No abstract available.
Brain Injuries* ; Brain* ; Dentate Gyrus*

PURPOSE: The expression of c-Fos protein has been shown to be a useful marker for elevated levels of neuronal activity generated in the brain following different stimuli, including seizures. This study was conducted to investigate distribution and numbers of neurons where dentate and cingulate gyrus become activated following pentylenetetrazol-induced seizures by means of expression patterns of c-Fos protein. METHODS: Rats were sacrificed at increasing times(1 hour, 2 hours, 8 hours, 1 day, 4 days and 7 days) after pentylenetetrazol-induced seizure. Rat brains were removed and sliced in rat brain matrix. Brain slices were coronal sectioned at interaural 5.70-6.70mm. Serial sections were immunohistochemically reacted with polyclonal c-Fos antibody. The distribution and numbers of c-Fos protein immunoreactive neurons in dentate gyrus and cingulate gyrus were examined and analyzed statistically with Mann-Whitney U test. RESULTS: The numbers of c-Fos protein immunoreactive neurons in dentate gyrus peaked at 1 hours and reached almost normal conditions at 7 days after seizure. Also, same patterns were occurred in cingulate gyrus. Concentration value that pentylenetetrazol can induce was different from each animals and c-Fos immunoreactive cells were various kinds of neurons. CONCLUSION: Higher numbers of c-Fos protein immunoreactive neurons were found in dentate and cingulate gyrus at the same times after seizure. These findings suggest that neurons of dentate and cingulate gyrus play a crucial role in seizure onset following pentylenetetrazol-induced seizure.
Animals ; Brain* ; Dentate Gyrus ; Gyrus Cinguli ; Neurons ; Pentylenetetrazole ; Rats* ; Seizures*

Stress induces degeneration of brain structures and functions. Particularly, hippocampus is sensitive to stressful stimulations. In the present study, the change of synaptic related molecules in the mouse dentate gyrus was examined with immunohistochemistry after restraint stress. We subjected mice to restraint stress for 6 h per day for 4 days. As a result, the number of Ki-67, a marker for proliferation, and doublecortin (DCX), a marker for neurogenesis, immunoreactive cells was decreased in the stress group. On the other hand, the intensity of calbindinD-28k, a marker of pre-existing granule cells, immunoreactivity was increased in the granule cell layer after 4 days restraint stress. As well as, the immunoreactivity of synaptic related molecules, postsynaptic density-95 (PSD-95), growth association protein-43 (GAP-43) and beta-NADPH-d reactivity were increased in the inner molecular layer of dentate gyrus after 4 days restraint stress. In conclusion, this study shows that repeated restraint stress suppresses neurogenesis in dentate gyrus and strengthens synaptic plasticity of existing granule cells.
Animals ; Brain ; Dentate Gyrus* ; Hand ; Hippocampus ; Immunohistochemistry ; Mice* ; Neurogenesis ; Plastics*

PURPOSE: The aim of this study was to investigate the potential effects of mild hypoxia in the mature and immature brain. METHODS: We prepared organotypic slice cultures of the hippocampus and used hippocampal tissue cultures at 7 and 14 days in vitro (DIV) to represent the immature and mature brain, respectively. Tissue cultures were exposed to 10% oxygen for 60 minutes. Twenty-four hours after this hypoxic insult, propidium iodide fluorescence images were obtained, and the damaged areas in the cornu ammonis 1 (CA1), CA3, and dentate gyrus (DG) were measured using image analysis. RESULTS: In the 7-DIV group compared to control tissue, hypoxia-exposed tissue showed decreased damage in two regions (CA1: 5.59%+/-2.99% vs. 4.80%+/-1.37%, P=0.900; DG: 33.88%+/-12.53% vs. 15.98%+/-2.37%, P=0.166), but this decrease was not statistically significant. In the 14-DIV group, hypoxia-exposed tissue showed decreased damage compared to control tissues; this decrease was not significant in the CA3 (24.51%+/-6.05% vs. 18.31%+/-3.28%, P=0.373) or DG (15.72%+/-3.47% vs. 9.91%+/-2.11%, P=0.134), but was significant in the CA1 (50.91%+/-5.90% vs. 32.30%+/-3.34%, P=0.004). CONCLUSION: Although only CA1 tissues cultured for 14 DIV showed significantly less damage after exposure to hypoxia, the other tissues examined in this study showed a tendency towards less damage after hypoxic exposure. Therefore, mild hypoxia might play a protective role in the brain.
Anoxia* ; Brain ; Dentate Gyrus ; Fluorescence ; Hippocampus ; Neuroprotective Agents* ; Oxygen ; Propidium

