Clinical Study of Neurodegenerative Treatment on Glaucoma by Insulin Intravitreal Injection

Purpose: Our trail was to study insulin intravitreal injection’s (IIV) efficacity and safety to treat glaucoma neurodegeneration.Methods: Eleven subjects (11eyes) were recruited;10 patients treated in a double masked randomized sham controlled including 5 patients received one IIV injection 3UI and 5 patients received one injection of balanced salt solution(BSS) 3UI. A follow up during 168days was realized using Optical Coherence Tomography(OCT) and visual field(VF).The eleventh patient received two IIV injection without masking the injection content within one month between each injection and followed up for 877days.All the patients have a correct ocular pressure and no ocular treatment was stopped.Results: The 5 patients who received IIV revealed a swift improvement of decibel (DB), and remains stable during the first month. The average improvement was 6.62DB during 168days.The 5 patients treated with one BSS injection showed no significant improvement regaining 1. 45DB.The last patient who received two injections showed increase from 7.54DB to 17.22DB with a functional amelioration of 9. 68DB.The OCT examination showed a structural improvement during the first month, then returned to the initial value. No complication was observed during and after the treatment.Conclusion: Insulin shows not only efficacity and safety but more than that, the visual field(VF) of the patients became stable and show no deterioration in all the follow up, which confirmed that insulin act to improve the function rather than structure. it means insulin reconnect the stoma and improve the neurite outgrowth This treatment will change the evolution of this pathology and protect the glaucomatous patients against blindness.

MicroRNA-146a inhibition promotes total neurite outgrowth and suppresses cell apoptosis, inflammation, and STAT1/MYC pathway in PC12 and cortical neuron cellular Alzheimer's disease models

This study aimed to explore the effect of microRNA (miR)-146a inhibition on regulating cell apoptosis, total neurite outgrowth, inflammation, and STAT1/MYC pathway in Alzheimer's disease (AD). PC12 and cortical neuron cellular AD models were constructed by Aβ1-42 insult. For the former model, nerve growth factor (NGF) stimulation was previously conducted. miR-146a inhibitor and negative-control (NC) inhibitor were transfected into the two cellular AD models, and then cells were named miR-inhibitor group and NC-inhibitor group, respectively. After transfection, cell apoptosis, total neurite outgrowth, supernatant inflammation cytokines, and STAT1/MYC pathway were detected. miR-146a expression was similar between PC12 cellular AD model and control cells (NGF-stimulated PC12 cells), while miR-146a expression was increased in cortical neuron cellular AD model compared with control cells (rat embryo primary cortical neurons). In both PC12 and cortical neuron cellular AD models, miR-146a expression was reduced in miR-inhibitor group compared with NC-inhibitor group after transfection. Furthermore, cell apoptosis was attenuated, while total neurite outgrowth was elevated in miR-inhibitor group compared with NC-inhibitor group. As for supernatant inflammatory cytokines, tumor necrosis factor-α, interleukin (IL)-1β, IL-6, and IL-17 levels were lower in miR-inhibitor group than in NC-inhibitor group. Additionally, STAT1 and c-Myc mRNA and protein expressions were attenuated in miR-inhibitor group compared with NC-inhibitor group. In conclusion, miR-146a potentially represented a viable therapeutic target for AD.

