Many recently developed N management strategies have been extremely successful in improving N use efficiency. How- ever, attempts to further increase grain yields have had limited success. Field experiments were condu...Many recently developed N management strategies have been extremely successful in improving N use efficiency. How- ever, attempts to further increase grain yields have had limited success. Field experiments were conducted in 2007 and 2008 at four sites to evaluate the effect of an in-season root-zone N management strategy on maize （Zea mays L.）. According to the in-season root-zone N management, the optimal N rate （ONR） was determined by subtracting measured soil mineral N （NHa＋-N and NO3-N） in the root zone from N target values. Other treatments included a control without N fertilization, 70% of ONR~ 130% of ONR, and recommended N rate （RNR） by agronomists in China that have been shown to approach maize yield potentials. Although apparent N recovery for the ONR treatment was significantly higher than that under RNR in 2007, grain yield declined from 13.3 to 11.0 Mg ha-1 because of an underestimation of N uptake. In 2008, N target values were adjusted to match crop uptake, and N fertilization rates were reduced from 450 kg N ha-1 for RNR to 225 to 265 kg N ha 1 for ONR. High maize yields were maintained at 12.6 to 13.5 Mg ha 1 which were twice the yield from typical farmers＇ practice. As a result, apparent N recovery increased from 29% to 66%, and estimated N losses decreased significantly for the ONR treatment compared to the RNR treatment. In conclusion, the in-season root-zone N management approach was able to achieve high yields, high NUE and low N losses.展开更多
Background Activation of glial cells and the extracellular signal-regulated kinase （ERK） signaling pathway play an important role in the development and maintenance of neuropathic pain. Curcumin can alleviate the sy...Background Activation of glial cells and the extracellular signal-regulated kinase （ERK） signaling pathway play an important role in the development and maintenance of neuropathic pain. Curcumin can alleviate the symptom of inflammatory pain by inhibiting the production and release of interleukin and tumor necrosis factor. However, whether curcumin affects neuropathic pain induced by nerve injury and the possible mechanism involved are still unknown. This study investigated the effects of tolerable doses of curcumin on the activation of astrocytes and ERK signaling in the spinal dorsal horn in rat model of neuropathic pain. Methods Adult male Sprague-Dawley rats were randomly divided into three groups： a control （sham operated） group, and chronic constriction injury groups （to induce neuropathic pain） that were either untreated or treated with curcumin. Thermal and mechanical hyperalgesia thresholds were measured. The distribution and morphological changes of astrocytes were observed by immunofluorescence. Western blotting was used to detect changes in the expression of gtial fibrillary acid protein （GFAP） and phosphorylated ERK. Results Injured rats showed obvious mechanical allodynia and thermal hyperalgesia. The number of GFAP-positive astrocytes, and the fluorescence intensity of GFAP were significantly increased in the spinal dorsal horn of injured compared with control rats. The soma of astrocytes also appeared hypertrophied in injured animals. Expression of GFAP and phosphorylated ERK was also significantly increased in the spinal dorsal horn of injured compared with control rats. Curcumin reduced the injury-induced thermal and mechanical hyperalgesia, the increase in the fluorescence intensity of GFAP and the hypertrophy of astrocytic soma, activation of GFAP and phosphorylation of ERK in the spinal dorsal horn. Conclusions Curcumin can markedly alleviate nerve injury-induced neuropathic pain in rats. The analgesic effect of curcumin may be attributed to its inhibition of astrocyte hypertrophy in the spinal dorsal horn and phosphorylation of the ERK signaling pathway.展开更多
