Eunkuk Park

Electroacupuncture attenuates mechanical and warm allodynia through suppression of spinal glial activation in a rat model of neuropathic pain

Neuropathic pain remains one of the most difficult clinical pain syndromes to treat. It is traditionally viewed as being mediated solely by neurons; however, glial cells have recently been implicated as powerful modulators of pain. It is known that the analgesic effects of electroacupuncture (EA) are mediated by descending pain inhibitory systems, which mainly involve spinal opioid, adrenergic, dopaminergic, serotonergic, and cholinergic receptors. However, studies investigating the suppressive effects of EA on spinal glial activation are rare. In the present study, we assessed the cumulative analgesic effects of EA on mechanical and warm allodynia in a rat model of neuropathic pain. We investigated the clinical efficacy of EA as long-term therapy and examined its effects on spinal glia, matrix metalloproteinase (MMP)-9/MMP-2, proinflammatory cytokines and serum immunoglobulin G (IgG) concentration. Rats were randomly divided into four groups as follows: the operation group (OP), operation with EA-non acupoint (EA-NA), operation with EA-ST36 acupoint (EA-ST36), and sham operation (shamOP). Following neuropathic or sham surgery, repeated EA was performed every other day after the behavioral test. On day 53 after the behavioral test, rats were perfused for immunohistochemistry and Western blot analysis to observe quantitative changes in spinal glial markers such as OX-42, astrocytic glial fibrillary acidic protein (GFAP), MMP-9/MMP-2, and proinflammatory cytokines. Allodynia and OX-42/GFAP/MMP-9/MMP-2/tumor necrosis factor (TNF)-α/interleukin (IL)-1β activity in the EA-ST36 group was significantly reduced, compared to the OP and EA-NA groups, and IgG in EA-ST36 rats significantly increased. Our results suggest that the analgesic effect of EA may be partly mediated via inhibition of inflammation and glial activation and repeated EA stimulation may be useful for treating chronic pain clinically.

Neuroprotective effects of magnesium-sulfate on ischemic injury mediated by modulating the release of glutamate and reduced of hyperreperfusion.

This study examined the neuroprotective effects of magnesium-sulfate (MgSO(4)) on the cerebral blood flow (CBF) and extracellular glutamate concentration in an eleven vessel occlusion (11VO) rat model. Twenty-one male Sprague-Dawley rats (250-350g) were used for the 11VO ischemic model, which was induced by a 10-min transient occlusion. The animals were divided into 3 groups, including ischemic-induced animals (ischemia group), ischemic-induced and MgSO(4) treated animals (MgSO(4) group), and sham animals for comparison. The real-time extracellular glutamate concentration was measured using a microdialysis biosensor, and the CBF was monitored by laser Doppler flowmetry. Neuronal cell death in the hippocampal region was observed 72h after ischemia by several stains (Nissl, DAPI, NeuN, and cleaved caspase3). A significant decrease in %CBF was observed in both the ischemia and MgSO(4) groups, such as ~10% during the ischemic period. However, the MgSO(4) group showed a significant decrease in the initial reperfusion %CBF compared to the ischemia group. A significantly lower level of glutamate release was observed in the MgSO(4) group than in the ischemia group during the ischemic and reperfusion episode. Our staining results revealed a significant decrease in neuronal cell death in the hippocampus in the MgSO(4) group compared to the ischemia group. These results suggest that MgSO(4) is responsible for the protection of neuronal cells by suppressing the release of extracellular glutamate under ischemic conditions and the CBF response during the initial reperfusion period.

The role of glutamate release on voltage-dependent anion channels (VDAC)-mediated apoptosis in an eleven vessel occlusion model in rats.

