Involvement of Serotonergic Neurons in the Ventilatory Response to Hypercapnia in Birds (Chicken, Gallus gallus )

• Published in: The FASEB journal Vol. 31; no. S1
• Main Authors: Santos, Kassia M, Abreu, Sheila B, Garcia, Giuliana Milan Andrade, Bícego, Kenia C, Gargaglioni, Luciane H, da Silva, Glauber S F
• Format: Journal Article
• Language: English
• Published: 01-04-2017
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.31.1_supplement.719.1

Abstract only
Respiratory system regulates acid‐base balance by eliminating carbon dioxide (CO
2
), with PCO
2
/pH variations detected mainly by central chemoreceptors. In mammals, serotonergic neurons (5‐HT) have been demonstrated to play a crucial role in the ventilatory response to CO
2
. It is known that birds have central CO
2
/pH chemoreceptors and that 5‐HT neurons are organized in the raphe. However, it is not known the neuronal phenotype involved in central chemoreception in birds. We hypothesized that 5‐HT neurons play a role in the central CO
2
/pH chemoreception in birds. Therefore, the present study aimed to verify the involvement of 5‐HT neurons in respiratory control in chicken (
Gallus gallus
) exposed to hypercapnia. Five‐day old male chicks were submitted to surgical procedures and 1μl of anti‐SERT‐SAP immunotoxin (0.1mM) was microinjected into the fourth ventricle for specific deletion of 5‐HT neurons. The control group received IgG‐SAP injections. Animals underwent to hypercapnia exposure (7% CO
2
) ten days after surgery. Pulmonary ventilation (VE; barometric method, whole body plethysmography) and body temperature were measured. Brainstem 5‐HT lesion was verified by immunohistochemistry. Both groups (control and lesioned) augmented VE during hypercapnia. Ventilatory response to hypercapnia of lesioned chickens was attenuated by ~30% compared to the control animals [mean values of VE during hypercapnia: 2429 and 1805 ml/kg/min, control vs lesioned group, respectively; P<0.05, (n=6)]. The attenuated response to hypercapnia was due to the lower respiratory frequency (77 and 59 breaths/min, control vs lesioned group, respectively. P<0.05). The results suggest that brainstem serotonergic neurons contribute to the respiratory response to CO
2
in chicken, playing an excitatory role in CO
2
‐drive to breathing.
Support or Funding Information
Sao Paulo Research Foundation (FAPESP)