Effects of normal aging on myelin sheath ultrastructures in the somatic sensorimotor system of rats

Xie, Fang; Liang, Ping; Han, Fangfang; Zhang, Jiu‐Cong

doi:10.3892/mmr.2014.2228

Cited by 32 publications

(24 citation statements)

References 33 publications

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“…The 2-fold increase in neural noise with aging found in the current study could be due to various age-related neurobiological alterations such as more spontaneous activity, less inhibition, a decrease of the myelin density, or fewer synapses. 4,47 In any case, this aging effect on neural noise was not specific to some SFs, which suggests that there was not a greater loss in density of neurons sensitive to low SFs than neurons sensitive to high SFs.…”

Section: Discussionmentioning

confidence: 87%

Healthy Aging Impairs Photon Absorption Efficiency of Cones

Silvestre

Arleo

Allard

2019

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. Vision decline with healthy aging is a major public health concern with the unceasing growth of the aged population. In order to prevent or remedy the age-related visual loss, a better understanding of the underlying causes is needed. The current psychophysical study used a novel noise paradigm to investigate the causes of age-related contrast sensitivity loss by estimating the impact of optical factors, absorption rate of photon by photoreceptors, neural noise, and calculation efficiency on contrast sensitivity.METHODS. The impact of these factors on contrast sensitivity was assessed by measuring contrast thresholds with and without external noise over a wide range of spatial frequencies (0.5-16 cycles per degree [cyc/deg]) and different luminance intensities for 20 young (mean ¼ 26.5 years, SD ¼ 3.79) and 20 older (mean ¼ 75.9 years, SD ¼ 4.30) adults, all having a good visual acuity ( ‡6/7.5). RESULTS.The age-related contrast sensitivity losses were explained by older observers absorbing considerably fewer photons (43), having more neural noise (1.93), and a lower processing efficiency (1.43). The aging effect on optical factors was not significant.CONCLUSIONS. The age-related contrast sensitivity loss was mostly due to less efficient cones absorbing four times fewer photons than young adults. Thus, besides the ocular factors known to be considerably affected with aging, the decline of absorption efficiency of cones is also responsible for a considerable age-related visual decline, especially under dim light.

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Section: Discussionmentioning

confidence: 87%

Healthy Aging Impairs Photon Absorption Efficiency of Cones

Silvestre

Arleo

Allard

2019

Invest. Ophthalmol. Vis. Sci.

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“…However, we found that a reduction of the myelin sheath thickness occurred in middle-aged but not young KO mice, which is quite different from what we saw in the older population. During normal aging, the thickness of the myelin sheath usually increases with age (Peters, 2002; Xie et al, 2014; Li et al, 2017). In middle-aged Fb Ctgf KO mice, the reduction of the myelin thickness was evident and the underlying mechanism requires further investigation.…”

Section: Discussionmentioning

confidence: 99%

Genetic Elimination of Connective Tissue Growth Factor in the Forebrain Affects Subplate Neurons in the Cortex and Oligodendrocytes in the Underlying White Matter

Chang

Chen

et al. 2019

Front. Neuroanat.

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Connective tissue growth factor (CTGF) is a secreted extracellular matrix-associated protein, which play a role in regulating various cellular functions. Although the expression of CTGF has been reported in the cortical subplate, its function is still not clear. Thus, to explore the significance of CTGF in the brain, we created a forebrain-specific Ctgf knockout (Fb Ctgf KO) mouse model. By crossing Ctgf fl/fl mice with Emx1-Cre transgenic mice, in which the expression of Cre is prenatally initiated, the full length Ctgf is removed in the forebrain structures. In young adult (2–3 months old) Fb Ctgf KO mice, subplate markers such as Nurr1 and Cplx3 are still expressed in the cortical layer VIb; however, the density of the subplate neurons is increased. Interestingly, in these mutants, we found a reduced structural complexity in the subplate neurons. The distribution patterns of neurons and glial cells, examined by immunohistochemistry, are comparable between genotypes in the somatosensory cortex. However, increased densities of mature oligodendrocytes, but not immature ones, were noticed in the external capsule underneath the cortical layer VIb in young adult Fb Ctgf KO mice. The features of myelinated axons in the external capsule were then examined using electron microscopy. Unexpectedly, the thickness of the myelin sheath was reduced in middle-aged (>12 months old), but not young adult Fb Ctgf KO mice. Our results suggest a secretory function of the subplate neurons, through the release of CTGF, which regulates the density and dendritic branching of subplate neurons as well as the maturation and function of nearby oligodendrocytes in the white matter.

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“…A study on rat somatic sensorimotor system has shown that the structure of myelin sheath in the spinal cord underwent changes throughout the aging process [41]. Furthermore myelination properties have been shown to be regulated by neuronal activity and the environment [42,43].…”

Section: B-12 Supplementation and The Myelin Sheathmentioning

confidence: 99%

Supplemental Vitamin B-12 Enhances the Neural Response to Sensory Stimulation in the Barrel Cortex of Healthy Rats but Does Not Affect Spontaneous Neural Activity

Kang

Hayashi²,

Bruyns‐Haylett

et al. 2019

The Journal of Nutrition

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Background Although vitamin B-12 (B-12) is known to contribute to the structural and functional development of the brain, it is unclear if B-12 supplementation has any beneficial effect in healthy populations in terms of enhanced neurologic status of the brain or improved cognitive function. Objectives We investigated the effect of dietary supplementation of B-12 on the cortical neural activity of well-nourished young adult rats and tested the hypothesis that B-12 supplementation in healthy rats may reduce sensory-evoked neural activity due to enhanced inhibition. Methods Female Lister Hooded rats weighing 190–265 g (2–4 mo old) were included in the study. The experimental group was fed with B-12 (cyanocobalamin)–enriched water at a concentration of 1 mg/L, and the control (CON) group with tap water for 3 wk. Animals were then anesthetized and cortical neural responses to whisker stimulation were recorded in vivo through the use of a multichannel microelectrode, from which local field potentials (LFPs) were extracted. Results Somatosensory-evoked LFP was 25% larger in the B-12 group (4.13 ± 0.24 mV) than in the CON group (3.30 ± 0.21 mV) (P = 0.02). Spontaneous neural activity did not differ between groups; frequency spectra at each frequency bin of interest did not pass the cluster-forming threshold at the 5% significance level. Conclusions These findings do not provide evidence supporting the hypothesis of decreased neural activity due to B-12 supplementation. As the spontaneous neural activity was unaffected, the increase in somatosensory-evoked LFP may be due to enhanced afferent signal reaching the barrel cortex from the whisker pad, indicating that B-12–supplemented rats may have enhanced sensitivity to sensory stimulation compared with the CON group. We suggest that this enhancement might be the result of lowered sensory threshold, although the underlying mechanism has yet to be elucidated.

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Effects of normal aging on myelin sheath ultrastructures in the somatic sensorimotor system of rats

Cited by 32 publications

References 33 publications

Healthy Aging Impairs Photon Absorption Efficiency of Cones

Healthy Aging Impairs Photon Absorption Efficiency of Cones

Genetic Elimination of Connective Tissue Growth Factor in the Forebrain Affects Subplate Neurons in the Cortex and Oligodendrocytes in the Underlying White Matter

Supplemental Vitamin B-12 Enhances the Neural Response to Sensory Stimulation in the Barrel Cortex of Healthy Rats but Does Not Affect Spontaneous Neural Activity

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