The perception of motion is an important function of vision. Neural wiring diagrams for extracting directional information have been obtained by connectome reconstruction. Direction selectivity in Drosophila is thought to originate in T4/T5 neurons through integrating inputs with different temporal filtering properties. Through genetic screening based on synaptic distribution, we isolated a new type of TmY neuron, termed TmY-ds, that form reciprocal synaptic connections with T4/T5 neurons. Its neurites responded to grating motion along the four cardinal directions and showed a variety of direction selectivity. Intriguingly, its direction selectivity originated from temporal filtering neurons rather than T4/T5. Genetic silencing and activation experiments showed that TmY-ds neurons are functionally upstream of T4/T5. Our results suggest that direction selectivity is generated in a tripartite circuit formed among these three neurons-temporal filtering, TmY-ds, and T4/T5 neurons, in which TmY-ds plays a role in the enhancement of direction selectivity in T4/T5 neurons.
Animals ; Neurites ; Drosophila ; Neurons ; Connectome

Neurons in the nucleus raphe magnus are involved in descending modulation of nociceptive transmission. In this study, we attempted to investigate electrophysiological properties of the NRM neurons dissociated from the postnatal rat medulla. The NRM neurons in the coronal slices of and the dissociated neurons from the postnatal rat medullae were immunohistochemically identified using antibody against serotonin. Relatively small number of neurons were positively stained in both preparations. The positively stained neurons displayed large cell body with double or multiple neurites. Using whole-cell patch clamp configuration ionic currents were recorded from the dissociated NRM-like neurons selected by criteria such as size and shape of cell body and cell population. Two types, high- and low-threshold, of voltage-dependent calcium currents were recorded from the dissociated NRM-like neurons. Some neurons displayed both types of calcium currents, whereas others displayed only high-threshold calcium current. Voltage-dependent potassium currents were also recorded from the dissociated NRM neurons. Some neurons displayed both transient outward and delayed rectifier currents but others showed only delayed rectifier current. These results suggest that there are at least two types of calcium currents and two types of potassium currents in the dissociated NRM neurons.
Animals ; Calcium ; Neurites ; Neurons* ; Potassium ; Rats* ; Serotonin

Inhibition of Rho-associated coiled coil-containing kinase (ROCK) has been reported to promote differentiation of neuronal cells. Here, we examined the effect of Y-27632, a ROCK inhibitor, on the outgrowth of neurites in PC12 cells. Y-27632 caused a rapid induction of neurite outgrowth in PC12 cells in a time-dependent manner. The neurite outgrowth, triggered by Y-27632, was accompanied by Rac1 activation, and was attenuated by Rac1 inhibitor NSC23766, in a concentration-dependent manner. Y-27632 also induced an increase in the production of reactive oxygen species (ROS). Pretreatment with N-acetylcysteine, an ROS scavenger, inhibited the ROS generation and neurite outgrowth in response to Y-27632. These results indicate that the activation of Rac1 and the generation of ROS contribute to the neurite outgrowth triggered by Y-27632 in PC12 cells.
Acetylcysteine ; Animals ; Neurites* ; Neurons ; PC12 Cells* ; Phosphotransferases ; Reactive Oxygen Species*

We examined the neuroprotective and neurotrophic effects of Tremella fuciformis. The neurotrophic effects of the hot water extract of T. fuciformis was evaluated by microscopically monitoring its potency to induce neurite outgrowth in PC12h cells. The hot water extract of T. fuciformis promoted neurite outgrowth in PC12h cells in this study, superior to other natural substances which was reported previously. When cells were treated with the hot water extract of T. fuciformis prior to beta-amyloid peptide treatment (active domain of A peptide 25~35 treated), toxicity was significantly diminished (p<0.01). These results suggest that T. fuciformis might potentially be used as a precautionary agent in neurodegenerative disease, such as Alzheimer's disease, etc.
Alzheimer Disease ; Neurites ; Neurodegenerative Diseases ; Neuroprotective Agents ; Water

