Astrocytic changes with aging and Alzheimer's disease-type pathology in chimpanzees.
Emily L MungerMelissa K EdlerWilliam D HopkinsJohn J ElyJoseph M ErwinDaniel P PerlElliott J MufsonPatrick R HofChet C SherwoodMary Ann RaghantiPublished in: The Journal of comparative neurology (2019)
Astrocytes are the main homeostatic cell of the central nervous system. In addition, astrocytes mediate an inflammatory response when reactive to injury or disease known as astrogliosis. Astrogliosis is marked by an increased expression of glial fibrillary acidic protein (GFAP) and cellular hypertrophy. Some degree of astrogliosis is associated with normal aging and degenerative conditions such as Alzheimer's disease (AD) and other dementing illnesses in humans. The recent observation of pathological markers of AD (amyloid plaques and neurofibrillary tangles) in aged chimpanzee brains provided an opportunity to examine the relationships among aging, AD-type pathology, and astrocyte activation in our closest living relatives. Stereologic methods were used to quantify GFAP-immunoreactive astrocyte density and soma volume in layers I, III, and V of the prefrontal and middle temporal cortex, as well as in hippocampal fields CA1 and CA3. We found that the patterns of astrocyte activation in the aged chimpanzee brain are distinct from humans. GFAP expression does not increase with age in chimpanzees, possibly indicative of lower oxidative stress loads. Similar to humans, chimpanzee layer I astrocytes in the prefrontal cortex are susceptible to AD-like changes. Both prefrontal cortex layer I and hippocampal astrocytes exhibit a high degree of astrogliosis that is positively correlated with accumulation of amyloid beta and tau proteins. However, unlike humans, chimpanzees do not display astrogliosis in other cortical layers. These results demonstrate a unique pattern of cortical aging in chimpanzees and suggest that inflammatory processes may differ between humans and chimpanzees in response to pathology.
Keyphrases
- prefrontal cortex
- oxidative stress
- inflammatory response
- poor prognosis
- cognitive decline
- stem cells
- cerebral ischemia
- functional connectivity
- dna damage
- lipopolysaccharide induced
- cerebrospinal fluid
- white matter
- neuropathic pain
- spinal cord injury
- transcranial magnetic stimulation
- protein protein
- signaling pathway
- lps induced
- amino acid
- heat stress
- heat shock protein