Association between anti-fibrillin-2 protein induced retinal degeneration via intravitreous delivery and activated TGF-ß signalling in mice.

Fibrillin-2 (FBN2) is a major component of tissue microfibrils, and the decrease of FBN2 perturbs the signalling events mediated by transforming growth factor-ß (TGF-ß), thereby playing a role in macular degeneration. However, the association between the retinal degeneration resulting from the abnormality of FBN2 and the activation of TGF-ß signalling has not been fully addressed. In the present study, the mice were divided into a normal control group (NC group), a phosphate-buffered saline (PBS) injection group (PBS group), and an anti-FBN2 protein injection group (anti-FBN2 group), and the mice in PBS and anti-FBN2 groups received the relevant treatment via the intravitreal injection once a week for three consecutive weeks. One week later after injection, the retinal morphology and visual function of the fundus were detected. Further, the expression of FBN2, TGF-ß1, TGF-ß2 and TGF-ß3 in retina was measured using quantitative polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA), respectively. As a result, fundus examination suggests that after intravitreous injection of anti-FBN2 protein, there were a large patchy yellow white degeneration region and numerous pigmentations in the retina in anti-FBN2-treated mice; by contrast, there was no apparent change in mice from the NC and PBS groups. The retina suffered markedly damage, and the thickness of whole retina and outer nuclear layer markedly thinned. The expression of FBN2 was decreased whereas the levels of TGF-ß1, TGF-ß2 and TGF-ß3 were upregulated. Together, our findings indicate that the intravitreous delivery of anti-FBN2 protein could induce retina degeneration in mice, accompanied by the higher activated TGF-ß. The retinal degeneration mouse model established will provide a platform for the investigation of the retinal diseases.

Changes in visual cortical function in moderately myopic patients: a functional near-infrared spectroscopy study.

PURPOSE: To investigate haemoglobin oxygenation in the visual cortex of myopic patients using functional near-infrared spectroscopy (fNIRS). METHODS: The experiment consisted of two parts. Part 1 examined functional changes in the visual cortex before and after refractive correction in myopic patients. Subjects were divided into normal controls, uncorrected and corrected myopes. Part 2 examined functional changes in the visual cortex caused by lens-induced myopia in normal subjects, and whether this activity recovered after a period of rest. Here, subjects were divided into three groups: emmetropes, lens-induced myopia and a rest group. The rest group completed a test with the uncorrected eye following lens removal and 5 min of rest. The visual stimulus was a black and white checkerboard. fNIRS was used to detect changes in oxyhaemoglobin content within the visual cortex. The original fNIRS data were analysed using MATLAB to obtain the ß values (the visual cortical activity response caused by the task); these were used to calculate Δß, which represents the degree of change in oxygenated haemoglobin caused by visual stimulation. RESULTS: The Δß value measured in each single channel or only in the region of interest (ROI) was significantly higher in the emmetropic control group than the uncorrected myopic group. After optical correction, the responses of myopic subjects approached those of the emmetropes and were not significantly different. If myopia was induced in emmetropic subjects by imposing defocus with positive lenses, a decline in functional activity was observed similar that observed in uncorrected myopes. Activity recovered after the lenses were removed. CONCLUSIONS: Myopic defocus reduced the level of haemoglobin oxygenation in the visual cortex, but activity could be restored by optical correction.

[Application of fiber photometry in neuroscience research].

In recent years, fiber photometry has been widely used in the field of neuroscience as an important technique for recording the activity of neurons in the specific nuclei of freely moving animal. This review summarized the application of single-channel, multi-channel, and multi-color fiber photometry techniques in the neuroscience research of cognition, behavior, psychology and neurological diseases. In addition, it briefly introduced the applications of fiber photometry combined with functional magnetic resonance imaging technology, and fiber photometry combined with probe technology in the neuroscience research.

Changes in Intrinsically Photosensitive Retinal Ganglion Cells, Dopaminergic Amacrine Cells, and Their Connectivity in the Retinas of Lid Suture Myopia.

Purpose: This study investigates alterations in intrinsically photosensitive retinal ganglion cells (ipRGCs) and dopaminergic amacrine cells (DACs) in lid suture myopia (LSM) rats. Methods: LSM was induced in rats by suturing the right eyes for 4 weeks. Double immunofluorescence staining of ipRGCs and DACs in whole-mount retinas was performed to analyze changes in the density and morphology of control, LSM, and fellow eyes. Real-time quantitative PCR and Western blotting were used to detect related genes and protein expression levels. Results: Significant myopia was induced in the lid-sutured eye, but the fellow eye was not different to control. Decreased ipRGC density with paradoxically increased overall melanopsin expression and enlarged dendritic beads was observed in both the LSM and fellow eyes of the LSM rat retinas. In contrast, DAC changes occurred only in the LSM eyes, with reduced DAC density and tyrosine hydroxylase (TH) expression, sparser dendritic processes, and fewer varicosities. Interestingly, contacts between ipRGCs and DACs in the inner plexiform layer (IPL) and the expression of pituitary adenylate cyclase-activating polypeptide (PACAP) and vesicular monoamine transporter protein 2 (VMAT2) mRNA were decreased in the LSM eyes. Conclusions: The ipRGCs and DACs in LSM rat retinas undergo multiple alterations in density, morphology, and related molecule expressions. However, the ipRGC changes alone appear not to be required for the development of myopia, given that myopia is only induced in the lid-sutured eye, and they are unlikely alone to drive the DAC changes. Reduced contacts between ipRGCs and DACs in the LSM eyes may be the structural foundation for the impaired signaling between them. PACAP and VMAT2, strongly associated with ipRGCs and DACs, may play important roles in LSM through complex mechanisms.