PURPOSE: This study evaluated the extent of damage due to hypothermia in the mature and immature brain. METHODS: Hippocampal tissue cultures at 7 and 14 days in vitro (DIV) were used to represent the immature and mature brain, respectively. The cultures were exposed at 25degrees C for 0, 10, 30, and 60 minutes (n=30 in each subgroup). Propidium iodide fluorescent images were captured 24 and 48 hours after hypothermic injury. Damaged areas of the cornu ammonis 1 (CA1), CA3, and dentate gyrus (DG) were measured using image analysis. RESULTS: At 7 DIV, the tissues exposed to cold injury for 60 minutes showed increased damage in CA1 (P<0.001) and CA3 (P=0.005) compared to the control group at 48 hours. Increased damage to DG was observed at 24 (P=0.008) and 48 hours (P=0.011). The 14 DIV tissues did not demonstrate any significant differences compared with the control group, except for the tissues exposed for 30 minutes in which DG showed less damage at 48 hours than the control group (P=0.048). In tissues at 7 DIV, CA1 (P=0.040) and DG (P=0.013) showed differences in the duration of cold exposure. CONCLUSION: The immature brain is more vulnerable to hypothermic injury than the mature brain.
Animals ; Brain ; Dentate Gyrus ; Hippocampus ; Hypothermia, Induced* ; Neurons* ; Propidium ; Rats*

PURPOSE: To investigate the effect of low dose radiation on neuronal cell proliferation in diabetic rats. MATERIALS AND METHODS: A group of rats (first group) were divided into three subgroups (nondiabetic control, nondiabetic 0.1 Gy and nondiabetic 10 Gy groups) to determine the effect of radiation on normal hippocampal neuronal cell proliferation. A further group of rats (second group) were divided into six subgroups (nondiabetic control, diabetic control, diabetic 0.01 Gy, diabetic 0.1 Gy, diabetic 1 Gy and diabetic 10 Gy groups) to determine the effect of radiation on hippocampal neuronal cell proliferation under diabetic conditions. Using immunohistochemistry for 5-bromo-2'-deoxyuridine (BrdU), the number of neuronal cells in the dentate gyrus of all the groups was counted. RESULTS: The number of BrdU-positive cells in the dentate Gyrus of the nondiabetic control, nondiabetic 0.1 Gy and nondiabetic 10 Gy subgroups of the first group were 45.96+/-3.42, 59.34+/-5.20 and 19.26+/-2.98/mm2, respectively. The number of BrdU-positive cells in the dentate gyrus of the diabetic control, diabetic 0.01 Gy, diabetic 0.1 Gy, diabetic 1 Gy and diabetic 10 Gy subgroups of the second group were 55.44+/-8.57, 33.33+/-6.46, 67.75+/-10.54, 66.63+/-10.05, 23.59+/-6.37 and 14.34+/-7.22/mm2, respectively. CONCLUSION: Low dose radiation enhances cell proliferation in the dentate gyrus of STZ-induced diabetic rats.
Animals ; Bromodeoxyuridine ; Cell Proliferation* ; Dentate Gyrus ; Hippocampus ; Immunohistochemistry ; Neurons* ; Rats*

PURPOSE: To investigate the effect of low dose radiation on neuronal cell proliferation in diabetic rats. MATERIALS AND METHODS: A group of rats (first group) were divided into three subgroups (nondiabetic control, nondiabetic 0.1 Gy and nondiabetic 10 Gy groups) to determine the effect of radiation on normal hippocampal neuronal cell proliferation. A further group of rats (second group) were divided into six subgroups (nondiabetic control, diabetic control, diabetic 0.01 Gy, diabetic 0.1 Gy, diabetic 1 Gy and diabetic 10 Gy groups) to determine the effect of radiation on hippocampal neuronal cell proliferation under diabetic conditions. Using immunohistochemistry for 5-bromo-2'-deoxyuridine (BrdU), the number of neuronal cells in the dentate gyrus of all the groups was counted. RESULTS: The number of BrdU-positive cells in the dentate Gyrus of the nondiabetic control, nondiabetic 0.1 Gy and nondiabetic 10 Gy subgroups of the first group were 45.96+/-3.42, 59.34+/-5.20 and 19.26+/-2.98/mm2, respectively. The number of BrdU-positive cells in the dentate gyrus of the diabetic control, diabetic 0.01 Gy, diabetic 0.1 Gy, diabetic 1 Gy and diabetic 10 Gy subgroups of the second group were 55.44+/-8.57, 33.33+/-6.46, 67.75+/-10.54, 66.63+/-10.05, 23.59+/-6.37 and 14.34+/-7.22/mm2, respectively. CONCLUSION: Low dose radiation enhances cell proliferation in the dentate gyrus of STZ-induced diabetic rats.
Animals ; Bromodeoxyuridine ; Cell Proliferation* ; Dentate Gyrus ; Hippocampus ; Immunohistochemistry ; Neurons* ; Rats*

