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OBJECTIVE@#To investigate whether Hainan papayas has protective effects in an Aβ40-induced primary neuron injury model and elucidate the underlying molecular mechanism.@*METHODS@#Cultured primary neurons from the dorsal root ganglia (DRG) of Sprague-Dawley (SD) rats were treated with 20 μM Aβ40 peptide, 100 μg/L Hainan papaya water extract, peptide plus extract, or culture medium for 24 h. Cell viability was measured by MTT assay, and neuronal apoptosis was evaluated by DAPI staining. ERK signaling pathway-associated molecule activation and changes in Bax expression were analyzed by Western blotting and immunofluorescence.@*RESULTS@#A cell viability rate of (44.11 ± 6.59)% in the Aβ40 group was rescued to (79.13 ± 6.64)% by adding different concentrations of the extract. DAPI showed pyknotic nuclei in 39.5% of Aβ40-treated cells; the fraction dropped to 17.4% in the 100 μg/L extract group. ERK phosphorylation was observed in the Aβ40 group but was ameliorated by pretreatment with 100 μg/L extract. Hainan papaya water extract also prevented Aβ40-induced phosphorylation of MEK, RSK1 and CREB associated with ERK signaling and downregulated Bax expression in the neurons.@*CONCLUSION@#The results suggest that Hainan papaya water extract has protective effects on neurons; the mechanism may be related to suppression of ERK signaling activation.
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Objective To investigate whether Hainan papayas has protective effects in an Aβ40-induced primary neuron injury model and elucidate the underlying molecular mechanism. Methods Cultured primary neurons from the dorsal root ganglia (DRG) of Sprague–Dawley (SD) rats were treated with 20 μM Aβ40 peptide, 100 μg/L Hainan papaya water extract, peptide plus extract, or culture medium for 24 h. Cell viability was measured by MTT assay, and neuronal apoptosis was evaluated by DAPI staining. ERK signaling pathway-associated molecule activation and changes in Bax expression were analyzed by Western blotting and immunofluorescence. Results A cell viability rate of (44.11 ± 6.59)% in the Aβ40 group was rescued to (79.13 ± 6.64)% by adding different concentrations of the extract. DAPI showed pyknotic nuclei in 39.5% of Aβ40-treated cells; the fraction dropped to 17.4% in the 100 μg/L extract group. ERK phosphorylation was observed in the Aβ40 group but was ameliorated by pretreatment with 100 μg/L extract. Hainan papaya water extract also prevented Aβ40-induced phosphorylation of MEK, RSK1 and CREB associated with ERK signaling and downregulated Bax expression in the neurons. Conclusion The results suggest that Hainan papaya water extract has protective effects on neurons; the mechanism may be related to suppression of ERK signaling activation.
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OBJECTIVE@#To explore effect of srGAP3 promotes neurite outgrowth of dorsal root ganglion neurons.@*METHODS@#In this study, expression of Slit1 was observed predominantly in the glia, while expression of Robo2 and srGAP3 was detected in sensory neurons of postnatal rat cultured dorsal root ganglion (DRG). Furthermore, upregulation of srGAP3 following sciatic nerve transection was detected by immunohistochemistry and Western blotting.@*RESULTS@#It was observed that inhibition of neurite outgrowth in cultured adult DRG neurons following treatment with anti-srGAP3 or anti-Robo2 was more effectively (1.5-fold higher) than that following treatment with an anti-BDNF positive control antibody. It demonstrated that srGAP3 interacted with Robo2 and Slit1 protein to decrease Rac1-GTP activity in cultured adult rat DRG neurons and the opposite effect on Rac1-GTP activity was detected by co-immunoprecipitation and immunoblotting analyses following treatment with anti-Robo2 or anti-srGAP3. These data demonstrated a role for srGAP3 in neurite outgrowth of DRG sensory neurons.@*CONCLUSIONS@#Our observations suggest that srGAP3 promotes neurite outgrowth and filopodial growth cones by interacting with Robo2 to inactivate Rac1 in mammalian DRG neurons.