Orexin B Enhances the Synaptic Transmission from LGN to Orexin-sensitive Neurons in L6b of Visual Cortex / 中山大学学报(医学科学版)

@#【Objective】To unmask the effect of Orexin B on the synaptic transmission between feed-forward projection from the lateral geniculate nucleus（LGN）to orexin-sensitive neurons in layer 6b（L6b）of visual cortex（VC）.【Methods】C57 mice at P25-P30 were used for micro-injection of CTB555 and ChR2-EGFP into LGN to label the neurons feedback projection to LGN from L6b and the feed-forward projection from LGN to the neurons in L6b of VC respectively. The EPSC in L6b cells was intracellularly recorded from the neurons labeled by CTB555.【Results】The neurons feedback projection to LGN in L6b are mainly pyramidal neurons, and the most of these cells are activated by orexin B，called orexin- sensitive neurons. Orexin B enhanced the NMDAR-mediated postsynaptic current in orexin-sensitive neurons in L6b by electrical or optical stimulation on the LGN projection to VC［electrical stimulation：（125.1 ± 3.7）%，optical stimulation：（123.8 ±3.8）%. In the case of OX2R′s blocker，the effect of Orexin B on EPSC amplitude disappeared with significant statistical significance，P < 0.05］，thus，strengthening the synaptic transmission between LGN and orexin-sensitive neurons in L6b.【Conclusions】Orexin B enhances the synaptic transmission between LGN to pyramidal neurons in L6b of VC.

Comparison of dopamine levels in the lateral geniculate nucleus in guinea pigs with flickering light?induced and form deprivation myopia / 中国实验动物学报

Objective To observe the dopamine(DA)concentrations in the lateral geniculate nucleus in guinea pigs with flickering light-induced and form deprivation myopia,and to compare and analyze the pathogenetic mechanisms in the centers of vision of these two different myopia models. Methods Twenty-four two-week-old guinea pigs were randomly assigned to three groups(n=8):flickering light-induced myopia(FLM)group, form deprivation myopia(FDM)group and control group. All the groups were fed for 8 weeks. The refraction and axial length(AL)were measured before and af-ter modeling. After eight-week modeling,the contents of dopamine in the left lateral geniculate nucleus were detected by high performance liquid chromatography with electrochemical detection(HPLC-ECD). Results Before modeling,no sig-nificant difference was found in refraction and AL among the three groups. After eight-week modeling,in contrast with the control group,significant differences were found in changes of both refraction(P<0.001)and AL(P<0.05)in the right eyes of FLM and FDM groups,indicating that the two myopic models were successfully established. The result of HPLC-ECD showed that the contents of DA in the left lateral geniculate nucleus in FLM group were significantly higher than the control group(P=0.01),while in the FDM group it was lower than the control group(P=0.021). The average contents of DA were as follows:(37.04 ± 1.18)pg/μL in the control group;(24.27 ± 3.46)pg/μL in the FDM group; and (45.58 ± 1.98)pg/μL in the FLM group. Conclusions The content of DA in the lateral geniculate nucleus is increased in FLM,while decreased in FDM,indicating that the expression of DA in LGN and the mechanisms of formation of these two experimental myopia are different.

Neuroprotective effect of epigallocatechin-3-gallate on lateral geniculate nucleus after optic nerve crush in rats / 中华实验眼科杂志

Background Researches demonstrated that epigallocatechin-3-gallate(EGCG) can protect retinal ganglion cells(RGCs) against damage induced by retinal ischemia-reperfusion and optic nerve crush(ONC),but the effect of EGCG on lateral geniculate nucleus(LGN) was under study.Objective This study was designed to detect neuroprotective effect of EGCG on LGN in the rat model with ONC.Methods Forty-eight 7-week-old female clean Wistar rats were randomly divided into normal control group,sham operation+EGCG group,ONC+normal saline(NS) group and ONC+EGCG group.ONC models were created by clamping the optical nerve for 60 seconds with the clipper with the force of 40 grams in the right eyes of 24 rats.The EGCG solution(25mg/kg) was intraperitoneally injected from 2 days before operation daily for 5 consecutively days and orally administered(2mg/kg) after that,and NS was used in the same way for ONC+NS group.Four weeks after ONC,the brain tissue of the rats was obtained,and the neurons of dorsal LGN(dLGN) were counted by Nissl staining under the light microscopy.The expression of neurofilament triplet L(NF-L) was detected by immunohistochemistry and Western blot analysis.Meanwhile,the neuronal nitric oxide synthase(nNOS) positive cells were counted.Results Compared with normal control group,no significant differences were found in neuron number both between sham operation+EGCG group or ipsilateral LGN of operative eyes in ONC+normal saline group and ONC+EGCG group(P=0.906,0.561,0.794,0.646 respectively) in 4 weeks after ONC,but loss of neurons in contralateral LGN in both ONC+normal saline group and ONC+EGCG group were observed(P=0.000,0.015 respectively).However,compared with ONC+normal saline group,the density of neurons in ONC+EGCG group was higher(P=0.007).Moreover,a higher expression level of NF-L protein was seen in ONC+EGCG group compared with ONC+normal saline group at contralateral LGN of operative eyes(P=0.002).Concerning the number of nNOS positive cells in LGN,there was no significant difference among normal control group,sham operation+EGCG group and ONC+EGCG group(P＞0.05).The number of nNOS positive cells in the contralateral LGN of operative eyes of ONC+normal saline group was higher than that of ONC+EGCG group(P=0.000).Conclusion EGCG plays the protective effect on LGN after ONC in rats through mediating the expression of nNOS.

