Hippocampal Interneurons are Required for Trace Eyeblink Conditioning in Mice / 神经科学通报·英文版

While the hippocampus has been implicated in supporting the association among time-separated events, the underlying cellular mechanisms have not been fully clarified. Here, we combined in vivo multi-channel recording and optogenetics to investigate the activity of hippocampal interneurons in freely-moving mice performing a trace eyeblink conditioning (tEBC) task. We found that the hippocampal interneurons exhibited conditioned stimulus (CS)-evoked sustained activity, which predicted the performance of conditioned eyeblink responses (CRs) in the early acquisition of the tEBC. Consistent with this, greater proportions of hippocampal pyramidal cells showed CS-evoked decreased activity in the early acquisition of the tEBC. Moreover, optogenetic suppression of the sustained activity in hippocampal interneurons severely impaired acquisition of the tEBC. In contrast, suppression of the sustained activity of hippocampal interneurons had no effect on the performance of well-learned CRs. Our findings highlight the role of hippocampal interneurons in the tEBC, and point to a potential cellular mechanism subserving associative learning.

Teaching design of innovation experiment for closed-loop control of optogenetics / 中华医学教育探索杂志

Combining with advances in optogenetics and feedback control of physiological function, we have utilized self-made PPDP (preview, presentation, demonstration, promotion) teaching method to clarify how various physiological functions are regulated by the nervous system and carried out physiological innovation experiment activities. The innovative experiments aim to cultivate students' self-study capability, broaden their vision, enhance their interest in physiology, and finally promote the effect of physiological theory teaching. We herein summarize our practice of closed-loop control of innovative experimental teaching in optogenetics from the following four facets: education concept, students and teacher resources, teaching design, and teaching experience. This summary is trying to explore new experiences of promoting students' participation in teaching activities and improving the teaching quality of physiology.

Changes in neural cell adhesion molecule mRNA expression and protein level in the CA1 region of the hippocampus during long term potentiation induction and maintenance / 生理学报

It has been demonstrated that neural cell adhesion molecule (NCAM) is critical for the induction and maintenance of long term potentiation (LTP) in the CA1 region of rat hippocampus. In the present study, we investigated the changes in NCAM mRNA expression and NCAM protein level after the induction of LTP in vitro using the techniques of in situ hybridization and Western blot. The results showed that the number of NCAM mRNA positive labelled neurons significantly increased (76.6+/-11.5 neurons) 10 min after tetanus when the slope of fEPSP markedly increased. The level of NCAM protein also increased significantly (7.190+/-0.64 arbitrary unit/50 microg protein) 10 min after tetanus. The number of NCAM mRNA positive labelled neurons no longer changed (73.3+/-14.0) 1 h after tetanus, however, the NCAM protein level (9.031+/-0.71) at 1 h after tetanus was higher than that at 10 min after tetanus. Moreover, the NMDA receptor inhibitor AP-5, which blocked LTP, prevented the increase in NCAM mRNA expression and NCAM protein level. The results demonstrate that NCAM mRNA expression maintains a high level, whereas NCAM protein changes from a low level to a high level during induction and maintenance of LTP.

Microinjection of adenosine into orexinergic zone of lateral hypothalamus on sleep-wake cycle in rats / 第三军医大学学报

Objective To investigate the effect of extragenous adenosine(AD) by microinjection in the orexinergic area of rat lateral hypothalamus(LH) on the sleep-wake cycle.Methods A total of 14 male SD rats were given 1,10 or 20 nmol AD and artificial cerebrospinal fluid(aCSF) as own control through three different models of microinjections into the LH.Their electroencephalogram(EEG) and electromyogram(EMG) were recorded by a polygraph recording instrument to observe the changes of sleep-wake after microinjections.Results AD administration to LH at doses of 1,10 and 20 nmol decreased the total amount of wakefulness by 84%,62% and 60% fold during that first 3-hour recording period and concomitantly increased non rapid eye movement(NREM) and REM sleep,when compared with aCSF treatment.The sleep-inducing effect was maintained even in 3 hour after the 20 nmol AD microinjection.The maximal sleep-inducing effect was obtained at the 20 nmol dose of AD administration into the orexinergic LH(P

Changes in electrophysiological and morphological properties of neurons during the development of the visual cortex in the rat / 生理学报

To investigate the intracellular mechanism of activity-dependent synapses formation and redistribution, we studied the electrophysiological and morphological characteristics of neurons of the developing visual cortex, and observed the level of synchronism of age and changes in the properties. Whole cell patch-clamp recordings and intracellular biocytin staining were used to record postsynaptic currents (PSCs) from neurons in the visual cortex of Sprague-Dawley rats (postnatal d 4-28). The histological processing was made. There were three types of PSCs in 156 cells: silent response, monosynaptic response and polysynaptic response, during the first developmental month. Before eyes opened the number of the neurons with the silent response (57.3%) was significantly higher than that after the eyes opened (11.9%) (P<0.001). However, the incidence of polysynaptic PSCs increased from 12.4% before eyes opened to 28.9% after eyes opened (P<0.01). During postnatal week 1, all cells were classified as immature. The immature cells had very high input resistances (R(N)>1.0 G Omega), low amplitude (-0.87 mA) and short decay time (-0.98 ms). During postnatal week 4, all cells were mature with lower input resistance (R(N)<310 M Omega), larger amplitude (-66 mA), and longer decay time (-225 ms). From postnatal weeks 1 to 3, the cells had electrophysiological properties that were intermediate between the immature and mature types of cells. With biocytin intracellular staining, five types of neurons were obtained: pyramidal cells, satellite cells, basket cells, neuroglial cells and immature cells. On the basis of their electrophysiological and morphological characteristics, pyramidal cells were classified into three categories: immature, intermediate, and mature cell types. During postnatal week 1, cells were immature with very high input resistance. Morphologically immature cells had short simple dendritic arborizations which incompletely penetrated the layer where the cell body lies. From postnatal weeks 2 to 4, the cells were mature with low input resistance. They were morphologically more complex with dendritic arborizations which completely penetrated the whole layers of the visual cortex. From postnatal weeks 1 to 2, a third, intermediate cell type had electrophysiological properties that were intermediate between the immature and mature cell types. Three distinctive types of pyramidal cells in visual cortex only co-exist during postnatal weeks 1 to 2. Data show that activity-dependent synapes are formed and integrated into local neuronal networks with visual stimulation. In the critical period of visual development, the level of synchronism of age and changes in electrophysiological and morphological properties in the visual cortex is higher than that in the subcortex.

Relationship between hippocampal long term potentiation induction and activity of 26S proteasome / 生理学报

The present study examined the changes in 26S proteasome activity and the signal molecule mechanism regulating 26S proteasome activity in long term potentiation (LTP) in rat hippocampal slices. The results are as follows: 26S proteasome activity was 190+/-14.3 cpm/(100 microg.2 h) before tetanus, a significant increase in 26S proteasome activity (273+/-18.3 cpm/(100 microg.2 h) was found 10 min after tetanus, when the slope of fEPSP was markedly increased. Interestingly, 26S proteasome activity returned to baseline level (210+/-12.8 cpm/(100 microg.2 h) 60 min after tetanus. Moreover, the N-methyl-D-aspartate (NMDA) receptor inhibitor AP-5, which blocked LTP, prevented the increase in the 26S proteasome activity. The results suggest that NMDA receptors contribute to the transient increase in 26S proteasome activity during induction of LTP in the hippocampal CA1 region.