Effects of parental environment on the prevalence of convulsive seizures in Onychomys torridus.

Male and female southern grasshopper mice (Onychomys torridus) were reared in 1 of 3 different parental environments: (a) with the natural male and female parents; (b) with the female parent only; or (c) with foster parents of a closely related species, Peromyscus leucopus. All mice were weaned at 25 days of age, then observed individually in an open field arena at 10-day intervals from 30 to 100 days of age. Twenty-seven of 59 subjects (45.8%) that were reared by the natural parents exhibited convulsive seizures during at least 1 of the 8 tests in the open field arena. The prevalence of convulsive seizures increased significantly in subjects that received altered parental care: 27 of 41 subjects (65.9%) reared by the female parent only or by Peromyscus foster parents seized during at least 1 of the 8 tests in the open field. Subjects from the 3 treatment groups did not differ in the mean number of seizures observed during the 8 open field tests. These results demonstrate a significant influence of the preweaning parental environment on the prevalence of convulsive seizures on Onychomys torridus.