Galanin Transgenic Mice with Elevated Circulating Galanin Levels Alleviate Demyelination in a Cuprizone-Induced MS Mouse Model

Multiple Sclerosis (MS) is a demyelinating autoimmune disease of the central nervous system (CNS) with a presumed autoimmune etiology. Approved treatments for MS are immunoregulatory and are able to reduce the inflammatory components of the disease. However, these treatments do not suppress progressive clinical disability. Approaches that directly protect myelin-producing oligodendrocytes and enhance remyelination are likely to improve long-term outcomes and reduce the rate of axonal damage. Galanin (GAL) is a bioactive neuropeptide that is widely distributed throughout the nervous system and has diverse neuromodulatory effects. In this study, using the cuprizone (CPZ) demyelination model of MS, we demonstrate that GAL has pronounced neuroprotective effects with respect to demyelination and remyelination. Using our GAL transgenic mouse (GAL-Tg), we identified a novel attenuation of OLs against CPZ induced demyelination, which was exerted independently of progenitor cells. Alleviation of myelin breakdown in the GAL-Tg mice was observed to be significant. Furthermore, we observed changes in the expression of the GAL receptor GalR1 during the demyelination and remyelination processes. Our data strongly indicate that GAL has the capacity to influence the outcome of primary insults that directly target OLs, as opposed to cases where immune activation is the primary pathogenic event. Taken together, these results suggest that GAL is a promising next-generation target for the treatment of MS

RNA sample sources.

<p>The illustration on the left represents the mouse brain. The top dashed line represents the first coronal cut, 5 mm away from the edge of olfactory bulb. The bottom dashed line represents the second coronal cut, 2.5 mm away from the first cut. The illustration on the right represents the brain section isolated on the left. The tissue within the dashed rectangle, containing mainly corpus callosum and part of the cortex, was used for RNA extraction. Abbreviations: CC – corpus callosum; LV – lateral ventricle; aca – anterior commissure.</p

The effect of GAL over-expression on body weight.

<p>Body weight was measured at the age of 8–9 weeks old as the starting point 0 w. The raw body weight growth in normal control groups (A) and the CPZ-treated groups (B) is shown. Both the cuprozone groups and the cuprizone-challenge plus 3-week recovery groups were measured at the same time. Data are expressed as the mean ± SEM. (n = 12–17 per group). * p<0.05, ** p<0.01, *** p<0.001.</p

Primary antibodies used for immunohistochemistrical staining.

<p>Abbreviations: MBP – myelin basic protein; GST-π – Glutathione S-Transferase π form; GFAP – glial fibrillary acidic protein; PDGFR-α – alpha-type platelet-derived growth factor receptor; OPC – oligodendrocyte precursor cell; OL – oligodendrocyte.</p

Primer pairs provided by SABiosciences™.

<p>Primer pairs provided by SABiosciences™.</p

Increased number of PDGFR-α positive cells in WT mice that underwent the CPZ-induced demyelination challenge.

<p>WT and Tg mice were given CPZ challenge for six weeks (6wCPZ, B and E) while the control mice (CLT, A and D) received normal CPZ-free rodent chow. After six weeks of challenge, two groups of animals (6wCPZ+3wR, C and F) were allowed to recover for three weeks on a normal CPZ-free diet. The bar graph shows the results of the optical-density measurements of the PDGFR-α-positive cells; a significant difference was observed between the 6wCPZ+3wR WT and Tg groups. The scale bar represents 200 µm in the low-magnification. Data are expressed as mean ± SEM values (n = 3 per group). *p<0.05, ** p<0.01.</p