Neuroscience
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The cerebrospinal fluid-contacting nucleus(CSF-contacting nucleus) is a pair of unique nuclei in the brain parenchyma which has long been demonstrated to play an important role in pain signal processing. However, the mechanisms by which the CSF-contacting nucleus intervenes in pain is unclear. The NRG1-ErbB4 signaling plays an important role in the nervous system and has been shown to be involved in the regulation of pain. ⋯ With immunofluorescence staining and Western blot, the NRG1-ErbB4 signaling in the CSF-contacting nucleus showed upregulated during the acute pain phase. And, activating NRG1-ErbB4 signaling in the CSF-contacting nucleus specifically by intracranial injection of drugs, the naïve mice displayed thermal hyperalgesia while inhibiting this signaling by intracranial injection could reverse the hyperalgesia caused by CSF-contacting nucleus activation, and execute an analgesic effect during the painful phase in mice. Our study suggested that the CSF-contacting nucleus plays a regulatory role in thermal pain in mice via NRG1-ErbB4 signaling.
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Corticotropin-releasing factor (CRF) is an important stress hormone, and because of the different distributions and functions of its receptors, CRF has various effects on the stress response of animals. CRF receptor 2 (CRFR2) is a functional receptor of CRF that may be related to appetite regulation and sex differences. In this study, male and female C57BL/6 mice were exposed to an ambient temperature of 4 °C, and feed intake were determined. ⋯ As a result, 1) there were only significant changes in 2 h feed intake and rectal temperature in males; 2) neuronal excitability was elevated in the paraventricular thalamus (PVT) and paraventricular hypothalamic nucleus (PVH) brain regions of both male and female mice; 3) serum corticosterone and the expression of corticosterone receptors in the PVH were elevated in males but not in females; 4) the activation of the CRFR2 signal in the PVT and PVH brain regions differed by sex: the expression of CRFR2 was upregulated in male mice, and the phosphorylation of protein kinase B (AKT) and cAMP-response element binding protein (CREB) was significantly reduced; and 5) the cold-evoked eating behavior of male mice was abolished when CRFR2 in the PVT was knocked down. In summary, we conclude that male mice are more sensitive to cold stress than are female mice. The CRFR2/AKT/CREB signaling pathway in the PVT and PVH may mediate sex differences in the eating behavior of cold-exposed mice.
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Microglia polarization plays a crucial role in inflammatory injury of brain following intracerebral hemorrhage (ICH). Heme oxygenase-1 (HO-1) has demonstrated protective properties against inflammation and promote hematoma clearance after ICH. The objective of this study was to explore impacts of HO-1 on microglia polarization and phagocytosis after ICH, along with the underlying mechanism. ⋯ Therefore, our data demonstrated that HO-1 alleviated nerve injury and induced M2 polarization and phagocytosis of microglia after ICH via inhibiting NF-κB signaling pathway, which could provide deepen the pathological understanding of ICH and provide potential intervention targets and drug candidate for ICH.
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Prepulse inhibition (PPI) refers to the phenomenon in which a weak sensory stimulus before a strong one significantly reduces the startle reflex caused by the strong stimulus. Perceptual spatial separation, a phenomenon where auditory cues from the prepulse and background noise are distinguished in space, has been shown to enhance PPI. This study aims to investigate the neural modulation mechanisms of PPI by the spatial separation between the prepulse stimulus and background noise, particularly in the deep superior colliculus (deepSC). ⋯ The prepulse stimulus was a segment of narrowband noise, with interaural time differences adjusted so that the prepulse stimulus and background noise were perceived as either ipsilaterally leading or contralaterally leading, resulting in perceptual spatial fusion or spatial separation. The results showed that under conditions of spatial separation, the stimulus-response coherence of the envelope and fine structure components of the prepulse stimulus in the deepSC was significantly enhanced, the response of the deepSC to the stimulus was significantly reduced in the presence of the prepulse stimulus, and the envelope component of the prepulse stimulus was positively correlated with the inhibitory effect. The above results suggest that perceptual spatial dissociation can significantly enhance the expression of deepSC, particularly the precision of the envelope component, thereby significantly affecting the electrophysiological response of PPI.
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The optimal stimulation frequency for inducing neuromodulatory effects remains unclear. The purpose of our study was to investigate the effect of neuromuscular electrical stimulation (NMES) with different frequencies on cortical and spinal excitability. Thirteen able-bodied individuals participated in the experiment involving NMES: (i) low-frequency at 25 Hz, (ii) high-frequency at 100 Hz, and (iii) mixed-frequency at 25 and 100 Hz switched every one second. ⋯ Our results showed that mixed frequency was most effective in modulating corticospinal excitability, although motor performance was not affected by any intervention. The cortical silent period was prolonged and Mmax was inhibited by all frequencies, while the F-wave and MVC were unaffected. Mixed-frequency stimulation could recruit a more diverse range of motor units, which are recruited in a stimulus frequency-specific manner, than single-frequency stimulation, and thus may have affected corticospinal facilitation.