Neuregulins (NRGs) and their cognate ErbB receptors (ErbB2–ErbB4) constitute a vast group of proteins encoded by six different genes (NRG1–6) and many isoforms with critical roles in the development and functioning of the nervous system. NRGs are known to regulate important processes in the nervous system like neural development, neuronal differentiation, neurite outgrowth, and specification. These factors are involved in the regulation of neurotransmission pathways and the modulation of several forms of synaptic plasticity. Due to NRGs’ role in synaptic plasticity, defects in their normal functioning are translated into altered signaling networks, which have been linked to susceptibility to developing psychiatric disorders like schizophrenia (SZ), autism, depression, and bipolar disorders. Additionally, deviation of the NRG normal functioning is involved in neurological diseases like Alzheimer’s and Parkinson’s disease. Contrastingly, NRG/ErbB signaling is also involved in the recovery after traumatic brain injuries (e.g., ischemic stroke). The NRG/ErbB signaling complex is highly unusual because the ligands (mainly NRG1–NRG3, with their multiple isoforms) and receptors (ErbB2–ErbB4) can orchestrate vast signaling complexes, with a wide reach within the processes that govern the development and appropriate function of the nervous system. This may explain why NRGs and ErbB receptor genes have been linked to complex brain disorders, like SZ. This review, are discussed important aspects of NRG and their relevance for nervous system functioning, including 1) subcellular localization, 2) signaling pathways involved in neuronal functions, 3) effect on neurite development and synapse formation, 4) modulation of some mechanisms of synaptic plasticity [long-term potentiation (LTP), depotentiation, long-term depression (LTD)] and 5) roles of NRGs in some neurological diseases. This review intends to present a summary of the main findings about this family of proteins, which might position them as one of the master regulators of brain functioning.

This brief statement describes some recent achievements of neuropathological research, with the focus on Alzheimer’s and other age-related diseases, neurodegenerative disorders (tauopathies, synucleinopathies), multimorbidity of the aged brain, multiple sclerosis (MS), and other neuroinflammatory disorders, including central nervous system involvement by coronavirus disease 2019 (COVID-19), as well as new developments in neurovascular diseases, neurooncology, and myopathies. Although neuropathology, using modern technologies, such as cryo-electron microscopy, proteomic and experimental methods, has helped to increase diagnostic accuracy and provided insight into the pathogenesis of many neurological disorders, future studies in co-operation with clinical and other neurosciences should overcome the challenges of disease-influencing therapeutic approaches.

All living organisms exhibit circadian rhythms. Humans show circadian rhythm of the different physiological functions such as sleep-wake cycle, core body temperature, feeding behavior, metabolic activity, heart rate variability, hormone secretion, and others. The hypothalamic suprachiasmatic nucleus (SCN) acts as a primary circadian pacemaker. Peripheral tissues have an endogenous circadian clock; however, SCN synchronizes the circadian activity of the peripheral clocks. The retinohypothalamic tract (RHT) from retinal ganglionic cells carries the photic signal into the SCN that regulates the rhythmic expression of the core clock genes through the feedback loop. At the output level, the SCN connects with the pineal gland and the peripheral tissues with the help of neuroendocrine mediators. Disruption of circadian clock functions is detrimental to health. Shift work, night work, chronic or acute jet lag, and light-at-night have adverse effects on circadian functions. Misalignment of circadian rhythm alters the expression of core clock genes, leading to deregulation of cellular activity and metabolic functions. Circadian rhythm dysfunction causes many pathologic conditions, including sleep disorders, cardiovascular problems, metabolic dysfunction, infertility, poor physical performance, as well as cancer. The present work has reviewed the relationship between circadian clock dysfunction and impaired physiological activities.

Ischemic stroke is a highly prevalent condition that frequently results in life-long disability and death. Considerable efforts have been made to establish treatments that prevent secondary ischemic damage and promote stroke recovery. Until now, the recanalization of occluded blood vessels via thrombolysis and thrombectomy, although highly potent, remains the only treatment in humans that enhances stroke outcome. Small extracellular vesicles are non-replicating, nano-sized (70–150 nm) lipid bilayer-enclosed vesicles, which have shown remarkable biological activities in various physiological and pathophysiological contexts. When administered post-stroke, mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) induce neuroprotection, promote brain remodeling and plasticity, and enhance neurological recovery in rodents and non-human primates via mechanisms that involve immunomodulation and anti-inflammation. In this review, experimental studies on the therapeutic actions of MSC-EVs in animal stroke models are summarized and perspectives for clinical translation are outlined.

The therapy of many neurological disorders has advanced markedly during recent decades. Not so for neurodegenerative disorders. Early detection, deep individual genotyping and phenotyping, and personalized therapies have been suggested as the way forward. However, we still do not know enough about the aetiology and molecular basics of these diseases. In fact, the term neurodegenerative disorder may be a misleading categorization that constitutes a major cognitive barrier against better characterization and understanding of these disorders. Therefore, we need to go back to the basics and employ novel, open-minded observational study protocols that combine very extensive and robust clinical, molecular and epidemiological data collection methods. Moreover, we need to reconsider our basic orientation towards these diseases to increase our chances of finding out what we are actually trying to care for and cure.