The principal objective of this study was to evaluate the chemopreventive and therapeutic effects of a combination of all-trans-retinoic acid (RA) and knockdown of delta-like 1 homologue (Drosophila) (DLK1) on neuroblastoma, the most common malignant disease in children. As unfavorable neuroblastoma is poorly differentiated, neuroblastoma cell was induced differentiation by RA or DLK1 knockdown. Neuroblastoma cells showed elongated neurite growth, a hallmark of neuronal differentiation at various doses of RA, as well as by DLK1 knockdown. In order to determine whether or not a combination of RA and DLK1 knockdown exerts a greater chemotherapeutic effect on neuroblastoma, cells were incubated at 10 nM RA after being transfected with SiRNA-DLK1. Neuronal differentiation was increased more by a combination of RA and DLK1 knockdown than by single treatment. Additionally, in order to assess the signal pathway of neuroblastoma differentiation induced by RA and DLK1 knockdown, treatment with the specific MEK/ERK inhibitors, U0126 and PD 98059, was applied to differentiated neuroblastoma cells. Differentiation induced by RA and DLK1 knockdown increased ERK phosphorylation. The MEK/ERK inhibitor U0126 completely inhibited neuronal differentiation induced by both RA and DLK1 knockdown, whereas PD98059 partially blocked neuronal differentiation. After the withdrawal of inhibitors, cellular differentiation was fully recovered. This study is, to the best of our knowledge, the first to demonstrate that the specific inhibitors of the MEK/ERK pathway, U0126 and PD98059, exert differential effects on the ERK phosphorylation induced by RA or DLK1 knockdown. Based on the observations of this study, it can be concluded that a combination of RA and DLK1 knockdown increases neuronal differentiation for the control of the malignant growth of human neuroblastomas, and also that both MEK1 and MEK2 are required for the differentiation induced by RA and DLK1 knockdown.
Butadienes ; Child ; Flavonoids ; Humans ; Neurites ; Neuroblastoma ; Neurons ; Nitriles ; Phosphorylation ; Signal Transduction ; Tretinoin

Neurite outgrowth and its maintenance are essential aspects of neuronal cells for their connectivity and communication with other neurons. Recent studies showed that over-expression of either leucine-rich repeat kinase 2 (LRRK2), whose mutations are associated with familial Parkinson's disease (PD), or Rab5b, an early endosomal marker protein, induces reduction in neurite length. Based on our recent findings that LRRK2 co-localizes and interacts with Rab5, we tested the hypothesis that LRRK2 and Rab5 may functionally interplay while controlling neurite outgrowth. Firstly, we confirmed previous reports that over-expression of either the LRRK2 PD-specific G2019S mutant or the Rab5 constitutively active Q79L mutant, but not of dominant negative N133I mutant, significantly reduces neurite outgrowth. Secondly, when over-expression of either LRRK2 wild type (WT) or G2019S was accompanied with over-expression of one of the Rab5 variants (WT, Q79L and N133I), or with down-regulation of Rab5, the reduction extent of its neurite length was similar to that of cells over-expressing LRRK2 alone, regardless of Rab5's status. Finally, we observed similar patterns of neurite length regulation in embryonic rat hippocampal neuron cultures. Taken together, our results suggest that LRRK2 and Rab5 functionally coordinate their regulation of neurite outgrowth and that LRRK2 is a more critical factor than Rab5.
Animals ; Down-Regulation ; Neurites ; Neurons ; Parkinson Disease ; PC12 Cells ; Phosphotransferases ; Rats

OBJECTIVE: The aim of this study was to identify diffrentially regulated genes after the treatment of fluoxetine in rat C6 glioma cells using cDNA microarray chip techniques and real-time RT-PCR. METHODS: Cells were incubated for 24 hours, and for 72 hours with or without 10 uM fluoxetine. Total RNAs extracted from cells were reversely transcribed to cDNA. These cDNA were used to carry out cDNA microarray chip. A part of the up-/down-regulated genes in cDNA microarray result were confirmed by real-time RT-PCR. RESULTS: 1) Genes in fluoxetinetreated cells for 72 hours (chronic treatment) were more regulated than that in fluoxetine-treated cells for 24 hours (acute treatment). 2) The expression level of Gs gene in fluoxetine-treated cells for 24 hours hardly altered, but that of Gs in fluoxetine-treated cells for 72 hours significantly increased. The expression of Gi2 also decreased in 72 hours in relation to 24 hours after the administration of fluoxetine. 3) The expression level of NCAM140 gene in fluoxetine-treated cells was higher than that in control cells. CONCLUSION: We identified genes (Gs, Gi2 and NCAM140) related to neural plasticity and intracellular signal transduction cascade from our result. This implies that fluoxetine may inhibit atrophy or death of impaired neural cells by promoting neurite outgrowth.
Animals ; Atrophy ; DNA, Complementary ; Fluoxetine* ; Glioma* ; Neurites ; Oligonucleotide Array Sequence Analysis ; Plastics ; Rats* ; RNA ; Signal Transduction

