Jin-Koo Lee

Effect of Agrimonia pilosa Ledeb Extract on the Antinociception and Mechanisms in Mouse

In the present study, the antinociceptive profiles of Agrimonia pilosa Ledeb extract were examined in ICR mice. Agrimonia pilosa Ledeb extract administered orally (200 mg/kg) showed an antinociceptive effect as measured by the tail-flick and hot-plate tests. In addition, Agrimonia pilosa Ledeb extract attenuated the writhing numbers in the acetic acid-induced writhing test. Furthermore, the cumulative nociceptive response time for intrathecal (i.t.) injection of substance P (0.7 µg) was diminished by Agrimonia pilosa Ledeb extract. Intraperitoneal (i.p.) pretreatment with yohimbine (α2-adrenergic receptor antagonist) attenuated antinociceptive effect induced by Agrimonia pilosa Ledeb extract in the writhing test. However, naloxone (opioid receptor antagonist) or methysergide (5-HT serotonergic receptor antagonist) did not affect antinociception induced by Agrimonia pilosa Ledeb extract in the writhing test. Our results suggest that Agrimonia pilosa Ledeb extract shows an antinociceptive property in various pain models. Furthermore, this antinociceptive effect of Agrimonia pilosa Ledeb extract may be mediated by α2-adrenergic receptor, but not opioidergic and serotonergic receptors.

Antinociceptive Profiles and Mechanisms of Orally Administered Curcumin in Various Pain Models

Antinociceptive profiles of curcumin in ICR mice were examined. Curcumin administered orally (from 1 to 10 mg/kg) showed an antinociceptive effect in a dose-dependent manner as measured in the acetic acid-induced writhing test. Duration of antinociceptive action of curcumin was maintained at least for 60 min. Moreover, cumulative response time of nociceptive behaviors induced with intraplantar formalin injection was reduced by curcumin treatment during second phase. Cumulative nociceptive response time for intrathecal injection of substance P (0.7 μg) or glutamate (20 μg) was diminished by curcumin. Intraperitoneal pretreatment with naloxone (opioid receptor antagonist) or methysergide (5-HT serotonergic receptor antagonist)-attenuated antinociceptive effect induced by curcumin in the writhing test, whereas yohimbine (α2-adrenergic receptor antagonist) did not affect antinociception induced by curcumin, suggesting that curcumin shows antinociceptive property in various pain models, and this antinociceptive effect of curcumin may be mediated by opioidergic and serotonergic receptors, but not α2-adrenergic receptor.

Anti-Depressant Like Effect of Methyl Gallate Isolated from Acer barbinerve in Mice

In the present study, the anti-depressant like effect of methyl gallate (MG) isolated from the stem bark of Acer barbinerve was examined in ICR mice. Body weight (BDW) and blood glucose (BDG) levels significantly decreased in the repeated restraint stress (RRS) group (2 h/day for 14 days) compared to the no stress (NS) group. To examine the effect of MG on RS-induced BDW loss and hypoglycemia, MG (10 mg/kg) and the anti-depressant fluoxetine (10 mg/kg) were administered daily for 14 days. Orally administered MG and fluoxetine significantly attenuated the RS-induced BDW loss and hypoglycemia. Interestingly, MG administered mice showed increased BDG levels in the normal and glucose feeding condition. Chronic RS-subjected mice showed immobilized and depressed behaviors. The effect of MG on the depressed behaviors was evaluated using the tail-suspension test (TST) and the forced swimming test (FST). In both tests, RS-induced immobilized behaviors were significantly reversed in MG and fluoxetine administered groups. Taken together, MG significantly attenuated the RS-induced BDW loss, hypoglycemia, and depressed behaviors. Considering that decreased BDG levels (hypoglycemia) can cause depression, MG may exert its anti-depressant like effect by preventing hypoglycemia. Our results suggest that MG isolated from A. barbinerve can exert anti-depressant like effect, and could be used as a new and natural anti-depressant therapy.

Deficiency of alpha-calcitonin gene-related peptide induces inflammatory responses and lethality in sepsis.

