Neurons are the structural and functional unit of the nervous system. Precisely regulated dendrite morphogenesis is the basis of neural circuit assembly. Numerous studies have been conducted to explore the regulatory mechanisms of dendritic morphogenesis. According to their action regions, we divide them into two categories: the intrinsic and extrinsic regulators of neuronal dendritic morphogenesis. Intrinsic factors are cell type-specific transcription factors, actin polymerization or depolymerization regulators and regulators of the secretion or endocytic pathways. These intrinsic factors are produced by neuron itself and play an important role in regulating the development of dendrites. The extrinsic regulators are either secreted proteins or transmembrane domain containing cell adhesion molecules. They often form receptor-ligand pairs to mediate attractive or repulsive dendritic guidance. In this review, we summarize recent findings on the intrinsic and external molecular mechanisms of dendrite morphogenesis from multiple model organisms, including , and mice. These studies will provide a better understanding on how defective dendrite development and maintenance are associated with neurological diseases.
Animals ; Caenorhabditis elegans ; cytology ; Dendrites ; Mice ; Morphogenesis ; Nervous System Diseases ; physiopathology ; Neurons ; cytology ; Transcription Factors ; metabolism

The aim of this study was to investigate whether G protein-coupled estrogen receptor (GPER) could alleviate hippocampal neuron injury under cerebral ischemia-reperfusion injury (CIRI) by acting on endoplasmic reticulum stress (ERS). The CIRI animal model was established by middle cerebral artery occlusion (MCAO). Female ovariectomized (OVX) Sprague-Dawley (SD) female rats were randomly divided into 4 groups: control, ischemia-reperfusion injury (MCAO), vehicle (MCAO+DMSO), and GPER-specific agonist G1 (MCAO+G1) groups. The neurobehavioral score was assessed by the Longa score method, the morphological changes of the neurons were observed by the Nissl staining, the cerebral infarction was detected by the TTC staining, and the neural apoptosis in the hippocampal CA1 region was detected by TUNEL staining. The distribution and expression of GRP78 (78 kDa glucose-regulated protein 78) in the hippocampal CA1 region were observed by immunofluorescent staining. The protein expression levels of GRP78, Caspase-12, CHOP and Caspase-3 were detected by Western blot, and the mRNA expression levels of GRP78, Caspase-12, and CHOP were detected by the real-time PCR. The results showed that the neurobehavioral score, cerebral infarct volume, cellular apoptosis index, as well as GRP78, Caspase-12 and CHOP protein and mRNA expression levels in the MCAO group were significantly higher than those of control group. And G1 reversed the above-mentioned changes in the MCAO+G1 group. These results suggest that the activation of GPER can decrease the apoptosis of hippocampal neurons and relieve CIRI, and its mechanism may involve the inhibition of ERS.
Animals ; Apoptosis ; Brain Ischemia ; CA1 Region, Hippocampal ; cytology ; Caspase 12 ; metabolism ; Caspase 3 ; metabolism ; Endoplasmic Reticulum Stress ; Female ; Heat-Shock Proteins ; metabolism ; Neurons ; cytology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptors, Estrogen ; physiology ; Receptors, G-Protein-Coupled ; agonists ; Reperfusion Injury ; Transcription Factor CHOP ; metabolism

OBJECTIVE: To investigate the mechanism by which doublecortin promotes the recovery of cytoskeleton in arginine vasopressin (AVP) neurons in rats with electrical lesions of the pituitary stalk (PEL). METHODS: Thirty-two SD rats were randomized into PEL group with electrical lesions of the pituitary stalk through the floor of the skull base (=25) and sham operation group (=7), and the daily water consumption (DWC), daily urine volume (DUV) and urine specific gravity (USG) of the rats were recorded. Four rats on day 1 and 7 rats on each of days 3, 7 and 14 after PEL as well as the sham-operated rats were sacrificed for detection of the expressions of β-Tubulin (Tuj1), doublecortin and caspase- 3 in the AVP neurons of the supraoptic nucleus using immunofluorescence assay and Western blotting. RESULTS: After PEL, the rats exhibited a typical triphasic pattern of diabetes insipidus, with the postoperative days 1-2 as the phase one, days 3-5 as the phase two, and days 6-14 as the phase three. Immunofluorescent results indicated the repair of the AVP neurons evidenced by significantly increased doublecortin expressions in the AVP neurons following PEL; similarly, the expression of Tuj1 also increased progressively after PEL, reaching the peak level on day 7 after PEL. The apoptotic rates of the AVP neurons exhibited a reverse pattern of variation, peaking on postoperative day 3 followed by progressive reduction till day 14. Western blotting showed that the expressions of c-Jun and p-c-Jun were up-regulated significantly on day 3 ( < 0.05) and 7 ( < 0.01) after PEL, while an upregulated p-JNK expression was detected only on day 3 ( < 0.05), as was consistent with the time-courses of neuronal recovery and apoptosis after PEL. CONCLUSIONS JNK/c-Jun pathway is activated after PEL to induce apoptosis of AVP neurons in the acute phase and to promote the repair of neuronal cytoskeleton by up-regulation of doublecortin and Tuj1 expressions.
Animals ; Apoptosis ; Arginine Vasopressin ; pharmacology ; Cytoskeleton ; metabolism ; MAP Kinase Signaling System ; Neurons ; cytology ; Pituitary Gland ; cytology ; injuries ; Proto-Oncogene Proteins c-jun ; metabolism ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Regeneration ; Tubulin ; metabolism