Background Parvalbumin （PV）, as a mobile endogenous calcium buffer, plays an important role in affecting temporospatial characteristics of calcium transients and in modulating calcium homeostasis. PV is expressed in...Background Parvalbumin （PV）, as a mobile endogenous calcium buffer, plays an important role in affecting temporospatial characteristics of calcium transients and in modulating calcium homeostasis. PV is expressed in neurons in the dorsal root ganglion （DRG） and spinal dorsal horn and may be involved in synaptic transmission through regulating cytoplasm calcium concentrations. But the exact role of PV in peripheral sensory neurons remains unknown.Microtubule-associated protein 2 （MAP-2）, belonging to structural microtubule-associated protein family, is especially vulnerable to acute central nervous system （CNS） injury, and there will be rapid loss of MAP-2 at the injury site. The present study investigated the changes of PV expressing neurons and the MAP-2 neurons in the DRG after an operation for chronic constriction injury to the unilateral sciatic nerve （CCI-SN）, in order to demonstrate the possible roles of PV and MAP-2 in transmission and modulation of peripheral nociceptive information.Methods Seventy-two adult male Sprague-Dawley （SD） rats, weighing 180-220 g, were randomly divided into two groups （36 rats in each group）, the sham operation group and chronic constriction injury （CCI） group. Six rats in each group were randomly selected to receive mechanical and thermal sensitivity tests at one day before operation and 1,3, 5,7, and 14 days after surgery. After pain behavioral test, ipsilateral lumbar fifth DRGs were removed and double immunofluorescence staining was performed to assess the expression changes of PV and of MAP2 expressing neurons in the L5 DRG before or after surgery.Results The animals with CCI-SN showed obvious mechanical allodynia and thermal hyperalgesia （P＜0.05）. Both the thermal and mechanical hyperalgesia decreased to their lowest degree at 7 days after surgery compared to the baseline before surgery （P＜0.01）. In normal rats before surgery, a large number of neurons were MAP-2 single labeled cells, and just a small number of PV-expressed neurons were found. PV-positive neurons, PV-positive nerve fibers and PV-negative neurons, formed a direct or close contact for cross-talk. We used immunocytochemical staining to quantify the time course of changes to PV and MAP-2 expressing neurons in tissue, and found that the number of PV expressing neurons began to slightly decrease at 3 days after surgery, and had a significant reduction at CCI day 5, day 7 （P＜0.05）. But MAP-2 neurons significantly decreased on just the 3rd day after CCI （P＜0.05）. No changes in PV and MAP-2 expression were almost found in sham operated rats. The number of PV positive neurons, was positively correlated with the hyperalgesia threshold.Conclusions A sharp decline in MAP-2 neurons may be the early response to surgical injury, and PV positive neurons were much more effective at affecting the changes of pain behaviors, indicating that the down-regulation of PV protein could participate in, at least in part, the modulation of nociceptive transmission.展开更多
基金Supported by the National Basic Research Program (973 Program) of China (No. 2009CB118606)the Special Fund for Agriculture Profession of China (No. 200803030)the National Key Technologies Research and Development Program of China during the 11th Five-Year Plan Period (No. 2006BAD25B02)
文摘Many recently developed N management strategies have been extremely successful in improving N use efficiency. How- ever, attempts to further increase grain yields have had limited success. Field experiments were conducted in 2007 and 2008 at four sites to evaluate the effect of an in-season root-zone N management strategy on maize （Zea mays L.）. According to the in-season root-zone N management, the optimal N rate （ONR） was determined by subtracting measured soil mineral N （NHa＋-N and NO3-N） in the root zone from N target values. Other treatments included a control without N fertilization, 70% of ONR~ 130% of ONR, and recommended N rate （RNR） by agronomists in China that have been shown to approach maize yield potentials. Although apparent N recovery for the ONR treatment was significantly higher than that under RNR in 2007, grain yield declined from 13.3 to 11.0 Mg ha-1 because of an underestimation of N uptake. In 2008, N target values were adjusted to match crop uptake, and N fertilization rates were reduced from 450 kg N ha-1 for RNR to 225 to 265 kg N ha 1 for ONR. High maize yields were maintained at 12.6 to 13.5 Mg ha 1 which were twice the yield from typical farmers＇ practice. As a result, apparent N recovery increased from 29% to 66%, and estimated N losses decreased significantly for the ONR treatment compared to the RNR treatment. In conclusion, the in-season root-zone N management approach was able to achieve high yields, high NUE and low N losses.
