Chemical lesions of the nucleus isthmi increase the hypoxic and hypercarbic drive to breathing of toads

Gargaglioni, Luciane H.; Coimbra, Norberto Cysne; Branco, Luiz G.S.

doi:10.1016/s1569-9048(02)00116-7

Cited by 19 publications

(17 citation statements)

References 27 publications

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“…The dose and IBO administration method were chosen based on pilot experiments and previous studies (Gargaglioni et al . , Dias et al . , Lopes et al .…”

Section: Methodsmentioning

confidence: 99%

“…Sham-operated rats were injected with phosphate-buffered saline (PBS, 0.5 or 1.0 lL over 10 min; pH = 7.4). The dose and IBO administration method were chosen based on pilot experiments and previous studies (Gargaglioni et al 2002, Dias et al 2007, Lopes et al 2012. Ibotenic acid administration was controlled with an infusion pump (310 Stoelting, Wood Hale, IL, USA) programmed to deliver a volume of 1.0 lL over a period of 5 min.…”

Section: Surgerymentioning

confidence: 99%

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Participation of the dorsal periaqueductal grey matter in the hypoxic ventilatory response in unanaesthetized rats

et al. 2014

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Middle to caudal portions of the dorsolateral/dorsomedial periaqueductal grey matter neurones modulate the hypoxic ventilatory response, exerting an inhibitory modulation during low O2 situations. In addition, the middle to caudal portions of the dorsolateral/dorsomedial or ventrolateral/lateral periaqueductal grey matter do not appear to exert a tonic role on cardiovascular or thermal parameters during normoxic and hypoxic conditions.

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“…The dose and IBO administration method were chosen based on pilot experiments and previous studies (Gargaglioni et al . , Dias et al . , Lopes et al .…”

Section: Methodsmentioning

confidence: 99%

Section: Surgerymentioning

confidence: 99%

Participation of the dorsal periaqueductal grey matter in the hypoxic ventilatory response in unanaesthetized rats

et al. 2014

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“…Sham-operated rats were injected with phosphate-buffered saline (PBS, 0.250 μL over 10 min; pH07.4). The dose and IBO administration method were chosen based on pilot experiments and previous studies [30,32]. Pressure injections were performed with a pipette end connected to polyethylene tubing attached to a Hamilton microsyringe (5 μL), and administration was controlled with an infusion pump (310 Stoelting, Wood Hale, IL, USA) programmed to deliver a volume of 0.250 μL over a period of 5 min.…”

Section: Surgerymentioning

confidence: 99%

“…To histochemically assess neurochemical lesion characteristics, the brains were sectioned, and the slices were mounted on glass slides coated with chrome alum gelatin to prevent detachment and stained using the Kluver-Barrera method [32] to qualitatively assess the intensity of perikarya damage with preservation of neuronal fibers [32]. Large lesions into the PAG reached other midbrain structures, such as the deep layers of the superior colliculus of deep mesencephalon, and these data were removed from the statistical analysis.…”

Section: Assessment Of Ibo Chemical Lesion Placement and Effectivenessmentioning

confidence: 99%

Periaqueductal gray matter modulates the hypercapnic ventilatory response

Tenorio‐Lopes

Patrone

Bícego

et al. 2012

Pflugers Arch - Eur J Physiol

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The periaqueductal gray (PAG) is a midbrain structure directly involved in the modulation of defensive behaviors. It has direct projections to several central nuclei that are involved in cardiorespiratory control. Although PAG stimulation is known to elicit respiratory responses, the role of the PAG in the CO(2)-drive to breathe is still unknown. The present study assessed the effect of chemical lesion of the dorsolateral and dorsomedial and ventrolateral/lateral PAG (dlPAG, dmPAG, and vPAG, respectively) on cardiorespiratory and thermal responses to hypercapnia. Ibotenic acid (IBO) or vehicle (PBS, Sham group) was injected into the dlPAG, dmPAG, or vPAG of male Wistar rats. Rats with lesions outside the dlPAG, dmPAG, or vPAG were considered as negative controls (NC). Pulmonary ventilation (VE: ), mean arterial pressure (MAP), heart rate (HR), and body temperature (Tb) were measured in unanesthetized rats during normocapnia and hypercapnic exposure (5, 15, 30 min, 7 % CO(2)). IBO lesioning of the dlPAG/dmPAG caused 31 % and 26.5 % reductions of the respiratory response to CO(2) (1,094.3 ± 115 mL/kg/min) compared with Sham (1,589.5 ± 88.1 mL/kg/min) and NC groups (1,488.2 ± 47.7 mL/kg/min), respectively. IBO lesioning of the vPAG caused 26.6 % and 21 % reductions of CO(2) hyperpnea (1,215.3 ± 108.6 mL/kg/min) compared with Sham (1,657.3 ± 173.9 mL/kg/min) and NC groups (1,537.6 ± 59.3). Basal VE: , MAP, HR, and Tb were not affected by dlPAG, dmPAG, or vPAG lesioning. The results suggest that dlPAG, dmPAG, and vPAG modulate hypercapnic ventilatory responses in rats but do not affect MAP, HR, or Tb regulation in resting conditions or during hypercapnia.

