Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Safflower Yellow Improves Synaptic Plasticity in APP/PS1 Mice by Regulating Microglia Activation Phenotypes and BDNF/TrkB/ERK Signaling Pathway


Alzheimer’s disease (AD) is a common neurodegenerative disease that is always accompanied by synaptic loss in the brain. Safflower yellow (SY) is the extract of safflower, a traditional Chinese medicine, which has shown neuroprotective effects in recent studies. However, the mechanism of SY in protecting synapses remains unclear. In this study, we are going to study the mechanism of how SY treats AD in terms of synaptic plasticity. We found, via behavioral experiments, that SY treatment could improve the abilities of learning and memory in APP/PS1 mice. In addition, using Golgi staining and HE staining, we found that SY treatment could reduce the loss of dendritic spines in the pathological condition and could maintain the normal physiological state of the cells in cortex and in hippocampus. In addition, the results of immunofluorescence staining and western blotting showed that SY treatment could significantly increase the expression of synapse-related proteins. Moreover, after being treated with SY, the expression of iNOS (marker of M1 microglia) declined remarkably, and the level of Arginase-1 (marker of M2 microglia) increased significantly. Finally, we found BDNF/TrkB/ERK signaling cascade was activated. These results indicate that SY enhances synaptic plasticity in APP/PS1 mice by regulating microglia activation phenotypes and BDNF/TrkB/ERK signaling pathway.

This is a preview of subscription content, log in to check access.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8


  1. Bailey, C. H., & Kandel, E. R. (1993). Structural changes accompanying memory storage. The Annual Review of Physiology,55, 397–426.

  2. Bharne, A. P., Borkar, C. D., Bodakuntla, S., Lahiri, M., Subhedar, N. K., & Kokare, D. M. (2016). Pro-cognitive action of CART is mediated via ERK in the hippocampus. Hippocampus,26(10), 1313–1327.

  3. Bloom, G. S. (2014). Amyloid-β and Tau. JAMA Neurology,71(4), 505–508.

  4. Chakroborty, S., Kim, J., Schneider, C., West, A. R., & Stutzmann, G. E. (2015). Nitric oxide signaling is recruited as a compensatory mechanism for sustaining synaptic plasticity in Alzheimer's disease mice. Journal of Neuroscience,35(17), 6893–6902.

  5. Cherry, J. D., Olschowka, J. A., & O'Banion, M. K. (2014). Neuroinflammation and M2 microglia: The good, the bad, and the inflamed. Journal of Neuroinflammation,11(1), 98.

  6. Chong, Y. H., Shin, Y. J., Lee, E. O., Kayed, R., Glabe, C. G., & Tenner, A. J. (2006). ERK1/2 activation mediates abeta oligomer-induced neurotoxicity via caspase-3 activation and tau cleavage in rat organotypic hippocampal slice cultures. Journal of Biological Chemistry,281(29), 20315–20325.

  7. Cotman, C. W., & Berchtold, N. C. (2002). Exercise: A behavioral intervention to enhance brain health and plasticity. Trends in Neurosciences,25(6), 295–301.

  8. Devi, L., & Ohno, M. (2012). 7,8-dihydroxyflavone, a small-molecule TrkB agonist, reverses memory deficits and BACE1 elevation in a mouse model of Alzheimer's disease. Neuropsychopharmacology Official Publication of the American College of Neuropsychopharmacology,37(2), 434–444.

  9. El-Husseini, E. D., Schnell, E., Chetkovich, D. M., Nicoll, R. A., & Bredt, D. S. (2000). PSD-95 Involvement in maturation of excitatory synapses. Science,290(5495), 1364–1368.

  10. Gallagher, J. J., Minogue, A. M., & Lynch, M. A. (2013). Impaired performance of female APP/PS1 mice in the Morris water maze is coupled with increased Aβ accumulation and microglial activation. Neuro-degenerative Diseases,11(1), 33–41.

  11. Giachello, C. N., Fiumara, F., Giacomini, C., Corradi, A., Milanese, C., Ghirardi, M., et al. (2010). MAPK/Erk-dependent phosphorylation of synapsin mediates formation of functional synapses and short-term homosynaptic plasticity. Journal of Cell Science,123(Pt 6), 881–893.

  12. Gylys, K. H., Fein, J. A., Yang, F., Wiley, D. J., Miller, C. A., & Cole, G. M. (2004). Synaptic changes in Alzheimer's disease: Increased amyloid-beta and gliosis in surviving terminals is accompanied by decreased PSD-95 fluorescence. American Journal of Pathology,165(5), 1809–1817.