Voltage-dependent anion channel (VDAC) is the main protein in mitochondria-mediated apoptosis, and the modulation of VDAC may be induced by the excessive release of extracellular glutamate. This study examined the role of glutamate release on VDAC-mediated apoptosis in an eleven vessel occlusion model in rats. Male Sprague-Dawley rats (250–350 g) were used for the 11 vessel occlusion ischemic model, which were induced for a 10-min transient occlusion. During the ischemic and initial reperfusion episode, the real-time monitoring of the extracellular glutamate concentration was measured using an amperometric microdialysis biosensor and the cerebral blood flow (CBF) was monitored by laser-Doppler flowmetry. To confirm neuronal apoptosis, the brains were removed 72 h after ischemia to detect the neuron-specific nuclear protein and pro-apoptotic proteins (cleaved caspase-3, VDAC, p53 and BAX). The changes in the mitochondrial morphology were measured by atomic force microscopy. A decrease in the % of CBF was observed, and an increase in glutamate release was detected after the onset of ischemia, which continued to increase during the ischemic period. A significantly higher level of glutamate release was observed in the ischemia group. The increased glutamate levels in the ischemia group resulted in the activation of VDAC and pro-apoptotic proteins in the hippocampus with morphological alterations to the mitochondria. This study suggests that an increase in glutamate release promotes VDAC-mediated apoptosis in an 11 vessel occlusion ischemic model.

Stress‐induced activation of ovarian heat shock protein 90 in a rat model of polycystic ovary syndrome

Aim:  Polycystic ovarian syndrome is the most common endocrine disorder affecting infertile women of reproductive age. This study evaluated the activation of heat shock protein 90 (Hsp 90) during the formation of stress‐induced polycystic ovaries.

Correlation between extracellular glutamate release and neuronal cell death in an eleven vessel occlusion model in rat

The aim of this study was to define the effects of glutamate release on cell death in an eleven vessel rat occlusion model. Male Sprague-Dawley rats (250-350g) were used for the 11 vessel occlusion ischemic model, which was induced by a 5- and 10-min transient occlusion. During the surgical procedure, the extracellular glutamate concentration was measured in real-time using a microdialysis amperometirc biosensor with cerebral blood flow. In order to confirm neuronal cell death, brains were removed 72h after ischemia for the detection of the neuron-specific nuclear protein and cleaved caspase-3 levels, using double-immunofluorescence. A significant decrease in % cerebral blood flow was observed in both the 5- and 10-min 11 vessel occlusion models, while an increase in glutamate release was detected after the onset of ischemia that continued to rise during the ischemic period. However, a significantly higher level of glutamate release was observed in the 10-min ischemia group compared to the 5-min group. Unlike the small amount of brain damage in the 5-min group, the increased glutamate levels in the 10-min group resulted in ischemic cell death in the hippocampal region with the activation of cleaved caspase-3 and the inhibition of neuron-specific nuclear protein expression. This study suggests that the increased level of glutamate release induces apoptotic cell death in the 11 vessel occlusion ischemic model.

Rams genetically superior for IGF-I do not exhibit improved male reproductive traits

Insulin-like growth factors (IGFs) play an important role in regulating normal physiology, and may be involved in the control of reproduction. The aim of this study was to define the relationship between IGF-I concentrations and reproductive performance over the breeding and non-breeding seasons in lines of New Zealand Romney rams that had been selected for low and high blood serum IGF-I concentration. Yearling rams from two selection lines (13 from the high line and 19 from the low line) were examined in July (winter), September (autumn) and November (summer) 2006 and March (spring) 2007. Scrotal circumference including the inguinal skin was recorded. Semen was collected by electroejaculation on 4 occasions over a 12-month period. Semen was evaluated according to standard procedures (volume, motility, density and morphology). Samples were collected from four animals from each group for measurements of mRNA for IGF-I and the IGF type 1 receptor (IGF 1R) in the testis, and IGF-I, IGF 1R and the insulin receptor (IR) in the liver. Blood samples were collected via jugular venipuncture for the measurement of IGF-I, insulin and testosterone. The incidences of morphologically abnormal sperm cells, the scrotal circumference and sperm motility were higher in the breeding than in non-breeding season. Seasonal changes were found in the percentage of abnormal sperm, scrotal circumference, sperm motility and sperm density, but there were no differences between lines in any reproductive parameters. IGF-I mRNA levels were higher in the high than the low line in the liver but not in the testis, whereas the opposite was found for levels of IGF 1R mRNA. mRNA levels for the insulin receptor in the liver were higher in the high line. Plasma testosterone concentrations did not differ between lines, whereas the concentrations of IGF-I and insulin were higher in the high line. The results suggest that IGF-I may be locally produced in the liver and the testis, and that selection for high IGF-I may not be associated with improved reproductive performance in rams.

