REVIEW | doi:10.20944/preprints202101.0282.v1
Subject: Biology, Anatomy & Morphology Keywords: oligodendrogenesis; remyelination; hormones; steroids; peptides
Online: 15 January 2021 (08:25:46 CET)
Alterations in myelin, the protective and insulating sheath surrounding axons, affect brain function, as is evident in demyelinating diseases where the loss of myelin leads to cognitive and motor dysfunction. Recent evidence suggests that changes in myelination, including both hyper- and hypo-myelination, may also play a role in numerous neurological and psychiatric diseases. Protecting myelin and promoting remyelination is thus crucial for a wide range of disorders. Oligodendrocytes (OLs) are the cells that generate myelin, and oligodendrogenesis (OLgenesis), the creation of new OLs, continues throughout life and is necessary for myelin plasticity and remyelination. Understanding the regulation of OLgenesis and myelin plasticity within disease contexts is therefore critical for the development of novel therapeutic targets. In our companion manuscript , we review literature demonstrating that multiple hormone classes are involved in the regulation of OLgenesis under physiological conditions. The majority of hormones enhance OLgenesis, increasing oligodendrocyte precursor cell differentiation and inducing maturation and myelin production in OLs. Thus, hormonal treatments present a promising route to promote remyelination. Here, we review literature on hormonal regulation of OLgenesis within the context of disorders. We focus on steroid hormones, including glucocorticoids and sex hormones, peptide hormones such as insulin-like growth factor 1, and thyroid hormones. For each hormone, we describe whether they aid in OL survival, differentiation, or remyelination, and we discuss their mechanisms of action, if known. Several of these hormones have yielded promising results in both animal models and in human conditions; however, a better understanding of hormonal effects, interactions, and their mechanisms will ultimately lead to more targeted therapeutics for myelin repair.
REVIEW | doi:10.20944/preprints202102.0277.v1
Subject: Life Sciences, Biochemistry Keywords: energy metabolism; oligodendrocyte; oligodendrocyte progenitor cell; myelin; remyelination; multiple sclerosis; glucose; ketone bodies; lactate; N-acetyl aspartate; demyelination
Online: 11 February 2021 (10:57:28 CET)
Central nervous system (CNS) myelin has a crucial role in accelerating the propagation of action potentials and providing trophic support to the axons. Defective myelination and lack of myelin regeneration following demyelination can both lead to axonal pathology and neurodegeneration. Energy deficit has been evoked as an important contributor to various CNS disorders, including multiple sclerosis (MS). This suggests that dysregulation of energy homeostasis in oligodendroglia may be an important contributor to myelin dysfunction and lack of repair observed in the disease. This article will focus on energy metabolism pathways in oligodendroglial cells and highlight differences dependent on the maturation stage of the cell. In addition, it will emphasize that the use of alternative energy sources by oligodendroglia may be required to save glucose for functions that cannot be fulfilled by other metabolites, thus ensuring sufficient energy input for both myelin synthesis and trophic support to the axons. Finally, it will point out that neuropathological findings in a subtype of MS lesions likely reflect defective oligodendroglial energy homeostasis in the disease.