Routine Tail Suspension Husbandry Facilitates Onset of Seizure Susceptibility in EL Mice

Abstract

Tail suspension can elicit seizures in susceptible EL mice, a model of idiopathic, multifactorial epilepsy. Further, repeated tail suspension hastens the lifetime onset of seizure susceptibility in these mice. The present study tested the hypothesis that curtailing human handling during development would delay the onset of seizure susceptibility relative to EL mice handled regularly by using tail suspension for standard laboratory husbandry. Control mice were handled by the tail for bedding changes, whereas unhandled mice bedding was changed by using specially designed connector cages that allowed mice to transfer without handling to a cage containing clean bedding. Seizure susceptibility was tested beginning at 70, 80, 90, 100, or 140 days of age by using a handling-induced seizure-susceptibility paradigm. Among handled mice, more than half of the sample exhibited seizures by age 80 days relative to fewer than one fourth of unhandled mice. In addition, each group was tested a second time 10 days after the initial seizure-susceptibility test to detect potential experience-induced increases in seizure susceptibility. Once again, a higher frequency of handled mice expressed seizures at significantly younger ages relative to unhandled mice. Although it was already known that repeated tail suspension could speed the onset of seizure susceptibility in EL mice, the present results are the first to demonstrate the converse finding that decreasing routine human handling can delay significantly the onset of seizure susceptibility. This suggests that removal of nonconsensual aspects of human-animal contact may delay or prevent the onset of seizure susceptibility.