In the present study, we examined the role of alpha-calcitonin gene-related peptide (αCGRP) on expression of neuropeptides in the brain, inflammatory responses, and survival rate in septic shock condition. We examined expression of neuropeptides such as αCGRP, proopiomelanocortin (POMC), corticotrophin releasing hormone (CRH), and proenkephalin (ProENK) in the hippocampus and hypothalamus in C57BL/6 (WT) or αCGRP-/- (KO) mice subjected to sepsis. Cecal ligation and puncture (CLP) or lipopolysaccharide/D-galactosamine (LPS/D-GalN) treatment showed significant increases of hippocampal and hypothalamic αCGRP, POMC, CRH, and ProENK mRNA levels in WT mice, but not ProENK mRNA in the hypothalamus at 6h after on-set of sepsis. However, enhanced mRNA levels of POMC, CRH, and ProENK genes were not increased in the hippocampus and hypothalamus of CLP-subjected KO mice at 6h following sepsis. KO mice treated with LPS/D-GalN displayed a significant enhancement of plasma corticosterone, aspartate aminotransferase, and alanine aminotransferase levels compared to LPS/D-GalN treated WT mice at 12h after induction of sepsis. In addition, plasma levels of pro-inflammatory cytokines, such as IL-1β and TNF-α, were also further increased in KO mice compared to WT mice at 24h after CLP or LPS/D-GalN treatment. Interestingly, mRNA expressions of IL-6 and IL-10, anti-inflammatory cytokines, were synergistically enhanced in liver and lymph node of KO mice compared to WT mice at 6h after CLP. However, plasma level of IL-10 but not IL-6 was significantly decreased in KO mice compared to WT mice at 24h after CLP or LPS/D-GalN challenge. The survival rate of KO mice was significantly reduced compared to WT mice following mild (1 punch) and moderate (2 punch) CLP and LPS/D-GalN administration. Taken together, our findings suggest that the activation of αCGRP may induce other neuropeptides associated with immunomodulation at CNS level and modulate immune responses as enhancing anti-inflammatory cytokines and reducing pro-inflammatory cytokines during the sepsis.

Neuroprotective Effect of Ginseng against Alteration of Calcium Binding Proteins Immunoreactivity in the Mice Hippocampus after Radiofrequency Exposure

Calcium binding proteins (CaBPs) such as calbindin D28-k, parvalbumin, and calretinin are able to bind Ca2+ with high affinity. Changes in Ca2+ concentrations via CaBPs can disturb Ca2+ homeostasis. Brain damage can be induced by the prolonged electromagnetic field (EMF) exposure with loss of interacellular Ca2+ balance. The present study investigated the radioprotective effect of ginseng in regard to CaBPs immunoreactivity (IR) in the hippocampus through immunohistochemistry after one-month exposure at 1.6 SAR value by comparing sham control with exposed and ginseng-treated exposed groups separately. Loss of dendritic arborization was noted with the CaBPs in the Cornu Ammonis areas as well as a decrease of staining intensity of the granule cells in the dentate gyrus after exposure while no loss was observed in the ginseng-treated group. A significant difference in the relative mean density was noted between control and exposed groups but was nonsignificant in the ginseng-treated group. Decrease in CaBP IR with changes in the neuronal staining as observed in the exposed group would affect the hippocampal trisynaptic circuit by alteration of the Ca2+ concentration which could be prevented by ginseng. Hence, ginseng could contribute as a radioprotective agent against EMF exposure, contributing to the maintenance of Ca2+ homeostasis by preventing impairment of intracellular Ca2+ levels in the hippocampus.

Lactosylceramide Mediates the Expression of Adhesion Molecules in TNF-α and IFNγ-stimulated Primary Cultured Astrocytes.

Here we have investigated how lactosylceramide (LacCer) modulates gene expression of adhesion molecules in TNF-α and IFNγ (CM)-stimulated astrocytes. We have observed that stimulation of astrocytes with CM increased the gene expression of ICAM-1 and VCAM-1. D-Threo-1-phenyl- 2-decanoylamino-3-morpholino-1-propanol (PDMP) and N-butyldeoxynojirimycin (NBDNJ), inhibitors of glucosylceramide synthase (GLS) and LacCer synthase (galactosyltransferase, GalT-2), inhibited the gene expression of ICAM-1 and VCAM-1 and activation of their gene promoter induced by CM, which were reversed by exogenously supplied LacCer. Silencing of GalT-2 gene using its antisense oligonucleotides also attenuated CM-induced ICAM-1 and VCAM-1 expression, which were reversed by LacCer. PDMP treatment and silencing of GalT-2 gene significantly reduced CM-induced luciferase activities in NF-KB, AP-1, GAS, and STAT-3 luciferase vectors-transfected cells. In addition, LacCer reversed the inhibition of NF-KB and STAT-1 luciferase activities by PDMP. Taken together, our results suggest that LacCer may play a crucial role in the expression of ICAM-1 and VCAM-1 via modulating transcription factors, such as NF-KB, AP-1, STAT-1, and STAT-3 in CM-stimulated astrocytes.

Role of α-CGRP in the regulation of neurotoxic responses induced by kainic acid in mice.

