Skip to main content

Advertisement

Log in

Microglia activation and phagocytosis: relationship with aging and cognitive impairment in the rhesus monkey

  • Original Article
  • Published:
GeroScience Aims and scope Submit manuscript

Abstract

While cognitive decline is observed in the normal aging monkey, neurons are not lost with age. Instead, frontal white matter is lost as myelin degenerates and both correlate with age-related cognitive decline. As age-related myelin damage increases, there should be an increase in clearance of damaged myelin by microglial phagocytosis. In this study, brains of behaviorally tested rhesus monkeys were assessed using unbiased stereology to quantify the density of activated microglia (LN3 antibody positive) and phagocytic microglia (galectin-3 (Gal-3) antibody positive) in three white matter regions: the corpus callosum, cingulum bundle (CGB), and frontal white matter (FWM). LN3 cell density was significantly increased in the CGB, whereas Gal-3 cell density was significantly increased in all regions. Increases in Gal-3 cell density in the FWM were associated with cognitive impairment. In the FWM of old animals, Gal-3-positive microglia were classified by morphological subtype as ramified, hypertrophic, or amoeboid. The densities of hypertrophic and amoeboid microglia significantly correlated with cognitive impairment. Finally, microglia were double-labeled with LN3 and Gal-3 showing that 91% of Gal-3 cells were also LN3 positive, thus expressing an “activated” phenotype. Furthermore, 15% of all double-labeled cells formed phagocytic cups. Overall, these results suggest that microglia become activated in white matter with age where the majority express a phagocytic phenotype. We hypothesize that age-related phagocytic activation of microglia is a response to accumulating myelin pathology. The association of Gal-3 in the FWM with cognitive impairment may reflect regional differences in damage or dysfunction of normal clearance mechanisms.

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

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

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

Similar content being viewed by others

References

Download references

Acknowledgements

We would like to acknowledge our technicians and staff, without whom these studies would not be possible: Bethany Bowley, Alana Carmichael, Simrat Dhaliwal, Penny Schultz, Karen L. Slater, and Rebecca Smith. This work was supported by NIH grants R01-AG043640 and NIH R01-AG042512.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Eli Shobin.

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Shobin, E., Bowley, M.P., Estrada, L.I. et al. Microglia activation and phagocytosis: relationship with aging and cognitive impairment in the rhesus monkey. GeroScience 39, 199–220 (2017). https://doi.org/10.1007/s11357-017-9965-y

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s11357-017-9965-y

Keywords

Navigation