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Multiple sclerosis (MS) is an autoimmune disease affecting the CNS and characterized by neuroinflammation. Clinical observations revealed different incidence between males and females, suggesting a possible influence of sex steroids. These molecules, produced by peripheral steroidogenic glands, can exert their actions into the CNS, directly, or after metabolic conversion, and, for this reason, they are also called neuroactive steroids. Observations on experimental autoimmune encephalomyelitis (EAE) rodents, the most used animal model for MS, also suggest an involvement for neuroactive steroids in the pathology. In particular, castration worsen, while testosterone or its metabolite dihydrotestosterone (DHT) improve the pathological course of the disease. Based on these evidences, male Dark Agouti rats were induced with EAE in order to develop a relapsing-remitting pathology, similar to the most common human form of MS. EAE animals were treated with DHT or vehicle (sesame oil) and monitored through the experiment. After 45 days post induction, we evaluated inflammatory parameters in spinal cord tissues. The pathological course was improved in EAE rats treated with DHT compared to vehicle. Moreover, neuroinflammatory parameters such as microglial and astrocytes markers as well as cytokine expression and thiobarbituric acid-reactive substances, that were increased in the EAE-vehicle group, are significantly reduced after treatment with DHT. In conclusion, DHT treatment ameliorates not only the pathological course of the disease but also neuroinflammatory parameters in spinal cord tissues. These observations may suggest DHT as potential therapeutic option for male MS patients.

Multiple sclerosis (MS) is an autoimmune pathology characterized by inflammatory and demyelinating phases. Clinical observations indicate an involvement for sex hormones in thepathology, so that, recently, a therapy for MS based on hormones has been proposed. A clinicaltrial, involving male MS patients, revealed improvement in cognitive performances after one yeartreatment with testosterone (Sicotte et al., 2007). In the experimental autoimmune encephalomyelitis (EAE) mice, a MS animal model, neuroprotective effects of testosterone, and of its metabolite dihydrotestosterone (DHT), were observed (Dalal et al., 1997; Palaszynski et al.,2004). In the same model, castration has deleterious effects on clinical course, suggesting a protective role for androgens (Bebo et al., 1998). Moreover, in vitro evidences showed that testosterone is able to reduce inflammatory cytokines produced by human macrophages (D’Agostino et al., 1999) and monocytes (Li et al., 1993; Liva and Voskuhl, 2001). These antiinflammatory properties may be mediated by the conversion of testosterone into estradiol, or, alternatively, by some direct effects on androgen receptor (AR), mediated by DHT. This steroid can be subsequently converted into 3 alpha-diol, a GABAA receptor agonist, acting as antiinflammatory agent. Based on these evidences, we were interested in explore the protective effects of androgens treatment in a rat EAE model characterized by acute inflammatory events. We induced male Lewis rats with myelin basic protein in order to develop EAE; animals were treated with 3 alpha-diol or vehicle (sesame oil) every other day for two weeks, whereas control rats (i.e., rats not induced with EAE) received in same days only vehicle. Neurological deficits were assessed throughout the experiment (i.e., until 15 days post induction; dpi), and, at 15dpi, spinal cords were dissected. The clinical course and the weight loss of EAE rats treated with 3 alpha-diol were not different when compared to vehicle treated animals. Significant differences between these two groups were instead observed in the spinal cord after immunostaining analysis for the glial fibrillary acidic protein and the major histocompatibility complex class II, where 3 alpha-diol treatment was able to reduce the inflammatory parameters. In agreement with this observation, gene expression for tumor necrosis factor alpha, a pro-inflammatory cytokine, was decreased after 3 alpha-diol administration compared to oil-treated EAE animals. This effect seems specific for proinflammatory cytokine, because the expression of transforming growth factor beta 1, an antiinflammatory cytokine, was not different between vehicle and 3 alpha-diol treated EAE rats. To asses the metabolic fate of the injected 3 alpha-diol, liquid chromatography tandem mass spectrometry analysis were performed in spinal cord from all groups. 3 alpha-diol levels were significantly increased in steroid treated animals; moreover, a significant raise in DHT levels was observed in the same animals, indicating a retroconversion of 3 alpha-diol into DHT. The data we obtained may suggest that the reduction of inflammatory parameters could be due by both the action of DHT on AR and/or of 3 alpha-diol on GABAA receptor. These observations pointed out, for the first time, the effects of 3 alpha-diol on inflammatory parameters in EAE Lewis rats. Future studies will be aimed to elucidate the involvement of androgen and/or GABAA receptors on the observed effects.

Translocator protein (TSPO) is a multi-functional mitochondrial transmembrane protein primarily localised in steroid-producing tissues, including the brain. TSPO ligands elicit pleiotropic neuroprotective and cognitive benefits mechanistically linked to the regulation of steroid synthesis and consequently represent emerging treatment strategies for several neurodegenerative conditions. To investigate the potential of TSPO as a therapeutic target for Alzheimer's disease (AD), the current study assessed the effects of the TSPO ligand Ro5-4864 on the development of neuropathology in the triple transgenic mouse model (3xTgAD). In 3xTgAD mice, the effects of the TSPO ligand on neurosteroidogenesis and AD-related neuropathology including β-amyloid accumulation, gliosis and behavioral impairment were examined under both early intervention (7 month-old young-adult male mice with low pathology) and treatment (24 month-old, aged male mice with advanced neuropathology) conditions. Ro5-4864 treatment not only effectively attenuated development of neuropathology and behavioral impairment in young adult mice, but also reversed these indices in aged 3xTgAD mice. In the young-adult mice, these benefits were associated with increased brain levels of the potent neuroactive steroid hormones, testosterone and progesterone. Because TSPO ligands can differentially modulate TSPO activities, we also compared the independent and combined effects of Ro5-4864 with PK-11195 (a non-benzodiazepine TSPO ligand) on endogenous β-amyloid in wild type mice, finding an additive anti-amyloidogenic effect of combined treatment. To determine the contribution of increased neurosteroid synthesis to the β-amyloid reducing effects of Ro5-4864 in the wild type mice, we co-administered Ro5-4864 with a neurosteroidogenesis inhibitor, aminoglutethimide. We next compared the effect of old (Ro5-4864, PK-11195) and new-generation TSPO ligands (AC-5216, DAA-1106) on endogenous β-amyloid in wild type mice. New generation TSPO ligands such as AC-5216 have already undergone significant clinical development for treatment of anxiety disorders and depression, however our findings suggest these ligands may also have a therapeutic potential for the treatment of Alzheimer`s., The Society for Neuroscience meeting 2013