Inducible Nitric Oxide Synthase In Rat Model Of Pathological Process Of Alzheimer's Disease

PartⅠInducible nitric oxide synthase paticaptes in the pathological progress of mouse model of Alzheimer's diseaseBackground and Objective: Nitric oxide (NO) is a neurostransmitter involved in a variety of physiological activities. However, overproduction of NO may cause oxidative stress and nitric damage to neuron and synapses in the pathological state. In the central nervous system, NO is mainly synthesized by neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS). Several studies indicate that iNOS participate in the pathogenesis and progression of Alzheimer's disease (AD). Previous studies from our laboratory indicated that ovariectomized rats injected with D-galactose mimic pathological progress of sporadic AD patients. The purpose of this study was to verify whether iNOS is involved in the pathological progression of this AD model.Methods and Results: Adult female ICR mice received bilateral ovariectomy and then daily injection of D-galactose for eight weeks.1. Compared with control group, model group had increased NO production and activities of iNOS, and reduced activities of nNOS, as revealed by biochemical analysis. Consistently, western blot revealed increased expression of iNOS and reduced expression of nNOS.2. Immunohistochemistry showed that, compared with control mice, the number of IBa1-positive microglia and glial fibrillary acidic protein (GFAP)-positive astrocytes increased and the ratio of reactived glial cells also enhanced in the hippocampus and cerebral cortex of model mice.3. Moreover, immunofluorescence labeling revealed that a subpopulation of MAC-1 labeled microglia or GFAP labeled astrocytes coexpressed iNOS and some neuron-like cells also coerpressed iNOS.Conclusion: These results indicated that upregulation of iNOS occurred in the variectomized mice injected with D-galactose AD model, which was.derived from activated microglia, astrocytes and neurons. PartⅡGlutamatergic neurons and astrocytes paticapte in the acute pain transmission induced by formalin injectionBackground and Objective: Glutamate (Glu) widely distributed in central nervous system serves a series of adaptive functions in the mammalian nervous system, including pain sense. Astrocytes can modulate Glu transmission via the glutamate–glutamine cycle. Recent studies reported that glutamatergic neurons and astrocytes are activated in the dorsal horn of spinal cord of rats received subcutaneous formalin injection. The purpose of this study was to further adress whether and how glutamatergic neurons and astrocytes are involved in pain transmission in the central nervous system.Methods and Results: After subcutaneous formalin injection into the hind paw of adult male mice, a series of investigation were performed:1. Behaviors test revealed a typical biphasic nociceptive pattern of licking in model group rats compared with control group.2. Double immunofluorescence labeling for c-Fos/Glu showed that many c-Fos/Glu double labeled neurons were observed in the dorsal horn, ventral posterior lateral nucleus and somatosensory cortex of model mice. In contrast, few double labeled neurons were stained in control mice.3. Immunostaining for glial fibrillary acidic protein (GFAP) revealed that, in model group, the ratio of reactive astrocytes with hypertrophic body drmatically increased in the dorsal horn, but astrocytes were not activated in the ventral posterior lateral nucleus and somatosensory cortex, compared with model group,4. The semi quantitative analysis showed that expressions of GLT1, GLAST, GS and AQP4 in model group were improved when compared with control group, as revealed by immunohistochemistry and western-blot analyses.Conclusion: Glutamatergic neurons participate in the pain transmission in the spinal dorsal horn, ventral posterior lateral nucleus and somatosensory cortex. Astrocytes mediate nociceptive processing by up-regulation of GLT1, GLAST, GS and AQP4 at the dorsal horn of the spinal cord level.