Calcium and magnesium levels in tissues and serum of hibernating and cold-acclimated hamsters

Ferren, L.G.; South, Frank E.; Jacobs, H.K.

doi:10.1016/0011-2240(71)90042-3

Cited by 22 publications

(4 citation statements)

References 4 publications

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“…The rate and extent of cell body shrinkage measured in the hibernator suggests water flux out of the cell, possibly because of changes in ion concentrations at cold temperatures. Although there are no reports on ion concentrations in brain interstitium during hibernation, values from blood plasma indicate that the ionic microenvironment may change (Ferren et al, 1971;Tempel and Musacchia, 1975). The depression of ion pump activity during torpor could contribute to disturbed ionic homeostasis, although hibernators have developed a means to balance this with channel arrest (for review, see Storey and Storey, 2004).…”

Section: Discussionmentioning

confidence: 99%

Ubiquitous and Temperature-Dependent Neural Plasticity in Hibernators

Ohe¹,

Darian‐Smith²,

Garner³

et al. 2006

J. Neurosci.

140

100

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Hibernating mammals are remarkable for surviving near-freezing brain temperatures and near cessation of neural activity for a week or more at a time. This extreme physiological state is associated with dendritic and synaptic changes in hippocampal neurons. Here, we investigate whether these changes are a ubiquitous phenomenon throughout the brain that is driven by temperature. We iontophoretically injected Lucifer yellow into several types of neurons in fixed slices from hibernating ground squirrels. We analyzed neuronal microstructure from animals at several stages of torpor at two different ambient temperatures, and during the summer. We show that neuronal cell bodies, dendrites, and spines from several cell types in hibernating ground squirrels retract on entry into torpor, change little over the course of several days, and then regrow during the 2 h return to euthermia. Similar structural changes take place in neurons from the hippocampus, cortex, and thalamus, suggesting a global phenomenon. Investigation of neural microstructure from groups of animals hibernating at different ambient temperatures revealed that there is a linear relationship between neural retraction and minimum body temperature. Despite significant temperature-dependent differences in extent of retraction during torpor, recovery reaches the same final values of cell body area, dendritic arbor complexity, and spine density. This study demonstrates large-scale and seemingly ubiquitous neural plasticity in the ground squirrel brain during torpor. It also defines a temperature-driven model of dramatic neural plasticity, which provides a unique opportunity to explore mechanisms of large-scale regrowth in adult mammals, and the effects of remodeling on learning and memory.

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Section: Discussionmentioning

confidence: 99%

Ubiquitous and Temperature-Dependent Neural Plasticity in Hibernators

Ohe¹,

Darian‐Smith²,

Garner³

et al. 2006

J. Neurosci.

140

100

View full text Add to dashboard Cite

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“…The effects of hibernation on serum calcium levels are difficult to discern because considerable variation is reported in the literature. Compared with active controls, serum calcium is elevated in hibernating hamsters (54), has been reported to either increase (20,99) or decrease (151,152) in hibernating little brown bats, and remains constant in hibernating ground squirrels during 6 days of continuous torpor and during extended hibernation interrupted by periodic arousals (144). Variation between studies is likely influenced by factors like species differences, food availability, hibernation length, and sampling time relative to interbout arousal periods.…”

Section: Calcium Recycling and Hibernation-induced Bone Lossmentioning

confidence: 96%

Mammalian hibernation as a model of disuse osteoporosis: the effects of physical inactivity on bone metabolism, structure, and strength

McGee‐Lawrence¹,

Carey²,

Donahue³

2008

American Journal of Physiology-Regulatory, Integrative and Comp

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Reduced skeletal loading typically leads to bone loss because bone formation and bone resorption become unbalanced. Hibernation is a natural model of musculoskeletal disuse because hibernating animals greatly reduce weight-bearing activity, and therefore, they would be expected to lose bone. Some evidence suggests that small mammals like ground squirrels, bats, and hamsters do lose bone during hibernation, but the mechanism of bone loss is unclear. In contrast, hibernating bears maintain balanced bone remodeling and preserve bone structure and strength. Differences in the skeletal responses of bears and smaller mammals to hibernation may be due to differences in their hibernation patterns; smaller mammals may excrete calcium liberated from bone during periodic arousals throughout hibernation, leading to progressive bone loss over time, whereas bears may have evolved more sophisticated physiological processes to recycle calcium, prevent hypercalcemia, and maintain bone integrity. Investigating the roles of neural and hormonal control of bear bone metabolism could give valuable insight into translating the mechanisms that prevent disuse-induced bone loss in bears into novel therapies for treating osteoporosis.

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“…Mitochondrial phospholipase A has been shown to be activated by free fatty acids and CaC12, inducing the formation of lysoglycerophosphatides and permeability changes resulting in maximal mitochondrial swelling (83). The fact that free fatty acid levels in some hibernating species (hedgehog [84]) and the heart-muscle Ca ++ content of other species (hamster [85]) are almost doubled during hibernation indicates a possible mechansim for the high content of lysocompounds found in the heart of the hibernating ground squirrel. Conversely, if the transacylase enzymes were simply more cold-inhibited than the phospholipases, this too would account for the accumulation of lysoglycerophosphatides, as well as the decrease in PE, PC, DPG, and PS, seen in Table I.…”

Section: Discussionmentioning

confidence: 99%