Ontogeny of homeothermy in the immature rat: metabolic and thermal responses

Spiers, Donald E.; Adair, E. R.

doi:10.1152/jappl.1986.60.4.1190

Cited by 101 publications

(74 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Interscapular probes were preferred over rectal probes, which are poorly tolerated in newborn mice during prolonged recordings (36 min). Previous studies in newborn rats showed that colonic and interscapular temperatures were closely correlated over TAs ranging from 22°C to 37°C (43). Each pup was placed in a restraining device in the plethysmograph to ensure that the temperature probe position remained unchanged.…”

Section: Methodsmentioning

confidence: 99%

Effects of temperature on ventilatory response to hypercapnia in newborn mice heterozygous for transcription factor Phox2b

Ramanantsoa¹,

Vaubourg²,

Matrot³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

show abstract

Section: Methodsmentioning

confidence: 99%

Effects of temperature on ventilatory response to hypercapnia in newborn mice heterozygous for transcription factor Phox2b

Ramanantsoa¹,

Vaubourg²,

Matrot³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

show abstract

“…This provides an ambient temperature in which isolated animals can maintain a stable body temperature for many hours (33). Infant rats treated with LPS at this temperature did not develop the hypothermia observed with the same dose of LPS at 22…”

Section: Fever Inductionmentioning

confidence: 98%

Lipopolysaccharide‐induced Febrile Convulsions in the Rat: Short‐term Sequelae

2004

View full text Add to dashboard Cite

Summary:Purpose: Febrile convulsions (FCs) occur in children as a result of fever. The mechanisms involved in the genesis of FCs and their long-term consequences on brain development remain unclear. We have developed a model of FC, by using fever as a parameter, to test the hypothesis that fever can lower seizure threshold and to examine the neurologic sequelae of FCs.Methods: Fourteen-day-old rat pups equipped with bodytemperature telemetry devices exhibited ∼1.5• C fevers after lipopolysaccharide (Escherichia coli, 200 µg/kg). During such fevers, concurrently administered doses of kainic acid that are normally subconvulsant were used to induce convulsions with fever. Animals were then killed at varying times for pathological and immunohistochemical studies.Results: The pairing of lipopolysaccharide and subconvulsant kainic acid resulted in convulsions in ∼50% of febrile animals, with very low mortality. To study the neural correlates of these FCs, we used fos immunohistochemistry and found that animals with FCs had fos-positive immunoreactivity in brain regions involved in seizures. After a period of 72 h, we also examined brains for pathologic changes and found no differences among our groups.Conclusions: Our data indicate that a neuroimmune challenge and its accompanying fever reduce the seizure threshold. Furthermore, the FCs induced by fever in this model do not have short-term adverse effects on the brain. In addition, this model, by incorporating physiologic fever, may be useful for examining the role of fever and its constituent mediators in the genesis of FCs. Key Words: LPS-Fever-Febrile convulsions-FosNeonate.Febrile convulsions (FCs) are seizures induced by fever that affect 3 to 5% of children between the ages of 6 months and 5 years and are the most common type of convulsion in humans (1,2). Substantial disagreement exists regarding their effects on the developing brain, both in the acute period and in the months to years after the initial event (3-6). Even the etiology of FCs is unknown. In special cases of FCs, those found in generalized epilepsy with febrile seizures plus (GEFS+), mutations in genes encoding cation channels (specifically sodium channels) as well as the γ -aminobutyric acid receptor (GABAR) have been found to have causal links (7-9). However, GEFS+ is a rare familial disorder with mutations found only in certain pedigrees, and these fail to explain the effect involved in the remaining majority of FCs. Experimental models may elucidate the basic mechanisms involved in these convulsions (10).Many experimental models have used hyperthermiainduced convulsions as a model to study This is because most animals readily convulse when hyperthermic, but not usually when febrile. However, this model may not be appropriate, as fever and hyperthermia are very different physiologic processes (17). Fever is a regulated increase in body temperature that results from an immune challenge. It involves peripheral and central nervous system (CNS) cytokine signaling and generation of prostaglandins t...

