Biomaterial Database

Endotoxin shock: thermoregulatory mechanisms. 1996

A A Romanovsky, and O Shido, and S Sakurada, and N Sugimoto, and T Nagasaka

Department of Physiology, Kanazawa University Medical School, Japan.

To clarify mechanisms of hypothermia in lipopolysaccharide (LPS) shock, four experiments were conducted in 72 chronically instrumented Wistar rats. They were intended to accomplish the following: experiment 1, determine the dose of intravenous Escherichia coli LPS that induces a body temperature (Tb) fall at a minimal mortality [the dose chosen (0.5 mg/kg) was then used in experiments 2-4]; experiment 2, identify the time course of the arterial blood pressure (BP) fall (shock) during the response to LPS; experiment 3, measure threshold Tb values for skin vasodilation and activation of metabolic heat production (M) during the LPS shock; and experiment 4, ascertain behavioral thermoregulation in LPS shock. For experiments 1-3, rats were kept in restrainers; ambient temperature (Ta) was 26 degrees C. In experiment 4, rats freely moved in a thermogradient (18-33 degrees C). Variables monitored were colonic (Tc) and tail skin (Tsk) temperatures (experiment 1); BP (experiment 2); hypothalamic temperature (Thy), M (from oxygen consumption), and Tsk (experiment 3); and preferred Ta (Tpr) and abdominal temperature (experiment 4). In experiment 1, LPS induced no Tc changes at 0 mg/kg, a biphasic fever (no mortality) at 0.05 mg/kg, a biphasic hypothermia (42% mortality) at 0.5 mg/kg, and a rapid fall of Tc (100% mortality) at 5 mg/kg. LPS-induced (0.5 mg/kg) hypotension (experiment 2) occurred simultaneously with the first hypothermic phase; both Tc and BP reached their nadirs (-0.8 +/- 0.1 degrees C and -34 +/- 12 mmHg) at approximately 1.5 h post-LPS. The major autonomic mechanism of the shock hypothermia was a shift in the threshold Thy for M from 37.9 +/- 0.3 to 36.0 +/- 0.3 degrees C (experiment 3; P < 0.05). In experiment 4, rats selected Tpr below 25 degrees C (vs. 28-30 degrees C in control; P < 0.05) throughout the duration of the shock; their Tb dropped to 36.2 +/- 0.3 degrees C (P < 0.05). In sum, the LPS shock-associated hypothermia involves a decrease in the threshold Tb for M, the resultant widening of the interthreshold zone, and cold-seeking behavior.

UI	MeSH Term	Description	Entries
D008070	Lipopolysaccharides	Lipid-containing polysaccharides which are endotoxins and important group-specific antigens. They are often derived from the cell wall of gram-negative bacteria and induce immunoglobulin secretion. The lipopolysaccharide molecule consists of three parts: LIPID A, core polysaccharide, and O-specific chains (O ANTIGENS). When derived from Escherichia coli, lipopolysaccharides serve as polyclonal B-cell mitogens commonly used in laboratory immunology. (From Dorland, 28th ed)	Lipopolysaccharide,Lipoglycans
D008297	Male		Males
D001831	Body Temperature	The measure of the level of heat of a human or animal.	Organ Temperature,Body Temperatures,Organ Temperatures,Temperature, Body,Temperature, Organ,Temperatures, Body,Temperatures, Organ
D001833	Body Temperature Regulation	The processes of heating and cooling that an organism uses to control its temperature.	Heat Loss,Thermoregulation,Regulation, Body Temperature,Temperature Regulation, Body,Body Temperature Regulations,Heat Losses,Loss, Heat,Losses, Heat,Regulations, Body Temperature,Temperature Regulations, Body,Thermoregulations
D004056	Differential Threshold	The smallest difference which can be discriminated between two stimuli or one which is barely above the threshold.	Difference Limen,Just-Noticeable Difference,Weber-Fechner Law,Difference Limens,Difference, Just-Noticeable,Differences, Just-Noticeable,Differential Thresholds,Just Noticeable Difference,Just-Noticeable Differences,Law, Weber-Fechner,Limen, Difference,Limens, Difference,Threshold, Differential,Thresholds, Differential,Weber Fechner Law
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001522	Behavior, Animal	The observable response an animal makes to any situation.	Autotomy Animal,Animal Behavior,Animal Behaviors
D012772	Shock, Septic	Sepsis associated with HYPOTENSION or hypoperfusion despite adequate fluid resuscitation. Perfusion abnormalities may include but are not limited to LACTIC ACIDOSIS; OLIGURIA; or acute alteration in mental status.	Endotoxin Shock,Septic Shock,Shock, Endotoxic,Shock, Toxic,Toxic Shock,Toxic Shock Syndrome,Endotoxin Shocks,Shock Syndrome, Toxic,Shock, Endotoxin,Shocks, Endotoxin,Toxic Shock Syndromes
D017208	Rats, Wistar	A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.	Wistar Rat,Rat, Wistar,Wistar Rats