Effects of Nogo-A and its receptor on the repair of sciatic nerve injury in rats

Regeneration of injured peripheral nerves is an extremely complex process. Nogo-A (neurite outgrowth inhibitor-A) inhibits axonal regeneration by interacting with Nogo receptor in the myelin sheath of the central nervous system (CNS). The aim of this study was to investigate the effects of Nogo-A and its receptor on the repair of sciatic nerve injury in rats. Sprague-Dawley rats (n=96) were randomly divided into 4 groups: control group (control), sciatic nerve transection group (model), immediate repair group (immediate repair), and delayed repair group (delayed repair). The rats were euthanized 1 week and 6 weeks after operation. The injured end tissues of the spinal cord and sciatic nerve were obtained. The protein expressions of Nogo-A and Nogo-66 receptor (NgR) were detected by immunohistochemistry. The protein expressions of Nogo-A, NgR, and Ras homolog family member A (RhoA) were detected by western blot. At 1 week after operation, the pathological changes in the immediate repaired group were less, and the protein expressions of Nogo-A, NgR, and RhoA in the spinal cord and sciatic nerve tissues were decreased (P<0.05) compared with the model group. After 6 weeks, the pathological changes in the immediate repair group and the delayed repair group were alleviated and the protein expressions decreased (P<0.05). The situation of the immediate repair group was better than that of the delayed repair group. Our data suggest that the expression of Nogo-A and its receptor increased after sciatic nerve injury, indicating that Nogo-A and its receptor play an inhibitory role in the repair process of sciatic nerve injury in rats.

Human placental laminin: Role in neuronal differentiation, cell adhesion and proliferation

Human placental extract has wound healing potential. Immuno-blots revealed presence of laminin in placentalextract (70 ± 0.257 lg/ml; n=3). It was purified using immuno-affinity chromatography. SDS-PAGE and SEHPLC indicated a188 kDa protein with some small peptides. Since placental laminin existed in its truncatedform, its roles in cellular migration, differentiation and wound healing were verified. Induction of cellularmigration and motility in rat fibroblasts were enhanced by placental laminin as observed from scratch woundassay. Promotion of neuronal differentiation of PC12 cells by placental laminin was observed by phase contrastmicroscopy. Confocal images showed presence of laminin on the cell surface and along the axonal processes.Significant interaction between integrin receptors and laminin responsible for cellular differentiation wasdemonstrated from co-localization experiments. Union between integrin receptor and its synthetic antagonistrevealed retarded pattern of neurite outgrowth in laminin treated cells. Animal model studies revealed fasterwound healing in the presence of placental laminin. Induction of re-epithelialization and angiogenesis inwound area by cellular proliferation and adhesion were observed. The cytokine levels showed an initial riseand gradual fall over the duration of wound healing on application of the fragmented laminin. Thus, roles ofplacental laminin in neuronal differentiation and wound healing were indicated.

Effect of acupuncture intervention on neurological function, cerebral microglia activation and secondary nerve damage in traumatic brain injury rats / 针刺研究

OBJECTIVE: To observe the effect of acupuncture on activities of microglia in traumatic brain injury (TBI) rats. METHODS: Fifty-four male SD rats were randomly and equally divided into normal control, model and acupuncture groups according to the random number table (n＝18 rats in each group). The TBI model was established by using a free fall brain injury striking device after exposing the local cranial bone (to induce the left parietal cerebral contusion). Acupoints "Baihui" (GV20), "Shuigou" (GV26), "Fengfu" (GV16), "Yamen" (GV15) and bilateral "Hegu" (LII4) were stimulated intensively by twirling the filiform needles with force at a range of >360° and a frequency of 160－180 cycles/min for 10 sec in every acupoint, once every 5 min during the 15 minutes' needle retaining. The treatment was given once every day for successive 14 days. The rats of the normal and model groups were grabbed and fixed with the same procedure. The behavioral changes were tested using modified neurological severity score (mNSS). The histopathological changes of the injured cerebral cortex tissues were observed by using hematoxylin-eosin (H.E.) staining, and the fluorescence intensity of Iba-1 (marker of microglia) positive products in the surrounding tissue of the cerebral focus was displayed by immunofluorescence staining, and the contents of neuron specific enolate (NSE) and neurite outgrowth inhibitor-A (Nogo-A) in serum (indicating a secondary nerve damage) were assayed by ELISA. RESULTS: The mNSS scores were significantly increased on day 1, 3, 7 and 14 in the model group in comparison with the normal group (P<0.01) and considerably decreased at the 4 time-points after acupuncture intervention relevant to the model group (P<0.05, P<0.01). H．E. staining showed that modeling induced pathological changes such as the excursion of cell nucleus, cellular swel-ling, vacuole-like change, neuron death, karyopyknosis dissolution, and proliferation of fibrous tissue were relatively milder in the acupuncture group. The average fluorescence intensity values of Iba-1-positive products, serum NSE and Nogo-A contents on day 3, 7 and 14 were significantly higher in the model group than in the normal group (P<0.05, P<0.01), and notably down-regulated in the acupuncture group than in the model group (P<0.05, P<0.01, except Nogo-A on day 3). CONCLUSION: Acupuncture intervention may accelerate neurological function recovery in TBI rats, which is closely related to its effects in inhibiting the activation of microglia and secondary nerve damage.

