To investigate the effects of early sleep deprivation(SD) on depressive-like behavior and hippocampus synaptic plasticity in adult mice with chronic unpredictable mild stress(CUMS) model.

Thirty 2-week-old clean grade male mice were randomly divided into control group (CON group), CUMS group and SD + CUMS group according to the random number table, with 10 mice in each group. The mice in SD + CUMS group were subjected with sleep deprivation for 4 hours once a day during puberty (3 ~ 6 weeks old), and then were stimulated by CUMS after adulthood (9 weeks old). The mice in CUMS group were subjected with CUMS at the age of 9 weeks. And the mice in CON group were not given any intervention.The depressive-like behavior was evaluated by body weight, sugar water preference, tail suspension test and forced swimming test.The density of dendritic spines of basal and apical neurons in hippocampal CA1 was measured by Golgi staining, the frequency and amplitude of miniature excitatory postsynaptic current(mEPSC) of pyramidal neurons in the hippocampal CA1 region of mice were measured by electro-physiological patch clamp technique.Graphpad prism 7.0 software was used for statistical analysis and mapping. One-way ANOVA was used for comparison among multiple groups, and Tukey test was used for further pairwise comparison.

(1) After stress modeling, there were significant differences in body weight, sugar water preference percentage, forced swimming immobility time and tail suspension time among the three groups (F=71.63, 39.82, 44.13, 43.07, all P<0.01). Compared with CON group, the mice in CUMS group and SD+ CUMS group had lower body weight ((25.51±0.37) g, (22.92±0.31) g, (20.12±0.27) g, both P<0.01), lower sugar water percentage preference ((87.40±1.65) %, (63.42±3.33) %, (49.68±3.70)%, both P<0.01), longer immobile time of forced swimming ((34.30±5.32) s, (119.20±12.03) s, (153.80±9.17) s, both P<0.01) and longer immobile time of tail suspension test((115.20±8.19)s, (156.80±4.35) s, (192.00±4.12) s, both P<0.01). Compared with CUMS group, SD+ CUMS group had lower body weight (P<0.01), lower sugar water preference percentage (P<0.05), longer immobile time in forced swimming test(P<0.05) and longer immobile time in tail suspension test(P<0.01). (2) Golgi staining results showed that the densities of dendritic spines of apical neurons and basal neurons in hippocampal CA1 area of the three groups were significantly different (F=38.41, 41.34, both P<0.01). The densities of dendritic spines of basal and apical hippocampal neurons in CUMS group and SD+ CUMS group were lower than those in CON group ((7.74±0.22)/10 μm, (6.58±0.27)/10 μm, (5.00±0.13)/10 μm, both P<0.01), ((8.90±0.23)/10 μm, (7.63±0.30)/10 μm, (6.01±0.14)/10 μm, both P<0.01). Compared with CUMS group, the mice in SD+ CUMS group had lower densities of dendritic spines of basal and apical hippocampal neurons(both P<0.01). (3) Electrophysiological results showed that there were significant differences in the frequency and amplitude of mEPSC in hippocampal pyramidal neurons of the three groups (F=38.90, 63.37, both P<0.01). Compared with CON group, the frequency and amplitude of mEPSC in pyramidal neurons of CA1 in CUMS group and SD+ CUMS group were significantly lower ((0.39±0.03)Hz, (0.20±0.02)Hz, (0.07±0.02)Hz, both P<0.01; (9.98±0.31)pA, (7.74±0.21)pA, 6.36±0.13)pA, both P<0.01). Compared with CUMS group, the frequency and amplitude of mEPSC in SD+ CUMS group were lower (both P<0.01).

Adolescent sleep deprivation aggravates depressive behavior and hippocampus synaptic plasticity impairment in adult CUMS model mice.

Sleep deprivation; Chronic unpredictable mild stress; Depression; Synaptic plasticity; Hippocampus; Patch clamp; Adolescent; Mice