Chung-Min Shin

Immunocytochemical study on the distribution of nitrotyrosine in the brain of the transgenic mice expressing a human Cu/Zn SOD mutation

In the previous study, we reported increased NOS expression in the astrocytes in the spinal cord of the transgenic mice that are used as ALS animal model. In the present study, we performed immunocytochemical studies to investigate the changes of nitrotyrosine-immunoreactivity in the brains of the transgenic mice, and demonstrated in vivo evidence of peroxynitrite-mediated oxidative damage in the pathogenesis of ALS. In the spinal cord of the transgenic mice, immunocytochemistry showed intensely stained nitrotyrosine-IR glial cells with the appearance of astrocytes, but no nitrotyrosine-IR glial cells were observed in the spinal cord of the control mice. In the transgenic mice, nitrotyrosine-IR neurons were observed in the hypoglossal nucleus, lateral reticular nucleus, medullary reticular formation and cerebellar nuclei. Interestingly, nitrotyrosine-IR neurons were observed in the hippocampal formation and septal area of the transgenic mice. In the hippocampus, nitrotyrosine-IR neurons in the CA1 region showed intense staining, and the immunoreactivity was localized mainly in the pyramidal cell layer. Recent studies have shown that antioxidants and selective neuronal NOS inhibitor increase survival in the SOD1 transgenic mouse model of FALS. It is possible that therapy with these agents may slow the neurodegenerative process in human ALS, perhaps through reduction of nitrotyrosine formation.

Immunohistochemical study on the distribution of six members of the Kv1 channel subunits in the rat cerebellum

Voltage-gated K(+) (Kv) channels are critical for a wide variety of processes, and play an essential role in neurons. In the present study, we have demonstrated a unique pattern of expression of the six Kv1 channel subunits in the rat cerebellum, for the first time. The greatest concentration of Kv1.2 was found in the basket cell axon plexus and terminal regions around the Purkinje cells. Relatively weak immunoreactivity for Kv1.1 was also found in this area. The somatodendritic Purkinje cell areas were intensely stained with anti-Kv1.5 antibodies. In the cerebellar nuclei, the cell bodies of cerebellar output neurons showed strong Kv1.5 and Kv1.6 immunoreactivities in the nucleus medialis, interpositus and lateralis. Interestingly, Kv1.2 immunoreactivity was found in some neurons with their processes. Our immunohistochemical results may support the notion that the formation of heteromultimeric Kv channels possibly represents an important contribution to the generation of Kv channel diversity in the brain, especially in the cerebellum.

Bisphosphonate use and increased incidence of subtrochanteric fracture in South Korea: results from the National Claim Registry

SummaryWe evaluated trends in the incidences of typical and atypical hip fracture in relation to bisphosphonate use in Korea from 2006 to 2010, using nationwide data obtained from the Health Insurance Review and Assessment Service (HIRA).IntroductionRecently, atypical hip fractures in the subtrochanteric region have been reported among patients on bisphosphonate. However, the association between atypical hip fracture and bisphosphonate is controversial. We evaluated trends in the incidences of typical and atypical hip fracture in relation to bisphosphonate use in Korea from 2006 to 2010, using nationwide data obtained from the HIRA.MethodsAll new visits or admissions to clinics or hospitals for a typical and atypical hip fractures were recorded nationwide by HIRA using the ICD-10 code classification. Typical and atypical hip fractures were defined as femoral neck/intertrochanteric and subtrochanteric fracture, respectively. Bisphosphonate prescription data were also abstracted from the HIRA database.ResultsThe absolute number of typical and atypical hip fracture increased during the study period. Although age-adjusted incidence rates of typical hip fractures were stable in men and women, those of atypical hip fractures increased in women. Nationally, the annual numbers of prescriptions of bisphosphonate also increased during the study period.ConclusionsThe results of this study suggest a possible causal relationship between bisphosphonate use and the increased incidence of atypical hip fracture in Korea.