Kainic acid (KA) is an excitatory and neurotoxic substance. The role of α-calcitonin gene-related peptide (α-CGRP) in the regulation of KA-induced hippocampal neuronal cell death was investigated in the present study. The intracerebroventricular (i.c.v.) administration with KA (0.07 μg) increased hippocampal α-CGRP mRNA level in ICR mice. The α-CGRP mRNA level began to increase at 1h, reached at maximal level at 6 and 12h, and returned to the control level by 24h after i.c.v. administration with KA. In addition, KA-induced hippocampal CA3 neuronal death in C57BL6 (wild type) group was more pronounced compared to KA-induced hippocampal CA3 pyramidal cell death in α-CGRP knock-out (KO) group. Furthermore, sumatriptan, a CGRP releasing inhibitor, significantly protected the pyramidal cell death in CA3 hippocampal region induced by KA administered i.c.v. in ICR mice. Our results suggest that α-CGRP may play an important role in the regulation of KA-induced pyramidal cell death in CA3 region of the hippocampus.

Exposure to 835 MHz radiofrequency electromagnetic field induces autophagy in hippocampus but not in brain stem of mice

The exploding popularity of mobile phones and their close proximity to the brain when in use has raised public concern regarding possible adverse effects from exposure to radiofrequency electromagnetic fields (RF-EMF) on the central nervous system. Numerous studies have suggested that RF-EMF emitted by mobile phones can influence neuronal functions in the brain. Currently, there is still very limited information on what biological mechanisms influence neuronal cells of the brain. In the present study, we explored whether autophagy is triggered in the hippocampus or brain stem after RF-EMF exposure. C57BL/6 mice were exposed to 835 MHz RF-EMF with specific absorption rates (SAR) of 4.0 W/kg for 12 weeks; afterward, the hippocampus and brain stem of mice were dissected and analyzed. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis demonstrated that several autophagic genes, which play key roles in autophagy regulation, were significantly upregulated only in the hippocampus and not in the brain stem. Expression levels of LC3B-II protein and p62, crucial autophagic regulatory proteins, were significantly changed only in the hippocampus. In parallel, transmission electron microscopy (TEM) revealed an increase in the number of autophagosomes and autolysosomes in the hippocampal neurons of RF-EMF-exposed mice. The present study revealed that autophagy was induced in the hippocampus, not in the brain stem, in 835 MHz RF-EMF with an SAR of 4.0 W/kg for 12 weeks. These results could suggest that among the various adaptation processes to the RF-EMF exposure environment, autophagic degradation is one possible mechanism in specific brain regions.

Antinociceptive effect of glyasperin F isolated from Glycyrrhiza inflata in mice

Antinociceptive effect of glyasperin F isolated from Glycyrrhiza inflata extract (GIE) in ICR mice was studied. Oral administration of GIE (1–100 mg/kg) caused a dose-dependent reduction in acetic acid-induced writhing responses. To identify the active antinociceptive compound from the GIE, sub-fractions were obtained from the EtOAc layer of GIE by using a medium pressure liquid chromatography. From the sub-fractions obtained, the sub-fraction, which, when administered orally (10 mg/kg) showed an antinociceptive effect in both the writhing test and second phase of the formalin test was identified as glyasperin F using NMR and MS analyses. Finally, the antinociceptive effect of glyasperin F in mouse models of pain was confirmed. Orally administered glyasperin F (0.1–10mg/kg) showed a dose-dependent antinociceptive effect in both the writhing test and second phase of the formalin test. Taken together, glyasperin F isolated from the GIE may be used as a leading compound for further studies on pain and as a new drug derived from natural products for pain therapy.

Immunohistochemical Localization of Calbindin D28k, Parvalbumin, and Calretinin in the Superior Olivary Complex of Circling Mice

The circling mouse serves as a hearing loss model. It has spontaneous tmie gene mutations that cause hair cell and cochlear degeneration. However, little is known about the role of the tmie gene in superior olivary complex (SOC) regions, in which sound information from the two ears is integrated and primarily relayed to the nuclei of the lateral lemniscus and inferior colliculus. Several studies have reported that abnormal calcium (Ca2+) homeostasis is associated with the pathology of hearing loss. This study investigated the distribution of Ca2+-binding proteins (CaBPs), such as calbindin D28k, parvalbumin, and calretinin, in the SOC of the circling mouse on postnatal day 16. A comparison of wild-type (+/+), heterozygous (+/cir), and homozygous (cir/cir) mice showed that CaBP immunoreactivity was significantly decreased in the auditory nucleus of the SOC of homozygous (cir/cir) mice. A decline in the CaBPs level in the SOC may be the result of hearing loss through hair cell and cochlear degeneration following tmie gene mutation.