Neuroscience
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It is well established that astrocytes play pivotal roles in neuronal synapse formation and maturation as well as in the modulation of synaptic transmission. Despite their general importance for brain function, relatively little is known about the maturation of astrocytes during normal postnatal development, especially during adolescence, and how that maturation may influence astroglial-synaptic contact. The medial prefrontal cortex (mPFC) and dorsal hippocampus (dHipp) are critical for executive function, memory, and their effective integration. ⋯ Here we utilize an astrocyte-specific viral labeling approach paired with high-resolution single-cell astrocyte imaging and three-dimensional reconstruction to determine whether mPFC and dHipp astrocytes have temporally distinct maturation trajectories. mPFC astrocytes, in particular, continue to mature well into emerging adulthood (postnatal day 70). Moreover, this ongoing maturation is accompanied by a substantial increase in colocalization of astrocytes with the postsynaptic neuronal marker, PSD-95. Taken together, these data provide novel insight into region-specific astrocyte-synapse interactions in late CNS development and into adulthood, thus raising implications for the mechanism of post-adolescent development of the mPFC.
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The parallel processing of chemical signals by the main olfactory system and the vomeronasal system has been known to control animal behavior. The physiological significance of peripheral parallel pathways consisting of olfactory sensory neurons and vomeronasal sensory neurons is not well understood. Here, we show complementary characteristics of the information transfer of the olfactory sensory neurons and vomeronasal sensory neurons. ⋯ In contrast, tonic firing of the vomeronasal sensory neurons was able to convey information about smaller stimuli changing slowly with longer cycles (>500 ms). Thus, the parallel pathways of the two types of sensory neurons can convey information about a wide range of dynamic stimuli. A combination of complementary characteristics of olfactory information transfer may enhance the synergy of the interaction between the main olfactory system and the vomeronasal system.
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Day-to-day life involves the perception of events that resemble one another. For the sufficient encoding and correct retrieval of similar information, the hippocampus provides two essential cognitive processes. Pattern separation refers to the differentiation of similar input information, whereas pattern completion reactivates memory representations based on noisy or degraded stimuli. ⋯ In volumetry, we found a global hippocampal volume reduction. The deficits in pattern separation performance were best predicted by the DG (p = 0.029), whereas CA1 was highly predictive of recognition memory deficits (p < 0.001). These results corroborate the framework of a regional specialization of hippocampal functions involved in cognitive processing.
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Intrauterine growth restriction (IUGR) associates with increased preference for palatable foods and altered insulin sensitivity. Insulin modulates the central dopaminergic response and changes behavioral responses to reward. We measured the release of dopamine in the accumbens during palatable food intake in IUGR rats both at baseline and in response to insulin. ⋯ FR rats showed metabolic alterations and a delay in the dopaminergic response to palatable foods. This could explain the increased palatable food intake and behavioral entropy found in FR rats. IUGR may lead to binge eating, obesity and its metabolic consequences by modifying the central dopaminergic response to sweet food.
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The medial prefrontal cortex (mPFC) is implicated in the rewarding effect of psychostimulants, although molecular mechanisms underlying the rewarding properties of stimulants in this region are poorly understood. Group I metabotropic glutamate (mGlu) receptors (mGlu1/5 subtypes) are believed to be critical in this event. We thus in this study investigated changes in mGlu1/5 receptor expression and function in the rat mPFC in response to conditioned place preference (CPP) induced by amphetamine. ⋯ The mGlu1/5 agonist-stimulated Src kinase phosphorylation was also augmented in rats treated with amphetamine. These results demonstrate the sensitivity of mPFC mGlu1/5 receptors to amphetamine-induced CPP. Amphetamine conditioning results in the upregulation of mGlu1/5 receptor expression at subcellular and/or subsynaptic levels and mGlu1/5-mediated postreceptor signaling in mPFC neurons.