Gravity and thermoregulation: metabolic changes and circadian rhythms

Robinson, E. L.; Fuller, Charles A.

doi:10.1007/s004240000329

Cited by 20 publications

(14 citation statements)

References 40 publications

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“…To date, no heat-balance studies have addressed alterations in T b regulation, metabolism, or rhythmicity in either microgravity or hypergravity. However, inferentially, previous spaceflight and centrifuge metabolic data from homeotherms suggest that HP is decreased during spaceflight and increased during centrifugation (27). Still, the relative contribution of HP vs. heat loss to these changes is not known.…”

Section: Discussionmentioning

confidence: 92%

Neurovestibular modulation of circadian and homeostatic regulation: Vestibulohypothalamic connection?

Fuller

Jones

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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101

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Chronic exposure to increased force environments (+G) has pronounced effects on the circadian and homeostatic regulation of body temperature (T(b)), ambulatory activity (Act), heart rate, feeding, and adiposity. By using the Brn 3.1 knockout mouse, which lacks vestibular hair cells, we recently described a major role of the vestibular system in mediating some of these adaptive responses. The present study used the C57BL6JEi-het mouse strain (het), which lacks macular otoconia, to elucidate the contribution of specific vestibular receptors. In this study, eight het and eight WT mice were exposed to 2G for 8 weeks by means of chronic centrifugation. In addition, eight het and eight WT mice were maintained as 1G controls in similar conditions. Upon 2G exposure, the WT exhibited a decrease in T(b) and an attenuated T(b) circadian rhythm. Act means and rhythms also were attenuated. Body mass and food intake were significantly lower than the 1G controls. After 8 weeks, percent body fat was significantly lower in the WT mice (P < 0.0001). In contrast, the het mice did not exhibit a decrease in mean T(b) and only a slight decrease in T(b) circadian amplitude. het Act levels were attenuated similarly to the WT mice. Body mass and food intake were only slightly attenuated in the het mice, and percent body fat, after 8 weeks, was not different in the 2G het group. These results link the vestibular macular receptors with specific alterations in homeostatic and circadian regulation.

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Section: Discussionmentioning

confidence: 92%

Neurovestibular modulation of circadian and homeostatic regulation: Vestibulohypothalamic connection?

Fuller

Jones

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

101

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“…Chronic exposure to hypergravity has pronounced effects on circadian and homeostatic regulation of body temperature, activity, heart rate, and feeding (Fuller et al, 2000; Murakami and Fuller, 2000; Robinson and Fuller, 2000; Warren et al, 2000). Exposure of adult male mice to 2g hypergravity caused an immediate 4-day loss in circadian rhythm in both core body temperature and activity.…”

Section: Discussionmentioning

confidence: 99%

“…Circadian rhythms allow organisms to anticipate and prepare for precise and regular environmental changes and can be entrained by external cues (Hastings et al, 2007). Although light is the primary environmental cue that entrains circadian clocks, gravity significantly affects circadian patterns of behavior, hormones, body temperature, and metabolism (Czeisler et al, 1991; Whitson et al, 1995; Fuller et al, 2000; Murakami and Fuller, 2000; Robinson and Fuller, 2000; Dijk et al, 2001; Fuller et al, 2002; Holley et al, 2003). …”

Section: Introductionmentioning

confidence: 99%

Hypergravity disruption of homeorhetic adaptations to lactation in rat dams include changes in circadian clocks

