alpha-Synucleinopathy in the human olfactory system in Parkinson's disease: involvement of calcium-binding protein- and substance P-positive cells.
Hyposmia is an early symptom of idiopathic Parkinson's disease but the pathological bases of such dysfunction are largely unknown. The distribution of alpha-synuclein, which forms Lewy bodies and Lewy neurites, and the types of neurons (based on their neurotransmitters) affected by alpha-synucleinopathy were investigated in the olfactory system in Parkinson's disease. Immunohistochemical distribution of alpha-synuclein and its co-localization with tyrosine hydroxylase, somatostatin, calbindin, calretinin, parvalbumin and substance P in the olfactory bulb, anterior olfactory nucleus, olfactory tubercle and piriform, periamygdaloid and rostral entorhinal cortices of idiopathic Parkinson's disease cases (n = 11) and age-matched controls (n = 11) were investigated. Lewy bodies and Lewy neurites were present in the olfactory bulb, particularly in mitral cells and in the inner plexiform layer. alpha-synuclein was particularly abundant in the different divisions of the anterior olfactory nucleus (bulbar, intrapeduncular, retrobulbar and cortical). In contrast, Lewy bodies and Lewy neurites were less abundant in the olfactory tubercle and olfactory cortices. In the olfactory bulb, anterior olfactory nucleus and olfactory cortices, cells affected by alpha-synucleinopathy rarely co-localized tyrosine hydroxylase or somatostatin, but they frequently co-localized calbindin, calretinin, parvalbumin and substance P. The present data provide evidence that alpha-synucleinopathy affects neurons along the olfactory pathway. Dopamine- and somatostatin-positive cells are rarely affected; whereas the cell types most vulnerable to neurodegeneration include glutamate- (mitral cells), calcium-binding protein- and substance P-positive cells. These results provide data on the distribution and cell types involved by alpha-synucleinopathy in the human olfactory system during Parkinson disease that may be useful for future clinical investigation.
Ubeda-Bañon
Isabel
I
Laboratorio de Neuroanatomía Humana, Facultad de Medicina/Centro Regional de Investigaciones Biomédicas, Universidad de Castilla-La Mancha, 02006 Albacete, Spain.
Saiz-Sanchez
Daniel
D
de la Rosa-Prieto
Carlos
C
Argandoña-Palacios
Lucia
L
Garcia-Muñozguren
Susana
S
Martinez-Marcos
Alino
A
D000368:Aged; D000369:Aged, 80 and over; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D016022:Case-Control Studies; D002452:Cell Count; D002540:Cerebral Cortex / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D016631:Lewy Bodies / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D016501:Neurites / Q000378:metabolism / Q000473:pathology; D009830:Olfactory Bulb / Q000378:metabolism* / Q000473:pathology; D009833:Olfactory Pathways / Q000378:metabolism / Q000473:pathology; D010300:Parkinson Disease / Q000378:metabolism* / Q000473:pathology; D013373:Substance P / Q000378:metabolism*; D051844:alpha-Synuclein / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D051844:alpha-Synuclein; C043697:calcium-binding protein (brain); D013373:Substance P