Proteome profiling of different rat brain regions reveals the modulatory effect of prolonged maternal separation on proteins involved in cell death-related processes

Abstract

Background Early-life stress in the form of maternal separation can be associated with alterations in offspring neurodevelopment and brain functioning. Here, we aimed to investigate the potential impact of prolonged maternal separation on proteomic profiling of prefrontal cortex, hippocampus and cerebellum of juvenile and young adult rats. A special attention was devoted to proteins involved in the process of cell death and redox state maintenance. Methods Long-Evans pups were separated from their mothers for 3 h daily over the first 3 weeks of life (during days 2–21 of age). Brain tissue samples collected from juvenile (22-day-old) and young adult (90-day-old) rats were used for label-free quantitative (LFQ) proteomic analysis. In parallel, selected oxidative stress markers and apoptosis-related proteins were assessed biochemically and by Western blot, respectively. Results In total, 5526 proteins were detected in our proteomic analysis of rat brain tissue. Approximately one tenth of them (586 proteins) represented those involved in cell death processes or regulation of oxidative stress balance. Prolonged maternal separation caused changes in less than half of these proteins (271). The observed alterations in protein expression levels were age-, sex- and brain region-dependent. Interestingly, the proteins detected by mass spectrometry that are known to be involved in the maintenance of redox state were not markedly altered. Accordingly, we did not observe any significant differences between selected oxidative stress markers, such as the levels of hydrogen peroxide, reduced glutathione, protein carbonylation and lipid peroxidation in brain samples from rats that underwent maternal separation and from the corresponding controls. On the other hand, a number of changes were found in cell death-associated proteins, mainly in those involved in the apoptotic and autophagic pathways. However, there were no detectable alterations in the levels of cleaved products of caspases or Bcl-2 family members. Taken together, these data indicate that the apoptotic and autophagic cell death pathways were not activated by maternal separation either in adolescent or young adult rats. Conclusion Prolonged maternal separation can distinctly modulate expression profiles of proteins associated with cell death pathways in prefrontal cortex, hippocampus and cerebellum of juvenile rats and the consequences of early-life stress may last into adulthood and likely participate in variations in stress reactivity.

Sex Differences in Affective Dysfunction and Alterations in Parvalbumin in Rodent Models of Early Life Adversity

“…One widely used model leverages maternal separation (MS) as an analog of early caregiver deprivation during the postnatal and pre-weaning periods. MS protocols typically involve the removal and isolation of pups from dam and littermates for a designated period of time over a series of days, typically ranging from 3–4 h per day from postnatal day (P) 2 to 20 (e.g., Grassi-Oliveira et al, 2016 ; Coley et al, 2019 ; Köhler et al, 2019 ; Honeycutt et al, 2020 ; Drastichova et al, 2021 ), though some research groups only maintain separations for the first 14 days of life (e.g., Uchida et al, 2010 ; Callaghan and Richardson, 2011 ; Teissier et al, 2020 ). This ELA model is widely used as it closely models early life caregiver deprivation seen in institutionalized rearing (Kundakovic and Champagne, 2015 ), and MS in rodents also shows outcomes comparable to those in humans with a history of abuse (Teicher et al, 2006 ; Nemeroff, 2016 ).…”

Effect of Family Integrated Care on maternal stress in preterm infants in the Neonatal Intensive Care Unit: A bi‐center experience

“…Many studies have explored the effects of maternal separation on newborns and their mothers. Animal experiments (Alves et al, 2020; Drastichova et al, 2021; Tractenberg et al, 2016) found that maternal separation not only affected the neurodevelopment of pups by modulating the expression profiles of proteins associated with cell death pathways in the brain but also had adverse effects on their mothers' mental health. Mother‐infant separation may be a major source of stressors for both parents and their infants.…”

Proteome Profiling of Rat Brain Cortical Changes during Early Postnatal Brain Development

“…Twenty-six apoptosis-related rat proteins were grouped and graphed (Figure S17); however, they were not characterized by a clear up or down trend, which could be attributed to a complex role of different proteins in the apoptotic neuronal network−brain cortex shaping processes occurring in the early rat PND period; 6 this finding was in agreement with the finding that apoptotic cell death in the rat cortex reached the highest level at PND 1. 6 Notably, there were no statistically significant PND changes reported for these proteins in the synaptosome (mouse) 1 and the synaptosome and mitochondrial (rat) 5 fractions.…”

“…1−5 Biological and environmental stresses and insults sustained during this period might negatively impact brain development. 6 Therefore, to be able to better assess the impact of a chemical exposure on developing brain, it is important to gather information about the biological transformations occurring during postnatal development of the animals used in toxicoproteomic studies. Working toward this goal, we applied proteomics to investigate the protein changes occurring during the early postnatal rat cortical development.…”

“…During the perinatal period, environmental stressors pose a potential threat to brain development because the brain undergoes extensive, rapid developmental and organizational changes. − Biological and environmental stresses and insults sustained during this period might negatively impact brain development . Therefore, to be able to better assess the impact of a chemical exposure on developing brain, it is important to gather information about the biological transformations occurring during postnatal development of the animals used in toxicoproteomic studies.…”