Osmolyte Depletion and Thirst Suppression Allow Hibernators to Survive for Months without Water

Abstract

Highlights d Hibernating squirrels employ several strategies to survive for months without water d Hibernating squirrels have decreased blood osmolality despite water deprivation d Basal thirst is inhibited in ground squirrels during hibernation d Antidiuretic hormonal release and water seeking are uncoupled during hibernation

Water Balance: Abstaining from Obtaining While Retaining

“…Music is free to use any sounds in the world, and to arrange them in any way it pleases. So, music should be a unique product of its own culture, profoundly alien to any outsider -but this is not the case [2,3]. There are statistical universals that, presumably, tell us profound truths about how sound is processed by the human brain.…”

“…The blue arrows depict one of the repeating torpor-arousal cycles that characterizes hibernation. Four physiological conditions were examined [3] for serum osmolality, concentrations of the antidiuretic hormones (ADH) oxytocin and vasopressin, and drinking behavior; solid up arrows represent the greatest observed, dashed or solid down arrows less or least, and x, none observed, of the adjacent measured feature. The unexpected uncoupling of ADH release and drinking during arousal from torpor where osmolality returns to active levels is highlighted.…”

Optogenetic induction of hibernation-like state with modified human Opsin4 in mice

“…Hibernation serves as a biological strategy for thermostatic mammals to adapt to harsh environments, typically described as regulated, hypothermic, and hypometabolic states that last longer than 24 h. 12 , 15 , 16 , 17 We recently identified a neuronal population that induces a hibernation-like hypometabolic state in mice and rats, 18 which normally do not hibernate. 19 These neurons, called quiescence-inducing neurons (Q neurons), express a gene encoding a neuropeptide, pyroglutamylated RFamide peptide (QRFP), and reside in the anteroventral periventricular nucleus (AVPe) in the preoptic area (POA) of the hypothalamus, 18 known as the thermoregulatory region, which regulates the thermogenic capacity of brown adipose tissue (BAT) via the sympathetic nervous system in mice.…”

Urinary creatinine varies with microenvironment and sex in hibernating Greater Horseshoe bats (Rhinolophus ferrumequinum) in Korea

“…As metabolic water alone is not sufficient for rehydration for small mammals, including bats, they adopt various strategies to maintain proper hydration status. For example, thirteen-lined ground squirrels ( Ictidomys tridecemlineatus ) reduce serum osmolality and suppress thirst, which helps them to maintain body fluid water balance during several months of hibernation [ 5 ]. Some bat species may form large clusters during hibernation to reduce evaporative water loss, and may also arouse to drink water inside or outside the hibernaculum [ 6 – 8 ].…”

“…thirteen-lined ground squirrels (Ictidomys tridecemlineatus) reduce serum osmolality and suppress thirst, which helps them to maintain body fluid water balance during several months of hibernation [5]. Some bat species may form large clusters during hibernation to reduce evaporative water loss, and may also arouse to drink water inside or outside the hibernaculum [6][7][8].…”