Predictors of the first onset of a major depressive episode and changes in depressive symptoms across adolescence: Stress and negative cognitions.

This 6-year longitudinal study examined stressors (e.g., interpersonal, achievement), negative cognitions (self-worth, attributions), and their interactions in the prediction of (a) the first onset of a major depressive episode (MDE), and (b) changes in depressive symptoms in adolescents who varied in risk for depression. The sample included 240 adolescents who were first evaluated in Grade 6 (M = 11.86 years old; SD = 0.57; 54.2% female) and then again annually through Grade 12. Stressful life events and depressive diagnoses were assessed with interviews; negative cognitions and depressive symptoms were assessed with self-report questionnaires. Discrete time hazard modeling revealed a significant interaction between interpersonal stressors and negative cognitions, indicating that first onset of an MDE was predicted by high negative cognitions in the context of low interpersonal stress, and by high levels of interpersonal stressors at both high and low levels of negative cognitions. Analyses of achievement stressors indicated significant main effects of stress, negative cognitions, and risk in the prediction of an MDE, but no interactions. With regard to the prediction of depressive symptoms, multilevel modeling revealed a significant interaction between interpersonal stressors and negative cognitions such that among adolescents with more negative cognitions, higher levels of interpersonal stress predicted higher levels of depressive symptoms, whereas at low levels of negative cognitions, the relation between interpersonal stressors and depression was not significant. Risk (i.e., maternal depression history) and sex did not further moderate these interactions. Implications for intervention are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Maternal High-Fat Diet Results in Long-Term Sex-Specific Alterations to Metabolic and Gut Microbial Diurnal Oscillations in Adult Offspring

Scope: Circadian rhythms profoundly impact metabolism and the gut microbiota. A maternal high-fat diet (HFD) exerts effects on the metabolic syndrome of adult offspring in a sex-specific manner, the underlying mechanisms, however, remain unclear. Methods and results: Female mice are fed an HFD and raise their offspring on a standard chow diet until 24 weeks. The glucose tolerance, insulin sensitivity, and diurnal rhythms of serum metabolic profiles are assessed in male and female adult offspring. Simultaneously, 16S rRNA is applied to characterize gut microbiota diurnal rhythms. The study finds that maternal HFD tends to deteriorate glucose tolerance and impairs insulin sensitivity in male offspring, but not female offspring, which can be associated with the circadian alterations of serum metabolic profiles in male offspring. As expected, maternal HFD sex-specifically alters diurnal rhythms of the gut microbiota, which exhibits putative associations with metabolic profiles in males. Conclusions: The present study identifies the critical role of gut microbiota diurnal rhythms in triggering sex-biased metabolic diurnal rhythms in response to maternal HFD, at least in part. As early life may be a critical window for preventing metabolic diseases, these findings provide the basis for developing chronobiology applications targeting the gut microbiota to combat early metabolic alterations, especially in males.     

Feed restriction around parturition does not affect colostrum immunoglobulin G concentration in dairy fat-tailed sheep but does affect performance and blood metabolites in newborn lambs

This study aimed to investigate the effect of prepartum and postpartum feed restriction of fat-tailed dairy sheep on colostrum IgG concentration, and performance and blood metabolites of newborn fat-tailed lambs. Twenty fat-tailed dairy sheep were randomly allocated into control (Ctrl; n = 10) and feed restriction (FR; n = 10) groups. The Ctrl group received a diet that met 100% of energy requirements, both prepartum (from wk −5 to parturition) and postpartum (from parturition to wk 5). The FR group received a diet equivalent to 100, 50, 65, 80, and 100% of the energy requirements in wk −5, −4, −3, −2, and −1 relative to parturition, respectively. After parturition, the FR group received a diet equivalent to the 100, 50, 65, 80, and 100% of the energy requirements in wk 1, 2, 3, 4, and 5, respectively. At birth, lambs were assigned to their dam's experimental group. Both the Ctrl lambs (n = 10) and the FR lambs (n = 10) were allowed to suck colostrum and milk from the dams. Colostrum samples (50 mL) were collected at parturition (0 h) and then at 1, 12, 24, 36, 48, and 72 h postpartum. Blood samples were collected from all lambs before suckling colostrum (0 h) and then at 1, 12, 24, 36, 48, and 72 h after birth and weekly until the end of the experimental period (i.e., wk 5 relative to birth). The data were evaluated using the MIXED procedure of SAS (SAS Institute Inc.). The model included feed restriction, time, and the interaction feed restriction × time as fixed effects. The individual lamb was set as a repeated subject. Variables measured in colostrum and plasma were considered dependent variables, and significance was set at P < 0.05. Prepartum and postpartum feed restriction in fat-tailed dairy sheep did not affect colostrum IgG concentration. Consequently, no differences in blood IgG concentrations were observed in the lambs. In addition, the prepartum and postpartum feed restriction experienced by fat-tailed dairy sheep caused decreased body weight and milk intake in lambs from the FR group compared with the Ctrl group. Feed restriction also promoted increased concentration of blood metabolites such as triglycerides and urea in FR lambs compared with control lambs. In conclusion, prepartum and postpartum feed restriction in fat-tailed dairy sheep did not affect either colostrum IgG concentration or blood IgG concentration of the lambs. However, prepartum and postpartum feed restriction decreased lamb milk intake and, therefore, lamb body weight gain during the first 5 wk after birth.