Effect of docosapentenoic acid on the neurite outgrowth in PC12 cells / 中华行为医学与脑科学杂志

ObjectiveTo explore the inductive action of docosapentenoic acid(DPA) on neurite outgrowth in PC12 cells in vitro.MethodsNeurite outgrowth in PC12 cells was examined after the treatment with different concentration of DPA using Motic Zamges Plus software mapping cell image system.Western blot was performed to detect the expression of β Ⅲ-tubulin regulated protein kinase,a neuronal marker as well as ERK and protein kinase B (Akt) phosphorylation.ResultsPC12 cell neurite formation rate was increased in a concentration dependent manner in the induction of DPA,increased by 2.4% (DPA 10 μg/ml,P>0.05),18.6% (DPA 30 μg/ml,P<0.05) and 25.0% (DPA 50 μg/ml,P<0.05) compared with that in the control group.DPA promoted the expression of β Ⅲ-tubulin (P<0.05) and the phosphorylation level of ERK and Akt (P<0.05,P<0.01).ConclusionDPA promotes PC12 cell neurites growth and its mechanism may be related to the activation of ERK and Akt signaling pathways.

Pharmacological Activities and Applications of Spicatoside A

Liriopogons (Liriope and Opiopogon) species are used as a main medicinal ingredient in several Asian countries. The Liriopes Radix (tuber, root of Liriope platyphylla) has to be a promising candidate due to their source of phytochemicals. Steroidal saponins and their glycosides, phenolic compounds, secondary metabolites are considered of active constituents in Liriopes Radix. Spicatoside A, a steroidal saponin, could be more efficacious drug candidate in future. In this review, we summarized the available knowledge on phytochemical and pharmacological activities for spicatoside A. It significantly suppressed the level of NF-κB, NO, iNOS, Cox-2, IL-1β, IL-6 and MAPKs in LPS-stimulated inflammation. The production of MUC5AC mucin was increased. MMP-13 expression was down-regulated in IL-1β-treated cells and reduced glycosaminoglycan release from IL-1α-treated cells. The neurite outgrowth activity, PI3K, Akt, ERK1/2, TrkA and CREB phosphorylation and neurotropic factors such as NGF and BDNF were upregulated with increased latency time. It also showed cell growth inhibitory activity on various carcinoma cells. From this, spicatoside A exerts anti-inflammation, anti-asthma, anti-osteoclastogenesis, neurite outgrowth, memory consolidation and anticancer activities. Further studies are needed on spicatoside A in order to understand mechanisms of action to treat various human diseases.

MiR-130a regulates neurite outgrowth and dendritic spine density by targeting MeCP2

