Membrane function in mammalian hibernation

Aloia, Roland C.; Raison, John K.

doi:10.1016/0304-4157(89)90007-5

Cited by 83 publications

(43 citation statements)

References 143 publications

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“…While the basic mechanisms allowing Tb to reach such low levels in hibernators are poorly understood, it is known that a diet rich in linoleic acid, which significantly changes the fatty acid composition of tissues and mitochondria1 membranes, lowers the Tb and lengthens the period of torpor in small hibernators (chipmunks, Eutamias amoenus) (Geiser and Kenagy 1987;Geiser 1990). These observations support the view that a seasonal change in the lipid composition of tissues and cellular membranes is one of the many adaptations for functioning at low Tb in hibernating mammals (Raison and Lyons 197 1 ;Goldman 1975;Platner et al 1976; Aloia and Pengelley 1973;Aloia and Raison 1989;Frank 199 1).…”

Section: Introductionsupporting

confidence: 54%

Dietary fats and torpor patterns in hibernating ground squirrels

Geiser¹,

Kenagy²

1993

Can. J. Zool.

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GEISER, F., and KENAGY, G.J. 1993. Dietary fats and torpor patterns in hibernating ground squirrels. Can. J. Zool. 71: [1182][1183][1184][1185][1186]. The effect of a sunflower oil diet (rodent chow with 10% addition by weight of sunflower seed oil, rich in linoleic acid), a sheep fat diet (rodent chow with 10% addition by weight of sheep fat, rich in saturated fatty acids and oleic acid), and a control diet (rodent chow without added fat or oil) on the pattern of torpor was investigated in the ground squirrel Spermophilus saturatus, a relatively large (250 g) hibernator. Torpid S. saturatus on the sunflower oil diet showed a lower minimum body temperature (2.1 vs. 3.5"C), a lower metabolic rate (0.029 vs. 0.043 mL 0 2 / g . h)), and longer bouts of torpor (252 vs. 193 h at an air temperature of -I .O°C) than animals on the sheep fat diet. These physiological variables showed intermediate values in controls. It appears, therefore, that the composition of dietary fatty acids, rather than the fat content of the diet, affected torpor patterns. It is likely that the observed physiological differences may be explained by diet-induced compositional differences in body lipid composition. GEISER, F., et KENAGY, G.J. 1993. Dietary fats and torpor patterns in hibernating ground squirrels. Can. J. Zool. 71 : 1182-1186.On trouvera ici les resultats d'une etude sur les effets d'un regime alimentaire a base d'huile de tournesol (moulee a rongeurs additionnee de 10% (masse) d'huile de tournesol, riche en acide linoleique), d'un regime a base de graisse de mouton (moulee a rongeurs additionnee de 10% de graisse de mouton, riche en acides gras satures et en acide oleique) et d'un regime temoin (moulee a rongeurs sans addition de graisse ou d'huile) sur la dormance du spermophile Spermophilus saturatus (250 g). Les spermophiles en dormance soumis au regime additionne d'huile de tournesol avaient une body temperature minimale plus basse (2,l vs. 3,5"C), un taux de metabolisme plus bas (0,029 vs. 0,043 mL O2 (g -h)) et des periodes de dormance plus longues (252 vs. 193 h a une temperature de I'aire de -I ,O°C), que les animaux nourris du regime additionne de graisse de mouton. Ces variables physiologiques avaient des valeurs intermediaires chez les temoins. II semble donc que ce soit la nature des acides gras alimentaires, plut6t que leur quantite, qui affecte la dormance. Les differences physiologiques observees s'expliquent sans doute par des differences dans la composition en lipides du corps apparues a la suite des regimes alimentaires imposes.[Traduit par la redaction]

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Section: Introductionsupporting

confidence: 54%

Dietary fats and torpor patterns in hibernating ground squirrels

Geiser¹,

Kenagy²

1993

Can. J. Zool.

