Overexpression of Insulin Degrading Enzyme could Greatly Contribute to Insulin Down-regulation Induced by Short-Term Swimming Exercise / 한국실험동물학회지

Exercise training is highly correlated with the reduced glucose-stimulated insulin secretion (GSIS), although it enhanced insulin sensitivity, glucose uptake and glucose transporter expression to reduce severity of diabetic symptoms. This study investigated the impact of short-term swimming exercise on insulin regulation in the Goto-Kakizaki (GK) rat as a non-obese model of non-insulin-dependent diabetes mellitus. Wistar (W/S) and GK rats were trained 2 hours daily with the swimming exercise for 4 weeks, and then the changes in the metabolism of insulin and glucose were assessed. Body weight was markedly decreased in the exercised GK rats compare to their non-exercised counterpart, while W/S rats did not show any exercise-related changes. Glucose concentration was not changed by exercise, although impaired glucose tolerance was improved in GK rats 120 min after glucose injection. However, insulin concentration was decreased by swimming exercise as in the decrease of GSIS after running exercise. To identify the other cause for exercise-induced insulin down-regulation, the changes in the levels of key factors involved in insulin production (C-peptide) and clearance (insulin-degrading enzyme; IDE) were measured in W/S and GK rats. The C-peptide level was maintained while IDE expression increased markedly. Therefore, these results showed that insulin down-regulation induced by short-term swimming exercise likely attributes to enhanced insulin clearance via IDE over-expression than by altered insulin production.

Topical Application of Selenium Can Significantly Relieve UV-induced Skin Aging in Hairless Mice / 한국실험동물학회지

Ultraviolet (UV) irradiation is an environmental factor that causes skin aging, and is also a major factor leading to cumulative alterations of skin structure, function and appearance. To investigate the effects of Selenium (Sel) on UV-induced skin aging, hairless mice were treated for 4 weeks with UV irradiation and topical application of Sel. Then, the effects of Sel were measured in the skin of these mice via histological analysis and Western blotting. According to the results of wrinkle formation analysis, the topical application of Sel induced a reduction in wrinkling formation in the damaged skin of the UV-irradiated mice. Additionally, our histological analysis demonstrated that the skin thickness in the Sel-treated group was less than in the UV-irradiated group. Furthermore, in an effort to investigate the mechanisms underlying the effects of Sel, the expression levels of matrix-metalloproteinase (MMP) and MAPK protein were assessed in both groups. The application of Sel induced a reduction in MMP-1 expression levels to the levels observed in the non-irradiated group. However, the expression level of MMP-9 was increased slightly in the Sel application group as compared with the vehicle application group. Additionally, the levels of ERK phosphorylation were increased by the application of Sel, but the levels of JNK and p38 were not altered by Sel treatment. These results suggest the possibility that Sel should be considered as a skin aging-protective and therapeutic drug candidate, which functions via the regulation of MMP expression levels.

The Bone Grinding and Scaffold Grafting Techniques for Guide Bone Regeneration Induce the Stress on the Rat Brain / 한국실험동물학회지

Guided bone regeneration (GBR) is a technique that a barrier membrane is placed over the bone defect to prevent the cell growth from the connective tissue and epithelium. In this study, in order to determine whether GBR technique could induce stress in rats, the standardized bone defect in rat calvaria was covered with apatitte membrane. Bone and brain tissues were collected from rats at 3 days, 2, 4, and 16 weeks post-operation, and then alteration of the new bone formation at the defects and stress-related factors were detected with histological examination and Western blot, respectively. From 4 to 16 weeks after the operation, the apatitte membrane was attached to the region of regenerated bone and encapsulated with a thick fibrous layer. Furthermore, the concentration of cortisol, a good indicator of stress, significantly increased 3 days post-operation. However, the increase at 3 days was returned to the basal level in 2 weeks. In Western blot analysis, the highest phosphorylation level of extracellular signal-regulated kinase (ERK) was observed 3 day post-operation, while those of the c-jun N-terminal kinase (JNK) and p38 were detected 4 weeks post-operation. Taken together, the results suggest that GBR technique may induce the serious stress on the brain tissue via the induction of ERK phosphorylation during 2 weeks, and that the stress responses restored in 4 week via JNK and p38 signaling pathway.

