Effects of Hydration on Febrile Temperature Patterns in Rabbits

Abstract

Patients with fever have a predisposition to experience dehydration, which may alter their thermoregulatory responses to elevated body temperature. In view of the recent discovery of the antipyretic activity of arginine vasopressin (AVP), it is possible that dehydration has a beneficial role during fever. Dehydration may enhance endogenous antipyresis by stimulating AVP release, making aggressive fluid replacement, which may inhibit AVP release, undesirable during fever. This study addressed the effects of manipulation of hydration status on temperature and cardiovascular responses in endotoxin-injected rabbits. Eight unanesthetized chronically instrumented rabbits were exposed to lipopolysaccharide (LPS) while in euhydrated state, after furosemide (5 mg/kg) and 24 hours of water deprivation (dehydrated), after infusion of saline (30 mL/kg) while in euhydrated state (hyperhydrated), and after saline (mL/per overnight body weight loss in grams) while in dehydrated state (rehydrated). Dehydrated rabbits display higher fevers that are biphasic in nature and are accompanied by increased vasoconstriction and duration of mean arterial pressure increases, indicating that activation of antipyretic mechanisms in dehydrated rabbits was not sufficient to reduce body core temperature. In addition, fluid supplementation in euhydrated rabbits did not alter the febrile response; however, a marked decrease in heart rate was noted. Furthermore, fluid supplementation in dehydrated rabbits significantly attenuates the rectal temperature and heart rate response to LPS injection, indicating the possibility that activation of antipyretic mechanisms of AVP in rehydrated rabbits was sufficient to reduce body core temperature. The results suggest that fluid supplementation has a beneficial role in keeping body temperature lower .

Unraveling the molecular pathobiology of vocal fold systemic dehydration using an in vivo rabbit model

“…In our study, an in vivo systemic dehydration model using rabbits was developed to analyze the transcriptome of vocal folds in response to systemic dehydration. The rabbits received furosemide IP injection to induce systemic dehydration; furosemide alone or a combination with water withholding to study different effects of dehydration in rabbits are reported in the literature [ 29 , 34 ]. Systemic dehydration was verified by body weight loss (4.8% average) and significant changes in the level of blood analytes compared to the control group.…”

“…Systemic dehydration is characterized by reduced fluid within the body and can have many causes as simple as decreased water consumption and increased physical activity to more severe body fluid losses as a consequence of vomiting and diarrhea [23][24][25][26][27]. Experimentally, systemic dehydration is commonly induced by water withholding, with or without food access, or use of diuretics, or a combination of both [28][29][30][31][32][33]. Furosemide is a diuretic with a relatively fast onset of action that has been used to induce dehydration in numerous studies with animal and human subjects [25,30,[34][35][36][37][38].…”

Lipopolysaccharide reduces sodium intake and sodium excretion in dehydrated rats

“…Lipopolysaccharide (LPS), an endotoxin derived from the wall of gram-negative bacteria, triggers not only a general reduction in animal activity, but also has a broad influence on body fluid balance, linked to neurohypophyseal secretion, sodium transport in the gut and renal sodium excretion [2][3][4][5]. Although the sickness behavior may have an adaptive value, reduced thirst, associated with impaired sodium balance and dehydration, plus concurrent hypotension, may lead to a general collapse of volume compartments in response to LPS [6][7][8][9]. Therefore, a complete understanding of the effects of LPS on fluid balance has important practical and theoretical consequences.…”