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Introduction: GNAO1 encephalopathy is characterized by severe hypotonia, psychomotor retardation, epilepsy, and movement disorders. Genetic variations in GNAO1 have been linked to neurological symptoms including movement disorders like dystonia. The correlation between the E246K mutation in the Gα subunit and aberrant signal transduction of G proteins has been established but no data are reported regarding the efficacy of medical treatment with tetrabenazine. Methods: Molecular modeling studies were performed to elucidate the molecular mechanisms underlying this mutation. We developed drug efficacy models using molecular dynamic simulations that replicated the behavior of wild-type and mutated proteins in the presence or absence of ligands. Results and discussion: We demonstrated that the absence of the mutation leads to normal signal transduction upon receptor activation by the endogenous ligand, but not in the presence of tetrabenazine. In contrast, the presence of the mutation resulted in abnormal signal transduction in the presence of the endogenous ligand, which was corrected by the drug tetrabenazine. Tetrabenazine was identified as a promising therapeutic option for pediatric patients suffering from encephalopathy due to an E246K mutation in the GNAO1 gene validated through molecular dynamics. This is a potential first example of the use of this technique in a rare neurological pediatric disease. [ABSTRACT FROM AUTHOR]

Objective and design: The sigma 1 (σ) receptor, which is widely distributed in the CNS in areas that are known to be important for pain control, may play a role in persistent pain characterized by the hypersensitivity of nociceptive transmission. Here, we investigated the effect of σ blockade in an inflammatory pain model. Treatment and methods: An intraplantar injection of carrageenan (2 %) was used to induce paw inflammation. The effects of the σ antagonist (+)-MR200, given subcutaneously at a dose of 0.1, 0.25, 0.5,1, 1.5, and 2 mg/kg prior to injection of carrageenan, on inflammatory pain and inflammation were assessed. Mechanical allodynia with von Frey filaments, thermal hyperalgesia with the plantar test and edema evaluation with a plethysmometer were measured. Intergroup comparisons were assessed by one- or two-way analysis of variance when appropriate, followed by post-hoc tests (Dunnett's test for one-way or Bonferroni for two-way ANOVA). Results: (+)-MR200 dose-dependently prevented allodynia and hyperalgesia induced by carrageenan. Furthermore, it reduced paw edema with a significant inhibition percentage of 37.82 % at 3 h after carrageenan treatment. Conclusions: The blockade of the σ receptor with the selective antagonist (+)-MR200 may contribute to the suppression of the typical symptoms of inflammatory pain. [ABSTRACT FROM AUTHOR]

The compound (−)-MRV3 [(−)-methyl (1S,2R)-2-[(4-hydroxy-4-phenylpiperidin-1-yl)-methyl]-1-phenylcyclopropanecarboxylate] has an assessed antagonist sigma 1 (σ) profile and showed improved σ/σ selectivity with respect to the parent compound (+)-MR200. The σ receptor is reported to play a role in both central sensitization and pain hypersensitivity, which suggests a potential use of σ antagonists for the treatment of persistent pain conditions. The present study was performed to assess the effects of the selective σ antagonist (−)-MRV3, in carrageenan-induced inflammatory hyperalgesia, allodynia, and edema. Mechanical allodynia with a series of calibrated von Frey's filaments, thermal hyperalgesia with plantar test, and edema evaluation with a plethysmometer were measured. Subcutaneous (s.c.) treatment with (−)-MRV3 (1, 2, 3, 4, 5 mg/kg) dose-dependently reduced allodynia and hyperalgesia induced by intraplantar carrageenan. Furthermore, treatment with (−)-MRV3 (3 mg/kg s.c.) also inhibited paw edema with a significant inhibition of 37.82 % 3 h after carrageenan treatment. These results provide a strong basis for the use of σ receptor antagonists in the treatment of inflammatory pain. [ABSTRACT FROM AUTHOR]