Sparse labeling of neurons contributes to uncovering their morphology, and rapid expression of a fluorescent protein reduces the experiment range. To achieve the goal of rapid and sparse labeling of neurons in vivo, we established a rapid method for depicting the fine structure of neurons at 24 h post-infection based on a mutant virus-like particle of Semliki Forest virus. Approximately 0.014 fluorescent focus-forming units of the mutant virus-like particle transferred enhanced green fluorescent protein into neurons in vivo, and its affinity for neurons in vivo was stronger than for neurons in vitro and BHK21 (baby hamster kidney) cells. Collectively, the mutant virus-like particle provides a robust and convenient way to reveal the fine structure of neurons and is expected to be a helper virus for combining with other tools to determine their connectivity. Our work adds a new tool to the approaches for rapid and sparse labeling of neurons in vivo.
Animals ; Cells, Cultured ; Gene Expression ; Genetic Vectors ; genetics ; metabolism ; Green Fluorescent Proteins ; genetics ; metabolism ; Immunohistochemistry ; methods ; Male ; Mice, Inbred C57BL ; Microscopy, Fluorescence ; methods ; Neurons ; cytology ; metabolism ; Purkinje Cells ; cytology ; metabolism ; Semliki forest virus ; genetics

OBJECTIVE: To study the protective effect of enhanced peroxisome proliferator activated receptor γ (PPARγ) pathway against apoptosis of long-term cultured primary nerve cells. METHODS: A natural aging model was established in primary rat nerve cells by long-term culture for 22 days. The cells were divided into control group, 0.1, 1.0, 5.0, and 10 μmol/L GW9662 intervention groups, and 0.1, 1.0, 5.0, and 10 μmol/L pioglitazone intervention groups. The cell viability was assessed using MTT assay and the cell morphological changes were observed after the treatments to determine the optimal concentrations of GW9662 and pioglitazone. Double immunofluorescence labeling and flow cytometry were used to observe the changes in the number of viable cells and cell apoptosis following the treatments; immunocytochemical staining was used to assess the changes in the anti-oxidation ability of the treated cells. RESULTS: The optimal concentrations of GW9662 and pioglitazone determined based on the cell viability and morphological changes were both 1 μmol/L. Compared with the control group, GW9662 treatment significantly lowered while pioglitazone significantly increased the total cell number and nerve cell counts ( < 0.05), and nerve cells in the cell cultures maintained a constant ratio at about 80% in all the groups ( > 0.05). GW9662 significantly enhanced while pioglitazone significantly lowered the cell apoptosis rates compared with the control group ( < 0.05). GW9662 obviously lowered SOD activity and GSH content in G group ( < 0.05) and increased MDA content in the cells ( < 0.05), and pioglitazone resulted in reverse changes in SOD, GSH and MDA contents in the cells ( < 0.05). CONCLUSIONS Activation of PPARγ pathway protects long-term cultured primary nerve cells by enhancing cellular anti-oxidant capacity and reducing cell apoptosis, suggesting a potential strategy for anti-aging treatment of the nervous system through intervention of the PPARγ pathway.
Anilides ; administration & dosage ; pharmacology ; Animals ; Apoptosis ; Cell Proliferation ; Cell Survival ; Cells, Cultured ; Cellular Senescence ; physiology ; Neurons ; cytology ; PPAR gamma ; metabolism ; Pioglitazone ; administration & dosage ; pharmacology ; Rats

