Chloramphenicol prevents carbachol-induced REM sleep in cats

Twenty-four cats were implanted for chronic sleep recordings. One week after the surgery, cats were divided into four groups. Two groups were treated with three i.p. injections of 150 mg/kg chloramphenicol (CAP) separated by 12 h. Carbachol (8 micrograms/1 microliter) or saline (1 microliter) was injected into the pontine reticular formation (PRF) 1 h after the last injection of CAP. The other two groups received saline or carbachol into the PRF without CAP pre-treatment. Polygraphic recordings were started immediately after the microinjection and lasted 11 h. Carbachol increased REM sleep (P < 0.001) and reduced SWS2 (P < 0.05). In contrast, chloramphenicol reduced REM sleep (P < 0.001) and increased SWS2 (P < 0.01). The combination of these drugs increased wakefulness (P < 0.01) and reduced both SWS2 and REM sleep (P < 0.001). This data shows that chloramphenicol prevents carbachol induced REM sleep. Results are discussed in terms of an interaction between brain proteins and the cholinergic system to induce REM.