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The Wnt signaling pathway plays key roles in various developmental processes. Wnt5a, which activates the non-canonical pathway, has been shown to be particularly important for axon guidance and outgrowth as well as dendrite morphogenesis. However, the mechanism underlying the regulation of Wnt5a remains unclear. Here, through conditional disruption of Foxg1 in hippocampal progenitors and postmitotic neurons achieved by crossing Foxg1
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Objective To observe the pyramidal neurons in the hippocampal CA1 area varying with time after heat stroke in rats. Meth-ods Sprague-Dawley rats were divided into sham group (n=5) and heat stroke group (n=14), and the heat stroke group was divided into 7-day subgroup and 21-day subgroup (n=7 at each group) after heat stroke. Heat stroke group was established model of heat stroke. The brain tissues of rats were observed with Nissl staining to count the living pyramidal neurons in hippocampal CA1 area. Results The number of living pyramidal neurons in hippocampal CA1 area decreased in the heat stroke group (F=11.80, P<0.01), and decreased more in the 21-day subgroup than in the 7-day subgroup (P<0.05). Conclusion Pyramidal neurons in hippocampal CA1 area decrease with time after heat stroke, which may be associated with the learning and memory impairment.
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Objective To explore the effects of restraint water-immersion stress (RWIS) on the firing activities of pyramidal neurons in the medial prefrontal cortex (MPFC) of rats.Methods Multi-channel in vivo recording techniques were used to record firing activities of pyramidal neurons before and during 4-h RWIS in rats.Firing rates,inter-spike intervals and burst firing rates were taken as indices to study the influence of RWIS on neuronal firing activities.Results Twenty-five pyramidal neurons of 12 rats were recorded.The opposite patterns of firing activities were observed in two different classes of neurons,type A and type B neurons which account for 72％ and 28％,respectively.In type A neurons,inhibited firing activities were in direct proportion to the stress-exposure.Mean firing rates and mean burst firing rates were significantly reduced to (0.81 ± 0.11) Hz and (1.012 ± 0.50) counts/min after 4h constant RWIS compared with those before RWIS,(3.57 ± 0.63) Hz and (10.29 ± 3.04) counts/min.However,in type B neurons,firing activities were enhanced.After 2h constant RWIS,mean firing rates and mean burst firing rates were increased from (1.77±0.45) Hz and (2.01±0.73) counts/min to (2.67±0.74)Hz and (9.04±2.42) counts/min,respectively.Moreover,the percentage of spikes in bursts was significantly increased and mean inter-spike intervals were remarkably shortened.Interestingly,the effect of RWIS on type B neurons lasted for shorter time compared with its effect on type A neurons.Conclusion RWIS differentially affects the firing activity of pyramidal neuron in the MPFC,i.e.,inhibiting the firing activity of type A neurons,but enhancing the firing activity of type B neurons.
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Objective To investigate the effects of unaggregated amyloid ? protein(A?25～35) on transient outward potassium channel(IA) in Rat Hippocampal CA3 Pyramidal Neurons.Methods Patch-clamp technique with whole cell recording was used.Results Unaggregated A?25～35 inhibited IA in neonatal rat hippocampal CA3 pyramidal neurons and displayed a time-,concentration- and voltage-dependent manner;the dynamic characteristics of IA were influenced:shifted the steady-state activation and inactivation curves to left significantly.Conclusion These results suggest that the inhibition of unaggregated A?25-35 on transient outward potassium channel in acutely isolated hippocampal CA3 pyramidal neurons may be an important mechanism of its toxicity,which participates in pathological changes of AD.
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AIM: To study the effects of huperzine A on the theta-rhythm and long-term potentiation in CA1 pyramidal neurons in adult rat hippocampal slices and to get insight into the cell electrophysiological mechanisms underlying the potentiation of learning and memory by Huperzine A. METHODS: The intracellular recordings from CA1 pyramidal neurons in hippocampal slices related to learning and memory were made to analyze the mechanisms of Hup-A action. RESULTS: Power of frequencies ranged from 4 to 10 Hz was not significantly difference between pre-membrane potential oscillations (MPOs) and post-MPOs in control group, but it was significantly (P
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Neurons are very sensitive to various injuries such as ischemia, hypoxia, hypoglycemia, etc. Frequently, the hippocampal CA1 area has been used as a region for studying ischemic delayed neuronal death, which is induced by middle cerebral artery occlusion (MCAO). However, it is still controversial whether the delayed neuronal death is necrotic or apoptotic. In this study, we investigated the neuronal death in hippocampal CA1 areas by TUNEL stain and electron microscopic observation using a rat MCAO and reperfusion model. RESULTS: 1. The TUNEL positive reaction occurred only within the CA1 area ipsilateral to MCAO. 2. In EM images, many features that imply necrosis were found in the CA1 pyramidal neurons ipsilateral to MCAO. These results indicate that both necrotic and apoptotic features coexist in the delayed neuronal death of the hippocampal CA1 area after MCAO.