title: Serotonergic neurons in the nucleus raphé obscurus are not involved in the ventilatory and thermoregulatory responses to hypoxia in adult rats.
abstract: The medullary raphé is an important component of the central respiratory network, playing a key role in CO2 central chemoreception. However, its participation in hypoxic ventilatory responses is less understood. In the present study, we assessed the role of nucleus raphé obscurus (ROb), and specifically 5-HT neurons confined in the ROb, on ventilatory and thermoregulatory responses to hypoxia. Chemical lesions of the ROb were performed using either ibotenic acid (non-specific lesion; control animals received PBS) or anti-SERT-SAP (5-HT specific lesion; control animals received IgG-SAP). Ventilation (V˙E; whole body plethysmograph) and body temperature (Tb; data loggers) were measured during normoxia (21% O2, N2 balance) and hypoxia exposure (7% O2, N2 balance, 1h) in conscious adult rats. Ibotenic acid or anti-SERT-SAP-induced lesions did not affect baseline values of V˙E and Tb. Similarly, both lesion procedures did not alter the ventilatory or thermoregulatory responses to hypoxia. Although evidence in the literature suggests a role of the rostral medullary raphé in hypoxic ventilatory responses, under the present experimental conditions our data indicate that caudal medullary raphé (ROb) and its 5-HT neurons neither participate in the tonic maintenance of breathing nor in the ventilatory and thermal responses to hypoxia.
authors.affiliation: Department of Physiology, University of São Paulo - USP/FMRP, Ribeirão Preto, SP, Brazil. glauber@ymail.com
authors.forename: Glauber S F
authors.initials: GS
authors.lastname: da Silva
authors.forename: Humberto
authors.initials: H
authors.lastname: Giusti
authors.forename: Olagide W
authors.initials: OW
authors.lastname: Castro
authors.forename: Norberto
authors.initials: N
authors.lastname: Garcia-Cairasco
authors.forename: Luciane H
authors.initials: LH
authors.lastname: Gargaglioni
authors.forename: Luiz G S
authors.initials: LG
authors.lastname: Branco
authors.forename: Mogens L
authors.initials: ML
authors.lastname: Glass
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001784:Blood Gas Analysis; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D001833:Body Temperature Regulation / Q000187:drug effects / Q000502:physiology*; D002452:Cell Count; D004195:Disease Models, Animal; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity; D000860:Hypoxia / Q000473:pathology* / Q000503:physiopathology*; D007051:Ibotenic Acid / Q000633:toxicity; D008297:Male; D008845:Microinjections; D010993:Plethysmography, Whole Body; D012123:Pulmonary Ventilation / Q000187:drug effects / Q000502:physiology*; D016601:RNA-Binding Proteins / Q000276:immunology; D011903:Raphe Nuclei / Q000473:pathology*; D051381:Rats; D017208:Rats, Wistar; D059326:Serotonergic Neurons / Q000502:physiology*; D012701:Serotonin / Q000378:metabolism; D013997:Time Factors
chemical_list: D000906:Antibodies; D018690:Excitatory Amino Acid Agonists; D016601:RNA-Binding Proteins; C482440:Sert1 protein, rat; D007051:Ibotenic Acid; D012701:Serotonin