show abstract

“…Then the pup was placed in the plethysmograph in a restraining device to ensure that temperature probe position remained unchanged. Previous studies in newborn rats showed that colonic and interscapular temperatures were closely correlated over temperatures ranging from 22.5 to 37°C (38). Because the restraining device disrupted breathing measurements in several pups, we did not analyze the respiratory data.…”

Section: Animalsmentioning

confidence: 99%

Ventilatory response to hyperoxia in newborn mice heterozygous for the transcription factorPhox2b

Ramanantsoa¹,

Vaubourg²,

Dauger³

et al. 2006

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

Heterozygous mutations of the transcription factor PHOX2B have been found in most patients with central congenital hypoventilation syndrome, a rare disease characterized by sleep-related hypoventilation and impaired chemosensitivity to sustained hypercapnia and sustained hypoxia. PHOX2B is a master regulator of autonomic reflex pathways, including peripheral chemosensitive pathways. In the present study, we used hyperoxic tests to assess the strength of the peripheral chemoreceptor tonic drive in Phox2bϩ/Ϫ newborn mice. We exposed 69 wild-type and 67 mutant mice to two hyperoxic tests (12-min air followed by 3-min 100% O2) 2 days after birth. Breathing variables were measured noninvasively using whole body flow plethysmography. The initial minute ventilation decrease was larger in mutant pups than in wild-type pups: Ϫ37% (SD 13) and Ϫ25% (SD 18), respectively, P Ͻ 0.0001. Furthermore, minute ventilation remained depressed throughout O2 exposure in mutants, possibly because of their previously reported impaired CO2 chemosensitivity, whereas it returned rapidly to the normoxic level in wild-type pups. Hyperoxia considerably increased total apnea duration in mutant compared with wild-type pups (P ϭ 0.0001). A complementary experiment established that body temperature was not influenced by hyperoxia in either genotype group and, therefore, did not account for genotype-related differences in the hyperoxic ventilatory response. Thus partial loss of Phox2b function by heterozygosity did not diminish the tonic drive from peripheral chemoreceptors.control of breathing; chemosensitivity; apnea CENTRAL CONGENITAL HYPOVENTILATION syndrome (CCHS or Ondine's curse) is a rare disease, generally present from birth and characterized by hypoventilation during sleep in the absence of primary neuromuscular or lung disease or of brain stem lesions (3). Throughout life, patients with CCHS have absent or markedly reduced ventilatory responses to sustained hypercapnia (29) and, to a lesser extent, to sustained hypoxia (29). These respiratory impairments are generally ascribed to impaired central integration of chemosensory inputs at the brain stem level, rather than to failure of chemoreceptor activity, which is at least partially present (15,22,37). The genetic basis for CCHS was discovered recently: most patients with CCHS have a heterozygous mutation of the PHOX2B gene (2,23,41,43). PHOX2B is a master regulator of the noradrenergic phenotype and of all neuronal relays of autonomic medullary reflex pathways (30), including peripheral chemosensitive pathways (9).Mice with a single functional Phox2b allele (i.e., Phox2bϩ/Ϫ mice) provide a unique opportunity to investigate the genotype-phenotype relationship in CCHS. Our laboratory's previous studies showed that Phox2bϩ/Ϫ mice had longer sleep apnea times than their wild-type littermates on postnatal day (P) 5 (P5) (11) and a weaker response to CO 2 on P2, followed by normalization before P10 (9). These ventilatory impairments were reminiscent of CCHS. However, the hyperpneic response t...

show abstract

Ontogeny of homeothermy in the immature rat: metabolic and thermal responses

Cited by 101 publications

References 0 publications

Effects of temperature on ventilatory response to hypercapnia in newborn mice heterozygous for transcription factor Phox2b

Effects of temperature on ventilatory response to hypercapnia in newborn mice heterozygous for transcription factor Phox2b

Lipopolysaccharide‐induced Febrile Convulsions in the Rat: Short‐term Sequelae

Ventilatory response to hyperoxia in newborn mice heterozygous for the transcription factorPhox2b

Contact Info

Product

Resources

About