Search

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.

Different experimental autoimmune encephalomyelitis models (EAE) have been developed. However, due to the different experimental conditions applied, observations simultaneously considering different pathological targets are still scarce. Using EAE induced in Dark Agouti rats with syngenic whole spinal cord homogenate suspended in incomplete Freund's adjuvant, we here analyze neurosteroidogenic machinery, cytokine levels, microglial cells, infiltration of inflammatory cells, myelin proteins and Na(+), K(+)-ATPase pump activity in the spinal cord. Data obtained in the acute phase of the disease confirmed that neurological signs were accompanied by the presence of perivascular infiltrating T cells (CD3(+) cells) and activated monocytic/microglial cells (ED1(+) and MHC-II(+)) in the spinal cord. In particular, the number of MHC-II(+) cells was significantly increased in association with increased expression of pro- (i.e., TNF-α, IL-1β) and anti-inflammatory (i.e., TGF-β) cytokines as well as with decreased expression of proteolipid protein and myelin basic protein. During the chronic phase of the disease, the number of MHC-II(+) cells was still increased, although less than in the acute phase. Changes in the number of MHC-II(+) cells were associated with decreased Na(+),K(+)-ATPase enzymatic activity. A general decrease in the levels of neuroactive steroids, with the exception of an increase in tetrahydroprogesterone and 17β-estradiol, was detected in the acute phase. These changes were maintained or reverted in the chronic phase of EAE. In conclusion, we report that modifications in the neuroimmune response in the acute and chronic phases of EAE are associated with specific changes in myelin proteins, Na(+),K(+)-ATPase pump and in the levels of neuroactive steroids.