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NK‐1 receptors expressing neurons in the Locus coeruleus (LC) play a role in cardiorespiratory response to CO 2
Author(s) -
Gargaglioni Luciane H.,
Carvalho Debora,
Bicego Kenia C,
Ferreira da Silva Glauber S,
Castro Olagide W,
GarciaCairasco Norberto
Publication year - 2010
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.24.1_supplement.1026.13
Subject(s) - gabaergic , locus coeruleus , hypercapnia , catecholaminergic cell groups , endocrinology , chemistry , medicine , substance p , ventilation (architecture) , glomus cell , catecholaminergic , lesion , receptor , dopaminergic , catecholamine , respiratory system , biology , chemoreceptor , dopamine , central nervous system , neuropeptide , pathology , mechanical engineering , engineering
Male Wistar rats were injected in the LC with substance P‐saporin conjugate (SP‐SAP; 2μM), to kill NK‐1 receptors (NK1R) expressing neurons, or IgG‐SAP as a control. Pulmonary ventilation (VE), mean arterial pressure (MAP) and heart rate (HR) were determined after 60 min of hypercapnic exposure (7% CO 2 in air). To verify the effectiveness of the lesions, immunohistochemistry for NK1Rs was performed. Immunohystochemistries for tyrosine hydroxylase (TH‐ir) and Glutamic Acid Decarboxylase (GAD‐ir) were also performed to verify if catecholaminergic and GABAergic neurons were eliminated. A reduced NK1R immunoreactivity (NK1R‐ir) in the LC (72%) showed the effectiveness of the lesion. SP‐SAP lesion also caused a reduction of TH‐ir neurons (66%) and GABAergic neurons (70%). Hypercapnia caused a decreased ventilatory response in SP‐SAP group (30%), due to a reduction in tidal volume. SP‐SAP lesion in the LC did not affect MAP but caused an increase in HR during hypercapnia. The results suggest that NK1R‐ir neurons in the LC modulate hypercapnic ventilatory response but play no role in breathing control under resting conditions. Additionally, NK1R‐ir neurons in the LC seem to play no role in MAP regulation in resting conditions and during hypercapnia, but modulate HR during CO 2 exposure. Part of these modulations might be due to noradrenergic and GABAergic effects. Supported by: FAPESP, CNPq.