Experience with levetiracetam to epilepsy cases in neurodevelopmental disorders.

Objective: As a treatment for cases of developmental disorder accompanied with epilepsy, the author examined the efficacy and tolerability of combined administration of levetiracetam (LEV) on the cases. Methods: There were 21 participants (male-to-female-ratio was 16 to 5, 6 in their 10s, 7 in their 20s, 7 in their 30s and 1 in their 40s) to whom LEV was prescribed from October 2011 to December 2014. The effect was classified as loss of seizure, effective (more than 75% reduction in the number of seizures, more than 50% reduction in the number of seizures), unchanged (no change), and aggravation (increase in the number of seizures). Results: The study included 19 autistic spectrum disorder (ASD) cases (13 with profound intellectual disability, 5 with severe intellectual disability, and 1 with high functioning autism), 1 borderline intelligence case, and 1 attention deficit/hyper activity disorder (AD/HD) case. By classification of epilepsy seizure, there were 15 symptomatic localization-related epilepsy cases and 6 generalized epilepsy cases. The initial dose of LEV was an average of 488.1 mg/day, and the maintenance dose was an average of 1,714.2 mg/day. The average duration of administration was 2 years and 3 months. In terms of the response rate, there were 11 cases of loss of seizure (52.4%), 4 cases of more than 75% reduction in the number of seizures, (19.0%), and 3 cases of more than 50% reduction in the number of seizures (14.3%). The overall response rate was 85.7% (18 cases). 14.3% was unchanged (3 cases). No aggravation case was observed. There was only one case of dizziness in the initial period, but all cases continued taking LEV. The kinds of anticonvulsant agent could be adjusted from 2.5 at the beginning of LEV administration to 1.5. Emotional stability was also observed. Some cases could stop taking tranquilizers. Conclusions: LEV showed high response rate and tolerability on the cases of ASD and other developmental disorder accompanied with epilepsy. Administration of this drug led to reduction in the number of concomitant medications, which indicates the possibility that LEV may contribute to enhancing compliance.

Novel G423S mutation of human alpha7 nicotinic receptor promotes agonist-induced desensitization by a protein kinase C-dependent mechanism.

The alpha7 nicotinic acetylcholine receptor subunit (CHRNA7) gene harbors a high degree of polymorphism. In this study, we found a novel variant (1267 G to A) in exon 10 of the CHRNA7 gene in a Japanese population. This variant results in glycine-to-serine substitution at position 423 (G423S) located in the large cytoplasmic loop of the protein. To clarify the possibility that the G423S mutation alters the pharmacological properties of alpha7 receptors, acetylcholine (ACh)-elicited current through alpha7-G423S mutant receptors expressed in Xenopus laevis oocytes was measured using the two-electrode voltage-clamp technique. We found that the current elicited by ACh (1 mM, 5 s) through alpha7-G423S receptors, but not through alpha7 receptors, was significantly decreased by treatment with a protein kinase C activator, phorbol-12-myristate-13-acetate (PMA, 10-30 nM). In addition, PMA (10 nM) selectively promoted a progressive decrease in alpha7-G423S current induced by repetitive application of ACh pulses (1 mM, 0.1 s, 0.17-0.33 Hz) compared with alpha7 current. PMA also enhanced the inactivation of alpha7-G423S mutant receptors induced by a prolonged application of choline (30 microM) without affecting alpha7 receptor responses. Western blot analysis showed that the treatment with PMA (30 nM) increased the serine phosphorylation level of the alpha7-G423S mutant receptors but not that of the wild-type receptors. These findings demonstrate that the G423S mutation promotes receptor desensitization by a protein kinase C-dependent mechanism. Thus, we provide the first evidence that a variant in the human CHRNA7 gene alters the function of alpha7 nicotinic receptors.