Joong-Sun Kim

Melatonin attenuates neutrophil inflammation and mucus secretion in cigarette smoke-induced chronic obstructive pulmonary diseases via the suppression of Erk-Sp1 signaling.

The incidence of chronic obstructive pulmonary disease (COPD) has substantially increased in recent decade. Cigarette smoke (CS) is the most important risk factor in the development of COPD. In this study, we investigated the effects of melatonin on the development of COPD using a CS and lipopolysaccharide (LPS)‐induced COPD model and cigarette smoke condensate (CSC)‐stimulated NCI‐H292 cells, a human mucoepidermoid carcinoma cell. On day 4, the mice were treated intranasally with LPS. The mice were exposed to CS for 1 hr per day (8 cigarettes per day) from day 1 to day 7. Melatonin (10 or 20 mg/kg) was injected intraperitoneally 1 hr before CS exposure. Melatonin markedly decreased the neutrophil count in the BALF, with reduction in the proinflammatory mediators and MUC5AC. Melatonin inhibited Erk phosphorylation and Sp1 expression induced by CS and LPS treatment. Additionally, melatonin decreased airway inflammation with a reduction in myeloperoxidase expression in lung tissue. In in vitro experiments, melatonin suppressed the elevated expression of proinflammatory mediators induced by CSC treatment. Melatonin reduced Erk phosphorylation and Sp1 expression in CSC‐stimulated H292 cells. In addition, cotreatment of melatonin and Erk inhibitors significantly limited the proinflammatory mediators with greater reductions in Erk phosphorylation and Sp1 expression than that observed in H292 cells treated with Erk inhibitor alone. Taken together, melatonin effectively inhibited the neutrophil airway inflammation induced by CS and LPS treatment, which was closely related to downregulation of Erk phosphorylation. These findings suggest that melatonin has a therapeutic potential for the treatment of COPD.

Differential patterns of nestin and glial fibrillary acidic protein expression in mouse hippocampus during postnatal development

Intermediate filaments, including nestin and glial fibrillary acidic protein (GFAP), are important for the brain to accommodate neural activities and changes during development. The present study examined the temporal changes of nestin and GFAP protein levels in the postnatal development of the mouse hippocampus. Mouse hippocampi were sampled on postnatal day (PND) 1, 3, 6, 18, and 48. Western blot analysis showed that nestin expression was high at PND 1 and markedly decreased until PND 18. Conversely, GFAP expression was acutely increased in the early phase of postnatal development. Nestin immunoreactivity was localized mainly in the processes of ramified cells at PND 1, but expression subsequently decreased. In contrast, GFAP was evident mainly in the marginal cells of the hippocampus at PND 1, but immunoreactivity revealed satellite, radial, or ramified shapes of the cells from PND 6-48. This study demonstrates that the opposing pattern of nestin and GFAP expressions in mouse hippocampus during postnatal development occur in the early development stage (PND 1-18), suggesting that the opposing change of nestin and GFAP in early postnatal development is important for neural differentiation and positioning in the mouse hippocampus.

Melatonin reduces airway inflammation in ovalbumin-induced asthma

Asthma is a common chronic inflammatory airway disease that is recognized as a major public health problem. In this study, we evaluated the effects of melatonin on allergic asthma using a murine model of ovalbumin (OVA)-induced allergic asthma and BEAS-2B cells. To induce allergic asthma, the mice were sensitized and airway-challenged with OVA. Melatonin was administered by intraperitoneal injection once per day at doses of 10 and 15 mg/kg from days 21 to 23 after the initial OVA sensitization. We investigated the effects of melatonin on proinflammatory cytokines and matrix metalloproteinase-9 (MMP-9) activity and expression in tumor necrosis factor (TNF)-α-stimulated BEAS-2B cells. The administration of melatonin significantly decreased the number of inflammatory cells, airway hyperresponsiveness, and immunoglobulin (Ig) E with reductions in interleukin (IL)-4, IL-5, and IL-13. Melatonin attenuated the airway inflammation and the mucus production in lung tissue and significantly suppressed elevated MMP-9 expression and activity induced by an OVA challenge. In TNF-α-stimulated BEAS-2B cells, treatment with melatonin significantly reduced the levels of proinflammatory cytokines and lowered the expression and activity of MMP-9. These results indicate that melatonin effectively suppressed allergic asthma induced by an OVA challenge. The results suggest a potential role for melatonin in treating asthma.