MicroRNAs (miRNAs) are critical for both development and function of the central nervous system. Significant evidence suggests that abnormal expression of miRNAs is associated with neurodevelopmental disorders. MeCP2 protein is an epigenetic regulator repressing or activating gene transcription by binding to methylated DNA. Both loss-of-function and gain-of-function mutations in the MECP2 gene lead to neurodevelopmental disorders such as Rett syndrome, autism and MECP2 duplication syndrome. In this study, we demonstrate that miR-130a inhibits neurite outgrowth and reduces dendritic spine density as well as dendritic complexity. Bioinformatics analyses, cell cultures and biochemical experiments indicate that miR-130a targets MECP2 and down-regulates MeCP2 protein expression. Furthermore, expression of the wild-type MeCP2, but not a loss-of-function mutant, rescues the miR-130a-induced phenotype. Our study uncovers the MECP2 gene as a previous unknown target for miR-130a, supporting that miR-130a may play a role in neurodevelopment by regulating MeCP2. Together with data from other groups, our work suggests that a feedback regulatory mechanism involving both miR-130a and MeCP2 may serve to ensure their appropriate expression and function in neural development.

Chondroitin sulfate with potential pharmacological activities: research progress and its application prospect / 中国药学杂志

Chondroitin sulfate (CS) is a heterogeneous and negatively charged polysaccharide composed of repeating disaccharideunits, and has many pharmacological activities. CS has been recommended as symptomatic slow acting drugs for osteoarthritis (SYSADOA) in clinical practice. CS is shown to have promising prospect as a potential candidate for anti-metastasis of cancers and as a neurite outgrowth agent for neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease characterized by progressive loss of neurons. Moreover, CS is also involved in interaction with virus during its cell entry, wound healing and osteogenesis, and may be a promising drug candidate in these areas. Based on original publications, the research advances of CS in these areas and its applications were reviewed. The possibility of chemoenzymatic synthesis of specific CS chains as potential drugs was also discussed here, which may be used in the treatment of osteoarthritis, anti-metastasis of cancers, and so on.

Reactive Oxygen Species are Involved in Y-27632-induced Neurite Outgrowth in PC12 Cells

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.

Effects of minocycline on neurite outgrowth of PC12 cells following oxygen glucose deprivation / 重庆医学

Objective To investigate the effects of minocycline on cell viability and neurite outgrowth of pheochromocytoma cells (PC12) after oxygen‐glucose deprivation(OGD) injury .Methods PC12 cells were exposed to OGD insult for 2 ,4 ,6 ,8 h to estab‐lish a cerebral ischemia model in vitro .High‐differentiated PC12 cells were cultivated and randomly divided into three groups :con‐trol group ,OGD group and various doses of minocycline(0 .1 ,1 .0 ,10 .0 μM) treated group .24 h after OGD‐reperfusion ,PC12 cells viability was assessed by CCK‐8 assay ,the neurite was labeled with MAP‐2 by immunofluorescence and neurite length was meas‐ured by the Image‐Pro Plus 7 .0 software ,GAP‐43 protein expression was determined by Western blotting .Results Compared to the OGD groups ,minocycline induced a concentration‐dependent increase in cells viability [(46 .1 ± 2 .9)% vs .(77 .0 ± 2 .5)% ,P<0.01],improvedneuriteoutgrowthandincreasedtheexpressionofGAP‐43proteininPC12cellsafterOGDinjury([(0.34±0.04) vs .(2 .11 ± 0 .10) ,P<0 .01] .Conclusion Minocycline could protect against oxygen glucose deprivation injury and promote neurite outgrowth .This finding suggests minocycline may be a novel therapy for cerebral ischemia .

Role of activin A and NGF in co-stimulating neurite outgrowth of dorsal root ganglia ofembryonic chicken / 中国免疫学杂志

Objective:To investigate the effect of activin A and nerve growth factor ( NGF) NGF on stimulating neurite outgrowth of dorsal root ganglia(DRG)of the embryonic chicken.Methods:In this study,we observed that activin A and NGF together induced neurite outgrowth of DRG and kept survival of DRG neurons by the primary cultured DRGs from embryonic day 8 ( E8 ) chicken.calcitonin gene-related peptide(CGRP)CGRP mRNA expressions were analyzed by RT-PCR.Results: The DRG treated with activin A +NGF had obvious neurite outgrowth ,compared with only NGF group on day 3,and the number of living DRG neurons also increased.Activin A +NGF up-regulated the mRNA expressions of CGRP in DRG.Conclusion:The Data demonstrated that activin A with NGF can synergistically stimulate DRG neurite outgrowth and maintain the DRG neurons survival , suggesting that it is more effective that NGF and activin A together treat the associated disease of nerve system.