In this study, we showed that neurons could be generated from adult canine bone marrow stem cells by culturing with DMSO/BHA/FeCl2. These neurons differentiated from the bone marrow stem cells formed neurites, expressed neuron-specific markers. This differentiation was enhanced by FeCl2. These results suggest that iron can effectively initiate differentiation of adult bone marrow stem cells into neurons.
Adult* ; Bone Marrow* ; Cell Culture Techniques ; Humans ; Iron ; Neurites ; Neurons* ; Stem Cells* ; Tissue Engineering

Primary dissociated neuronal cultures are widely used research tools to investigate of pathological mechanisms and to treat various central and peripheral nervous system problems including trauma and degenerative neuronal diseases. We introduced a protocol that utilizes hippocampal and cortical neurons from embryonic day 17 or 18 mice. We applied appropriate markers (GAP-43 and synaptophysin) to investigate whether neurite outgrowth and synaptogenesis can be distinguished at a particular period of time. GAP-43 was found along the neural processes in a typical granular pattern, and its expression increased proportionally as neurites lengthened during the early in vitro period. Unlike GAP-43, granular immunoreactive patterns of synaptophysin along the neurites were clearly found from day 2 in vitro with relatively high immunoreactive levels. Expression of synaptic markers from cortical neurons reached peak level earlier than that of hippocampal neurons, although neurite outgrowths of hippocampal neurons were faster than those of cortical neurons. The amount of peak synaptic markers expressed was also higher in cortical neurons than that in hippocampal neurons. These results strongly suggest the usefulness of primary cultured neurons from mice embryos for synaptic function and plasticity studies, because of their clear and typical patterns of morphology that establish synapses. Results from this study also suggest the proper amount of time in vitro according to neuronal types (cortical or hippocampal) when utilized in experiments related with synaptogenesis or synaptic activities.
Animals ; Embryonic Structures ; GAP-43 Protein ; Mice ; Neurites ; Neurons ; Peripheral Nervous System ; Plastics ; Synapses ; Synaptophysin

Preservation of tissue viability is very important for successful fetal mesencephalic transplantation. Cryopreservation methods have been regarded as a kind of useful technique to maintain tissue viability during the preservation period. Tissue viability and neurite formation rate of cryopreserved tissue would be influenced by many factors. Authors have been looking for the most ideal condition for maintaining tissue viability of cryopreserved tissue after thawing. For the first step to define the most ideal condition of crypreservation, the present study investigated whether tissue viability and neurite formation rate could be influenced by length of cryopreservation time. We used the ventral mesencephalon from 14 day old rat embryos. Tissue blocks of ventral mesencephalon were cooled in a controlled rate freezer from room temperature to -80degreesC at a rate of 5degreesC per minute. Then tissue blocks were transfered into the liquid nitrogen tanks. We divided the tissue blocks into 4 groups(fresh, 1 week, 3 weeks, 5 weeks) by the duration of cryopreservation period. We compared the cell viability and neurite formation rate of each group after thawing. We estimated the cell viability and the neurite formation of the fresh group. The fresh group showed 92% cell viability and the other three cryopreserved groups showed 65% cell viability. Cell viability of cryopreserved group was reduced significantly after thawing, comparing with the fresh groups. But differences of neurite formation rate of each group was not significant. Our result indicates that cryopreservation time could not affect the cell viability and neurite formation rate. Therefore, if we improve the reduction rate of cell viability after thawing, we would be able to obtain the better result of fetal mesencephalic transplantation.
Animals ; Cell Survival* ; Cryopreservation ; Embryonic Structures ; Mesencephalon ; Neurites* ; Neurons* ; Nitrogen ; Rats ; Tissue Survival