  13. Hayashi, M. K., Tang, C., Verpelli, C., Narayanan, R., Stearns, M. H., Xu, R. M., et al. (2009). The postsynaptic density proteins Homer and Shank form a polymeric network structure. Cell,137(1), 159–171.

  14. Hong, S., Bejaglasser, V. F., Nfonoyim, B. M., Frouin, A., Li, S., Ramakrishnan, S., et al. (2016). Complement and microglia mediate early synapse loss in Alzheimer mouse models. Science,352(6286), 712–716.

  15. Huang, D., Lu, Y., Luo, X., Shi, L., Zhang, J., Shen, J., et al. (2012). Effect of safflower yellow on platelet activating factor mediated platelet activation in patients with coronary heart disease. Bangladesh Journal of Pharmacology,7(2), 140–144.

  16. Jansone, B., Kadish, I., Van, G. T., Beitnere, U., Plotniece, A., Pajuste, K., et al. (2016). Memory-enhancing and brain protein expression-stimulating effects of novel calcium antagonist in Alzheimer's disease transgenic female mice. Pharmacological Research,113(Pt B), 781–787.

  17. Kempf, S. J., Metaxas, A., Ibáñezvea, M., Darvesh, S., Finsen, B., & Larsen, M. R. (2016). An integrated proteomics approach shows synaptic plasticity changes in an APP/PS1 Alzheimer's mouse model. Oncotarget,7(23), 33627–33648.

  18. Knobloch, M., & Mansuy, I. M. (2008). Dendritic spine loss and synaptic alterations in Alzheimer’s disease. Molecular Neurobiology,37(1), 73–82.

  19. Kwon, S. E., & Chapman, E. R. (2011). Synaptophysin regulates the kinetics of synaptic vesicle endocytosis in central neurons. Neuron,70(5), 847–854.

  20. Lanté, F., Chafai, M., Raymond, E. F., Salgueiro Pereira, A. R., Mouska, X., Kootar, S., et al. (2015). Subchronic glucocorticoid receptor inhibition rescues early episodic memory and synaptic plasticity deficits in a mouse model of Alzheimer’s disease. Neuropsychopharmacology,40(7), 1772–1781.

  21. Lu, Z., Yu, F., Xu, Y., Lian, Y., Xie, N., Wu, T., et al. (2015). Curcumin improves amyloid β-peptide (1–42) induced spatial memory deficits through BDNF-ERK signaling pathway. PLoS ONE,10(6), e0131525.

  22. Madison, D. V., Malenka, R. C., & Nicoll, R. A. (1991). Mechanisms underlying long-term potentiation of synaptic transmission. Annual Review of Neuroscience,14(14), 379–397.

  23. Malinow, R. (1994). LTP: desperately seeking resolution. Science,266(5188), 1195–1196.

  24. Marguerite, P., Richard, D., Ehren, J. L., Chandramouli, C., & David, S. (2013). The neurotrophic compound J147 reverses cognitive impairment in aged Alzheimer's disease mice. Alzheimers Research & Therapy,5(3), 25.

  25. Mosher, K. I., & Wysscoray, T. (2014). Microglial dysfunction in brain aging and Alzheimer's disease. Biochemical Pharmacology,88(4), 594–604.

  26. Ma, Q., Ruan, Y-Y., Xu, H., Shi, X-M., Wang, Z-X., Hu, Y-L., et al. (2015). Safflower yellow reduces lipid peroxidation, neuropathology, tau phosphorylation and ameliorates amyloid β-induced impairment of learning and memory in rats. Biomedicine & Pharmacotherapy,76, 153–164.

  27. Nikonenko, I., Boda, B., Steen, S., Knott, G., Welker, E., & Muller, D. (2008). PSD-95 promotes synaptogenesis and multiinnervated spine formation through nitric oxide signaling. Journal of Cell Biology,183(6), 1115–1127.

  28. Nowack, A., Yao, J., Custer, K. L., & Bajjalieh, S. M. (2010). SV2 regulates neurotransmitter release via multiple mechanisms. American Journal of Physiology Cell Physiology,299(5), C960–967.

  29. O'Dell, T. J., Kandel, E. R., & Grant, S. G. N. (1991). Long-term potentiation in the hippocampus is blocked by tyrosine kinase inhibitors. Nature,353(6344), 558–560.

