Effects of chloramphenicol and thiamphenicol on sleep of the mouse]

The oral administration of 0.25-2.0 g/kg of chloramphenicol at 9h selectively suppresses paradoxical sleep in mice for a duration of 2-4 hours. A dose of 1 g/kg given at 17h suppresses paradoxical sleep for 7 hours. Slow wave sleep decreased for 2 hours after administration. Thiamphenicol (1 g/kg) has no effect under the same conditions.     

Absence of paradoxical sleep rebound in hypophysectomized rats pretreated at birth with sodium glutamate

Control untreated female rats and rats pretreated at birth with ten injections of monosodium glutamate (MSG; 4 mg/g b.w.) were hypophysectomized (Hypox) at 45-60 days of age and their sleep-waking cycle continuously registered. After 24 hrs. of PS deprivation, there was an immediate increase of PS (rebound) in the control Hypox and MSG rats while there was no increase in Hypox-MSG rats. Factors from arcuate nucleus and/or from the hypophysis are probably involved in the mechanisms of PS rebound.     

Thermophysiology of the paradoxical sleep

Data on interactions between the paradoxical sleep (PS) and thermoregulation under thermo-comfortable and extreme conditions (in high and low temperatures, forced and spontaneous fasting, acclimation to cold and acclimation to natural winter conditions) are reviewed. The hypothesis of the PS role in synchronising and endogenous "kindling" of the visceral function ultradian rhythms is substantiated. Some new data are presented on entering torpor as a phenomenon of the "dramatic" neuronal plasticity.     

The effect of the removal of the epiphysis on the antidepressive properties of paradoxical sleep deprivation in rats]

After REM sleep deprivation antidepressant shifts in forced swimming with increase of time of immobility and decrease of rhythmical index of depression were observed. Pinealectomy did not remove, but attenuated these behavioural changes.     

Self-deprivation of paradoxical sleep in cats

The phenomenon of paradoxical sleep (PS) self-deprivation has been detected and described. The self-deprivation is acquired just as a classical conditioned reflex during enforced PS deprivation both by water tank procedure and by the animal's awakenings in response to sensory stimuli or direct electric stimulation of activating structures of the midbrain and diencephalon, following the transition of slow-wave sleep to PS. In this situation the transition of the brain from one physiological state to another is a conditioned signal, and sensory stimulation or brain stimulation, resulting in arousal reaction, serves as an unconditioned stimulus. It is suggested that the detection and analysis of PS self-deprivation are of a great importance, on the one hand, for correct understanding of the functional significance of this physiological brain state, and, on the other hand, for accurate analysis and assessment of the dissociative processes, observed during PS deprivation and postdeprivation period.     

Hypothermia and paradoxical sleep. I. Pontile cats without hypothalamo-hypophysis

Chronic pontile cats (without hypothalamo-hypophysis) were kept during 4 days at central T (TC) between 37.5 and 30.8 degrees C at stable ambiant T (TA) between 28.5 and 23 degrees C. The vasomotor index of the forepaw was chosen for studying change in vasomotricity. Small and slow variations of TA (+1.5 degrees C) around 27 degrees C were followed by thermoregulatory response since a progressive decrease of TA under 27 degrees C led to vasoconstriction and increase of TC while progressive increase of TA above 27 degrees C led to vasodilatation and decrease of TC. However rapid and large decrease of TA under 27 degrees C (24-23 degrees C) led to the expected hypothermia with decrease of TC but without vasoconstriction. Paradoxical sleep (PS) amounts were strongly correlated with TC. At TC above 35.5 degrees C PS was almost totally suppressed while it increased significantly under 35 degrees C (Q10 = 0.10). Under 35 degrees C at stable TC and TA, PS occurred with an endogenous circahoral rhythm which did not vary significantly between 35 and 32 degrees C. These results strongly suggest that in pontile cats, PS is both gated and regulated by TC, while TC is regulated by pontobulbar vasomotor systems in response to TA. The putative role of the ventro-lateral medulla, in controlling both vasomotricity, TC and the excitability of the locus coeruleus is discussed in relation with PS.     

Striato-rhinencephalic activation during paradoxical sleep as revealed by c-fos expression

Sleep and Biological Rhythms -     

Deprivation of paradoxical sleep effect on weight and nucleic acid content of liver and brain

Male Wistar rats weighing between 200 and 350 g were deprived of paradoxical sleep (PS-D) by placing them on small platforms surrounded by water. In comparison with rats kept in similar cages but without water, PS-D animals manifested a marked decrease in body and liver weight, which depended on animal size and on time of exposure to the condition of PS-D. A comparable weight loss occurred in the spleen, while more limited effects were present in brain and cerebellum. Exposure to the condition of PS-D induced a pronounced increase in the concentration of liver DNA and RNA. The latter effect occurred considerably earlier. On the other hand, only limited and uncertain variations were noted in the DNA concentration of brain and cerebellum. Body and liver changes were readily reversed after a period of recovery lasting two days.