Combined cocaine and clonazepam administration induces REM sleep loss and anxiety-like withdrawal behaviors in rats

Abstract

Misuse of prescription medications has risen to popularity. Reasons for this practice include the self-medication of sleep and psychiatric disorders and attempts to counteract the dysphoric side effects of stimulant drugs. Clonazepam, a commonly prescribed benzodiazepine, has been increasingly used as a countermeasure to cocaine side-effects, including sleep reduction and anxiety. As both substances may impair sleep and aggravate psychiatric conditions, this study aimed to evaluate the long-term effects of the interaction of clonazepam and cocaine on anxiety-like behavior, and the short-term effects of this drug combination on sleep using male Wistar rats. Animals received saline, cocaine (15 mg/kg), clonazepam (1.25 mg/kg) or both drugs for 16 days. Sleep recording was performed on the first day of treatment to evaluate acute treatment effects. One day after the end of the treatment period, the open field and elevated plus-maze tests were used to assess anxiety-like behavior. Blood samples were collected for analysis of corticosterone levels. Rats receiving both drugs presented an increase in impulsivity when moving between arms in the elevated plus-maze and a reduction in exploratory behavior in the open field test. These findings suggest the presence of a withdrawal behavioral syndrome, which can manifest as a paradoxical increase in exploratory activity after a period without receiving the drug and may indicate the development of dependence. Combined treatment reduced paradoxical sleep time and increased its onset latency. There was no significant difference regarding corticosterone levels across any group. Our results contribute to the understanding of the risks of combining cocaine and clonazepam. Association of these drugs may impair sleep architecture and aggravate the dependence symptoms already seen when these substances are used separately. These findings may be useful in helping to counteract the impairments resulting from the combined use of these 2 substances and to raise awareness of these associated risks.