  30. Patterson, S. L. (2015a). Immune dysregulation and cognitive vulnerability in the aging brain: Interactions of microglia, IL-1β BDNF and synaptic plasticity. Neuropharmacology,96(Pt A), 11–18.

  31. Patterson, S. L. (2015b). Immune dysregulation and cognitive vulnerability in the aging brain: Interactions of microglia, IL-1β, BDNF and synaptic plasticity. Neuropharmacology,96, 11–18.

  32. Pyeon, H. J., & Lee, Y. I. (2012). Differential expression levels of synaptophysin through developmental stages in hippocampal region of mouse brain. Anatomy & Cell Biology,45(2), 97–102.

  33. Roghani, Z. M. T. B. M. (2017). The beneficial effects of riluzole on GFAP and iNOS expression in intrahippocampal Aβ rat model of Alzheimer's disease. Journal of Basic & Clinical Pathophysiology,5(1), 33–38.

  34. Ruan, Y-Y., Zhai, W., Shi, X-M., Zhang, L., & Hu, Y-L., et al. (2016). Safflower yellow ameliorates cognition deficits and reduces tau phosphorylation in APP/PS1 transgenic mice. Metabolic Brain Disease,31(5), 1133–1142.

  35. Sánchez Gil, J. (2016). Role of the SV2A protein in epilepsy and Alzheimer's mouse models. PLoS ONE,14(6), e0217882.

  36. Sandovalhernández, A. G., Hernández, H. G., Restrepo, A., Muñoz, J. I., Bayon, G. F., Fernández, A. F., et al. (2016). Liver X receptor agonist modifies the DNA methylation profile of synapse and neurogenesis-related genes in the triple transgenic mouse model of Alzheimer's disease. Journal of Molecular Neuroscience,58(2), 243–253.

  37. Selcher, J. C., Weeber, E. J., Varga, A. W., Sweatt, J. D., & Swank, M. (2002). Protein kinase signal transduction cascades in mammalian associative conditioning. Neuroscientist,8(2), 122–131.

  38. Selkoe, D. J. (2002). Alzheimer's disease is a synaptic failure. Science,298(5594), 789–791.

  39. Shao, C. Y., Mirra, S. S., Sait, H. B. R., Sacktor, T. C., & Sigurdsson, E. M. (2011). Postsynaptic degeneration as revealed by PSD-95 reduction occurs after advanced Aβ and tau pathology in transgenic mouse models of Alzheimer’s disease. Acta Neuropathologica,122(3), 285–292.

  40. Shi, X.-M., Zhang, H., Zhou, Z.-J., Ruan, Y.-Y., Pang, J., Zhang, L., et al. (2017). Effects of safflower yellow on beta-amyloid deposition and activation of astrocytes in the brain of APP/PS1 transgenic mice. Biomedecine & Pharmacotherapie,98, 553–565.

  41. Smith, J. A., Das, A., Ray, S. K., & Banik, N. L. (2012). Role of pro-inflammatory cytokines released from microglia in neurodegenerative diseases. Brain Research Bulletin,87(1), 10–20.

  42. Sominsky, L., De Luca, S., & Spencer, S. J. (2018). Microglia: Key players in neurodevelopment and neuronal plasticity. The International Journal of Biochemistry & Cell Biology,94, 56–60.

  43. Stancu, I. C., Vasconcelos, B., Terwel, D., & Dewachter, I. (2014). Models of β-amyloid induced Tau-pathology: the long and “folded” road to understand the mechanism. Molecular Neurodegeneration,9(1), 51.

  44. Steiner, P., Higley, M. J., Xu, W., Czervionke, B. L., Malenka, R. C., & Sabatini, B. L. (2008). Destabilization of the postsynaptic density by PSD-95 serine 73 phosphorylation inhibits spine growth and synaptic plasticity. Neuron,60(5), 788–802.

  45. Sun, J., Bronk, P., Liu, X., Han, W., & Südhof, T. C. (2006). Synapsins regulate use-dependent synaptic plasticity in the calyx of held by a Ca2+/calmodulin-dependent pathway. Proceedings of the National Academy of Sciences of the United States of America,103(8), 2880–2885.

  46. Sutton, M. A., & Schuman, E. M. (2006). Dendritic protein synthesis, synaptic plasticity, and memory. Cell,127(1), 49–58.

  47. Sweatt, J. D. (2001). The neuronal MAP kinase cascade: A biochemical signal integration system subserving synaptic plasticity and memory. Journal of Neurochemistry,76(1), 1–10.