Actions of neurosteroids in neurons and the treatment of neurodegenerative disease / 解剖学报

Neurons and glia in the central nervous system can express the key enzymes for the synthesis of neurosteroids .Once the concentration of neurosteroids is high enough , they will exert paracrine effects .Synthesis of neurosteroids declines with age in brain .So does it under stressful circumstances .Recent research reports indicate that the decrease of neurosteroids is associated with the neuronal dysfunction and degeneration in the brain .This paper reviews recent research on the most studied neurosteroids ( for example , dehydroepiandrosterone , pregnenolone and their sulphate esters, progesterone and allopregnanolone ) in affecting neuronal survival , neurite outgrowth and neurogenesis , and the potential roles of these neurosteroids in the treatment of neurodegenerative disease as well .

Aucubin Promotes Neurite Outgrowth in Neural Stem Cells and Axonal Regeneration in Sciatic Nerves

Aucubin is an iridoid glycoside with a wide range of biological activities, including anti-inflammatory, anti-microbial, anti-algesic as well as anti-tumor activities. Recently, it has been shown that aucubin prevents neuronal death in the hippocampal CA1 region in rats with diabetic encephalopathy. In addition, it has protective effects on H2O2-induced apoptosis in PC12 cells. We have shown here that aucubin promotes neuronal differentiation and neurite outgrowth in neural stem cells cultured primarily from the rat embryonic hippocampus. We also investigated whether aucubin facilitates axonal elongation in the injured peripheral nervous system. Aucubin promoted lengthening and thickness of axons and re-myelination at 3 weeks after sciatic nerve injury. These results indicate that administration of aucubin improved nerve regeneration in the rat model of sciatic nerve injury, suggesting that aucubin may be a useful therapeutic compound for the human peripheral nervous system after various nerve injuries.

Phosphatidylinositol 4-phosphate 5-kinase alpha negatively regulates nerve growth factor-induced neurite outgrowth in PC12 cells

Neurite outgrowth, a cell differentiation process involving membrane morphological changes, is critical for neuronal network and development. The membrane lipid, phosphatidylinositol (PI) 4,5-bisphosphate (PIP2), is a key regulator of many important cell surface events of membrane signaling, trafficking and dynamics. This lipid is produced mainly by the type I PI 4-phosphate 5-kinase (PIP5K) family members. In this study, we addressed whether PIP5Kalpha, an isoform of PIP5K, could have a role in neurite outgrowth induced by nerve growth factor (NGF). For this purpose, we knocked down PIP5Kalpha in PC12 rat pheochromocytoma cells by stable expression of PIP5Kalpha microRNA that significantly reduced PIP5Kalpha expression and PIP2 level. Interestingly, NGF-induced neurite outgrowth was more prominent in PIP5Kalpha-knockdown (KD) cells than in control cells. Conversely, add-back of PIP5Kalpha into PIP5Kalpha KD cells abrogated the effect of NGF on neurite outgrowth. NGF treatment activated PI 3-kinase (PI3K)/Akt pathway, which seemed to be associated with reactive oxygen species generation. Similar to the changes in neurite outgrowth, the PI3K/Akt activation by NGF was potentiated by PIP5Kalpha KD, but was attenuated by the reintroduction of PIP5Kalpha. Moreover, exogenously applied PIP2 to PIP5Kalpha KD cells also suppressed Akt activation by NGF. Together, our results suggest that PIP5Kalpha acts as a negative regulator of NGF-induced neurite outgrowth by inhibiting PI3K/Akt signaling pathway in PC12 cells.

Differential Expressions of Synaptogenic Markers between Primary Cultured Cortical and Hippocampal Neurons

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.