Relative biological effectiveness of fast neutrons in a multiorgan assay for apoptosis in mouse.

This study compared the effects of high linear energy transfer (LET) fast neutrons on the induction of apoptosis in several tissue types (hair follicle, intestine crypt, testis) of ICR mouse exposed to low LET 60Co γ‐rays. The changes that occurred from 0 to 24 h after exposing the mice to either 2 Gy of γ‐rays (2 Gy/min) or 0.8 Gy of neutrons (94 mGy/min, 35 MeV) were examined. The maximum frequency of apoptosis was observed at 8 or 12 h after irradiation. The mice that had received 0–8 Gy of γ‐rays or 0–1.6 Gy of neutrons were examined 8 h after irradiation. The best‐fitting dose–response curves were linear‐quadratic, and there was a significant relationship between the number of apoptotic cells and the dose. The stained products in the TUNEL‐positive cells or bodies correlated with the typical morphologic characteristics of apoptosis observed by optical microscopy. In the follicles showing an apoptosis frequency between 2 and 14 per hair follicle, the relative biological effectiveness (RBE) of the neutrons in the small and large follicles was 2.09 ± 0.31 and 2.15 ± 0.18, respectively. In the intestine crypts showing an apoptosis frequency between 1 and 3 per crypt, the RBE of the neutrons was 4.03 ± 0.06 and 3.87 ± 0.04 in the base and total crypts, respectively. The RBE of the neutrons in the seminiferous tubule showing an apoptosis frequency between 0.5 and 2 per tubule was 5.18 ± 0.06. The results determined the time–response relations and the RBE for fast neutron‐induced apoptosis in several organs at the same time. The differences in RBE observed between the high and low LET radiation and it is believed that the difference in the DSB repair capacity in hair follicle, intestine crypt, and seminiferous tubule cells plays a role in determining the RBE of the high‐LET radiation for the induced apoptotic cell formation.

Immunohistochemical analysis of cAMP response element-binding protein in mouse testis during postnatal development and spermatogenesis.

Basal activity and cellular localization of cAMP response element-binding protein (CREB) was examined in mouse testis during postnatal development and spermatogenesis. Testes of ICR mice sampled on postnatal day (PND) 3, 7, 14, 21, 28, 35, 42, and 49 were analyzed using Western blotting. Basal CREB activity was significantly higher in early phase (PND 3–7) developing testes than in intermediate- and late-phase developing (PND 14–42) and adult testes (PND 49). Furthermore, immunohistochemical analysis demonstrated the change of CREB phosphorylation in various testicular cell types during postnatal development. In particular, CREB phosphorylation in seminiferous tubules of the adult testis varied according to the spermatogenic cycle, while phosphorylation was evident in spermatogonia during all stages. Phosphorylation was moderate in pachytene spermatocytes of stages I–III and intense in round and elongate spermatids of spermiogenesis in stages XII–IX. These results suggest that CREB plays an important role in cell proliferation and differentiation in the early phase of postnatal development and spermatogenesis of mouse testis.

Granulocyte-colony stimulating factor ameliorates irradiation-induced suppression of hippocampal neurogenesis in adult mice

Granulocyte-colony stimulating factor (G-csf) is a member of the hematopoietic growth factor family and demonstrates neuroprotective functions in neurodegenerative diseases. This study evaluated the radioprotective effects of G-csf in the suppression of hippocampal neurogenesis in adult mice undergoing irradiation. The radioprotective effects were assessed using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay and immunohistochemical markers of neurogenesis, including the proliferating cell marker Ki-67 and the immature progenitor neuron marker doublecortin (DCX). Acute exposure to cranial irradiation (5Gy γ-rays) induced neural apoptosis and inhibited neurogenesis in the dentate gyrus (DG) of the adult mouse hippocampus. Pretreatment with G-csf (100μg/kg every 12h subcutaneously on three consecutive days) attenuated neural apoptosis and decreased the number of Ki-67- and DCX-positive cells in the DG of the irradiated mouse hippocampus. Therefore, G-csf inhibited the detrimental effects of irradiation on hippocampal neurogenesis, suggesting that G-csf administration has potential therapeutic utility in brain irradiation.