Region-specific involvement of actin rearrangement-related synaptic structure alterations in conditioned taste aversion memory.

Actin rearrangement plays an essential role in learning and memory; however, the spatial and temporal regulation of actin dynamics in different phases of associative memory has not been fully understood. Here, using the conditioned taste aversion (CTA) paradigm, we investigated the region-specific involvement of actin rearrangement-related synaptic structure alterations in different memory processes. We found that CTA training could induce increased postsynaptic density (PSD) length in insular cortex (IC), but not in basolateral amygdala (BLA) and prelimbic cortex (PrL) during short-term memory (STM) formation, whereas it led to increased PSD length and synapse density in both IC and PrL during long-term memory (LTM) formation. Inhibition of actin rearrangement in the IC, but not in the BLA and PrL, impaired memory acquisition. Furthermore, actin dynamics in the IC or PrL is necessary for memory consolidation. On the contrary, inhibition of actin dynamics in the IC, BLA, or PrL had no effect on CTA memory retrieval. Our results suggest temporal and regional-specific regulation of actin rearrangement-related synaptic structure in different phases of CTA memory.

Synaptosomal Actin Dynamics in the Developmental Visual Cortex Regulate Behavioral Visual Acuity in Rats.

Purpose: Synaptosomal actin dynamics are essential for synaptic structural stability. Whether actin dynamics are involved in structural and functional synaptic plasticity within the primary visual cortex (V1) or behavioral visual acuity in rats has still not been thoroughly investigated. Methods: Synaptosome preparation and western blot analysis were used to analyze synaptosomal actin dynamics. Transmission electron microscopy was used to detect synaptic density and mitochondrial area alterations. A visual water maze task was applied to assess behavioral visual acuity. Microinjection of the actin polymerization inhibitor or stabilizer detected the effect of actin dynamics on visual function. Results: Actin dynamics, the mitochondrial area, and synaptic density within the area of V1 are increased during the critical period for the development of binocularity. Microinjection of the actin polymerization inhibitor cytochalasin D into the V1 decreased the mitochondrial area, synaptic density, and behavioral visual acuity. Long-term monocular deprivation reduced actin dynamics, the mitochondrial area, and synaptic density within the V1 contralateral to the deprived eye compared with those ipsilateral to the deprived eye and impaired visual acuity in the amblyopic eye. In addition, the mitochondrial area, synaptic density, and behavioral visual acuity were improved by stabilization of actin polymerization by jasplakinolide microinjection. Conclusions: During the critical period of visual development of binocularity, synaptosomal actin dynamics regulate synaptic structure and function and play roles in behavioral visual acuity in rats.

[Effects of Restraint Manipulation on Learning-memory Ability, Visional Acuity and Body Mass of Rats].

OBJECTIVE: Restraint manipulation is necessary for observing the effect of acupuncture or moxibustion stimulation on various variables in the experimental study. Thus, the present study was designed to examine the impact of restraint manipulation on rats' learning-memory ability, visional acuity, and body mass, so as to have a reasonable assessment on the influence of restraint stress. METHODS: Normal Sprague Dawley rats were randomly assigned to a restraint group (n=15) and a control group (n=15). In the restraint group, self-made restraint devices were used to bind the rats for 30 min daily for 30 consecutive days. The body mass of the rats was monitored daily; and the learningmemory ability and the visional acuity assessed using visual water task. RESULTS: After 30 days' restraint, no significant differences were found between the two groups in the training times for acquiring a correct rate of 80% in the learning-memory tests, and visional acuity and body mass (P ï¹¥0.05). CONCLUSION: Thirty days' restraint has no obvious impact on the increase of body weight, learning-memory and visional acuity in normal rats, suggesting an applicable of restraint device in acupuncture study.

Different patterns of changes between actin dynamics and synaptic density in the rat's primary visual cortex during a special period of visual development.

