Neuroscience
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The arcuate nucleus (ARH) is an important hypothalamic area for the homeostatic control of feeding and other metabolic functions. In the ARH, proopiomelanocortin- (POMC) and agouti-related peptide (AgRP)-expressing neurons play a key role in the central regulation of metabolism. These neurons are influenced by circulating factors, such as leptin and growth hormone (GH). ⋯ LepR GHR knockout mice showed decreased density of POMC innervation in the PVH and DMH, compared to control mice, whereas a reduction in the density of AgRP innervation was observed in all areas analyzed. Conversely, AgRP-specific ablation of GHR led to a significant reduction in AgRP projections to the PVH, LHA and DMH, without affecting POMC innervation. Our findings indicate that GH has direct trophic effects on the formation of POMC and AgRP axonal projections and provide additional evidence that GH regulates hypothalamic neurocircuits controlling energy homeostasis.
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Valproic acid (VPA) administered to mice during the early postnatal period causes social, cognitive, and motor deficits similar to those observed in humans with autism spectrum disorder (ASD). However, previous studies on the effects of early exposure to VPA have largely focused on behavioral deficits occurring before or during the juvenile period of life. Given that ASD is a life-long condition, the present study ought to extend our understanding of the behavioral profile following early postnatal VPA into adulthood. ⋯ This may indicate a disinhibited or impulsive phenotype in male, but not female, mice treated with VPA during the second week of postnatal life. Decreased dendritic spine density and dendritic spine morphological abnormalities in the mPFC of VPA-treated mice may be indicative of PFC hypofunction, consistent with the observed behavioral differences. Since these types of long-lasting deficits are not exclusively found in ASD, early life exposure to VPA may reflect dysfunction of a neurobiological domain common to several developmental disorders, including ASD, ADHD, and conduct disorder.
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Stress induced tRNA halves (tiRNAs) as biomarkers for stroke and stroke therapy; Pre-clinical study.
tiRNAs are small non-coding RNAs generated by angiogenin-mediated tRNA cleavage during cellular stress. Some tiRNAs were shown to be cytoprotective, while other reports indicate that the generation of tiRNAs is cytotoxic. ⋯ We also evaluated the temporal changes in several tRNA modifying enzymes and showed a correlation between their expression and tRNA cleavage. In conclusion, we show that tiRNAs can serve as biomarkers for stroke and stroke therapy, further adding them to the repertoire of tools that can be used to monitor and treat stroke.
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Bisphenol-A (BPA) exposure can affect cognitive functions of rodents and humans. However, whether information inputs for these functions in the brain are perturbed by BPA remains unclear. Here, visual perception in rats was assessed by testing their ability to discriminate between vertical and horizontal grating. ⋯ However, BPA-exposed rat pups exhibited a significant decrease in IL-1β expression in the V1, accompanied by a decline in P38 phosphorylation. After local injection of IL-1β (10 ng/ml) in the V1, these two visual properties recovered to normal levels. Thus, our findings imply that physiological dysfunction of IL-1β may contribute to orientation perception deficits in BPA-exposed rats.
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Little is known about the neural mechanisms that mediate differential action-selection responses to communication and echolocation calls in bats. For example, in the big brown bat, frequency modulated (FM) food-claiming communication calls closely resemble FM echolocation calls, which guide social and orienting behaviors, respectively. ⋯ We combined information obtained from spike number and spike triggered averages (STA) to reveal a robust classification of neuron selectivity for communication or echolocation calls. These data highlight the importance of temporal acoustic structure for differentiating echolocation and food-claiming social calls and point to general mechanisms of natural sound processing across species.