Deficits in social behavioral tests in a mouse model of alternating hemiplegia of childhood

Abstract

Social behavioral deficits have been observed in patients diagnosed with alternating hemiplegia of childhood (AHC), rapid-onset dystonia-parkinsonism and CAPOS syndrome, in which specific missense mutations in ATP1A3, encoding the Na(+), K(+)-ATPase α3 subunit, have been identified. To test the hypothesis that social behavioral deficits represent part of the phenotype of Na(+), K(+)-ATPase α3 mutations, we assessed the social behavior of the Myshkin mouse model of AHC, which has an I810N mutation identical to that found in an AHC patient with co-morbid autism. Myshkin mice displayed deficits in three tests of social behavior: nest building, pup retrieval and the three-chamber social approach test. Chronic treatment with the mood stabilizer lithium enhanced nest building in wild-type but not Myshkin mice. In light of previous studies revealing a broad profile of neurobehavioral deficits in the Myshkin model - consistent with the complex clinical profile of AHC - our results suggest that Na(+), K(+)-ATPase α3 dysfunction has a deleterious, but nonspecific, effect on social behavior. By better defining the behavioral profile of Myshkin mice, we identify additional ATP1A3-related symptoms for which the Myshkin model could be used as a tool to advance understanding of the underlying neural mechanisms and develop novel therapeutic strategies.

Keywords: ATP1A3; mouse model; Alternating hemiplegia of childhood; social behavior.

Figure 1.

Nest building behavior. (a) Representative examples of nest building by singly-housed Myk/+ (right) and +/+ (left) mice provided with a ripped up paper towel in a previous circadian rhythm study. (b) Nest quality score (0–4 scale) at 30 min, 60 min, 90 min, 3 h and 24 h after placement into a clean cage. Main effects of genotype (F(1, 44) = 73.86, p < 0.0001) and time (F(4, 44) = 8.66, p < 0.0001) were observed. (c) Percentage of nestlet shredded at 30 min, 60 min, 90 min, 3 h and 24 h after placement into a clean cage. Main effects of genotype (F(1, 44) = 74.12, p < 0.0001), time (F(4, 44) = 17.87, p < 0.0001) and genotype × time interaction (F(4, 44) = 7.73, p < 0.0001) were observed. (d) Height of nests at 24 h after placement into a clean cage. A main effect of genotype (F(1, 8) = 15.82, p < 0.01) was observed. Myk/+ mice (n = 6); +/+ mice (n = 6). *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001 versus +/+ mice.

Figure 2.

Effects of chronic lithium treatment on nesting building. (a) Bouts of exploration and shredding of the nesting material. Main effects of genotype (F(1, 37) = 233.31, p < 0.0001), drug (F(1, 37) = 9.80, p < 0.01) and genotype × drug interaction (F(1, 37) = 5.39, p < 0.05) on bouts of shredding were observed. (b) Time spent exploring and shredding the nesting material over 5 min of observation in a clean cage. Main effects of genotype (F(1, 37) = 18.06, p < 0.0001) and drug (F(1, 37) = 4.39, p < 0.05) on time spent exploring, and a main effect of genotype (F(1, 37) = 101.27, p < 0.0001) on time spent shredding, were observed. (c) Nest quality score (0–4 scale) at 30 min, 60 min, 90 min, 3 h and 24 h after placement into a clean cage. Main effects of genotype (F(1, 212) = 595.26, p < 0.0001), drug (F(1, 212) = 9.87, p < 0.0001), time (F(4, 212) = 74.68, p < 0.0001), genotype × drug interaction (F(1, 212) = 24.82, p < 0.0001) and genotype × time interaction (F(4, 212) = 33.99, p < 0.0001) were observed. (d) Percentage of nestlet shredded at 30 min, 60 min, 90 min, 3 h and 24 h after placement into a clean cage. Main effects of genotype (F(1, 212) = 579.50, p < 0.0001), drug (F(1, 212) = 21.25, p < 0.0001), time (F(4, 212) = 100.05, p < 0.0001), genotype × drug interaction (F(1, 212) = 38.89, p < 0.0001), genotype × time interaction (F(4, 212) = 67.39, p < 0.0001), sex × drug interaction (F(1, 212) = 5.39, p < 0.05) and drug × time interaction (F(4, 212) = 5.69, p < 0.0001) were observed. (e) Height of nests at 24 h after placement into a clean cage. A main effect of genotype (F(1, 40) = 238.88, p < 0.0001) was observed. Myk/+ mice on standard diet (n = 15); Myk/+ mice on lithium diet (n = 11); +/+ mice on standard diet (n = 8); +/+ mice on lithium diet (n = 10). *p < 0.05; **p < 0.01; ****p < 0.0001 Myk/+ mice on standard diet versus +/+ mice on standard diet. ^# p < 0.05; ^### p < 0.001 +/+ mice on lithium diet versus +/+ mice on standard diet.

Figure 3.

Pup retrieval. Latency of Myk/+ (n = 8) and +/+ (n = 8) dams to return pup to the nest location. A main effect of genotype (F(1, 14) = 11.20, p < 0.01) was observed. **p < 0.01 Myk/+ mice versus +/+ mice.

Figure 4.

Three-chamber social approach test. (a) Sociability phase: time spent by the subject exploring a novel adult male mouse (Stranger 1) or an empty container. A main effect of genotype (F(1, 14) = 5.98, p < 0.05) on time in contact with the novel mouse was observed. (b) Social Novelty phase: time spent by the subject exploring the mouse previously explored (Stranger 1) and a second novel adult male mouse (Stranger 2). A main effect of genotype (F(1, 14) = 26.71, p < 0.0001) on time in contact with Stranger 2 was observed. (c) Distance travelled (m) in the Sociability and Social Novelty phases of the test. There was no main effect of genotype or sex. Myk/+ mice (n = 8); +/+ mice (n = 10). **p < 0.01; ****p < 0.0001 versus +/+ mice. ^#### p < 0.0001 versus Stranger 1.