  48. Tang, Y., & Le, W. (2016). Differential roles of M1 and M2 microglia in neurodegenerative diseases. Molecular Neurobiology,53(2), 1181–1194.

  49. Terry, R. D., Eliezer Masliah, M. D., Salmon, D. P., Butters, N., Richard DeTeresa, B. S., Hill, R., et al. (1991). Physical basis of cognitive alterations in alzheimer's disease: Synapse loss is the major correlate of cognitive impairment. Annals of Neurology,30(4), 572–580.

  50. Thangavel, R., Kempuraj, D., Zaheer, S., Raikwar, S., Ahmed, M. E., Iyer, S. S., et al. (2017). Glia Maturation factor and mitochondrial uncoupling proteins 2 and 4 expression in the temporal cortex of Alzheimer’s disease brain. Frontiers in Aging Neuroscience,9, 150.

  51. Tundis, R., Loizzo, M. R., Menichini, F., Statti, G. A., & Menichini, F. (2008). Biological and pharmacological activities of iridoids: recent developments. Mini Reviews in Medicinal Chemistry,8(4), 399–420.

  52. Vanguilder, H. D., Farley, J. A., Yan, H., Van Kirk, C. A., Mitschelen, M., Sonntag, W. E., et al. (2011). Hippocampal dysregulation of synaptic plasticity-associated proteins with age-related cognitive decline. Neurobiology of Disease,43(1), 201–212.

  53. Waterhouse, E. G., & Xu, B. (2009). New insights into the role of brain-derived neurotrophic factor in synaptic plasticity. Molecular & Cellular Neurosciences,42(2), 81–89.

  54. Wu, Y., Dissing-Olesen, L., Macvicar, B. A., & Stevens, B. (2015). Microglia: Dynamic mediators of synapse development and plasticity. Trends in Immunology,36(10), 605–613.

  55. Yang, T., Li, S., Xu, H., Walsh, D. M., & Selkoe, D. J. (2017). Large soluble oligomers of amyloid β-protein from Alzheimer brain are far less neuroactive than the smaller oligomers to which they dissociate. The Journal of Neuroscience,37(1), 152–163.

  56. Yao, J., Nowack, A., Kensel-Hammes, P., Gardner, R. G., & Bajjalieh, S. M. (2010). Cotrafficking of SV2 and synaptotagmin at the synapse. Journal of Neuroscience the Official Journal of the Society for Neuroscience,30(16), 5569–5578.

  57. Zhang, Z., Liu, X., Schroeder, J. P., Chan, C. B., Song, M., Yu, S. P., et al. (2014). 7,8-dihydroxyflavone prevents synaptic loss and memory deficits in a mouse model of Alzheimer's disease. Neuropsychopharmacology Official Publication of the American College of Neuropsychopharmacology,39(3), 638–650.

  58. Zhang, F., Zhong, R., Li, S., Fu, Z., Cheng, C., Cai, H., et al. (2017). Acute hypoxia induced an imbalanced M1/M2 activation of microglia through NF-κB signaling in Alzheimer's disease mice and wild-type littermates. Frontiers in Aging Neuroscience,9, 282.

  59. Zhang, L., Zhou, Z., Zhai, W., Pang, J., Mo, Y., Yang, G., et al. (2019). Safflower yellow attenuates learning and memory deficits in amyloid β-induced Alzheimer’s disease rats by inhibiting neuroglia cell activation and inflammatory signaling pathways. Metabolic Brain Disease,34, 927–939.

Download references


Thanks to American Journal Experts for providing language help in this article (Certificate Verification Key: 2840-1165-087E-4316-0A08).


This research was supported by the National Natural Science Foundation of China [Nos. 81660603 and 81960665].

Author information

JP and YH conceived and designed research. JP and JH conducted experiments. ZZ, MR, YM and JH analyzed data. JH wrote the manuscript; GY, ZQ and YH revised the manuscript. All authors read and approved the manuscript for publication.

Correspondence to Yanli Hu.

Ethics declarations

Conflict of interests

The authors declare that there are no conflicts of interest.

Ethical Approval

All applicable international and national guidelines for the care and use of animals were followed.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Pang, J., Hou, J., Zhou, Z. et al. Safflower Yellow Improves Synaptic Plasticity in APP/PS1 Mice by Regulating Microglia Activation Phenotypes and BDNF/TrkB/ERK Signaling Pathway. Neuromol Med (2020).

Download citation


  • Alzheimer’s disease
  • Synaptic plasticity
  • Safflower yellow
  • Microglia
  • APP/PS1 transgenic mice