Fat mass is negatively associated with bone mineral content in Koreans

SummaryAlthough obesity and osteoporosis are important public health problems, the effect of fat mass on bone mass remains controversial. This study demonstrated that fat mass was inversely related to bone mineral content, and abdominal obesity was significantly associated with bone mineral content independent of total fat mass.IntroductionObesity and osteoporosis, two disorders of body composition, have become increasingly important public health problems throughout the world. However, the effect of fat mass on bone mass remains controversial. This study investigates the effect of fat mass and regional fat distribution on bone mass within a community-dwelling cohort.MethodsA total of 3,042 subjects (1,284 men, 362 premenopausal women, and 1,396 postmenopausal women) were studied. Fat mass, percent fat mass, lean mass, percent lean mass, and bone mineral content (BMC) were measured by dual energy X-ray absorptiometry.ResultsFat mass and percent fat mass decreased significantly across increasing tertiles of BMC in all three subgroups (men, premenopausal and postmenopausal women). In contrast, lean mass and percent lean mass increased significantly across tertiles of BMC in men, and a similar trend was also identified in postmenopausal women. Interestingly, although correlation analysis showed a positive association between fat mass and BMC (p < 0.05), this association became negative after controlling for age and weight (p < 0.05). Finally, in premenopausal and postmenopausal women, subjects with the lowest waist circumference (WC) had the highest BMC in the higher three quartiles of percent fat mass after adjusting for age and weight (p < 0.05), indicating that abdominal obesity is associated with BMC independent of total fat mass.ConclusionThis study demonstrated that fat mass was inversely related to BMC after removing the mechanical loading effect in Korean men and women. Moreover, abdominal obesity as measured by WC was significantly associated with BMC independent of total fat mass.

Enhanced expression of L-type Ca2+ channels in reactive astrocytes after ischemic injury in rats.

In the present study, we have examined the expression of voltage-gated calcium channels in a rat model of transient focal ischemia using immunohistochemistry. Increased expression of class C L-type Ca2+ channels was clearly detected in reactive astrocytes in each region of the hippocampus 7 days after ischemic injury. On the contrary, class D L-type Ca2+ channels were not expressed in reactive astrocytes under these conditions. These patterns were also observed in reactive astrocytes in the affected cerebral cortex and fiber tracts. Our study showed the spatial and temporal localization of class C L-type Ca2+ channels in reactive astrocytes in ischemic rat brain, for the first time. The present studies may provide useful data for future investigations to understand the role of Ca2+ channels in reactive astrocytes following ischemia or glutamate toxicity.

Reactive astrocytes express p53 in the spinal cord of transgenic mice expressing a human Cu/ Zn SOD mutation

In a previous study, we reported increased NOS expression in the astrocytes in the spinal cord of SOD mutant transgenic mice that are used as ALS animal model. Recently, Messmer and Brune suggested that nitric oxide-induced apoptosis is intimately related with p53-dependent signaling pathway, and de la Monte et al. reported increased p53-immunoreactivity in the spinal cord of ALS patients. In the present study, we performed immunocytochemical studies to investigate the changes of p53-immunoreactivity in the brains of the mutant transgenic mice expressing a human Cu/Zn SOD mutation. Immunocytochemistry showed intensely stained p53-IR glial cells with the appearance of astrocytes in all levels of the spinal cord of the mutant transgenic mice, but no p53-IR glial cells were observed in the spinal cord of the control mice. P53-IR astrocytes were also detected in the brain stem of the mutant transgenic mice. In the medulla, they were observed in the medullary reticular formation, hypoglossal nucleus, vestibular nucleus, dorsal motor nucleus of the vagus and nucleus ambiguus. In the pons, their presences were noted in the pontine reticular formation, and trigeminal and facial nuclei. In the midbrain, astrocytes were detected in the mesencephalic reticular formation, red nucleus and periaqueductal gray matter. In the cerebellum, intensely stained p53-IR astrocytes were detected in the intracerebellar nuclei. In contrast to the mutant transgenic mice, no p53-IR astrocytes were detected in the brain stem and spinal cord of the control mice. Further multidisciplinary investigations involving p53-mediated cellular damage and pathogenesis of ALS are needed to clarify the importance of these results.

Immunocytochemical study on the distribution of p53 in the hippocampus and cerebellum of the aged rat