c-Fos Immunoreactivity in the Neurons of the Lateral Geniculate Nucleus in Albino Rats by Light Exposure after Dark Rearing

PURPOSE: To investigate the effect of dark rearing immediately after birth on the maturation of the visual relay neurons in the lateral geniculate nucleus. METHODS: Fifty neonatal rats were used. Neonates of the control groups were raised under a normal light/dark cycle. Neonates of the experiment groups were dark reared and isolated from light during the entire experimental period, then exposed to the sun light for 1 hour before sacrifice. RESULTS: In the control groups, the neurons in the dorsal lateral geniculate nucleus developed normally at each age tested. In the experiment groups, the cytoplasm of the large neurons in the dorsal lateral geniculate nucleus of 2-week-old rats contained small vesicles, and the cytoplasm of the large neurons of 4-week-old rats was converted into a vacuole-like space. Moreover, c-Fos immunoreactivity of the large neurons in the dorsal lateral geniculate nucleus in the experiment groups was significantly increased compared to that of the control groups. CONCLUSIONS: We suppose that the maturation of the neurons in the lateral geniculate nucleus might be influenced by light stimulation during the critical period. Furthermore, c-Fos could be a marker of the functional activity of the visual relay neurons of the lateral geniculate nucleus in albino rats.

PROPERTIES OF DENDRITIC FIELDS OF THE NEURONES IN THE VISUAL CORTEX AND DORSAL LATERAL GENICULATENUCLEUS OF CAT'S---A QUANTITATIVE ANALYSIS WITH BIAS / 解剖学报

Golgi and Golgi-Cox methods were used to stain the neurones in the II, III layers of 17, 18 areas, lateral suprasylvian area (LS area) of visual cortex and of dorsal lateral geniculate nucleus (LGNd). 298 cells in the II, III layers of 17, 18 areas, 310 cells in the II, III layers of LS area and 168 cells in LGNd were plotted with microscope and camera lucida. Bias was introduced to analyze the properties of dendritic fields of these cells quantitatively. Our results indicated that most of the cells in three areas had elongated and oriented dendritic fields. The proportion of the cells with dendritic fields parallel to the surface of 17, 18 areas was significantly higherthan that of LS area. In LGNd the orientation of dendritic fields of most adjacent cells was similar and the biases of class 3 cells were significantly higher than that of class 1.

MORPHOLOGY OF NEURONS AND IDENTIFICATION OF PROJECTING CELLS IN THE HAMSTER DORSAL LATERAL GENICULATE NUCLEUS / 解剖学报

Rapid Golgi preparations of golden hamster dorsal lateral geniculate nucleus (LGd)show three classes of neurons with different morphological characteristics. Class Ⅰ and class Ⅲ cells are distributed throughout the LGd.Class Ⅱ cells are found more common medially at mid-genieulate levels.Class Ⅰ cells are multipolar neurons with large cell body.The smooth primary dendrites branch extensively. Spine-like and small excrescences are found along distal dendrites.Class Ⅱ cells have medium size pear-like cell body.The distal dendrites are usually derived from one primary dentrite.Dense cluster of dentritic protrusions is usually found at branch points of the dendrites.Class Ⅲ cells have the smallest cell body and are paucidendritie but the dendrites have complex protrusions including pearl-like dendritic appendages.Class Ⅰ and class Ⅱ cells possess an axon but most of class Ⅲ cells are not found to have an axon. The connections between the LGd and visual cortex was investigated using the retrograde horseradish peroxidase(HRP)histochemical method.After injection of HRP into the visual cortex,Class Ⅰ and class Ⅱ neurons were labelled but class Ⅲ celts were not suggesting that class Ⅰ and class Ⅱ cells are projecting neurons.Class Ⅲ cells do not seem to project to the visual cortex and are probably local circuit neurons.