N-methyladenosine (mA), catalyzed by the methyltransferase complex consisting of Mettl3 and Mettl14, is the most abundant RNA modification in mRNAs and participates in diverse biological processes. However, the roles and precise mechanisms of mA modification in regulating neuronal development and adult neurogenesis remain unclear. Here, we examined the function of Mettl3, the key component of the complex, in neuronal development and adult neurogenesis of mice. We found that the depletion of Mettl3 significantly reduced mA levels in adult neural stem cells (aNSCs) and inhibited the proliferation of aNSCs. Mettl3 depletion not only inhibited neuronal development and skewed the differentiation of aNSCs more toward glial lineage, but also affected the morphological maturation of newborn neurons in the adult brain. mA immunoprecipitation combined with deep sequencing (MeRIP-seq) revealed that mA was predominantly enriched in transcripts related to neurogenesis and neuronal development. Mechanistically, mA was present on the transcripts of histone methyltransferase Ezh2, and its reduction upon Mettl3 knockdown decreased both Ezh2 protein expression and consequent H3K27me3 levels. The defects of neurogenesis and neuronal development induced by Mettl3 depletion could be rescued by Ezh2 overexpression. Collectively, our results uncover a crosstalk between RNA and histone modifications and indicate that Mettl3-mediated mA modification plays an important role in regulating neurogenesis and neuronal development through modulating Ezh2.
Adenosine ; analogs & derivatives ; metabolism ; Adult Stem Cells ; cytology ; metabolism ; Animals ; Brain ; metabolism ; Cell Differentiation ; genetics ; Cell Proliferation ; Enhancer of Zeste Homolog 2 Protein ; metabolism ; Gene Expression Regulation ; Methyltransferases ; metabolism ; Mice, Inbred C57BL ; Neural Stem Cells ; cytology ; metabolism ; Neurogenesis ; genetics ; Neurons ; cytology ; metabolism ; RNA, Messenger ; genetics ; metabolism

Voltage-gated sodium channels (Navs) play an important role in human pain sensation. However, the expression and role of Nav subtypes in native human sensory neurons are unclear. To address this issue, we obtained human dorsal root ganglion (hDRG) tissues from healthy donors. PCR analysis of seven DRG-expressed Nav subtypes revealed that the hDRG has higher expression of Nav1.7 (~50% of total Nav expression) and lower expression of Nav1.8 (~12%), whereas the mouse DRG has higher expression of Nav1.8 (~45%) and lower expression of Nav1.7 (~18%). To mimic Nav regulation in chronic pain, we treated hDRG neurons in primary cultures with paclitaxel (0.1-1 μmol/L) for 24 h. Paclitaxel increased the Nav1.7 but not Nav1.8 expression and also increased the transient Na currents and action potential firing frequency in small-diameter (<50 μm) hDRG neurons. Thus, the hDRG provides a translational model in which to study "human pain in a dish" and test new pain therapeutics.
Action Potentials ; drug effects ; Animals ; Antineoplastic Agents, Phytogenic ; pharmacology ; Dose-Response Relationship, Drug ; Electric Stimulation ; Excitatory Postsynaptic Potentials ; drug effects ; Female ; Ganglia, Spinal ; cytology ; Gene Expression Regulation ; drug effects ; Humans ; In Vitro Techniques ; Male ; Mice ; NAV1.7 Voltage-Gated Sodium Channel ; genetics ; metabolism ; Neurons ; drug effects ; metabolism ; Paclitaxel ; pharmacology ; Patch-Clamp Techniques ; Species Specificity

Mounting evidence supports an important role of chemokines, produced by spinal cord astrocytes, in promoting central sensitization and chronic pain. In particular, CCL2 (C-C motif chemokine ligand 2) has been shown to enhance N-methyl-D-aspartate (NMDA)-induced currents in spinal outer lamina II (IIo) neurons. However, the exact molecular, synaptic, and cellular mechanisms by which CCL2 modulates central sensitization are still unclear. We found that spinal injection of the CCR2 antagonist RS504393 attenuated CCL2- and inflammation-induced hyperalgesia. Single-cell RT-PCR revealed CCR2 expression in excitatory vesicular glutamate transporter subtype 2-positive (VGLUT2) neurons. CCL2 increased NMDA-induced currents in CCR2/VGLUT2 neurons in lamina IIo; it also enhanced the synaptic NMDA currents evoked by dorsal root stimulation; and furthermore, it increased the total and synaptic NMDA currents in somatostatin-expressing excitatory neurons. Finally, intrathecal RS504393 reversed the long-term potentiation evoked in the spinal cord by C-fiber stimulation. Our findings suggest that CCL2 directly modulates synaptic plasticity in CCR2-expressing excitatory neurons in spinal lamina IIo, and this underlies the generation of central sensitization in pathological pain.
Animals ; Benzoxazines ; pharmacology ; therapeutic use ; Chemokine CCL2 ; antagonists & inhibitors ; genetics ; metabolism ; pharmacology ; Excitatory Amino Acid Agents ; pharmacology ; Excitatory Amino Acid Agonists ; pharmacology ; Female ; Freund's Adjuvant ; toxicity ; Hyperalgesia ; chemically induced ; metabolism ; prevention & control ; Long-Term Potentiation ; drug effects ; physiology ; Luminescent Proteins ; genetics ; metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Transgenic ; Myelitis ; chemically induced ; drug therapy ; metabolism ; Neurons ; drug effects ; Pain Management ; Somatostatin ; genetics ; metabolism ; Spinal Cord ; cytology ; Spiro Compounds ; pharmacology ; therapeutic use ; Vesicular Glutamate Transport Protein 2 ; genetics ; metabolism ; Vesicular Inhibitory Amino Acid Transport Proteins ; genetics ; metabolism

