Neuroscience
-
Angiotensin II (Ang II) synthesized in response to body fluid loss caused by actions such as sweating and breathing is today considered as one of the essential factors for promoting hippocampal neurogenesis. Because heat stimuli, along with exercise, increase systemic levels of Ang II, the effects of short-term heat exposure on hippocampal neurogenesis were examined in adult male rats. When rats were exposed daily to a 1-h heat treatment (36.0 ± 0.1 °C) during a 7-d experimental period, the number of doublecortin-immunoreactive newborn cells in the hippocampal dentate gyrus was increased approximately 1.4-fold compared with that in controls that were exposed to a normothermic environment (25.0 ± 0.8 °C). ⋯ Western blot and immunohistochemical analyses revealed an enhancement of vascular endothelial growth factor (VEGF) expression in hippocampal astrocytes following short-term heat exposure. These beneficial effects of short-term heat exposure were prevented when an antagonist for Ang II type 1 receptor (AT1R), candesartan, was given orally. These results indicate that short-term heat exposure enhances adult neurogenesis via activation of AT1R in the hippocampal dentate gyrus, in which VEGF may participate by promoting cell proliferation and/or newborn neuron survival.
-
In mammals, mitoferrin-1 and mitoferrin-2, two homologous proteins of the mitochondrial solute carrier family are required for iron delivery into mitochondria. However, there is only one kind, called W02B12 (mitoferrin-1 or mfn-1), in Caenorhabditis elegans and its regulatory mechanism is unknown. In this study, we used C. elegans strains CL2006 and GMC101 as models to investigate what role mitoferrin-1 played in Alzheimer's disease (AD). ⋯ We tested whether knockdown of mitoferrin-1 could influence mitochondrial metabolism. Analysis of mitochondrial iron metabolism and mitochondrial ROS showed that knockdown of mitoferrin-1 could reduce mitochondrial iron content and reduce the level of mitochondrial ROS in the CL2006 and GMC101 strains. These results confirm that knockdown of mitoferrin-1 can slow the progress of disease in Alzheimer model of C. elegans and suggest that mitoferrin-1 plays a major role in mediating mitochondrial iron metabolism in this process.
-
Neonatal injury-induced exaggeration of pain hypersensitivity after adult trauma is a significant clinical challenge. However, the underlying mechanisms remain poorly understood. Growing evidence shows that spinal Src homology-2 domain-containing protein tyrosine phosphatase-2 (SHP2) contributes to chronic pain in adult rodents. ⋯ Finally, no alternation of SHP2 phosphorylation in the dorsal root ganglion and dorsal root of nIN-IN rats as well as PI3K expression in the dorsal root of nIN-IN rats intrathecally treated with NSC-87877 or SHP2 siRNA is observed. These results suggest that the phosphorylation and expression of SHP2 in the spinal dorsal horn play vital roles in neonatal incision-induced exaggeration of adult incisional pain via PI3K. Thus, SHP2 and PI3K may serve as potential therapeutic targets for exaggerated incisional pain induced by neonatal and adult injuries.
-
During mobile phone conversations, the temporal lobe neural networks involved in processing auditory information are exposed to electromagnetic fields (EMF) such as pulse-modulated GSM-1800 MHz radiofrequencies that convey wireless communications. The effects of these EMF on the brain affected by a pathological condition remain little investigated. In this study, rats injected with lipopolysaccharide (LPS) to induce neuroinflammation were exposed "head-only" to GSM-1800 MHz signals for two hours at a specific absorption rate (SAR) that reached an average value of 1.55 W/kg in the auditory cortex (ACx). ⋯ The response latency and the bandwidth of the frequency tuning were unchanged, but the GSM exposure led to a higher proportion of cortical sites exhibiting abnormally high acoustic thresholds. These modifications were not observed in rats exposed to GSM-1800 MHz without pretreatment with LPS. Together our data provide evidence that in neuroinflammatory conditions, acute exposure to GSM-1800 MHz can significantly affect microglia and neuronal activity underling auditory perception.
-
NG2 glia are self-renewal cells widely populating the entire central nervous system (CNS). The differentiation potential of NG2 glia in the brain has been systematically studied. However, the fate of NG2 glia in the spinal cord during development and after injury is still unclear. ⋯ Embryonic or neonatal NG2 glia generated more than 90% of the white matter OLs, but only 50% (embryonic) or 75% (neonatal) of gray matter OLs. Such differences disappeared after myelin completion coinciding with a decrease in the differentiation rate. While we never detected the generation of astrocytes from NG2 glia during spinal cord development, we found a small portion of NG2 glia could generate astrocytes in adult spinal cord upon acute traumatic injury.