Brain research
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Curcuma longa is a major constituent of the traditional Chinese medicine Xiaoyao-san, which has been used to effectively manage stress and depression-related disorders in China. Curcumin is the active component of curcuma longa, and its antidepressant effects were described in our prior studies in mouse models of behavioral despair. We hypothesized that curcumin may also alleviate stress-induced depressive-like behaviors and hypothalamic-pituitary-adrenal (HPA) axis dysfunction. ⋯ In addition, we also found that the chronic stress procedure induced a down-regulation of brain-derived neurotrophic factor (BDNF) protein levels and reduced the ratio of phosphorylated cAMP response element-binding protein (pCREB) to CREB levels (pCREB/CREB) in the hippocampus and frontal cortex of stressed rats. Furthermore, these stress-induced decreases in BDNF and pCREB/CREB were also blocked by chronic curcumin administration (5 or 10 mg/kg, p.o.). These results provide compelling evidence that the behavioral effects of curcumin in chronically stressed animals, and by extension humans, may be related to their modulating effects on the HPA axis and neurotrophin factor expressions.
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Inflammation is an important factor for hypoxia-ischemia (HI) brain injury. Interleukin (IL)-18 is a proinflammatory cytokine which may be a contributor to injury in the immature brain after HI. To investigate the effects of post-HI hypothermia on IL-18 in the developing brain, 7-day-old rats were subjected to left carotid artery ligation followed by 8% oxygen for 60 min and divided into a hypothermia group (rectal temperature 32 degrees C for 24 h) and a normothermia group (36 degrees C for 24 h). ⋯ The number of ameboid microglia (AM) in the normothermia group was significantly increased in cortex and CC, compared with the number in controls, but there were very few ramified microglia (RM) in these areas. In contrast, the number of AM in the hypothermia group was significantly decreased in cortex and CC, compared with the number in the normothermia group, and there were no significant differences in the number of AM and RM between the hypothermia group and controls. In conclusion, we found that IL-18 mRNA and the protein level were attenuated by post-HI hypothermia and that post-HI hypothermia may decrease microglia activation in the developing brain.
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Laser Speckle Contrast Analysis (LASCA), a novel, high-resolution blood flow imaging method, was performed on rat somatosensory cortex during functional activation. In the same animals, cerebral blood flow (CBF) was measured with Laser Doppler Flowmetry. To obtain a quantitative estimate of the underlying neuronal activity, somatosensory evoked potentials were recorded simultaneously with an epidural EEG. ⋯ LASCA imaging localizes the highest relative changes of CBF in microcirculatory areas, with a smaller contribution by larger vessels. This study demonstrates that LASCA is a reliable method that provides 2D-imaging of CBF changes that are comparable to LDF measurements. It further suggests that functional neuroimaging methods based on CBF enhance areas of microcirculation and thus might prove more accurate in localizing neural activity than oxygenation related methods like BOLD-fMRI.
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Comparative Study
Psychophysical 'perceptual maps' of heat and pain sensations by direct localization of CO2 laser stimuli on the skin.
Brain activation patterns derived from neurofunctional methods are often implicitly regarded as being directly related to subjective perceptual experience in an iso- or at least homomorph manner, neglecting the operational differences between these two dimensions. This paper (a) introduces a method for assessing 'perceptual maps' of stimulation patterns presented to the body surface, providing a means to parametrically relate neural representation and subjective percept, and (b) applies this method to demonstrate the existence of 'somatotopic maps' of hot and painful stimulus patterns independent from mechanoceptive co-activation. Brief (90 ms) CO2 laser pulses were presented in an array of multiple stimulation sites on the dorsal forearms (N. radialis area, C7 dermatome) of healthy subjects. ⋯ R2>0.80 in 10 out of 12 subjects). Nonlinear models were advantageous in some subjects only. Our method can be useful in assessing inter-individual differences or experimentally induced shifts in somatotopic processing.
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Comparative Study
Biphasic cytoarchitecture and functional changes in the BBB induced by chronic inflammatory pain.
The blood-brain barrier (BBB) is a dynamic system which maintains brain homeostasis and limits CNS penetration via interactions of transmembrane and intracellular proteins. Inflammatory pain (IP) is a condition underlying several diseases with known BBB perturbations, including stroke, Parkinson's, multiple sclerosis and Alzheimer's. Exploring the underlying pathology of chronic IP, we demonstrated alterations in BBB paracellular permeability with correlating changes in tight junction (TJ) proteins: occludin and claudin-5. ⋯ Confocal microscopy demonstrated continuous expression of both occludin and JAM-1, each co-localizing with ZO-1. The increased claudin-5 expression was not limited to the junction. These results provide evidence that chronic IP causes dramatic alterations in specific cytoarchitectural proteins and demonstrate alterations in molecular properties during CFA, resulting in significant changes in BBB paracellular permeability.