文摘Background Activation of glial cells and the extracellular signal-regulated kinase （ERK） signaling pathway play an important role in the development and maintenance of neuropathic pain. Curcumin can alleviate the symptom of inflammatory pain by inhibiting the production and release of interleukin and tumor necrosis factor. However, whether curcumin affects neuropathic pain induced by nerve injury and the possible mechanism involved are still unknown. This study investigated the effects of tolerable doses of curcumin on the activation of astrocytes and ERK signaling in the spinal dorsal horn in rat model of neuropathic pain. Methods Adult male Sprague-Dawley rats were randomly divided into three groups： a control （sham operated） group, and chronic constriction injury groups （to induce neuropathic pain） that were either untreated or treated with curcumin. Thermal and mechanical hyperalgesia thresholds were measured. The distribution and morphological changes of astrocytes were observed by immunofluorescence. Western blotting was used to detect changes in the expression of gtial fibrillary acid protein （GFAP） and phosphorylated ERK. Results Injured rats showed obvious mechanical allodynia and thermal hyperalgesia. The number of GFAP-positive astrocytes, and the fluorescence intensity of GFAP were significantly increased in the spinal dorsal horn of injured compared with control rats. The soma of astrocytes also appeared hypertrophied in injured animals. Expression of GFAP and phosphorylated ERK was also significantly increased in the spinal dorsal horn of injured compared with control rats. Curcumin reduced the injury-induced thermal and mechanical hyperalgesia, the increase in the fluorescence intensity of GFAP and the hypertrophy of astrocytic soma, activation of GFAP and phosphorylation of ERK in the spinal dorsal horn. Conclusions Curcumin can markedly alleviate nerve injury-induced neuropathic pain in rats. The analgesic effect of curcumin may be attributed to its inhibition of astrocyte hypertrophy in the spinal dorsal horn and phosphorylation of the ERK signaling pathway.
基金CAO Ming-hui and JI Feng-tao contributed equally to this study. This study was supported by a grant from the Natural Science Foundation of Guangdong Province （No. 7001595 ）.
文摘Background Parvalbumin （PV）, as a mobile endogenous calcium buffer, plays an important role in affecting temporospatial characteristics of calcium transients and in modulating calcium homeostasis. PV is expressed in neurons in the dorsal root ganglion （DRG） and spinal dorsal horn and may be involved in synaptic transmission through regulating cytoplasm calcium concentrations. But the exact role of PV in peripheral sensory neurons remains unknown.Microtubule-associated protein 2 （MAP-2）, belonging to structural microtubule-associated protein family, is especially vulnerable to acute central nervous system （CNS） injury, and there will be rapid loss of MAP-2 at the injury site. The present study investigated the changes of PV expressing neurons and the MAP-2 neurons in the DRG after an operation for chronic constriction injury to the unilateral sciatic nerve （CCI-SN）, in order to demonstrate the possible roles of PV and MAP-2 in transmission and modulation of peripheral nociceptive information.Methods Seventy-two adult male Sprague-Dawley （SD） rats, weighing 180-220 g, were randomly divided into two groups （36 rats in each group）, the sham operation group and chronic constriction injury （CCI） group. Six rats in each group were randomly selected to receive mechanical and thermal sensitivity tests at one day before operation and 1,3, 5,7, and 14 days after surgery. After pain behavioral test, ipsilateral lumbar fifth DRGs were removed and double immunofluorescence staining was performed to assess the expression changes of PV and of MAP2 expressing neurons in the L5 DRG before or after surgery.Results The animals with CCI-SN showed obvious mechanical allodynia and thermal hyperalgesia （P＜0.05）. Both the thermal and mechanical hyperalgesia decreased to their lowest degree at 7 days after surgery compared to the baseline before surgery （P＜0.01）. In normal rats before surgery, a large number of neurons were MAP-2 single labeled cells, and just a small number of PV-expressed neurons were found. PV-positive neurons, PV-positive nerve fibers and PV-negative neurons, formed a direct or close contact for cross-talk. We used immunocytochemical staining to quantify the time course of changes to PV and MAP-2 expressing neurons in tissue, and found that the number of PV expressing neurons began to slightly decrease at 3 days after surgery, and had a significant reduction at CCI day 5, day 7 （P＜0.05）. But MAP-2 neurons significantly decreased on just the 3rd day after CCI （P＜0.05）. No changes in PV and MAP-2 expression were almost found in sham operated rats. The number of PV positive neurons, was positively correlated with the hyperalgesia threshold.Conclusions A sharp decline in MAP-2 neurons may be the early response to surgical injury, and PV positive neurons were much more effective at affecting the changes of pain behaviors, indicating that the down-regulation of PV protein could participate in, at least in part, the modulation of nociceptive transmission.