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“…Sham-operated animals were injected with vehicle (0.2 g ascorbic acid in 0.2 l of saline over 5 min). Dose and methods of administration were chosen on the basis of pilot experiments and previous studies (1,15).…”

Section: Surgerymentioning

confidence: 99%

Locus coeruleus is a central chemoreceptive site in toads

Noronha-de-Souza¹,

Bícego²,

Michel³

et al. 2006

American Journal of Physiology-Regulatory, Integrative and Comp

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The locus coeruleus (LC) has been suggested as a CO2 chemoreceptor site in mammals. This nucleus is a mesencephalic structure of the amphibian brain and is probably homologous to the LC in mammals. There are no data available for the role of LC in the central chemoreception of amphibians. Thus the present study was designed to investigate whether LC of toads (Bufo schneideri) is a CO 2/H ϩ chemoreceptor site. Fos immunoreactivity was used to verify whether the nucleus is activated by hypercarbia (5% CO2 in air). In addition, we assessed the role of noradrenergic LC neurons on respiratory and cardiovascular responses to hypercarbia by using 6-hydroxydopamine lesion. To further explore the role of LC in central chemosensitivity, we examined the effects of microinjection of solutions with different pH values (7.2, 7.4, 7.6, 7.8, and 8.0) into the nucleus. Our main findings were that 1) a marked increase in c-fos-positive cells in the LC was induced after 3 h of breathing a hypercarbic gas mixture; 2) chemical lesions in the LC attenuated the increase of the ventilatory response to hypercarbia but did not affect ventilation under resting conditions; and 3) microinjection with acid solutions (pH ϭ 7.2, 7.4, and 7.6) into the LC elicited an increased ventilation, indicating that the LC of toads participates in the central chemoreception.ventilation; midbrain; brain stem; amphibian; isthmus; bufo; hypercarbia IT IS WELL ESTABLISHED THAT vertebrates display respiratory responses to changes in the arterial blood gases, and the underlying control mechanisms are very similar among different taxa. The transition of amphibians to air breathing was accompanied by an increase in the sensitivity to CO 2 /H ϩ (45). Interestingly, the ontogenetic changes of anuran amphibians involve modifications of the control system from being almost entirely oxygen driven to a combination of acid-base and oxygen driven (11).Central respiratory CO 2 chemoreceptors have been clearly established in adult anuran amphibians (8,46), and these receptors are probably distributed throughout the rostral medulla, surrounding the fourth ventricle (50). In mammals, these receptors were once thought to be located only close to the surface of the ventral medulla, but it is now clear that they are widespread within the brainstem (12). Recently, sites have been identified in the ventrolateral medulla, nucleus of the solitary tract, ventral respiratory group, locus coeruleus (LC), caudal medullary raphe, and fastigial nucleus of the cerebellum (for a review, see Ref. 35). However, it remains unclear whether chemoreceptors are also widely distributed in amphibians. An evaluation of specific contributions of these chemosensitive sites can be achieved by CO 2 challenge, focal stimulation, or focal disruption. Focal acidification of a single central chemosensitive site increases ventilation, whereas disruption decreases ventilation (3,28,37,47). According to Nattie (35), the presence of widespread central chemoreceptors may be related to the increased demands of a...

show abstract

Chemical lesions of the nucleus isthmi increase the hypoxic and hypercarbic drive to breathing of toads

Cited by 19 publications

References 27 publications

Participation of the dorsal periaqueductal grey matter in the hypoxic ventilatory response in unanaesthetized rats

Participation of the dorsal periaqueductal grey matter in the hypoxic ventilatory response in unanaesthetized rats

Periaqueductal gray matter modulates the hypercapnic ventilatory response

Locus coeruleus is a central chemoreceptive site in toads

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