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REDUCTION OF PERIAQUEDUCTAL GRAY PROJECTING NEURONS TO THE RETROTRAPEZOID NUCLEUS IN A 6‐OHDA MODEL OF PARKINSON'S DISEASE
Author(s) -
Lima Juliana C,
Moreira Thiago C,
Takakura Ana C
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.1054.4
Subject(s) - periaqueductal gray , parkinson's disease , neun , substantia nigra , neuroscience , medicine , dopaminergic , anesthesia , hypercapnia , respiratory system , endocrinology , dopamine , psychology , midbrain , central nervous system , disease , immunohistochemistry
Parkinson's disease (PD) is characterized by a reduction in the number of dopaminergic neurons of the substantia nigra (SN) accompanied by motor and non‐motor deficiencies such as respiratory failure. Among the non‐motor symptoms, the disease has respiratory complications, and the one that is the leading cause of death in PD is obstructive sleep apnea. Our laboratory suggested an impairment in brain regions crucial for breathing automaticity such as the retrotrapezoid nucleus (RTN) and a decrease in respiratory rate in a model of PD. In addition, we also showed no direct projections from SN to RTN, but we identified a connection that bypass the periaqueductal gray (PAG), a region with important modulatory role in respiratory activity. Therefore, our aim was to investigate whether there is a reduction in the number of neurons in PAG and whether the neurons in the PAG that project to RTN are reduced in the animal's model of PD. male Wistar rats (250 – 300 g; N = 3–5/group, CEUA:99/22/03) with vehicle or 6‐hydroxydopamine (6‐OHDA) injection in the Caudate and Putamen (CPu) region were used. After 30 days, one group of animals received the injection of the retrograde tracer Fluorogold (2%) in the RTN. Fourty days after 6‐OHDA or vehicle injection, all animals were submitted to hypercapnia for 3 hours and perfused for immunohistochemistry to evaluate the neuronal marker (NeuN‐ir), and the presence of fos in PAG neurons that project to RTN. In 6‐OHDA‐lesioned rats, there is a reduction in the density of NeuN‐ir in the dorsomedial (10 ± 3 vs. vehicle: 23 ± 1%), dorsolateral (15 ± 6 vs. vehicle: 38 ± 2%) and the ventrolateral (14 ± 5, vs. vehicle: 30 ± 1%) regions of the PAG and a reduction in the number of TH‐ir varicosities in the PAG (778 ± 135 vs. vehicle: 1338 ± 133). Moreover, the number of neurons in PAG activated by hypercapnia that project to RTN is reduced in the dorsolateral (3 ± 1 vs. vehicle: 21 ± 12) and ventrolateral (4 ± 1, vs. vehicle: 116 ± 8) regions in 6‐OHDA‐lesioned rats. We conclude that there is a commitment of the pathway between PAG and RTN in the animal's model of PD. Support or Funding Information FAPESP, CNPQ, CAPES