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Serotonergic neurons of Nucleus Raphe Magnus are involved in ventilatory (but not thermal) responses to CO 2 of rats.
Author(s) -
Dias Mirela Barros,
Gargaglioni Luciane Helena,
Margatho Lisandra Oliveira,
Navarro Valéria Pontelli,
AntunesRodrigues José,
Branco Luiz Guilherme S
Publication year - 2007
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.21.6.a917-c
Subject(s) - hypercapnia , serotonergic , nucleus raphe magnus , raphe nuclei , raphe , chemistry , ventilation (architecture) , anesthesia , ibotenic acid , endocrinology , medicine , serotonin , respiratory system , central nervous system , receptor , mechanical engineering , engineering
Background : We hypothesized that Nucleus Raphe Magnus (NRM) plays a role in the ventilatory and thermal responses to hypercapnia, and that its serotonergic neurons are involved in these responses.Methods : Non‐specific lesions of NRM were performed microinjecting ibotenic acid (IBO, 0.4μg/0.2μL) in male Wistar rats. To study the role of NRM serotonergic neurons, rats received microinjections of anti‐SERT‐SAP (0.2pmol/0.2μL). Measurements of ventilation ( VE , body plethysmography) and body temperature ( Tb , biotelemetry) were performed in room air, followed by 60 or 120min of 7% CO 2 . Results : NMR non‐specific lesions decreased the ventilatory response to CO 2 [ VE = 604.43±17.85 (IBO) vs 1275.10±17.64 mL kg‐1min‐1 (PBS); two‐way ANOVA]. Lesions of NMR serotonergic neurons caused hypoventilation during air breathing [ VE = 260.18± 45.52 mL kg‐1min‐1 (anti‐SERT‐SAP) vs 420.67±33.80 (anti‐IgG‐SAP, control group)] and a decreased ventilatory response to CO 2 [ VE = 558.69±64.58 (anti‐SERT‐SAP) vs 1167.83±68.91 mL kg‐1min‐1 (anti‐IgG‐SAP)]. The hypercapnia‐induced hypothermia was not affected by lesions. Conclusion : NRM plays a key role in the ventilatory but not in the thermal response to hypercapnia, and serotonergic neurons of this nucleus contribute to a non‐CO 2 dependent chemical drive to breathe and are involved in the ventilatory response to CO 2 . Financial Support : FAPESP, CNPq, PROEX, USP.