Antiproliferative effect of GTS-21 in glioblastoma cells

Neurotransmitters: Potential Targets in Glioblastoma

Simple Summary

Aiming to discover potential treatments for GBM, this review connects emerging research on the roles of neurotransmitters in the normal neural and the GBM microenvironments and sheds light on the prospects of their application in the neuropharmacology of GBM. Conventional therapy is blamed for its poor effect, especially in inhibiting tumor recurrence and invasion. Facing this dilemma, we focus on neurotransmitters that modulate GBM initiation, progression and invasion, hoping to provide novel therapy targeting GBM. By analyzing research concerning GBM therapy systematically and scientifically, we discover increasing insights into the regulatory effects of neurotransmitters, some of which have already shown great potential in research in vivo or in vitro. After that, we further summarize the potential drugs in correlation with previously published research. In summary, it is worth expecting that targeting neurotransmitters could be a promising novel pharmacological approach for GBM treatment.

Abstract

For decades, glioblastoma multiforme (GBM), a type of the most lethal brain tumor, has remained a formidable challenge in terms of its treatment. Recently, many novel discoveries have underlined the regulatory roles of neurotransmitters in the microenvironment both physiologically and pathologically. By targeting the receptors synaptically or non-synaptically, neurotransmitters activate multiple signaling pathways. Significantly, many ligands acting on neurotransmitter receptors have shown great potential for inhibiting GBM growth and development, requiring further research. Here, we provide an overview of the most novel advances concerning the role of neurotransmitters in the normal neural and the GBM microenvironments, and discuss potential targeted drugs used for GBM treatment.

Acetylcholine receptor agonists provide cardioprotection in doxorubicin-induced cardiotoxicity via modulating muscarinic M2 and α7 nicotinic receptor expression

The balance between cardiac sympathetic and parasympathetic activities has been intricately linked to mitochondrial function, cellular oxidative status, and immunomodulation in healthy and diseased myocardium. Cardiac autonomic neuropathy, along with the associated mitochondrial and cellular dysfunction, is an important pathophysiological feature of doxorubicin-induced cardiotoxicity (DIC). We tested the hypothesis that autonomic modulation by activation of acetylcholine receptors (AChR) effectively attenuates DIC. Rats were divided into control (0.9% sodium chloride solution) and doxorubicin groups (DOX, 3 mg/kg/d, 6 doses). Rats in the DOX group were equally subdivided into 4 interventional groups and treated for 30 days: vehicle, α7 nicotinic receptor agonist (PNU: PNU-282987, 3 mg/kg/d), muscarinic receptor agonist (BET: bethanechol, 12 mg/kg/d), and combined α7nAChR and mAChR agonists group (COM). Cardiac biochemical and functional analyses were done. The results show that AChR agonists protected the heart against DIC via improving mitochondrial and cardiac function, which was accompanied by reducing mitochondrial oxidative damage, apoptosis, and inflammation. Strikingly, PNU and BET exerted cardioprotection through different molecular pathways. PNU-mediated α7nAChR activation promoted mitochondrial fusion via upregulation of Mfn1-2 and attenuated DOX-induced autophagy. Contrarily, activation of mAChR by BET attenuated mitochondrial fission and mitophagy. The in vitro experiments confirmed the cytoprotective effects of AChR activation in DOX-treated H9c2 cells without compromising the anticancer effect of DOX in cancer cells. In conclusion, α7nAChR and mAChR agonists exerted cardioprotection against DIC via rebalancing autonomic function, improving mitochondrial function, reducing oxidative stress, and decreased cardiomyocyte apoptosis and inflammation, leading to improved cardiac function.

Marine Origin Ligands of Nicotinic Receptors: Low Molecular Compounds, Peptides and Proteins for Fundamental Research and Practical Applications

The purpose of our review is to briefly show what different compounds of marine origin, from low molecular weight ones to peptides and proteins, offer for understanding the structure and mechanism of action of nicotinic acetylcholine receptors (nAChRs) and for finding novel drugs to combat the diseases where nAChRs may be involved. The importance of the mentioned classes of ligands has changed with time; a protein from the marine snake venom was the first excellent tool to characterize the muscle-type nAChRs from the electric ray, while at present, muscle and α7 receptors are labeled with the radioactive or fluorescent derivatives prepared from α-bungarotoxin isolated from the many-banded krait. The most sophisticated instruments to distinguish muscle from neuronal nAChRs, and especially distinct subtypes within the latter, are α-conotoxins. Such information is crucial for fundamental studies on the nAChR revealing the properties of their orthosteric and allosteric binding sites and mechanisms of the channel opening and closure. Similar data are provided by low-molecular weight compounds of marine origin, but here the main purpose is drug design. In our review we tried to show what has been obtained in the last decade when the listed classes of compounds were used in the nAChR research, applying computer modeling, synthetic analogues and receptor mutants, X-ray and electron-microscopy analyses of complexes with the nAChRs, and their models which are acetylcholine-binding proteins and heterologously-expressed ligand-binding domains.