et al. 2012

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SummaryAltered gravity load induced by spaceflight (microgravity) and centrifugation (hypergravity) is associated with changes in circadian, metabolic, and reproductive systems. Exposure to 2-g hypergravity (HG) during pregnancy and lactation decreased rate of mammary metabolic activity and increased pup mortality. We hypothesize HG disrupted maternal homeorhetic responses to pregnancy and lactation are due to changes in maternal metabolism, hormone concentrations, and maternal behavior related to gravity induced alterations in circadian clocks. Effect of HG exposure on mammary, liver and adipose tissue metabolism, plasma hormones and maternal behavior were analyzed in rat dams from mid-pregnancy (Gestational day [G]11) through early lactation (Postnatal day [P]3); comparisons were made across five time-points: G20, G21, P0 (labor and delivery), P1 and P3. Blood, mammary, liver, and adipose tissue were collected for analyzing plasma hormones, glucose oxidation to CO2 and incorporation into lipids, or gene expression. Maternal behavioral phenotyping was conducted using time-lapse videographic analyses. Dam and fetal-pup body mass were significantly reduced in HG in all age groups. HG did not affect labor and delivery; however, HG pups experienced a greater rate of mortality. PRL, corticosterone, and insulin levels and receptor genes were altered by HG. Mammary, liver and adipose tissue metabolism and expression of genes that regulate lipid metabolism were altered by HG exposure. Exposure to HG significantly changed expression of core clock genes in mammary and liver and circadian rhythms of maternal behavior. Gravity load alterations in dam's circadian system may have impacted homeorhetic adaptations needed for a successful lactation.

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“…The vestibular nucleus might indirectly influence thermoregulation mechanisms through the imbalance between heat production and heat loss equilibrium encountered in altered gravity (19). However, thermoregulatory mechanisms in hypergravity or weightlessness did not reach a consensus (55). The role of gravity in temperature regulation through the vestibular system requires further study.…”

Section: Discussionmentioning

confidence: 99%

Vestibular loss disrupts daily rhythm in rats

Martin

Mauvieux

Bulla

et al. 2015

Journal of Applied Physiology

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Hypergravity disrupts the circadian regulation of temperature (Temp) and locomotor activity (Act) mediated through the vestibular otolithic system in mice. In contrast, we do not know whether the anatomical structures associated with vestibular input are crucial for circadian rhythm regulation at 1 G on Earth. In the present study we observed the effects of bilateral vestibular loss (BVL) on the daily rhythms of Temp and Act in semipigmented rats. Our model of vestibular lesion allowed for selective peripheral hair cell degeneration without any other damage. Rats with BVL exhibited a disruption in their daily rhythms (Temp and Act), which were replaced by a main ultradian period ( Ͻ20 h) for 115.8 Ϯ 68.6 h after vestibular lesion compared with rats in the control group. Daily rhythms of Temp and Act in rats with BVL recovered within 1 wk, probably counterbalanced by photic and other nonphotic time cues. No correlation was found between Temp and Act daily rhythms after vestibular lesion in rats with BVL, suggesting a direct influence of vestibular input on the suprachiasmatic nucleus. Our findings support the hypothesis that the vestibular system has an influence on daily rhythm homeostasis in semipigmented rats on Earth, and raise the question of whether daily rhythms might be altered due to vestibular pathology in humans. vestibular system; biological rhythms; temperature; locomotor activity; rats LOCATED IN THE TEMPORAL BONES, the vestibular system is composed of three semicircular canals that encode head rotation velocity and two otolithic macula that encode linear acceleration and gravity force. The vestibular system is primarily involved in gaze stabilization and postural control (23), but its influence has been expanded to autonomic and bone regulation (11,61,63), spatial learning and memory (5, 6, 56), and spatial orientation and perception of gravitational verticality (37). Studies carried out in environments in which gravity is altered have shown evidence of a possible influence of the vestibular system on hypothalamic circadian function in rats (27) and mice (18,46

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Gravity and thermoregulation: metabolic changes and circadian rhythms

Cited by 20 publications

References 40 publications

Neurovestibular modulation of circadian and homeostatic regulation: Vestibulohypothalamic connection?

Neurovestibular modulation of circadian and homeostatic regulation: Vestibulohypothalamic connection?

Hypergravity disruption of homeorhetic adaptations to lactation in rat dams include changes in circadian clocks

Vestibular loss disrupts daily rhythm in rats

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