Pre- and Post-natal Protein Malnutrition Alters the Effect of Rapid Eye Movements Sleep-deprivation by the Platform-technique upon the Electrocorticogram of the Circadian Sleep—wake Cycle and its Frequency Bands in the Rat

Abstract

Selective deprivation of paradoxical (or rapid eye movements) sleep (REMS) in protein malnourished young male rats, results in circadian and homeostatic alterations. By means of electrocorticographic recordings, we have examined the sleep-wake cycle as a functional maturity index, and its circadian and homeostatic mechanisms in prenatal (PM) and chronically (CM) protein malnourished young male rats. The effects of rapid eye movements sleep-deprivation (REMS-D), by the platform technique in a "conflict experiment" (i.e. recovery from REMS-D begun during the circadian phase of activity), revealed that in PM animals, wake (WAK) was increased significantly during recovery days 1 and 2 (RD1, RD2); and slow wave sleep (SWS) was reduced significantly during these days. Prenatal protein-malnutrition altered the phase of WAK and REMS rhythms, and the amplitude of SWS rhythm was decreased. The REMS compensatory increase after REMS-D (REMS rebound) was confined to the first 4-h block of the activity phase in all experimental groups and 24 h later another REMS rebound was displayed in PM animals. The paradoxical sleep-rebound in CM animals was significantly higher than control and PM rats and it was only shown at the first 4-h block after REMS-D. Before and after REMS-D the circadian distribution of both sleep states, and the electrocortical frequency bands showed different circadian phases at the same day-time in control, PM and CM rats. The aforementioned indicates that protein malnutrition exerts important effects on the circadian and homeostatic mechanisms driving sleep. Therefore, the temporal structure of the malnourished rats may not allow proper synchronization of some sleep parameters, particularly REMS, to the environmental time cues.

León Cintra's contribution to the field of protein malnutrition effects on sleep and the brain

“…During the first recovery day, delta activity during the light period was also lower than in the control group and remained that way during the following 48 hours, suggesting a reduction in the number of cells involved in cortical synchronization. 14 In contrast, the power of fast activity was higher in the chronically malnourished rats during the recovery days. Prenatally malnourished rats, in contrast, showed lower fast activity than controls during baseline and recovery days and poor light-dark cycle modulation.…”

Time–place learning is altered by perinatal low-protein malnutrition in the adult rat

“…Such delay has also been observed in other behaviors and sleep cycles in the same kind of malnutrition. 15,16 With regard to the effect on simple learning, all experimental groups presented alterations., i.e., PtM rats took latencies during exploration ('stem' latency) of under 20 seconds decreasing the time at rest, while CM increased the latencies. PrM rats had similar time between activity and rest latency, while Co rats spend more time in rest latency than that observed in CM.…”

“…37 Diminished glutamatergic activity as well as glutamate receptors density in brain cortex has been observed in chronic malnutrition with 8% protein diets. 38 All of these changes could potentially related to the differences found in behavioral and electrophysiological studies in animal models of malnutrition, particularly in studies related with physiology of sleep 4,8,15,17 circadian rhythms, 4,14,16,18 spontaneous behavior such as play, exploration, parental care 9,38 and cognition processes. 39,40 The temporal pattern in place-learning behavior tested in this study pertains to changes in an LD cycle of 24 hours.…”

“…[3][4][5][6][7][8][9][10] There is evidence that protein malnutrition (induced by 6% casein diets) produce long-term effects in the neural substrate of hippocampal formation, 11,12 and other brain areas involved in the sleep-wake cycle regulation; 4 also, it may affect the circadian organization in rats reducing the somatic size of SCN cells 13 and alter circadian behaviors. [14][15][16][17][18] In humans and other mammals, attention processes exhibit changes during the day and it is quite possible that some of these processes are clock regulated. 19 A deficit in memory in water maze experiments was observed in continuous phase shifting protocols in rats 20 as well as other cognitive functions, 21,22 indicating that a deficit in circadian regulation may produce deficits in cognitive and social memory 23 attention processes and learning.…”

Early-life nutrition interacts with developmental genes to shape the brain and sleep behavior inDrosophila melanogaster

“…Few studies have focused on the role of early life nutrition in sleep behavior. Prenatally malnourished rats exhibit decreased sleep and increased waking activity [21,22]; however, the genetic basis of such responses remains elusive. The influence of genetic variation on the effects of restrictive early life nutrition on adult sleep behavior and the extent to which this influence is mediated by changes in neural development and brain structure remains unknown.…”