| Objective:Healthy lifestyles,especially at younger ages,are important both for current health and also for prevention of diseases.Over the past 3 decades,children's and adolescents' lifestyles have changed,with dramatic increases in electronic products using,sedentary behavior,which are often acompanied by irregular sleep and eating time.Many adolescents don't sleep all night or eat breakfast each day to play games or do other things on computers,smart phones and other platforms.Some adolescents even do not consume anything all day for slimming in female and for playing games in male for a period of time in real life.Previous study showed that short sleep duration was significantly associated with increased risk of behavioral or emotional problems,particularly for anxious or depressed syndromes.However,the gender specificity of the effects of these irregular lifestyles on depression-like behaviors and endocrinology has not been studied.This study aims to assess the effects of environmental stress(ES)on depression-like behaviors and endocrinology in adolescent rats.Methods:1.Male and female Sprague-Dawley rats before or during puberty were divided into three groups,including control group(CON group,n = 10),low frequency ES group(LF group,n = 10)and high frequency ES group(HF group,n = 10),respectively.They were group housed whether in CON group or in ES group.Rats in LF or HF group were subject to the following stressors according to the ES schedule in Table 1 for 4 weeks.We designed low frequency of ES according to the CUMS paradigm with each environmental stressor appearance once a week in an unpredictable manner.We also designed another group with high frequency of ES,excepted for the CON group.The frequency of each environmental stressor appearance in HF group near twice a week also in an unpredictable manner.Behavioral tests were performed after 4 weeks of stress.The behavioral tests including: sucrose preference test(SPT),weight gain,food and water intake.2.Male and female Sprague-Dawley rats before or during puberty were divided into three groups,including control group(CON group,n = 10),low frequency ES group(LF group,n = 10)and high frequency ES group(HF group,n = 10),respectively.They were group housed whether in CON group or in ES group.Trunk blood were collected after 4 weeks' ES.Plasma concentrations of CORT,cholecystokinin(CCK),leptin and(NPY)were detected by ELISA kits.Result:1.Compared with CON group,environmental stress induced a significant decrease in sucrose preference value in female adolescent rats(p = 0.04),while male adolescent rats(p = 0.85)showed no similar changes;ES induced weight gain(p < 0.05)and food intake(p < 0.05)significant decrease in adolescent rats,but there was no sex specificity.However,the reduction of sucrose preference value(female: p = 0.04;male: p < 0.05),water intake(female: p < 0.05;male: p < 0.05)and food intake(female: p < 0.05;male: p < 0.05)was observed in prepuberty rats in both low frequency and high frequency ES group,but there was no sex-specific effect.2.Compared with CON group,ES induced a significant increase in adolescent female rats(p = 0.01)and a significant decrease in adolescent male rats(p = 0.02)in plasma CORT.For leptin,compared with CON group,ES induced a significant increase in both adolescent female rats(p = 0.03)and male rats(p = 0.02)in plasma leptin.ES induced a significant increase in adolescent female rats in both plasma CCK(p = 0.02),and plasma NPY(p < 0.05)compared to CON group,but not in male rats.However,there was no significant differences in plasma CORT,CCK,leptin and NPY in prepuberty rats compared to CON group.Conclusions:Our findings indicated that environmental stress can lead to depression-like behaviors,accompanied by increased CORT and CCK,and decreased NPY in adolescent female rats.The increased stress sensitivity and reduced stress resilience in adolescent female rats may be associated with the occurrence of depression-like behaviors. |
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