Laminar-specific distribution of zinc: Evidence for presence of layer IV in forelimb motor cortex in the rat

© 2014 Elsevier Inc.The rat is the most widely studied pre-clinical model system of various neurological and neurodegenerative disorders affecting hand function. Although brain injury to the forelimb region of the motor cortex in rats mostly induces behavioral abnormalities in motor control of hand movements, behavioral deficits in the sensory-motor domain are also observed. This questions the prevailing view that cortical layer IV, a recipient of sensory information from the thalamus, is absent in rat motor cortex. Because zinc-containing neurons are generally not found in pathways that run from the thalamus, an absence of zinc (Zn) in a cortical layer would be suggestive of sensory input from the thalamus. To test this hypothesis, we used synchrotron micro X-ray fluorescence imaging to measure Zn distribution across cortical layers. Zn maps revealed a heterogeneous layered Zn distribution in primary and secondary motor cortices of the forelimb region in the adult rat. Two wider bands with elevated Zn content were separated by a narrow band having reduced Zn content, and this was evident in two rat strains. The Zn distribution pattern was comparable to that in sensorimotor cortex, which is known to contain a well demarcated layer IV. Juxtaposition of Zn maps and the images of brain stained for Nissl bodies revealed a "Zn valley" in primary motor cortex, apparently starting at the ventral border of pyramidal layer III and ending at the close vicinity of layer V. This finding indicates the presence of a conspicuous cortical layer between layers III and V, i.e. layer IV, the presence of which previously has been disputed. The results have implications for the use of rat models to investigate human brain function and neuropathology, such as after stroke. The presence of layer IV in the forelimb region of the motor cortex suggests that therapeutic interventions used in rat models of motor cortex injury should target functional abnormalities in both motor and sensory domains. The finding is also critical for future investigation of the biochemical mechanisms through which therapeutic interventions can enhance neural plasticity, particularly through Zn dependent pathways

Parallel changes in cortical neuron biochemistry and motor function in protein-energy malnourished adult rats

While protein-energy malnutrition in the adult has been reported to induce motor abnormalities and exaggerate motor deficits caused by stroke, it is not known if alterations in mature cortical neurons contribute to the functional deficits. Therefore, we explored if PEM in adult rats provoked changes in the biochemical profile of neurons in the forelimb and hindlimb regions of the motor cortex. Fourier transform infrared spectroscopic imaging using a synchrotron generated light source revealed for the first time altered lipid composition in neurons and subcellular domains (cytosol and nuclei) in a cortical layer and region-specific manner. This change measured by the area under the curve of the d(CH2) band may indicate modifications in membrane fluidity. These PEM-induced biochemical changes were associated with the development of abnormalities in forelimb use and posture. The findings of this study provide a mechanism by which PEM, if not treated, could exacerbate the course of various neurological disorders and diminish treatment efficacy

Динамика изменения минимальных уровней и расходов на реке Мтквари (Минадзе).

მოყვანილია ორი მაგალითი მდინარე ტისაზე და მდინარე მტკვარზე მინიმალური დონეების ცვალებადობის შესახებ, სადაც დაკვირვებული მონაცემები არაერთგვაროვანია. ერთგვაროვნება მდინარე მტკვარზე როგორც ჩანს დარღვეულია მაქსიმალური ხარჯის (1110 მ/წმ) გავლის გამო, რამაც გამოიწვია კალაპოტის დეფორმაცია, ამიტომ ტრენდის შეფასებისას (მინიმალური დონეების შემთხვევაში) აუცილებელია პროცესის ექსტრემალურ შემთხვევათა და მათი შედეგების დეტალური ანალიზი განსახილველი რიგის ერთგვაროვნების შეფასებით და მათი დარღვევის მიზეზების გამოვლენით.Two examples are given on the change in the minimum levels on the Tisa and Mtkvari rivers, where the observation data are heterogeneous. The homogeneity on the Mtkvari River is evidently violated as a result of passing the maximum flow rate (1110 m3 / s), which caused the bed deformation, therefore, when assessing the trend (in the case of the minimum levels), a detailed analysis of the extreme cases of the process and their results is required with an assessment of homogeneity of the considered line and reasons of their violationПриведены два примера об изменении минимального уровня на реках Тиса и Тквари, где данные наблюдения неоднородны. Однородность на реке Мтквари, как видно, нарушена в результате прохождения максимального расхода (1110 м3/сек.), что вызвало деформацию русла, поэтому при оценке тренда (в случае минимального уровня) обязателен детальный анализ экстремальных случаев процесса и их результатов с оценкой однородности рассматриваемого ряда и причин нарушения