Amnesic patients who have damage in the hippocampus and in associated areas in the medial temporal lobe suffer from remembering specific events that may or may not share similar objects and locations. Computational models, behavioral studies, and physiological findings all suggest that neural circuits in the hippocampus are suitable for representing seemingly similar events as distinctively different individual event memories. This article offers a selective review on this particular function of the hippocampus and its associates areas such as the perirhinal cortex, mostly centering upon lesion studies and physiological studies using animals. We also present recent experimental results showing that the dentate gyrus subfield of the hippocampus and perirhinal cortex are particularly important for discriminating similar paired associates between same objects and different locations, or vice versa.
Animals ; Brain ; Dentate Gyrus ; Hippocampus ; Humans ; Temporal Lobe

This study was conducted to Identify the effects of diazepam on stress-induced c-fos expression In rat brain. The rats were divided into 4 groups according to injection agents [0.9% isotonic saline 1ml, diazepam(5 mg/kg)] and restraint stress, respectively. Saline or diazepam was injected into the peritoneum of rats 10 minutes before the restraint groups were restrained in a wire chamber. Fos-immunoreactive neurons were calculated in the hippocampal area CA2, dentate gyrus, amygdalohippocampal area, paraventricular nucleus, ventral lateral geniculate nucleus, supramammillary nucleus, temporal cortex area 3, occipital cortex area 2, piriform cortex, and cingulate cortex area 3. The results were as follows: 1) In the hippocampal formation including hippocampal area CA2 and dentate gyrus, Fos expression increased significantly in the saline-injected restraint animals than in any other groups. A two-way factorial ANOVA retreated a significant erects of stress and diazepam, and a significant stress by diazepam interaction. 2) In amygdalohippocampal area, Fos expression increased significantly in the saline-injected restraint animals than in diazepam-injected animals. A two-way factorial ANOVA revealed a significant effects of stress and diazepam, but no significant Interaction of stress and diazepam. 3) In paraventricular nucleus, Fos expression increased significantly in the saline-injected restraint animals than in saline-Injected animals and diazepam-injected animals. A two-way factorial ANOVA revealed a significant effects of stress, no significant effects of diazepam, and no significant Interaction of stress and diazepam. 4) In ventral lateral geniculate nucleus, Fos expression Increased significantly in the saline-injected restraint animals than in diazepam-Infected animals and diazepam-injected restraint animals. A two-way factorial ANOVA revealed a significant effects of diazepam, no significant effects of stress, and no significant interaction of stress and diazepam. 5) In supramammillary nucleus, temporal cortex area 3, occipital cortex area 2, piriform cortex, and cingulate cortex area 3, there was no significant difference of Fos expression in each group. A two-way factorial ANOVA revealed no significant effects of stress and diazepam, and no significant interaction of stress and diazepam. These results suggest that the hippocampal formation is involved in the response to the stress and the tension reduction effect of diazepam.
Animals ; Brain* ; Dentate Gyrus ; Diazepam* ; Gyrus Cinguli ; Hippocampus ; Neurons ; Paraventricular Hypothalamic Nucleus ; Peritoneum ; Rats*

Cyclooxygenase-2 (COX-2) is believed to be a multifunctional neural modulator that affects synaptic plasticity in the hippocampus. In the present study, we investigated the differential effects of treadmill exercise on COX-2 immunoreactivity in the dentate gyrus in early and chronic diabetic stages in Zucker diabetic fatty (ZDF) rats and lean control (ZLC) rats. To this end, ZLC and ZDF rats at 6 or 23 weeks of age were put on a treadmill with or without running for 1 h/day for 5 consecutive days at 16-22 m/min for 5 weeks or 12-16 m/min for 7 weeks, respectively. Treadmill exercise in prediabetic and chronic diabetic rats significantly reduced blood glucose levels. In particular, exercise in the prediabetic rat blocked the onset of diabetes. COX-2 immunoreactivity was mainly detected in the granule cell layer of the dentate gyrus and stratum pyramidale of the CA3 region in all groups. COX-2 immunoreactivity was significantly increased in these regions of ZLC and ZDF rats after treadmill exercise in the early diabetic stage. However, COX-2 immunoreactivity was not changed in these regions in ZDF rats after treadmill exercise in the chronic stage. These results suggest that treadmill exercise in diabetic animals in the chronic stage has limited ability to cause plasticity in the dentate gyrus.
Animals ; Blood Glucose ; Cyclooxygenase 2 ; Dentate Gyrus ; Hippocampus ; Plastics ; Rats ; Running