Clemastine Fumarate

Psychological stress can lead to emotional disorders, such as anxiety and depression; however, the underlying mechanisms are complicated and remain unclear. In this study, we established a mouse psychological stress model using an improved communication box, in which the psychologically stressed mice received visual, auditory, and olfactory emotional stimuli from the mice receiving electric foot shock, thus avoiding physical stress interference. After the 14-day psychological stress paradigm, our mice exhibited a significant increase in depressive and anxious behaviors. We then performed proteomic liquid chromatography-tandem mass spectrometry for proteomic data analysis of the amygdala, and the results demonstrated that differentially expressed proteins were more enriched in myelin-related biological processes, cellular components, and molecular functions, indicating a correlation between psychological stress-induced emotional disorders and amygdala myelin damage. Molecular and morphological evidence further confirmed that psychological stress damages myelin ultrastructure, downregulated myelin basic protein and proteolipid protein expression, and reduced oligodendrocyte proliferation in the amygdala. Moreover, clemastine, an antimuscarinic and antihistaminic compound that has been shown to enhance oligodendrocyte differentiation and myelination, rescued depressive behaviors accompanied by increased oligodendrogenesis. In the amygdala, psychological stress was also noted to activate microglia and increase the levels of NOD-like receptor protein 3 (NLRP3) and the proinflammatory cytokines interleukin 1β and tumor necrosis factor α, as indicated by ELISA and Western blot analyses. Moreover, in stressed mice, the administration of Brilliant Blue G, a purinergic ligand-gated ion channel 7 receptor (P2X7R) antagonist, completely reversed the increases in NLRP3 and cleaved caspase-1 levels and partially prevented amygdala myelin damage. In conclusion, amygdala demyelination may mediate psychological stress-induced emotional disorders, and P2X7R/NLRP3 cascade activation partially contributes to amygdala myelin damage after psychological stress.

Clemastine has emerged as a promising therapy for the restoration of neurologic function in patients with multiple sclerosis (MS). However, clemastine and other agents with prodifferentiative effects on oligodendrocyte progenitor cells (OPCs) in rodent models have underperformed in clinical trials. We hypothesized that the preclinical studies showed more robust effects because of the abundance of OPCs in rodent models. To better examine the therapeutic potential of clemastine, we examined its effect on demyelinated white matter lesions in rabbits, which exhibit progenitor densities and limited remyelination more closely matching those found in tissues from patients with MS.

We used lysolecithin to induce demyelination in white matter of New Zealand rabbits and then administered oral clemastine (10mg/kg/day) for various periods before assessing the OPC and oligodendrocyte (OL) populations in these lesions.

Daily administration of clemastine for the full study period (56 days) increased oligodendrogenesis in white matter lesions. However, shorter durations of treatment failed to increase overall OL density despite enhancing OPC‐to‐OL differentiation. This effect was due to exhaustion of the OPC pool, as the differentiating progenitors were not replaced because of reduced OPC proliferation. Notably, delayed administration of clemastine led to an accumulation of activated OPCs expressing markers of senescence.

Although capable of driving OL differentiation, clemastine treatment in rabbits hampered progenitor pool replenishment, induced senescence, and promoted conversion of microglia/macrophages to a proinflammatory phenotype. Whether these effects would also occur in humans or with other prodifferentiative therapies should be studied further, but our data suggest the need to carefully consider progenitor dynamics in the treatment of MS. ANN NEUROL 2025;97:116–133