Chronic Powder Diet After Weaning Induces Sleep, Behavioral, Neuroanatomical, and Neurophysiological Changes in Mice.

The purpose of this study is to clarify the effects of chronic powder diet feeding on sleep patterns and other physiological/anatomical changes in mice. C57BL/6 male mice were divided into two groups from weaning: a group fed with solid food (SD) and a group fed with powder food (PD), and sleep and physiological and anatomical changes were compared between the groups. PD exhibited less cranial bone structure development and a significant weight gain. Furthermore, these PD mice showed reduced number of neurogenesis in the hippocampus. Sleep analysis showed that PD induced attenuated diurnal sleep/wake rhythm, characterized by increased sleep during active period and decreased sleep during rest period. With food deprivation (FD), PD showed less enhancement of wake/locomotor activity compared to SD, indicating reduced food-seeking behavior during FD. These results suggest that powder feeding in mice results in a cluster of detrimental symptoms caused by abnormal energy metabolism and anatomical/neurological changes

Baseline sleep/wake characterizations.

<p>(A) Time course for amount of wake (top), NR (middle), and REM sleep (bottom) over 24hr in SD and PD fed mice (N = 8 each). The gray shaded part represents the dark period. G and T are a p-value of the group and time effect, respectively. (B) Total amounts of wake, NR and REM sleep over 24hr, light, and dark periods. Data are presented as mean ± SEM.</p

The maxillomandibular bone size between the groups.

<p>(°): degree</p><p>* Bonferroni adjustment</p><p>The maxillomandibular bone size between the groups.</p

The effect of food deprivation on locomotor activity and temperature.

<p>Data collecting of locomotor activity and temperature was carried out for 4 continuous days in both groups (N = 8 each). Foods were removed at ZT0 in the Fasting Day 1 and were re-provided at ZT0 in the Recovery day. G and T are a p-values of the group and time effect, respectively. Data are presented as mean ± SEM.</p

The effect of food deprivation between SD and PD diet groups at Baseline vs. Fasting Day 2.

<p>(A) Total wake amount per hour in SD (left, N = 8) and PD (right, N = 8) groups at Baseline vs. Fasting Day 2. F and T are a p-values of the fasting and time effect, respectively. (B) Mean episode duration of wake, NR, and REM at Baseline vs. Fasting Day 2. Food deprivation caused increase in wakefulness (associated with longer wake bouts) significantly in both light and dark periods in SD group, while increase in wakefulness in PD was minimum and only observed in the beginning of dark period. Data are presented as mean ± SEM.</p

Neurogenesis in hippocampal DG.

<p>(A-1) A schematic representation in the hippocampal DG area. GrDG: granule cell layer of DG, PoDG: polymorph layer of DG, MoDG: molecular layer of the DG. (A-2) Representative photomicrographs of BrdU labeled cells in hippocampal DG at one day after the last injection of BrdU in SD (top, N = 8) and PD (bottom, N = 8) group. (B) The total number and averaged number in each area of labeled cells are presented as mean ± SEM.</p

Body Weight Change in PD and SD fed mice.

<p>Body weight was measured through the experiments in both SD and PD groups (N = 8 for SD, N = 9 for PD). Each arrow indicates (a) marble burying test, (b) headstage implant for sleep recording, (c) baseline and food deprivation, and (d) BrdU injections. Data are presented as mean ± SEM.</p

Mean episode durations and FFT power spectra at Baseline.

<p>(A) Mean episode duration of wake, NR and REM in light and dark period, (B) EEG power during wake, NR and REM. Power density in theta frequency was calculated in wake and REM sleep, while delta power density was calculated in NREM sleep. Data are presented as mean ± SEM.</p