Instrumental REM sleep deprivation in neonates leads to adult depression-like behaviors in rats

Study Objectives: Previous studies have demonstrated that neonatal suppression of rapid eye movement (REM) sleep by pharmacologic agents, particularly clomipramine, produces adult depressive behavior. These findings suggest the hypothesis that REM sleep deprivation (RSD) mediates the depressogenic behaviors of neonatally administered antidepressant drugs. Drug suppression of RSD, however, was thought to be confounded by the other effects of the drugs. The current study was aimed to show the adult effect of neonatal RSD in rats by instrumental means, ie, a computer-controlled shaking method. Design: Three treatment groups were studied: an instrumental RSD group, a yoked control group, and a nonshaken, maternally separated, control group. All treatments began at the age of 14 days and lasted for 7 days. Adult behavior measurements including tests of sexual activity, locomotor activity, shock-induced fighting, and sleep recording were subsequently performed. Measurements and Results: The major findings of our investigation were that rats subjected to neonatal instrumental RSD demonstrated diminished sexual activity, decreased aggressive behavior, increased percentage of REM sleep, and decreased wake-REM sleep ratio compared with yoked control rats. These data are compatible with the findings from adult rats subjected to neonatal treatment with the REM-sleep suppressant, clomipramine, and supports the hypothesis that neonatal RSD results in adult depressive abnormalities. Conclusion: Neonatal RSD induced by a nondrug method results in adult depression-like changes similar to those induced by a REM-sleep suppressant drug, although the extent of these changes varies.