Project description:Water deprivation is a life-threatening condition that engages a protective physiological response to couple osmolyte retention with potentiation of thirst. This response, typical for most mammals, safeguards against short-term water deprivation, but fails in the long-term. Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) employ the short-term response during summer, whereas during winter they lack thirst and survive without water for months. Here, we show that long-term thirst suppression occurs despite hormonal and behavioral signs of a dramatic fluid deficit and originates from hypoactivity of neurons in the circumventricular organs, which exhibit marked functional suppression during winter that blunts their sensitivity to thirst cues. Our work reveals a remarkable capacity of the evolutionarily conserved brain regions which control fluid homeostasis in mammals to enable long-term survival without water.
2024-11-28 | GSE262723 | GEO
Project description:MicroRNA sequencing of euthermic vs. 24 hour hibernating cardiac tissue in Ictidomys tridecemlineatus
Project description:Hibernating mammals such as the thirteen-lined ground squirrel (Ictidomys tridecemlineatus) experience significant reductions in oxidative metabolism and body temperature when entering a state known as torpor. Animals entering or exiting torpor do not experience permanent loss of brain function or other injuries, and the processes that enable such neuroprotection are not well understood. To gain insight into changes in protein function that occur in dramatically different physiological states, we performed quantitative phosphoproteomics experiments on thirteen-lined ground squirrels that are summer active, winter torpid, and spring active. An important aspect of our approach was the use of focused microwave irradiation of the brain to sacrifice the animals and rapidly inactivate phosphatases and kinases to preserve the native phosphoproteome. Overall, our results showed pronounced changes in phosphorylated proteins for the transitions into and out of torpor, including for proteins involved in gene expression and DNA repair, cellular plasticity, and human disease. In contrast, the transition between active states showed minimal changes. This study offers valuable insight into the global changes of brain phosphorylation in hibernating mammals, the results of which may be relevant to the future therapeutic strategies for brain injury.