| Background and Objective There exists neurogenesis in adult brain, which mainly locate in the dentate gyrus and subventricular zone (SVZ), the function of newborn neurons in hippocampus are primarily connected with learning and memory function. the neural precursor cells in SVZ are mainly in the anterior of SVZ, neural precursor cells undergo tangential chain migration through the rostal migratory stream( RMS ) into the olfactory bulb,in which these cells differentiate into granule neurons and interneurons,and its function maybe connected with olfactory identification and memory. Pir as the hippocampus belongs to the limbic system, this area has close relationship with the learning and memory functions, the research on neurogenesis in Pir is very little up to now. Lots of research found that hyperbaric oxygen therapy can improve cognition ability and learning and memory function in patients with vascular dementia. Therefore, it is important that explore the neurogenesis in Pir of VD and the effect after hyperbaric oxygen therapy. AS ischemia is the mainly reason of vascular dementia , it is necessary to measure the blood supply in Pir of VD and that after hyperbaric oxygen therapy in order to understand it better.The object of this article was to explore the proliferation of neural stem cell and neurogenesis in piriform cortex (Pir) of VD adult rat ; Explore the blood supply in Pir of VD adult rat ; Explore the impact of neurogenesis and blood supply in Pir area after VD rats had received hyperbaric oxygen treatment; discuss the relationship between blood supply and neurogenesis in Pir zone.Methods Rats were divided randomly into 3 groups: Normal control group (NC group, normal adult male rats), Vascular dementia group(VD group, vascular dementia adult male rats), Hyperbaric oxygen group(HBO group, vascular dementia adult male rats treated by hyperbaric oxygen for 10 days).There were 10 rats in each group. The model of VD was made by 2-VO method; The rCBF (regional cerebral blood flow), The rCBV(regional cerebral blood volume)and The MTT(mean transit time)in the piriform cortex were measured by CT perfusion image formation technique, the ability of learning and memory were examined by the system of shuttle box, and the express of Nestin in the piriform cortex were detected by immunohistochemical method in order to estimate the proliferation of NSCs; and the express of doublecortin(DCX) in the piriform cortex were detected by immunohistochemical method in order to figure the migration,differentiation and neurogenesis.Results In Pir of VD group, the rCBF declined, rCBV improved, and MTT delayed than that in NC group; In Pir of HBO group, rCBF improved , rCBV declined, and MTT accelerated than that in VD group; In Pir of HBO group, the data of rCBF, rCBV and MTT approached to that in NC group; In pir, Nestin(+) cells mostly located in layer II and layer III. The expression was stronger on layer II than that in layer III. The positive cells were rarely seen on layer I (plexiform layer). The positive cells were few near rf and the expression was weak,while near af the expression was stronger. The intensity of expression of positive cells : HBO group > VD group > NCgroup; In pir, DCX(+) cells were arrayed as a belt, mostly located in layer II from amygdaline fissure (af) to rhinal fissure (rf). The distribution of DCX positive cells was uneven. Most cells were located near af, centering near the one third dividing point next to af in layer II. The positive cells were few near rf and they were rarely seen above rf. There were positive cells near af and there were even few positive cells beyond af.There was significant difference in AAR ratio of shuttle box between HBO group (49.5±9.3)% and VD group(27.5±7.9)%,(P<0.01); and There was also significant difference in AAR ratio of shuttle box between VD group (27.5±7.9)% and NC group(87.5±7.9)%, (P<0.01).Conclusion1. neurogenesis in Pir of vascular dementia adult rat is inhibited;2. blood supply in Pir of vascular dementia adult rat is poorer than that in normal rat;3. neurogenesis in Pir of vascular dementia adult rat is enhanced after hyperbaric oxygen therapy;4. blood supply in Pir of vascular dementia adult rat is improved after hyperbaric oxygen therapy;5. Hyperbaric oxygen therapy can improve learning and memory function in vascular dementia adult rat;6. HBO therapy can enhance the ability of study and memory and promote neurogenesis in Pir of vascular dementia adult rat, and that might be associated with HBO therapy improving neurogenesis in Pir of vascular dementia adult rat. |