In our previous study, we found that the normalized levels of the synaptosomal filament actin (F-actin) to monomeric global actin (G-actin) ratio in the primary visual cortex (V1) of rats was significantly lower on postnatal day (P) 45 compared with P30, however, the synaptic density in the monocular area of primary visual cortex (V1M) maintained a stable high level from P30 to P45. The mechanisms underlying the different patterned of change in synaptic density and actin rearrangements from P30 to P45 are unclear. During visual development, there is a synaptic pruning process in the binocular segment of primates' visual cortex (V1B) and we suppose the pruning activity may contribute to the decreased synaptosomal F-actin to G-actin ratio. To address this issue, first, samples were derived from the region of V1B for TEM analysis but no significant difference was demonstrated between the P30 and P45 groups. In addition, the expression of PSD-95 detected by immunobloting in the synaptosomes of V1 at P30 and P45 also showed no significant difference. Combined with the previous results of actin dynamics in the V1 and synaptic density in the V1M, we conclude that the synaptic density and actin dynamics in the rats' primary visual cortex are inter-related but not absolutely identical. This study suggests actin cytoskeleton not only provides the structural basis but also regulates a various array of cellular activities underlying synaptic function. Besides, it highlights a further research of synaptic pruning.

GABA and GABA receptors alterations in the primary visual cortex of concave lens-induced myopic model.

Until recently most researches on myopia mechanisms have mainly been focused on the eye ball and few investigations were explored on the upper visual pathway, such as the visual cortex. The roles of gamma-aminobutyric acid (GABA) in the retinal and in the upper visual pathway are inter-correlated. As the retinal glutamate decarboxylase (GAD), GABA, and the mRNA levels of GABA receptors increased during the concave lens induced myopia formation, however, whether GABA alterations also occurred in the visual cortex during the concave lens induction is still unknown. In the present study, using HPLC, Enzyme-Linked Immunosorbent Assay (ELISA) and Real-Time Quantitative-PCR (RT-PCR) methods, we observed the changing trends of GABA, glutamate decarboxylase (GAD), and GABA receptors in the visual cortex of concave lens-induced myopic guinea pigs. Similar to the changing patterns of retinal GABA, the concentrations of GAD, GABA and the mRNA levels of GABA receptors in the visual cortex also increased. These results indicate that the exploration on myopia mechanisms should possibly be investigated on the whole visual pathway and the detailed significance of cortical GABA alterations needs further investigation.

Myosin II regulates actin rearrangement-related structural synaptic plasticity during conditioned taste aversion memory extinction.

Similar to memory formation, memory extinction is also a new learning process that requires synaptic plasticity. Actin rearrangement is fundamental for synaptic plasticity, however, whether actin rearrangement in the infralimbic cortex (IL) plays a role in memory extinction, as well as the mechanisms underlying it, remains unclear. Here, using a conditioned taste aversion (CTA) paradigm, we demonstrated increased synaptic density and actin rearrangement in the IL during the extinction of CTA. Targeted infusion of an actin rearrangement inhibitor, cytochalasin D, into the IL impaired memory extinction and de novo synapse formation. Notably, we also found increased myosin II phosphorylation in the IL during the extinction of CTA. Microinfusion of a specific inhibitor of the myosin II ATPase, blebbistatin (Blebb), into the IL impaired memory extinction as well as the related actin rearrangement and changes in synaptic density. Moreover, the extinction deficit and the reduction of synaptic density induced by Blebb could be rescued by the actin polymerization stabilizer jasplakinolide (Jasp), suggesting that myosin II acts via actin filament polymerization to stabilize synaptic plasticity during the extinction of CTA. Taken together, we conclude that myosin II may regulate the plasticity of actin-related synaptic structure during memory extinction. Our studies provide a molecular mechanism for understanding the plasticity of actin rearrangement-associated synaptic structure during memory extinction.

Effects of Abeta1-42 on the subunits of KATP expression in cultured primary rat basal forebrain neurons.

ATP-sensitive potassium channels (KATP) play a crucial role in coupling metabolic energy to the membrane potential of cells, thereby functioning as cellular "metabolic sensors." Recent evidence has showed a connection between the amyloid neurotoxic cascade and metabolic impairment. With regard to their neuroprotection in other neuronal preparations, KATP channels may mediate a potential neuroprotective role in Alzheimer's disease (AD). To investigate the effects of Abeta1-42 on the subunits of KATP expression in cultured primary rat basal forebrain cholinergic neurons, primary rat basal forebrain neurons were cultured and evaluated. The subunits of KATP: Kir6.1, Kir6.2, SUR1 and SUR2 expressing changes were observed by double immunofluorescence and immunoblotting when the neurons were exposed to Abeta1-42(2 microM) for different time (0, 24, 72 h). We found a significant increase in the expression of Kir6.1 and SUR2 in the cultured neurons being exposed to Abeta1-42 for 24 h, while Kir6.2 and SUR1 showed no significant change. However, after being treated with Abeta1-42 for 72 h, the expression of the four subunits was all increased significantly compared with the control. These findings suggest that being exposed to Abeta1-42 for different time (24 and 72 h) induces differential regulations of KATP subunits expression in cultured primary rat basal forebrain cholinergic neurons. The change in composition of KATP may contribute to resist the toxicity of Abeta1-42.