Schwann cells promote neurite outgrowth of dorsal root ganglion neurons through secretion of nerve growth factor.

The transplantation of Schwann cells (SCs) could successfully promote axonal regeneration. This is likely to attribute to the adhesion molecules expression and growth factors secretion of SCs. But which factor(s) play a key role has not been precisely studied. In this study, an outgrowth assay using dorsal root ganglia (DRG) neuron-SC co-culture system in vitro was performed. Co-culture of SCs or application of SC-conditioned medium (CM) substantially and significantly increased DRG neurite outgrowth. Further, nerve growth factor and NGF receptor (TrkA) mRNA were highly expressed in Schwann cells and DRG neuron, respectively. The high concentration of NGF protein was detected in SC-CM. When K-252a, a specific inhibitor of NGF receptor was added, DRG neurite outgrowth was significantly decreased in a concentration-dependent manner. These data strongly suggest that SCs play important roles in neurite outgrowth of DRG neurons by secreted NGF.

Nitric Oxide Is an Essential Mediator for Neuronal Differentiation of Rat Primary Cortical Neuron Cells

Nitric oxide (NO) regulates proliferation, differentiation and survival of neurons. Although NO is reported to involve in NGF-induced differentiation of PC12 cells, the role of NO has not been characterized in primary neuron cells. Therefore, we investigated the role of NO in neuronal differentiation of primary cortical neuron cells. Primary cortical neuron cells were prepared from rat embryos of embryonic day 18 and treated with NMMA (NOS inhibitor) or PTIO (NO scavenger). Neurite outgrowth of neuron cells was counted and the mRNA levels of p21, p27, c-jun and c-myc were measured by RT-PCR. Neurite outgrowth of primary cortical neuron cells was inhibited a little by NOS inhibitor and completely by NO scavenger. The mRNA levels of p21 and p27, differentiation-induced growth arrest genes were increased during differentiation, but they were decreased by NOS inhibitor or NO scavenger. On the other hand, the level of c-jun mRNA was not changed and the level of c-myc mRNA was increased during differentiation differently from previously reported. The levels of these mRNA were reversed in NOS inhibitor- or NO scavenger-treated cells. The level of nNOS protein was not changed but NOS activity was inhibited largely by NOS inhibitor or NO scavenger. These results suggest that NO is an essential mediator for neuronal differentiation of primary cortical neuron cells.

Coordinate Regulation of Neurite Outgrowth by LRRK2 and Its Interactor, Rab5

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.

The neurite outgrowth measurement of dorsal root ganglia explants cultured on estrogen and schwann cell-conditioned medium by using image analysis.

Background: The neurite growth of dorsal root ganglion (DRG) explants is widely used for evaluating the promoting effects of neurotrophic factors on cultures. Counting the neurites directly is a tedious work because of the accuracy and the difficulty due to their branching and fasciculation. This study was aimed to compare quantitative measurement of neurite outgrowth, length and number of DRG explants in media containing estrogen (E2) and Schwann cell-conditioned medium (SCM). Methods: Schwann cells and DRG explants were harvested from nerve plexuses of P2-P3 rats and incubated separately. SCM was collected for treatment by adding into DRG culture. DRG explants were further incubated for 7 days with medium containing SCM, E2, SCM and E2. DRG cultures were stained for neurofilament to detect neurite growth. The neurite outgrowth, the length and number were measured by free software ImageTool. Results: The neurite outgrowth expressed as the percentage of pixels, occupied by the neurite extending from the ganglion, in the presence of E2 and SCM was the significantly increased parameter when compared to control. It was more reliable than the overestimated neurite outgrowth which resulted from the multiplying of neurite length and number. Conclusion: The neurite outgrowth was the parameter providing a robust means of evaluating the growth promoting activity of E2 and SCM. It could be rapidly measured. E2 might somehow increase the sensitivity of DRG neurons to the neurotrophic factors released from Schwann cells.