal cortex (mPFC), ventral tegmental area (VTA), and nucleus accumbens (NAc). These brain regions form a circuit called the mesocorticolimbic system, which is responsible for mediating the rewarding and reinforcing effects of drugs and natural stimuli. The increased levels of neurotransmitters in this circuit make the person feel euphoric, alert, confident, and energetic. However, repeated or chronic use of METH can also cause negative effects, such as anxiety, paranoia, psychosis, depression, and cognitive impairment. The effects of METH on the brain are not only due to the changes in neurotransmitter levels, but also to the changes in gene expression. Gene expression is the process by which genes are turned on or off to produce proteins that perform various functions in the cells. Gene expression can be influenced by environmental factors, such as drugs, stress, diet, etc. One way that environmental factors can affect gene expression is through epigenetic mechanisms. Epigenetics is a branch of genetics that studies the heritable changes in gene expression that are not caused by changes in DNA sequence. Epigenetic mechanisms include histone modifications, DNA methylation, and non-coding RNA regulation. These mechanisms can modulate the chromatin structure and accessibility, thereby affecting the transcriptional activity of genes. Chromatin is a complex of DNA and proteins that forms the chromosomes in the nucleus of the cell. The chromatin structure can be altered by adding or removing chemical groups to histones (proteins that wrap around DNA) or DNA itself. These chemical groups can either activate or repress gene expression by changing the affinity of transcription factors (proteins that bind to DNA and initiate transcription) or other regulatory molecules. Non-coding RNAs are RNA molecules that do not code for proteins but can regulate gene expression by interacting with DNA, RNA, or proteins. Epigenetic mechanisms provide a link between environmental stimuli and gene expression, and play an important role in various physiological and pathological processes, including drug addiction. Recent studies have shown that epigenetic mechanisms are involved in the regulation of neurotransmitter systems and neural plasticity in response to METH exposure. Neural plasticity is the ability of neurons to change their structure and function in response to experience or injury. Neural plasticity is essential for learning, memory, adaptation, and recovery. The expression of some genes related to METH addiction is altered by epigenetic modifications, such as histone acetylation, methylation, ubiquitination, and non-coding RNA regulation. These epigenetic changes may affect the synaptic function and morphology, neuronal connectivity, and circuitry formation in the brain regions implicated in METH addiction. Moreover, some epigenetic modifications may persist for a long time after METH withdrawal, suggesting that they may contribute to the development and maintenance of METH addiction. In this article, we review the current literature on the epigenetic mechanisms of METH addiction. We will first introduce METH and its pharmacological effects, and then discuss the epigenetic regulation of neurotransmitter systems and neural plasticity by METH. We will focus on the changes of histone, DNA, and RNA during METH addiction, and the possible causes and consequences of their relationship with METH addiction. We will also provide some perspectives on the potential applications of epigenetic interventions for METH addiction treatment.

A glass micropipette vacuum technique of cerebrospinal fluid sampling in C57BL/6 mice / 生理学报

The purpose of this study was to establish a suitable method for extracting cerebrospinal fluid (CSF) from C57BL/6 mice. A patch clamp electrode puller was used to draw a glass micropipette, and a brain stereotaxic device was used to fix the mouse's head at an angle of 135° from the body. Under a stereoscopic microscope, the skin and muscle tissue on the back of the mouse's head were separated, and the dura mater at the cerebellomedullary cistern was exposed. The glass micropipette (with an angle of 20° to 30° from the dura mater) was used to puncture at a point 1 mm inboard of Y-shaped dorsal vertebral artery for CSF sampling. After the first extraction, the glass micropipette was connected with a 1 mL sterile syringe to form a negative pressure device for the second extraction. The results showed that the successful rate of CSF extraction was 83.33% (30/36). Average CSF extraction amount was (7.16 ± 0.43) μL per mouse. In addition, C57BL/6 mice were given intranasally ferric ammonium citrate (FAC) to establish a model of brain iron accumulation, and the CSF extraction technique established in the present study was used for sampling. The results showed that iron content in the CSF from the normal saline control group was not detected, while the iron content in the CSF from FAC-treated group was (76.24 ± 38.53) μmol/L, and the difference was significant. These results suggest that glass micropipette vacuum technique of CSF sampling established in the present study has the advantages of simplicity, high success rate, large extraction volume, and low bleeding rate, and is suitable for the research on C57BL/6 mouse neurological disease models.

Exosomes and their roles in neurodegenerative diseases: from pathogenic, diagnostic and therapeutical perspectives / 生理学报

Exosomes are extracellular membranous vesicles with a diameter of 30-100 nm derived from a variety of eukaryocytes. The cargo of exosomes includes proteins, lipids, nucleic acids, and substances of the cells from which they originate. They can transfer functional cargo to neighboring and distal cells, therefore contributing to intercellular communication in both physiological and pathological processes. In recent years, it was shown that exosomes in several neurodegenerative diseases are closely related to the transmission of disease-related misfolded proteins (such as α-synuclein, tau, amyloid β-protein, etc). These proteins are transported by exosomes, thus promoting the propagation to unaffected cells or areas and accelerating the progression of neurodegenerative diseases. This review focuses on the origin and composition, biological synthesis, secretion, function of exosomes, as well as their roles in the pathogenesis and progression of neurodegenerative diseases. In addition, we also discuss that exosomes can serve as biomarkers and drug delivery vehicles, and play a role in the diagnosis and treatment of neurodegenerative diseases.

Efficacy and safety of intra-aortic balloon pump-assisted interventional therapy in different age groups of patients with acute coronary syndrome / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Currently intra-aortic balloon pump (IABP) has been widely used in patients with acute coronary syndrome (ACS) who undergo percutaneous coronary intervention (PCI). However, few studies have been done with regard to the clinical outcome and safety of IABP in assisting PCI in aged patients with ACS. The purpose of the present study was to evaluate the safety of IABP in different age groups of patients with ACS.</p><p><b>METHODS</b>Data on 292 ACS patients who received IABP-assisted PCI in Shenyang General Hospital of People's Liberation Army were retrospectively analyzed. More specifically, the successful rate, mortality and complications associated with the treatment were compared between the senior (>/= 60 years old) and the non-senior (< 60 years old) groups of patients.</p><p><b>RESULTS</b>The attack rate of non-ST segment elevation ACS was significantly higher in the senior group than in the non-senior group (38.8% vs 21.1%, P < 0.01). The incidence of the IABP-associated complications was not significantly different between both groups (P > 0.05).</p><p><b>CONCLUSION</b>The clinical outcome and safety of IABP-assisted PCI in the elderly patients were comparable to that for the non-elderly patients.</p>