Dataset Information

Aging and Exercise Affect Hippocampal Neurogenesis via Different Mechanisms.

ABSTRACT: The rate of neurogenesis is determined by 1) the number of neural stem/progenitor cells (NSCs), 2) proliferation of NSCs, 3) neuron lineage specification, and 4) survival rate of the newborn neurons. Aging lowers the rate of hippocampal neurogenesis, while exercise (Ex) increases this rate. However, it remains unclear which of the determinants are affected by aging and Ex. We characterized the four determinants in different age groups (3, 6, 9, 12, 21 months) of mice that either received one month of Ex training or remained sedentary. Bromodeoxyuridine (BrdU) was injected two hours before sacrificing the mice to label the proliferating cells. The results showed that the number of newborn neurons massively decreased (>95%) by the time the mice reached nine months of age. The number of NSC was mildly reduced during aging, while Ex delayed such decline. The proliferation rates were greatly decreased by the time the mice were 9-month-old and Ex could not improve the rates. The rates of neuron specification were decreased during aging, while Ex increased the rates. The survival rate was not affected by age or Ex. Aging greatly reduced newborn neuron maturation, while Ex potently enhanced it. In conclusion, age-associated decline of hippocampal neurogenesis is mainly caused by reduction of NSC proliferation. Although Ex increases the NSC number and neuron specification rates, it doesn't restore the massive decline of NSC proliferation rate. Hence, the effect of Ex on the rate of hippocampal neurogenesis during aging is limited, but Ex does enhance the maturation of newborn neurons.

SUBMITTER: Yang TT

PROVIDER: S-EPMC4493040 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Aging and Exercise Affect Hippocampal Neurogenesis via Different Mechanisms.

Yang Ting-Ting TT Lo Chen-Peng CP Tsai Pei-Shan PS Wu Shih-Ying SY Wang Tzu-Feng TF Chen Yun-Wen YW Jiang-Shieh Ya-Fen YF Kuo Yu-Min YM

PloS one 20150706 7

The rate of neurogenesis is determined by 1) the number of neural stem/progenitor cells (NSCs), 2) proliferation of NSCs, 3) neuron lineage specification, and 4) survival rate of the newborn neurons. Aging lowers the rate of hippocampal neurogenesis, while exercise (Ex) increases this rate. However, it remains unclear which of the determinants are affected by aging and Ex. We characterized the four determinants in different age groups (3, 6, 9, 12, 21 months) of mice that either received one mon ...[more]

PMID: 26147302

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Project description:Background:In humans, interferon-? treatment for chronic viral hepatitis is a well-recognized clinical model for inflammation-induced depression, but the molecular mechanisms underlying these effects are not clear. Following peripheral administration in rodents, interferon-? induces signal transducer and activator of transcription-1 (STAT1) within the hippocampus and disrupts hippocampal neurogenesis. Methods:We used the human hippocampal progenitor cell line HPC0A07/03C to evaluate the effects of 2 concentrations of interferon-?, similar to those observed in human serum during its therapeutic use (500 pg/mL and 5000 pg/mL), on neurogenesis and apoptosis. Results:Both concentrations of interferon-? decreased hippocampal neurogenesis, with the high concentration also increasing apoptosis. Moreover, interferon-? increased the expression of interferon-stimulated gene 15 (ISG15), ubiquitin-specific peptidase 18 (USP18), and interleukin-6 (IL-6) via activation of STAT1. Like interferon-?, co-treatment with a combination of ISG15, USP18, and IL-6 was able to reduce neurogenesis and enhance apoptosis via further downstream activation of STAT1. Further experiments showed that ISG15 and USP18 mediated the interferon-?-induced reduction in neurogenesis (potentially through upregulation of the ISGylation-related proteins UBA7, UBE2L6, and HERC5), while IL-6 mediated the interferon-?-induced increase in apoptosis (potentially through downregulation of aquaporin 4). Using transcriptomic analyses, we showed that interferon-? regulated pathways involved in oxidative stress and immune response (e.g., Nuclear Factor (erythroid-derived 2)-like 2 [Nrf2] and interferon regulatory factor [IRF] signaling pathway), neuronal formation (e.g., CAMP response element-binding protein [CREB] signaling), and cell death regulation (e.g., tumor protein(p)53 signaling). Conclusions:We identify novel molecular mechanisms mediating the effects of interferon-? on the human hippocampus potentially involved in inflammation-induced neuropsychiatric symptoms.

Project description:Mild exercise (ME) with an intensity below the lactate threshold (LT) is sufficient to enhance hippocampal function, while intense exercise (IE) above the LT negates such benefits. However, the question as to why ME more effectively enhances hippocampal function than does IE remains to be clarified. Here, we investigated adult hippocampal neurogenesis (AHN) as a mechanism of ME-induced cognitive improvement, and comprehensively delineated the transcriptomic profile of the hippocampus, using a rat whole-genome microarray approach through comparison with IE. Immunohistochemical results showed that less intense exercise (ME) is better suited to improve AHN, especially in regards to the survival and maturation of newborn neurons. DNA microarray analysis revealed that ME regulated more genes than did IE (ME: 604 genes, IE: 415 genes), and only 44 genes were modified with both exercise intensities. The identified molecular components did not comprise well-known factors related to exercise-induced AHN, such as brain-derived neurotrophic factor (BDNF) and insulin-like growth factor 1 (IGF1), probably due to the timing of hippocampal tissue collection after the last training session and the technical feature of microarray. Rather, network analysis of the microarray data using Ingenuity Pathway Analysis algorithms revealed that the ME-influenced genes were principally related to lipid metabolism, protein synthesis and inflammatory response, which are recognized as associated with hippocampal neuroadaptations including AHN. In contrast, IE-influenced genes linked to immune response, a negative regulatory system of AHN and hippocampal function, were identified. Collectively, these results support our hypothesis that AHN could explain why ME enhances hippocampal function, and provide the ME-specific gene list that contain some potential regulators of this positive regulation. The list will become a foundation to elucidate the molecular pathway involving the ME-induced cognitive gain.

Dataset Information

Aging and Exercise Affect Hippocampal Neurogenesis via Different Mechanisms.

Publications

Aging and Exercise Affect Hippocampal Neurogenesis via Different Mechanisms.

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