Динамика изменения минимальных уровней и расходов на реке Мтквари (Минадзе).

მოყვანილია ორი მაგალითი მდინარე ტისაზე და მდინარე მტკვარზე მინიმალური დონეების ცვალებადობის შესახებ, სადაც დაკვირვებული მონაცემები არაერთგვაროვანია. ერთგვაროვნება მდინარე მტკვარზე როგორც ჩანს დარღვეულია მაქსიმალური ხარჯის (1110 მ/წმ) გავლის გამო, რამაც გამოიწვია კალაპოტის დეფორმაცია, ამიტომ ტრენდის შეფასებისას (მინიმალური დონეების შემთხვევაში) აუცილებელია პროცესის ექსტრემალურ შემთხვევათა და მათი შედეგების დეტალური ანალიზი განსახილველი რიგის ერთგვაროვნების შეფასებით და მათი დარღვევის მიზეზების გამოვლენით.Two examples are given on the change in the minimum levels on the Tisa and Mtkvari rivers, where the observation data are heterogeneous. The homogeneity on the Mtkvari River is evidently violated as a result of passing the maximum flow rate (1110 m3 / s), which caused the bed deformation, therefore, when assessing the trend (in the case of the minimum levels), a detailed analysis of the extreme cases of the process and their results is required with an assessment of homogeneity of the considered line and reasons of their violationПриведены два примера об изменении минимального уровня на реках Тиса и Тквари, где данные наблюдения неоднородны. Однородность на реке Мтквари, как видно, нарушена в результате прохождения максимального расхода (1110 м3/сек.), что вызвало деформацию русла, поэтому при оценке тренда (в случае минимального уровня) обязателен детальный анализ экстремальных случаев процесса и их результатов с оценкой однородности рассматриваемого ряда и причин нарушения

Protein-Energy Malnutrition Exacerbates Stroke-Induced Forelimb Abnormalities and Dampens Neuroinflammation

Protein-energy malnutrition (PEM) pre-existing at stroke onset is believed to worsen functional outcome, yet the underlying mechanisms are not fully understood. Since brain inflammation is an important modulator of neurological recovery after stroke, we explored the impact of PEM on neuroinflammation in the acute period in relation to stroke-initiated sensori-motor abnormalities. Adult rats were fed a low-protein (LP) or normal protein (NP) diet for 28 days before inducing photothrombotic stroke (St) in the forelimb region of the motor cortex or sham surgery; the diets continued for 3 days after the stroke. Protein-energy status was assessed by a combination of body weight, food intake, serum acute phase proteins and corticosterone, and liver lipid content. Deficits in motor function were evaluated in the horizontal ladder walking and cylinder tasks at 3 days after stroke. The glial response and brain elemental signature were investigated by immunohistochemistry and micro-X-ray fluorescence imaging, respectively. The LP-fed rats reduced food intake, resulting in PEM. Pre-existing PEM augmented stroke-induced abnormalities in forelimb placement accuracy on the ladder; LP-St rats made more errors (29 ± 8%) than the NP-St rats (15 ± 3%; P < 0.05). This was accompanied by attenuated astrogliosis in the peri-infarct area by 18% and reduced microglia activation by up to 41 and 21% in the peri-infarct area and the infarct rim, respectively (P < 0.05). The LP diet altered the cortical Zn, Ca, and Cl signatures (P < 0.05). Our data suggest that proactive treatment of pre-existing PEM could be essential for optimal post-stroke recovery