Modification of thermoregulatory responses in rabbits reared at elevated environmental temperatures.

Cooper, K. E.; Ferguson, A. V.; Veale, W. L.

doi:10.1113/jphysiol.1980.sp013278

Cited by 33 publications

(11 citation statements)

References 18 publications

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“…Environmental exposures at crucial points in development have been shown to permanently alter sympathetic function (31,51). For example, mammals reared at elevated temperatures have altered sympathetic innervation of sweat glands, improved thermoregulatory responses, and are more tolerant of extreme temperatures as adults (6,9). In the chick, mild hypoxia during embryonic development results in increased basal sympathetic tone and sympathetic hyperinnervation of resistance arteries (45).…”

Section: Discussionmentioning

confidence: 99%

Early gestation dexamethasone alters baroreflex and vascular responses in newborn lambs before hypertension

Segar

Roghair²,

Segar³

et al. 2006

American Journal of Physiology-Regulatory, Integrative and Comp

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Exposure of the early gestation ovine fetus to exogenous glucocorticoids induces alterations in postnatal cardiovascular physiology, including hypertension. To determine whether autonomic function and systemic vascular reactivity are altered by in utero programming before the development of systemic hypertension, we examined arterial baroreflex function and in vivo hemodynamic and in vitro vascular responses to vasoactive agents in 10- to 14-day-old newborn lambs exposed to early gestation glucocorticoids. Dexamethasone (Dex, 0.28 mg.kg-1.day-1) or saline was administered to pregnant ewes by intravenous infusion over 48 h beginning at 27 days gestation (term 145 days), and lambs were allowed to deliver (n=6 in each group). Resting mean arterial blood pressure (MABP; 77+/-1 vs. 74+/-3 mmHg) and heart rate (HR; 249+/-9 vs. 226+/-21 beats/min) were similar in Dex-exposed and control animals, respectively. The arterial baroreflex curve, relating changes in HR to MABP, was significantly shifted toward higher pressure in the Dex-exposed lambs although no change in the sensitivity (gain) of the response was seen. In vivo changes in blood pressure in response to bolus doses of ANG II (20, 50, and 100 ng/kg) and phenylephrine (2, 5, and 10 microg/kg) were similar in the two groups. However, Dex lambs displayed greater decreases in MABP in response to ganglionic blockade with tetraethylammonium bromide (10 mg/kg; -30+/-3 vs. -20+/-3 mmHg, P<0.05) and greater increases in MABP after nitric oxide synthase blockade with NG-nitro-L-arginine (25 mg/kg; 23+/-3 vs. 13+/-2 mmHg, P<0.05) compared with control lambs. By in vitro wire myography, mesenteric and femoral artery microvessel contractile responses to KCl were similar, whereas responses to endothelin (in mesenteric) and norepinephrine (in femoral) were significantly attenuated in Dex lambs compared with controls. Femoral vasodilatory responses to forskolin and sodium nitroprusside were similar in the two groups (n=4). These findings suggest that resetting of the baroreflex, accompanied by increased sympathetic activity and altered nitric oxide-mediated compensatory vasodilatory function, may be important contributors to programming of hypertension.

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Section: Discussionmentioning

confidence: 99%

Early gestation dexamethasone alters baroreflex and vascular responses in newborn lambs before hypertension

Segar

Roghair²,

Segar³

et al. 2006

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

show abstract

“…RMR at 16°C T a was only approximately 3.1 times BMR in CR animals compared with 4.0 times BMR in WR animals, indicating only moderate thermoregulatory costs above BMR for CR animals. The reduced RMR values at 16°C T a in CR animals compared with WR animals in our study are most likely due to the improved defense to cold exposure in CR animals because thermoregulatory mechanisms are susceptible to modification by early postnatal experience (Hahn, 1956;Cooper et al, 1980;Young, 1985;Young and Shimano, 1998). It has been demonstrated in rats that continuous early life exposure to a cold environment induces a permanent and irreversible increase in brown adipose tissue (BAT) thermogenesis (Morrison et al, 2000), whereas when adult animals are exposed to cold (cold acclimation) the changes that occur in BAT are reversible when the animals are returned to normal temperatures (Vollmer and Skøtt, 2002).…”

Section: Resting Metabolic Ratementioning

confidence: 89%

Developmental phenotypic plasticity in a marsupial

Riek

Geiser

2012

Journal of Experimental Biology

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SUMMARYClimate change is likely to substantially affect the distribution ranges of species. However, little is known about how different mammalian taxa respond morphologically and physiologically to a rapid change of climate. Our objective was to provide the first quantitative data on the effect of continuous cold exposure during development on morphological and functional variables of a marsupial. Fat-tailed dunnarts (Sminthopsis crassicaudata, Dasyuridae) were reared at an ambient temperature (T a ) of 16°C [coldreared (CR)] or 22°C [warm-reared (WR)] until they reached adult age (>200days). Body and head length of CR animals were significantly longer than in WR animals (mean ± s.e.m.; body: CR 80.8±6mm, WR 76.4±5mm; head: CR 29.4±3mm, WR 27.5±2mm), but other body attributes were not significantly different. Use of torpor was more frequent, torpor bout duration was longer and average daily metabolic rate and percentage of savings when using torpor were significantly higher (P<0.01) in CR than in WR animals at 16°C T a but not at 24°C. Furthermore, resting metabolic rates measured at 16°C T a were significantly lower in CR than WR animals; at 30°C T a values were similar. Our results do not conform to Allenʼs rule, but to some extent they do conform to Bergmannʼs rule. However, the data demonstrate that a relatively moderate cold exposure from birth until adulthood induces marked changes in the morphology and thermal energetics of small marsupials. Such short-term phenotypic responses without the need for long-term selection are likely important for the ability to cope with different climates over a wide range of distribution, but will also play a crucial role in enhancing the survival of species during climate change.

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“…This latter difference may be more apparent than real. Cooper, Ferguson, and Veale (1980) reported that adult rabbits raised from birth in a warm environment (33°C) showed significant drops in colonic temperature when exposed to cold. Control animals reared at 20°C had no difficulty maintaining normal body temperatures.…”

Section: Hierarchical Organization Of Sexual Behaviormentioning

confidence: 99%

The Physiological Mechanisms of Motivation

Pfaff¹

1982

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Modification of thermoregulatory responses in rabbits reared at elevated environmental temperatures.

Cited by 33 publications

References 18 publications

Early gestation dexamethasone alters baroreflex and vascular responses in newborn lambs before hypertension

Early gestation dexamethasone alters baroreflex and vascular responses in newborn lambs before hypertension

Developmental phenotypic plasticity in a marsupial

The Physiological Mechanisms of Motivation

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