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991.
Many studies demonstrate that exposure to testicular steroids such as testosterone early in life masculinizes the developing brain, leading to permanent changes in behavior. Traditionally, masculinization of the rodent brain is believed to depend on estrogen receptors (ERs) and not androgen receptors (ARs). According to the aromatization hypothesis, circulating testosterone from the testes is converted locally in the brain by aromatase to estrogens, which then activate ERs to masculinize the brain. However, an emerging body of evidence indicates that the aromatization hypothesis cannot fully account for sex differences in brain morphology and behavior, and that androgens acting on ARs also play a role. The testicular feminization mutation (Tfm) in rodents, which produces a nonfunctional AR protein, provides an excellent model to probe the role of ARs in the development of brain and behavior. Tfm rodent models indicate that ARs are normally involved in the masculinization of many sexually dimorphic brain regions and a variety of behaviors, including sexual behaviors, stress response and cognitive processing. We review the role of ARs in the development of the brain and behavior, with an emphasis on what has been learned from Tfm rodents as well as from related mutations in humans causing complete androgen insensitivity. 相似文献
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994.
The GSK3 hypothesis of Alzheimer's disease 总被引:4,自引:0,他引:4
995.
Ascidians are lower chordates and their simple tadpole-like larvae share a basic body plan with vertebrates. Newly hatched larvae show no response to a stimulus of light. 4 h after hatching, the larvae were induced to swim upon a step-down of light and stop swimming upon a step-up of light. At weaker intensity of light, the larvae show the same response to a stimulus after presentation of repeated stimuli. When intensity of actinic light was increased, the larvae show sensitization and habituation of the swimming response to a stimulus after repeated stimuli of step-down and step-up of the light. Between 2 h 20 min and 3 h 40 min after hatching the larvae did not show any response to the first stimulus, but after several repeatedstimuli they show swimming response to a step-down of light. A repeated series of stimulus cause sensitization. Between 4 h and 7 h after hatching, the larvae show photoresponse to the first stimulus, but after several repetition of the stimuli, the larvae could not stop swimming to a stimulus of a step-up of the actinic light. A repeated series of stimulus cause greaterhabituation. Both sensitization and habituation depend upon intensity ofactinic light. 相似文献
996.
目的:进一步探讨蝎毒耐热蛋白(SVHRP)改善MPTP(1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine,MPTP)小鼠伴有空间学习记忆障碍的机制。方法:给予C57BL/6小鼠颈部皮下注射MPTP(20mg/kg),连续8d,同时设立SVHRP治疗纽,观察小胶质细胞免疫反应活性的改变。结果:与盐水对照组相比,MPTP小鼠脑区OX-42免疫反应阳性小胶质细胞免疫反应活性明显增强。模型给药组与模型组相比OX-42免疫反应阳性小胶质细胞免疫反应活性明显降低。结论:SVHRP可以抑制MPTP诱发的小鼠脑内小胶质细胞的激活以减轻脑内神经炎症。 相似文献
997.
目的:采用神经心理测验方法探讨海拔高度及时间对移居者记忆与肢体运动能力的影响及返回平原后的恢复情况。方法:选择即将进入高原的241名健康青年,在其进入高原前、初期、5个月、1年及返回平原时分别采用DDX-200型多功能心理生理能力测试康复仪进行左右手交叉敲击动作频率和数字记忆广度顺背数测验。结果:与进入高原前比较,进入高原5个月至1年,数字记忆广度顺背数测验得分降低,左右手交叉敲击动作频率总次数和正确次数减少,错误次数增多(P〈0.05,或P〈0.01),进入高原初期,5个月及返回平原5个月与进入高原1年相比,数字记忆广度顺背数测验得分增高,左右手交叉敲击动作频率总次数和正确次数增多,错误次数减少(P〈0.05,或P〈0.01)。移居5个月后4700m组各项测试指标均优于移居5000m以上地区组(P〈0.05,或P〈0.01)。结论:移居高原5个月后记忆力及肢体运动能力降低,特别是移居5000m以上地区,而这些能力在返回平原5个月将得到恢复。 相似文献
998.
Bernard A. Tarr Jeremy S. Rabinowitz Mubdiul Ali Imtiaz Timothy J. DeVoogd 《Developmental neurobiology》2009,69(14):972-981
In many naturalistic studies of the hippocampus wild animals are held in captivity. To test if captivity itself affects hippocampal integrity, adult black‐capped chickadees (Poecile atricapilla) were caught in the fall, injected with bromodeoxyuridine to mark neurogenesis, and alternately released to the wild or held in captivity. The wild birds were recaptured after 4–6 weeks and perfused simultaneously with their captive counterparts. The hippocampus of captive birds was 23% smaller than wild birds, with no hemispheric differences in volume within groups. Between groups there was no statistically significant difference in the size of the telencephalon, or in the number and density of surviving new cells. Proximate causes of the reduced hippocampal volume could include stress, lack of exercise, diminished social interaction, or limited caching opportunity—a hippocampal‐dependent activity. The results suggest the avian hippocampus—a structure essential for rapid, complex relational and spatial learning—is both plastic and sensitive, much as in mammals, including humans. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009 相似文献
999.
The effects of lesioning the ventral tegmental area (VTA) or substantia nigra (SN) neurons by means of bilateral stereotaxic
microinjections of kainic acid (KA) (0.4 mM) were investigated to clarify the role of the VTA and the SN neurons in learning
and memory processes. The present study demonstrates that KA in the SN and the VTA lesioned rats significantly decreased spontaneous
alternation in Y-maze task, working memory and reference memory in radial 8 arm-maze task, suggesting effects on spatial memory
performance. Our findings provide further support for the role of the VTA and the SN neurons in processing and storage of
information. 相似文献
1000.
Research over the last 5 years has firmly established that learning and memory abilities, as well as mood, can be influenced by diet, although the mechanisms by which diet modulates mental health are not well understood. One of the brain structures associated with learning and memory, as well as mood, is the hippocampus. Interestingly, the hippocampus is one of the two structures in the adult brain where the formation of newborn neurons, or neurogenesis, persists. The level of neurogenesis in the adult hippocampus has been linked directly to cognition and mood. Therefore, modulation of adult hippocampal neurogenesis (AHN) by diet emerges as a possible mechanism by which nutrition impacts on mental health. In this study, we give an overview of the mechanisms and functional implications of AHN and summarize recent findings regarding the modulation of AHN by diet. 相似文献