OBJECTIVETo study whether lithium agent produces neuroprotective effect by inhibiting the nerve cell apoptosis of rats after spinal cord injury.

METHODSForty-two male SD rats weighing 200 to 250 g were randomly divided into 3 groups: blank control group(=6) without surgery, normal saline(NS) group(=18) with intraperitoneal injection of NS (40 mg/kg); and Lithium chloride (Licl) group (=18) with intraperitoneal injection of Licl (40 mg/kg). After Allen method modeling, Licl group started intraperitoneal injection of Licl solution (40 mg·kg⁻¹·d⁻¹) within 15 min after operation to the second week. NS group, during the same interval, was injected with a same amount of NS. Postoperative 3, 7, 14 d, BBB scores in each group were measured;the expression of Bcl-2 and Bax protein were observed by immunohistochemisty staining;TUNEL staining was used to observe the nerve cell apoptosis.

RESULTSThe BBB scores in blank control group were 21. Postoperative 7, 14 d, BBB scores of Licl group were higher than that of NS group(<0.05). As for the Bcl-2 protein expression, black control group has a level of 0.081±0.003;7 d and 14 d postoperatively, the level in Licl group was 0.151±0.003, 0.163±0.003 and in NS group, 0.143±0.003, 0.154±0.002, respectively. Licl group showed significantly increased Bcl-2 protein expression(<0.05). As for the Bax protein expression, black control group showed a level of 0.071±0.003; 7 d and 14 d postoperatively, the level in Licl group was 0.121±0.002, 0.106±0.002 and in NS group was 0.126±0.001, 0.120±0.002, respectively. The Bax protein expression is significantly inhibited in the Licl group(<0.05). In nerve cell apoptosis by TUNEL staining, the positive cells were fewer in the black control group with apoptosis index (AI) of 1.98±0.19;while 7d and 14d postoperatively, the AI of Licl group was 13.12±0.69, 4.29±1.00 and of NS group, 18.26±0.87, 5.48±0.70, respectively. Licl group showed significant inhibition of the cell apoptosis(<0.05).

CONCLUSIONSLicl can promote the Bcl-2 protein expression and inhibit the Bax proteins expression in nerve cells of rat after SCI, thereby playing a role in the inhibition of nerve cell apoptosis. This may be one of the mechanisms that Licl can promote the recovery of motor function of rats after SCI.

Animals ; Apoptosis ; Lithium ; pharmacology ; Male ; Neurons ; cytology ; drug effects ; Neuroprotective Agents ; pharmacology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Spinal Cord Injuries ; drug therapy ; bcl-2-Associated X Protein ; metabolism

Animals choose among sleep, courtship, and feeding behaviors based on the integration of both external sensory cues and internal states; such choices are essential for survival and reproduction. These competing behaviors are closely related and controlled by distinct neural circuits, but whether they are also regulated by shared neural nodes is unclear. Here, we investigated how a set of male-specific P1 neurons controls sleep, courtship, and feeding behaviors in Drosophila males. We found that mild activation of P1 neurons was sufficient to affect sleep, but not courtship or feeding, while stronger activation of P1 neurons labeled by four out of five independent drivers induced courtship, but only the driver that targeted the largest number of P1 neurons affected feeding. These results reveal a common neural node that affects sleep, courtship, and feeding in a threshold-dependent manner, and provide insights into how competing behaviors can be regulated by a shared neural node.
Animals ; Animals, Genetically Modified ; Brain ; cytology ; Courtship ; Drosophila ; Drosophila Proteins ; genetics ; metabolism ; Feeding Behavior ; physiology ; Locomotion ; Male ; Neural Inhibition ; physiology ; Neural Pathways ; physiology ; Neurons ; physiology ; Sex Factors ; Sleep ; physiology