Daily Acclimation Handling Does Not Affect Hippocampal Long-Term Potentiation or Cause Chronic Sleep Deprivation in Mice

Abstract

Study Objectives: Gentle handling is commonly used to perform brief sleep deprivation in rodents. It was recently reported that daily acclimation handling, which is often used before behavioral assays, causes alterations in sleep, stress, and levels of N-methyl-D-aspartate receptor subunits prior to the actual period of sleep deprivation. It was therefore suggested that acclimation handling could mediate some of the observed effects of subsequent sleep deprivation. Here, we examine whether acclimation handling, performed as in our sleep deprivation studies, alters sleep/wake behavior, stress, or forms of hippocampal synaptic plasticity that are impaired by sleep deprivation. Design: Adult C57BL/6J mice were either handled daily for 6 days or were left undisturbed in their home cages. On the day after the 6th day of handling, long-term potentiation (LTP) was induced in hippocampal slices with spaced four-train stimulation, which we previously demonstrated to be impaired by brief sleep deprivation. Basal synaptic properties were also assessed. In three other sets of animals, activity monitoring, polysomnography, and stress hormone measurements were performed during the 6 days of handling. Results: Daily gentle handling alone does not alter LTP, rest/activity patterns, or sleep/wake architecture. Handling initially induces a minimal stress response, but by the 6th day, stress hormone levels are unaltered by handling. Conclusion: It is possible to handle mice daily to accustom them to the researcher without causing alterations in sleep, stress, or synaptic plasticity in the hippocampus. Therefore, effects of acclimation handling cannot explain the impairments in signaling mechanisms, synaptic plasticity, and memory that result from brief sleep deprivation.