Neuregulin 1 (Nrg1) is involved in multiple biological processes in the nervous system. The present study investigated changes in Nrg1 signaling in the major brain regions of mice subjected to lipopolysaccharide (LPS)-induced neuroinflammation. At 24 h post-intraperitoneal injection of LPS, mouse brain tissues, including tissues from the cortex, striatum, hippocampus and hypothalamus, were collected. Reverse transcription-polymerase chain reaction was used to determine the expression of Nrg1 and its receptors, Neu and ErbB4, at the mRNA level. Western blotting was performed to determine the levels of these proteins and the protein levels of phosphorylated extracellular signal-regulated kinases (Erk)1/2 and Akt1. Immunohistochemical staining was utilized to detect the levels of pNeu and pErbB4 in these regions. LPS successfully induced sites of neuroinflammation in these regions, in which changes in Nrg1, Neu and ErbB4 at the mRNA and protein levels were identified compared with controls. LPS induced a reduction in pNeu and pErbB4 in the striatum and hypothalamus, although marginally increased pErbB4 levels were found in the hippocampus. LPS increased the overall phosphorylation of Src but this effect was reduced in the hypothalamus. Moreover, increased phosphorylation of Akt1 was found in the striatum and hippocampus. These data suggest diverse roles for Nrg1 signaling in these regions during the process of neuroinflammation.
Although neuregulin 1 (Nrg1) has been identified in the rat hypothalamus, the localisation of Nrg1 in the hypothalamus-hypophyseal structure and its functions remain unclear and require further elucidation. In this study, we identified the existence of Nrg1β types I-III in the rat hypothalamus. We demonstrated that Nrg1 was partially localised in somatostatin-positive cells in the periventricular nucleus. It was also co-localised with arginine vasopressin in the supraoptic nucleus, median eminence and pituitary stalk. Nrg1 was also extensively distributed in the posterior pituitary (PP), including the projected neuronal fibres that surround the vascular structure and Herring bodies. Western blotting confirmed that these signals were primarily produced by soluble Nrg1 derived from a 45-kDa Nrg1 precursor mainly identified in the hypothalamus. Similar to Nrg1α, Nrg1β increased the prolactin (PRL) expression in rat pituitary RC-4B/C cells, which can be inhibited by an Akt inhibitor. In addition, Nrg1β had no apparent effect on growth hormone expression at the mRNA or protein levels. Collectively, we conclude that hypothalamic Nrg1 may be transported to the PP as the β form. We further hypothesise that Nrg1β may function via the regulation of PRL expression through a paracrine mechanism.
Air pollution is one of the biggest challenges for human health, and this is especially true for PM2.5 pollution in developing countries like China. Much of the PM2.5 research has been conducted in urban areas, but most tourist attractions are outdoors and outside cities and have been left out of related studies, leaving tourists unaware of the deadly air. To fill this gap, we investigated monthly PM2.5 concentrations in all of China’s outdoor tourist attractions. Our results indicated that summer is the healthiest time to travel in the Northeast, South, Southwest, and Northwest of China. Without air pollution management, our results also indicated that more than one third of the outdoor attractions would become unhealthy throughout the year. Thus, our work provides medical information to suggest that all tourists schedule China travel during periods of healthy air quality and also calls for instant air pollution management in China and beyond.
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