NOVEL SLEEP LATENCY TESTING IN C57 MICE DURING PERIODS OF NICOTINE ADMINISTRATION AND ABSTINENCE

Increased sleep latency is reported and observed during periods of nicotine consumption and withdrawal, in humans. Using mice, our lab has previously shown an increase in active phase latency during nicotine administration, and a decrease during nicotine abstinence. The present study utilized mice to characterize inactive phase sleep latency during periods of nicotine administration and abstinence and to measure corticosterone following a series of sleep latency testing trials. In experiment one (n=14), mice were implanted with EEG/EMG recording devices. During a pre-nicotine condition, mice had access to .2% saccharin water. To generate nicotine dependence, 200µg/ml of nicotine was added to the saccharin solution. After 14 days of nicotine, abstinence was initiated by excluding the nicotine from the water. Multiple sleep latency testing (MSLT) consisted of three consecutive trials spaced one hour apart under three conditions: baseline (BL), nicotine day 8 (N8), and withdrawal day 1 (WD1). During each trial, mice were kept awake for 5 mins by gentle handling or exposure to a novel object. In experiment two (n=4), an ELISA was use to assess plasma corticosterone following a third gentle handling sleep latency trial. An increase in sleep latency was observed on WD1 in the gentle handling group. No changes in latency were observed in the novel object group. Following a series of gentle handling MSLT, a significant decrease in corticosterone was observed during WD1, relative to BL. These data suggest gentle handling increases sleep latency during withdrawal, whereas a novel object does not. Additionally, changes in the gentle handling group might be mediated by a blunted corticosterone (stress) response. Grant: 5T32DA017637-14