Developmental neuroscience
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DNA methylation in the developing hippocampus and amygdala of anxiety-prone versus risk-taking rats.
All organisms exhibit a wide range of emotional behaviors and interact with the environment in different ways. Some individuals may be more quiet and shy whereas others are more outgoing and adventurous. These temperamental and personality differences can predispose individuals to certain psychopathologies which may be influenced by genetic vulnerability and/or early life experiences. ⋯ We focused on the first 3 postnatal weeks, in part to parallel our early microarray gene expression work, and because this represents a critical period of brain development, which shapes individuals' lifelong emotional and stress reactivity. We found significant differences in dentate gyrus and CA3 regions of the hippocampus at P7 with no differences seen at P14 or P21. Interestingly, we also found significant bHR-bLR DNMT1 differences at P7 within the lateral, basolateral and medial nuclei of the amygdala, with no difference at P14 and P21, suggesting that the first postnatal week is a critical period for DNA methylation during brain development.
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To examine the independent contributions of prenatal methamphetamine exposure (PME) and prenatal tobacco exposure (PTE) on brain morphology among a sample of nonalcohol-exposed 3- to 5-year-old children followed prospectively since birth. ⋯ Our results suggest that PME and PTE may have distinct differential cortical effects on the developing central nervous system. Additionally, PME may be associated with subtle deficits in attention mediated by caudate volume reductions.
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Brain development during early life in healthy individuals is rapid and dynamic, indicating that this period plays a very important role in neural and functional development. The frontal and temporal lobes are known to play a particularly important role in cognition. The study of healthy frontal and temporal lobe development in children is therefore of considerable importance. ⋯ In addition, the left frontal and temporal lobes increased in volume for a longer period of time. Taken together, these findings indicated that brain developmental trajectories differ depending on brain region, sex and brain hemisphere. Gender-related factors such as sex hormones and functional laterality may affect brain development.
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Perinatal hypoxic ischemic (HI) brain injury is a leading cause of long-term neurological handicap in newborn babies. Recently, excessive activity of matrix metalloproteinases (MMPs), and in particular MMP-9, has been implicated in the aetiology of HI injuries to the immature brain. Our previous study suggested that MMP-9 may be involved in the development of the delayed injury processes following HI injury to the developing brain. ⋯ Gelatin zymography revealed that pro-MMP-9 levels were significantly reduced at 6 h following hypoxic ischaemia (p ≤ 0.05). However, our results showed that despite significantly inhibiting brain pro-MMP-9 activity after hypoxic ischaemia, SB-3CT failed to confer significant neuroprotection in postnatal day 21 rats 3 days after an HI insult. Further investigations are warranted using a recently reported selective water-soluble version of SB-3CT or another MMP-9 selective inhibitor to resolve the role of MMP-9 in the aetiology of HI injury in the developing brain.