Chronic α-Synuclein Accumulation in Rat Hippocampus Induces Lewy Bodies Formation and Specific Cognitive Impairments.
Danielle Walu KasongoGioacchino de LeoNunzio VicarioGiampiero LeanzaGiuseppe LegnamePublished in: eNeuro (2020)
Occurrence of Lewy bodies (LBs)/Lewy neurites (LNs) containing misfolded fibrillar α-synuclein (α-syn) is one of the pathologic hallmarks of memory impairment-linked synucleinopathies, such as Parkinson's disease (PD) and dementia with LBs (DLB). While it has been shown that brainstem LBs may contribute to motor symptoms, the neuropathological substrates for cognitive symptoms are still elusive. Here, recombinant mouse α-syn fibrils were bilaterally injected in the hippocampus of female Sprague Dawley rats, which underwent behavioral testing for sensorimotor and spatial learning and memory abilities. No sensorimotor deficits affecting Morris water maze task performance were observed, nor was any reference memory disturbances detectable in injected animals. By contrast, significant impairments in working memory performance became evident at 12 months postinjection. These deficits were associated to a time-dependent increase in the levels of phosphorylated α-syn at Ser129 and in the stereologically estimated numbers of proteinase K (PK)-resistant α-syn aggregates within the hippocampus. Interestingly, pathologic α-syn aggregates were found in the entorhinal cortex and, by 12 months postinjection, also in the vertical limb of the diagonal band and the piriform cortices. No pathologic α-syn deposits were found within the substantia nigra (SN), the ventral tegmental area (VTA), or the striatum, nor was any loss of dopaminergic, noradrenergic, or cholinergic neurons detected in α-syn-injected animals, compared with controls. This would suggest that the behavioral impairments seen in the α-syn-injected animals might be determined by the long-term α-syn neuropathology, rather than by neurodegeneration per se, thus leading to the onset of working memory deficits.
Keyphrases
- working memory
- transcranial direct current stimulation
- attention deficit hyperactivity disorder
- neoadjuvant chemotherapy
- traumatic brain injury
- spinal cord
- cognitive impairment
- functional connectivity
- prefrontal cortex
- parkinson disease
- magnetic resonance
- risk assessment
- magnetic resonance imaging
- radiation therapy
- locally advanced
- computed tomography
- squamous cell carcinoma
- spinal cord injury
- deep brain stimulation
- depressive symptoms
- oxidative stress
- sleep quality
- cerebral ischemia
- blood brain barrier
- cell free