Dose-response and relative biological effectiveness of fast neutrons: induction of apoptosis and inhibition of neurogenesis in the hippocampus of adult mice.

Purpose: Our study compared the effects of high linear energy transfer (LET) fast neutrons on the induction of apoptosis and reduction of neurogenesis in the hippocampus of adult ICR mice with those of low-LET 60Co γ-rays, to evaluate the relative biological effectiveness (RBE) of fast neutrons in the adult hippocampal dentate gyrus (DG). Materials and Methods: The mice were exposed to 35 MeV fast neutrons or 60Co γ-rays. We evaluated acutely the incidence of apoptosis and expression of Ki-67 (a protein marker for cell proliferation originally defined by the monoclonal antibody Kiel-67) and doublecortin (DCX: an immature progenitor neuron marker) in the hippocampus after a single whole-body irradiation. Results: The number of terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labelling (TUNEL)-positive apoptotic nuclei in the DG increased and both Ki-67- and DCX-positive cells declined in a dose-dependent pattern, with fast neutrons or γ-rays. In the hippocampus, which showed an apoptosis frequency between 2 and 8 per DG, the RBE of fast neutrons was approximately 1.9. Additionally, the inhibitory effects of fast neutrons on the expression frequencies of Ki-67 (4–8) and DCX (8–32) were approximately 3.2 and 2.5 times, respectively, the effects of γ-rays at the same dose. Conclusions: Increased apoptotic cell death and decreased neurogenesis in the hippocampal DG were seen in a dose-dependent pattern after exposure to fast neutrons and γ-rays. In addition, the different rate of hippocampal neurogenesis between different radiation qualities may be an index of RBE.

Neurobiological toxicity of radiation in hippocampal cells

Worldwide radiation exposure is increasing due to recent nuclear accidents, space travel, atomic weapons testing and use, and medical treatments. In adult animals, ionizing radiation can significantly impact hippocampal neurogenesis and negatively affect hippocampal functions such as cognition. However, there is considerable uncertainty regarding the mechanisms underlying these effects. This article reviews in vivo and in vitro studies on the effects of irradiation on hippocampal neurogenesis and function in order to gain new mechanistic insights. This information will provide complementary views of our understanding of the normal brains tolerance to radiation exposure, the potentially serious implications of radiation exposure to cognition, and lead to a discussion of potential strategies for pharmacotherapy and behavioral intervention.

Fast neutron irradiation deteriorates hippocampus-related memory ability in adult mice

Object recognition memory and contextual fear conditioning task performance in adult C57BL/6 mice exposed to cranial fast neutron irradiation (0.8 Gy) were examined to evaluate hippocampus-related behavioral dysfunction following acute exposure to relatively low doses of fast neutrons. In addition, hippocampal neurogenesis changes in adult murine brain after cranial irradiation were analyzed using the neurogenesis immunohistochemical markers Ki-67 and doublecortin (DCX). In the object recognition memory test and contextual fear conditioning, mice trained 1 and 7 days after irradiation displayed significant memory deficits compared to the sham-irradiated controls. The number of Ki-67- and DCX-positive cells decreased significantly 24 h post-irradiation. These results indicate that acute exposure of the adult mouse brain to a relatively low dose of fast neutrons interrupts hippocampal functions, including learning and memory, possibly by inhibiting neurogenesis.

Efficacy of closantel against Fasciola hepatica in Korean native goats

Closantel (Flukiver), a salicylanilide antiparasitic compound, was tested in Korean native goats infected with Fasciola hepatica. The goats were administered closantel once orally at a dose of 10 mg/kg body weight. Efficacy was monitored weekly by fecal examination of all infected animals starting the second week post-treatment and continuing for 3 weeks. Closantel elicited 80.3, 97.8 and 92.7% efficacy in goats with naturally-acquired fasciolosis at the second, third and fourth week post-treatment, respectively. It elicited a 100% efficacy in goats experimentally infected with F. hepatica metacercariae and treated at 18 weeks post-infection.