A role for p53-mediated modulation of neuronal viability has been suggested by the finding that p53 expression is increased in damaged neurons in models of ischemia and epilepsy. P53 gene upregulation precedes apoptosis in many cell types, and a potential role for this molecule in apoptosis of neurons has already been demonstrated in Alzheimers disease. Recent studies suggest that p53-associated apoptosis may be a common mechanism of cell loss in several important neurodegenerative diseases. In the present study, we examined changes in p53-immunoreactive (IR) neurons in the brains of aged rats for the first time employing immunocytochemical and in situ hybridization methods. P53-IR neurons were found in the CA1 region of hippocampus, septal region and cerebellum in the aged rats, but there was no p53-IR cell in the brains of adult rats. In the hippocampus of the aged rat, p53-IR cells predominated in the stratum oriens and pyramidal layers, while the molecular layer contained relatively few p53-IR cells. The most prominent population of immunoreactive labeling in cerebellar cortex was localised within the cell bodies of Purkinje cells and dendrites in molecular layers. Upregulation of p53 in the Purkinje cells observed in this study suggests that significant loss of Purkinje cells with aging may be regulated with several apoptosis-controlling factors including p53 and oxidative stress mechanism. Further investigations are required to establish whether direct functional relations exist between p53 and the apoptotic neuronal death in normal aging or Alzheimer brains.

Immunohistochemical study on the distribution of six members of the Kv1 channel subunits in the rat basal ganglia.

The differential expression of specialized voltage-gated potassium (Kv) channel subtypes in the nervous system probably reflects the wide range of functions. Although there have been previous reports in the cellular and subcellular localizations of various Kv mRNAs and proteins, the comprehensive study described here is the first in which the expression of six Kv1 channel subunits have been directly compared in the rat basal ganglia. In the present study, we have found that staining patterns of the six Kv1 channel subunits overlap in some areas of the basal ganglia, but each has a unique pattern of expression. It was noted that Kv 1.4 subunit had a strikingly high level of expression in the globus pallidus compared to the caudate-putamen. This distinct distribution formed the clear demarcations between caudate-putamen and globus pallidus. The dot-like staining pattern of Kv1 subunits was observed through the accumbens nucleus. Strong staining for Kv1.4 was observed in the cerebral peduncle, not in the subthalamic nucleus. In the substantia nigra, immunoreactivity for Kv1.4 subunit was prominent in the pars reticulata of the substantia nigra. The staining intensity for Kv1.2 was high in the pars compacta of the substantia nigra. Our immunohistochemical results may support the notion that the formation of heteromultimeric Kv channels possibly represents an important contribution to the generation of Kv channel diversity in the brain, especially in the basal ganglia.

Region-specific changes of NOS-IR cells in the basal ganglia of the aged rat.

Nitric oxide (NO) is a free radical postulated to act as a neurotransmitter, neuromodulator, or second messenger molecule in the central nervous system. Several findings suggest that NO production may be decreased in the aged rats. In the present study, we investigated regional discrepancies in changes with aging in the number of nitric oxide synthase-immunoreactive (NOS-IR) cells in the basal ganglia of the aged rat by immunocytochemistry. The number of NOS-IR neurons in the striatum and substantia innominata of the aged rat decreased. In contrast, the number of NOS-IR neurons in the subthalamic nucleus increased in the aged rat. On the other hand, the number of NOS-IR neurons in the nucleus accumbens and olfactory tubercle did not change. Taken together, important functional changes can be caused by the region-specific changes of NOS-IR neurons in the basal ganglia with aging.

Immunohistochemical study on the distribution of neuronal voltage-gated calcium channels in the rat cerebellum.

Many neuronal processes are regulated by calcium influx through voltage-gated calcium channels (VGCCs), including protein phosphorylation, gene expression, neurotransmitter release, and firing patterns of action potential. In the present study, we have used anti-peptide antibodies directed against a unique sequence in rat alpha(1A), alpha(1B), alpha(1C) and alpha(1D) subunits of VGCCs to determine their cellular distribution in normal rat cerebellum. Throughout the molecular layer, immunoreactivity for alpha(1B) and alpha(1D) subunits were found in the cell bodies of basket and stellate cells as well as in the neuropil. In the Purkinje cells, only alpha(1C)-IR was observed in the dendritic branches of Purkinje cells, whereas immunoreactivity for alpha(1B) and alpha(1D) subunits were rarely found in the cell bodies of Purkinje cells. Immunoreactivity for the alpha(1A), alpha(1B,) and alpha(1D) subunits were strong in the granule cell bodies, whereas alpha(1C)-IR was not prominent in the cell bodies. In the cerebellar nuclei, a distinct band of punctate immunoreactivity for the alpha(1A), alpha(1B), alpha(1C), and alpha(1D) subunits were observed. The overall results of the above localization study showed clearly that the alpha(1A), alpha(1B,) alpha(1C) and alpha(1D) pore forming subunits of VGCCs have differential distribution in the rat cerebellum. The present studies may provide useful data for such future investigations to understand the role of calcium channels in neurological pathways.