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“…This suggests that although the receptors may be decreased in number or down-regulated, the biochemical mechanisms involved in contraction are working even more effectively. There is no simple explanation for the changes in efficacy and potency between 2 and 5 C. It is well known that as temperature is lowered, lipids may undergo phase transition from liquidcrystalline to a gel phase (Aloia and Raison 1989). A phase transition between 2 and 5C could account for the change in responsiveness observed.…”

Section: Discussionmentioning

confidence: 91%

“…However, salmonids are capable of acclimating by altering the proportion of saturated to unsaturated fatty acids in the membranes to maintain membrane structure in an optimal fluid state for function when subjected to altered temperatures for prolonged periods (Henderson and Tocher 1987). When acclimated fish are transferred to a tank of a different temperature (i.e., thermal stress), the immediate effect would be an alteration in membrane fluidity and enzymatic activity due to the physical and chemical properties of the constituent elements of the membranes (Aloia and Raison 1989;Prosser 1991).…”

Section: Introductionmentioning

confidence: 99%

The effects of acute temperature change on smooth muscle contractility of rainbow trout (Oncorhynchus mykiss Walbaum) intestine

Burka

Briand

Purcell

et al. 1993

Fish Physiol Biochem

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The effects of altered temperature in vivo on in vitro smooth muscle contractility of rainbow trout intestine were investigated. Initial analysis of the data revealed a seasonal variation in the maximal tension of intestinal smooth muscle attainable with 5-hydroxytryptamine (serotonin), carbachol, KCl, and transmural stimulation in vitro. Peaks occurred in spring and troughs in autumn. There was no seasonal cycling of the potency of the stimulants. All data regarding the efficacy of the stimulants were subsequently corrected for seasonal variation. The response of smooth muscle depends on the temperature of the water in which the fish are placed (2°C-20°C). There was a marked linear increase in efficacy and a slight increase in potency of the stimulants with increasing temperature. Changes in responsiveness of the intestinal smooth muscle occurred within 30 min of moving the fish between tanks. Smooth muscle reactivity returned to pretreatment values by 48h. Any changes in responsiveness with regards to time were unlikely to be as a consequence of water temperature, but may have been a result of handling stress.

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“…Whereas metabolic suppression (4-7) and membrane functions (8,9) in hibernators as well as anoxia-tolerant species have been the focus of recent research, the regulation of another major cellular process, protein biosynthesis, has been less well explored. Previously, preservation of mammalian cell structure and function was considered to be critically dependent on the continuous formation of new proteins and peptides especially under circumstances of reduced cerebral perfusion, in which lack of recovery of protein synthesis (PS) has been viewed as a reliable predictor of cell death (10,11).…”

mentioning

confidence: 99%

Suppression of protein synthesis in brain during hibernation involves inhibition of protein initiation and elongation

Frerichs

Smith

Brenner

et al. 1998

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

290

247

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Protein synthesis (PS) has been considered essential to sustain mammalian life, yet was found to be virtually arrested for weeks in brain and other organs of the hibernating ground squirrel, Spermophilus tridecemlineatus. PS, in vivo, was below the limit of autoradiographic detection in brain sections and, in brain extracts, was determined to be 0.04% of the average rate from active squirrels. Further, it was reduced 3-fold in cell-free extracts from hibernating brain at 37°C, eliminating hypothermia as the only cause for protein synthesis inhibition (active, 0.47 ؎ 0.08 pmol͞mg protein per min; hibernator, 0.16 ؎ 0.05 pmol͞mg protein per min, P < 0.001). PS suppression involved blocks of initiation and elongation, and its onset coincided with the early transition phase into hibernation. An increased monosome peak with moderate ribosomal disaggregation in polysome profiles and the greatly increased phosphorylation of eIF2␣ are both consistent with an initiation block in hibernators. The elongation block was demonstrated by a 3-fold increase in ribosomal mean transit times in cell-free extracts from hibernators (active, 2.4 ؎ 0.7 min; hibernator, 7.1 ؎ 1.4 min, P < 0.001). No abnormalities of ribosomal function or mRNA levels were detected. These findings implicate suppression of PS as a component of the regulated shutdown of cellular function that permits hibernating ground squirrels to tolerate ''trickle'' blood f low and reduced substrate and oxygen availability. Further study of the factors that control these phenomena may lead to identification of the molecular mechanisms that regulate this state.

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Membrane function in mammalian hibernation

Cited by 83 publications

References 143 publications

Dietary fats and torpor patterns in hibernating ground squirrels

Dietary fats and torpor patterns in hibernating ground squirrels

The effects of acute temperature change on smooth muscle contractility of rainbow trout (Oncorhynchus mykiss Walbaum) intestine

Suppression of protein synthesis in brain during hibernation involves inhibition of protein initiation and elongation

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