Neuroscience
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Deficits in dopaminergic function are thought to underlie attention-deficit/hyperactivity disorder (ADHD). Dopaminergic neurons are the main source of dopamine (DA), a neurotransmitter that acts as a neuromodulator of cognitive function in the prefrontal cortex, including the anterior cingulate cortex (ACC), which receives dopaminergic inputs from the ventral tegmental area. The spontaneously hypertensive rat (SHR) has been widely studied as an animal model of ADHD. ⋯ Furthermore, DA activity enhanced the amplitude of evoked and unitary IPSCs from fast-spiking interneurons; the amplitude was also larger in control WKY than in SHRs. Notably, the amplitude of evoked IPSCs was enhanced by the activation of D1-like receptor-mediated pathways. These results suggest that hypofunction of D1-like receptor-mediated regulation of GABAergic inhibitory synaptic transmission onto layer V pyramidal cells of the ACC may contribute to the pathophysiology of ADHD.
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Mitochondrial Carrier Homolog 2 (MTCH2) acts as a receptor for the BH3 interacting-domain death agonist (BID) in the mitochondrial outer membrane. Loss of MTCH2 affects mitochondria energy metabolism and function. MTCH2 forebrain conditional KO (MTCH2 BKO) display a deficit in hippocampus-dependent cognitive functions. ⋯ MTCH2 BKO exhibit impaired spatial but not motor learning and an impairment in long-term potentiation (LTP) in hippocampal slices. Moreover, MTCH2 BKO express an increase in activated microglia, in addition to a reduction in neuron density in the hippocampus, but do not express amyloid-β plaques or neurofibrillary tangles. These results highlight the role of mitochondria in the normal hippocampus-dependent memory formation.
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Primary cultures of rat dorsal root ganglia (DRG) consist of neurons, satellite glial cells and a moderate number of macrophages. Measurements of increased intracellular calcium [Ca2+]i induced by stimuli, have revealed that about 70% of DRG neurons are capsaicin-responsive nociceptors, while 10% responded to cooling and or menthol (putative cold sensors). Cultivation of DRG in the presence of a moderate dose of lipopolysaccharide (LPS, 1 µg/ml) enhanced capsaicin-induced Ca2+ signals. ⋯ In the presence of the cytotoxic agent cisplatin (5 or 10 µg/ml), the number of macrophages was decreased significantly, the growth of satellite glial cells was markedly suppressed, but the vitality and stimulus-induced Ca2+ signals of DRG neurons were not impaired. Under these conditions the LPS-induced production and expression of TNF-α and IL-6 were blunted. Our data suggest a potential role for macrophages and satellite glial cells in the initiation of inflammatory processes that develop in sensory ganglia upon injury or exposure to pathogens.
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Stress during development can shift the typical developmental trajectory. Maternal stress prior to conception has recently been shown to exert similar influences on the offspring. The present study questioned if a consistent maternal stressor prior to conception (elevated platform stress) would impact the pre-weaning development of offspring brain and behavior, and if maternal care was vulnerable to this experience. ⋯ The current study failed to find an effect of maternal preconception stress on early behavioral development. These results suggest that the PFC, and likely behavior dependent on the PFC, is vulnerable to maternal preconception stress and that a strong sex effect is evident. Further studies should examine how such offspring fare using a lifespan model and investigate potential mechanisms responsible for these effects.
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Little is known about the functional relationship between endoplasmic reticulum (ER) stress and development of pain hypersensitivity after nerve injury. The aim of this study was to investigate the role of ER stress in the development of pain hypersensitivity in the dorsal root ganglion (DRG) after spinal nerve ligation (SNL). SNL was performed in male Sprague-Dawley rats. ⋯ Treatment with salubrinal inhibited CHOP expression in L5 DRG and alleviated pain hypersensitivity for 5 days after SNL. Tunicamycin induced ER stress in the DRG and pain hypersensitivity 2 h after treatment. These results demonstrated that ER stress is induced in the injured DRG and contributes to the development of pain hypersensitivity after nerve injury.