Antiadipogenic Effects of Loganic Acid in 3T3-L1 Preadipocytes and Ovariectomized Mice

Obesity is caused by an excess storage of body fat, resulting from a chronic imbalance between energy intake and expenditure. Gentiana lutea L. (GL) root has been reported to reduce lipid accumulation in the aortic wall of diabetic rats. Here, we performed fractionation and isolation of the bioactive constituent(s) that may be responsible for the antiadipogenic effects of the GL root extract. A single compound, loganic acid, was identified as a candidate component in the 30% ethanol extract of GL. Loganic acid treatment significantly decreased the adipocyte differentiation of 3T3-L1 preadipocytes in a dose-dependent manner. The expression of key adipogenesis-related genes such as adiponectin (Adipoq), peroxisome proliferator-activated receptor gamma (Pparg), lipoprotein lipase (Lpl), perilipin1 (Plin1), fatty acid binding protein 4 (Fabp4), glucose transporter type 4 (Slc2a4), CCAAT/enhancer-binding protein alpha (Cebpa), and tumor necrosis factor-alpha (Tnf) were significantly reduced following treatment with loganic acid. In vivo experiments in an ovariectomy-induced obesity mouse model showed that loganic acid (oral administration with 10 and 50 mg/kg/day) significantly inhibited body weight gain, total fat increase, fatty hepatocyte deposition in the liver, and adipocyte enlargement in the abdominal visceral fat tissues. These results suggest that loganic acid in the GL root extract has antiadipogenic effects in vitro and in vivo. Loganic acid may be beneficial for the prevention and treatment of obesity, particularly in menopausal obese women.

Hochu-ekki-to Treatment Improves Reproductive and Immune Modulation in the Stress-Induced Rat Model of Polycystic Ovarian Syndrome

The traditional herbal medicine, Hochu-ekki-to, has been shown to have preventive effects on viral infection and stress. This study aimed to evaluate the clinical effects of Hochu-ekki-to on two stress-related rat models of polycystic ovarian syndrome. Female Sprague-Dawley rats were divided into control and treatment groups, the latter of which were subjected to stress induced by exposure to adrenocorticotropic hormone (ACTH) or cold temperatures. After these stress inductions, rats were orally treated with dissolved Hochu-ekki-to once per day for 7 days. Rats subjected to the two different stressors exhibited upregulation of steroid hormone receptors (in ovaries) and reproductive hormones (in blood), and consequent stimulation of abnormal follicle development accompanied by elevation of Hsp 90 expression (in ovaries). Treatment with Hochu-ekki-to for 7 days after stress induction increased immune functions, reduced the stress-induced activation of Hsp 90, and normalized the levels of the tested steroid hormone receptors and reproductive hormones. Our findings suggest that stress stimulations may promote the activation of Hsp 90 via the dysregulation of steroid hormone receptors and reproductive hormones, but that post-stress treatment with Hochu-ekki-to improves reproductive and immune functions in the ovaries of stressed rats.

Real Time Monitoring of Extracellular Glutamate Release in Rat Ischemia Model Treated by Nimodipine

It is well known that cerebral ischemia is associated with extracellular concentrations of the excitatory amino acids. Real time quantitative measurement of glutamate which is the most abundant excitatory neurotransmitter would be very helpful parameter, in order to evaluate brain injury during or after surgery, as well as validation of the instantaneous effect of drug. In order to define the effect of nimodipine on glutamate release and neuronal cell damage, we monitored real-time extracellular glutamate release and cerebral blood flow (CBF) in an eleven vessel occlusion global ischemia rat model. Changes in glutamate release and CBF were monitored by laser-Doppler flowmetry and amperometric biosensor, respectively. A ten minute 11VO cerebral ischemia was initiated by pulling the snares on the common carotid arteries (CCAs) and the external carotid arteries (ECAs). Nimodipine was infused during the ischemic period (0.025 μg/100gm/min: diluted 20 times by normal saline). The infusion site for nimodipine was located lateral to the probe of cerebral blood flowmeter. Three days after occlusion, histological analysis was performed by Nissel staining, in order to assessment of neuronal cell damage. In comparison with the ischemia and nimodipine group, the maximum changes in glutamate concentration showed statistically significant difference between two groups, resulting in neuronal cell death. It is considered that nimodipine may reduce glutamate release with brain damage during a global ischemic episode in the eleven vessel occlusion rat model.