Effect of Long-Term Food Restriction on Nitric Oxide Synthase-Positive Neurons in Rat Cerebral Cortex / 대한해부학회지

Nitric oxide is synthesized by cells containing the nitric oxide synthase (NOS), and NADPH-diaphorase (NADPH-d) is a selective histochemical marker for the NOS in the brain. The influence of feeding rats only half the amount of their normal daily intake of a purified diet on NOS was measured in the cerebral cortex by immunohistochemistry and NADPH-d histochemistry. iNOS was not detected in the cerebral cortex of control group. iNOS-positive neurons were induced in the cerebral cortex at 1 week after food restriction and found in specific cortical areas, such as primary motor cortex, secondary motor cortex, primary somatosensory cortex, secondary somatosensory cortex, parietal association cortex, auditory cortex, visual cortex, temporal association cortex and retrosplenial cortex. At 2 weeks after food restriction, iNOS-positive neurons were not found in all cortical areas. At 4 weeks after food restriction, iNOS-positive neurons were found in ectorhinal cortex and perirhinal cortex. In samples obtained 3 days after food restriction, the staining intensity of NADPH-d-positive neurons was decreased in most cortrical regions compared to the control group. At 1 week after food restriction, the staining intensity of NADPH-d was significantly increased in isocortical regions compared to the control group. At 9 weeks after food restriction, the staining intensity of NADPH-d was significantly decreased in all cortical regions. NO, a free radical synthesized in the brain by NOS, is a messenger molecule that mediates vascular dilatation and neural transmission. Therefore, neurons showing induced iNOS-positivity and upregulated NADPH-d-positive neurons may affect the neuronal activity in the cerebral cortex after food restriction.

A Study on the Postnatal Development of NADPH-Diaphorase Positive Neurons in the Cerebral Cortex and Striatum of Apodemus agrarius / 대한해부학회지

Nitric oxide (NO) is a short lived membrane permeable gas, a recently identified neuronal messenger molecule, and implicated in several activity-dependent forms of synaptic plasticity. The histochemical staining of NADPH-diaphorase (NADPH-d) provides a simple method to select populations of neurons containing nitric oxide synthase (NOS), throughout the brain. The NADPH-d positive neurons, uniquely resistant to toxic insults and neurodegenerative diseases, have been colocalized with neurons in the brain and peripheral tissue containing NOS. Apodemus agrarius has been used for experimental purpose to identify the route of infection and pathogenesis of korean hemorrhagic fever. However, despite of the increasing publication at present about the physiologic and ecologic characteristics of Apodemus, a few data are available about the morphologic findings in the brain. In this study we used NADPH-d histochemistry to evaluate the distribution of neurons, contain NOS, on the postnatal development in cerebral cortex and striatum of the Apodemus agrarius. In the cerebral cortex of Apodemus agrarius, NADPH-d positive neurons were observed in all cortical layers, but were concentrated in V-VI layer. NADPH-d positive neurons of forebrain were more dense than other cortical regions. At 1 week after birth, NADPH-d positive neurons had short processes and immature features. In contrast, at 12 weeks after birth, NADPH-d positive neurons had longer and more complex processes than that of earlier ages. In the striatum, NADPH-d positive neurons were intensely stained, predominantly medium-sized neurons. They had multipolar or bipolar dendritic branches which belong to fusiform or stellate cell types in all groups. In addition, at 4 and 12 weeks after birth, NADPH-d positive neurons had long and complex fiber network. The number of NADPH-d positive neurons in the striatum was relatively decreased during postnatal development. However, the length and complexity of their processes were relatively increased after birth. Present results showed postnatal maturation patterns such as morphological features of NADPH-d positive neurons. These findings suggest that NADPH-d positive neurons will be reach adult level after 4 weeks of postnatal age. Therefore, this report provide the morphological evidence supporting the hypothesis that NO may be play a role in regulation of neuronal development and synaptic plasticity during postnatal development of Apodemus agrarius.

Coexistence of Tyrosine Hydroxylase and Nicotinamide Adenine Dinucleotide Phosphate-Diaphorase in Hypothalamic Neurons of the Rat / 대한해부학회지

The presence and coexistence of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-diaphorase) with tyrosine hydroxylase (TH) was investigated by combining NADPH-diaphorase histochemistry with TH immunohistochemistry in hypothalamic nuclei of the rat. TH-immunoreactive and NADPH-diaphorase positive neurons were found in the medial preoptic area and medial preoptic nucleus, anterior hypothalamic area, dorsomedial hypothalamic nucleus, paraventricular nucleus, supraoptic nucleus and posterior hypothalamic area, respectively. TH and NADPH-diaphorase did not coexist in the anterior hypothalamic area, dorsomedial hypothalamic nucleus, medial preoptic area and posterior hypothalamic area. A considerable portion (30~50%) of the NADPH-diaphorase positive neurons in the supraoptic nucleus colocalized TH. In the medial preoptic area and paraventricular nucleus, some (5~15%) of TH-immunoreactive neurons also contained NADPH-diaphorase activity. NADPH-diaphorase is known to be an indicator of the enzyme nitric oxide synthase; these results therefore suggest that nitric oxide may play an important role in the regulation of the activity of the hypothalamic dopaminergic system of the rat.

A case of immunologic trombocytopenic purpura in pregnancy / 대한산부인과학회잡지

No abstract available.