Effects of ethanol on thermoregulation

A multicomponent ethanol response battery across a cumulative dose ethanol challenge reveals diminished adolescent rat ethanol responsivity relative to adults

Adolescence is a conserved developmental period associated with low alcohol responsivity, which can contribute to heavy drinking and development of an alcohol use disorder (AUD) later in life. To investigate ethanol responsivity between adolescent and adult rats, we developed an ethanol response battery (ERB) to assess acute ethanol responses across cumulative doses of ethanol during the rising phase of the blood ethanol curve. We tested the hypothesis that adolescent male and female rats would exhibit lower ethanol responsivity to a cumulative ethanol challenge relative to adults. Male and female adolescent (postnatal day [P]40) and adult (P85) Wistar rats underwent ERB assessment following consecutive doses of ethanol (i.e., 1.0, 1.0, and 1.0 g/kg) to produce cumulative ethanol doses of 0.0, 1.0, 2.0, and 3.0 g/kg. The ERB consisted of (1) the 6-point behavioral intoxication rating scale, (2) body temperature assessment, (3) tail blood collection, (4) accelerating rotarod assessment, (5) tilting plane assessment, and (6) loss of righting reflex (LORR) assessment. Across cumulative ethanol doses, adolescent and adult rats evidenced progressive changes in ERB measures. On the ERB, adolescent rats of both sexes evidenced (1) lower intoxication rating, (2) blunted hypothermic responses, particularly in females, (3) longer latencies to fall from the accelerating rotarod, and (4) less tilting plane impairment relative to adults despite comparable BECs. All adult rats, regardless of sex, displayed a LORR at the 3.0 g/kg cumulative ethanol dose while among the adolescent rats, only one male rat and no females showed the LORR. These data reveal decreased adolescent ethanol responsivity across body temperature, intoxication, balance, and coordination responses to a cumulative ethanol challenge as assessed using the novel ERB relative to adults. The results of this study suggest that adolescent-specific low ethanol responsivity may contribute to adolescent binge drinking and increased risk for development of an AUD.

Hypothermia: Beyond the Narrative Review-The Point of View of Emergency Physicians and Medico-Legal Considerations

Hypothermia is a widespread condition all over the world, with a high risk of mortality in pre-hospital and in-hospital settings when it is not promptly and adequately treated. In this review, we aim to describe the main specificities of the diagnosis and treatment of hypothermia through consideration of the physiological changes that occur in hypothermic patients. Hypothermia can occur due to unfavorable environmental conditions as well as internal causes, such as pathological states that result in reduced heat production, increased heat loss or ineffectiveness of the thermal regulation system. The consequences of hypothermia affect several systems in the body-the cardiovascular system, the central and peripheral nervous systems, the respiratory system, the endocrine system and the gastrointestinal system-but also kidney function, electrolyte balance and coagulation. Once hypothermia is recognized, prompt treatment, focused on restoring body temperature and supporting vital functions, is fundamental in order to avert preventable death. It is important to also denote the fact that CPR has specificities related to the unique profile of hypothermic patients.

Integrated transcriptome and metabolome analysis reveals molecular responses of spider to single and combined high temperature and drought stress

High temperature and drought are abiotic stresses restricting many arthropods' survival and growth. Wolf spiders are poikilothermic arthropods that are vital in managing insects and pests. Nonetheless, investigating changes in spiders under temperature and drought stress are limited, especially at the molecular and gene expression levels. The study found that the combined effects of high temperature and drought stress significantly reduced survival rates and raised superoxide dismutase and malondialdehyde levels in the wolf spider Pardosa pseudoannulata. An integrated transcriptome and metabolome analysis showed that differentially expressed genes and metabolites were highly enriched in pathways involved in the proteolysis and oxidation-reduction process. The gene expression profiles displayed that heat shock protein (HSP) families (i.e., small heat shock protein, HSP70, HSP90, and HSP beta protein) were up-regulated under temperature and/or drought stresses. Additionally, a conjoint analysis revealed that under the combined stress, several important enzymes, including maltase-glucoamylase, glycerol-6-phosphate transporter, alanine-glyoxylate transaminase, and prostaglandin-H2 D-isomerase, were altered, affecting the metabolism of starch, sucrose, amino acids, and arachidonic acid. The protein interaction network further confirmed that under the combined stress, metabolic processes, peptide metabolic processes, and ATP generation from ADP were up-regulated, indicating that spiders could accelerate the metabolism of carbohydrates and proteins to combat stress and maintain homeostasis. Overall, this work showed that exposure to a combination of pressures might cause distinct defensive reactions in spiders and offered novel perspectives to research the molecular underpinnings of spider adaptation to a changing climate.

Hard Boiled: Alcohol Use as a Risk Factor for MDMA-Induced Hyperthermia: a Systematic Review

Although MDMA (ecstasy) is a relatively safe recreational drug and is currently considered for therapeutic use for the treatment of posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD), recreational MDMA use occasionally elicits hyperthermia and hyponatremia, sometimes with a fatal outcome. Specific risk factors for both adverse effects are profuse sweating while vigorously dancing under unfavorable conditions such as high ambient temperatures and insufficient fluid suppletion which result in dehydration. Concomitant use of MDMA and alcohol is highly prevalent, but adds to the existing risk, because alcohol facilitates the emergence of MDMA-induced adverse events, like hyperthermia, dehydration, and hyponatremia. Because of potential health-related consequences of concomitant use of MDMA and alcohol, it is important to identify the mechanisms of the interactions between alcohol and MDMA. This review summarizes the main drivers of MDMA-induced hyperthermia, dehydration, and hyponatremia and the role of concomitant alcohol use. It is shown that alcohol use has a profound negative impact by its interaction with most of these drivers, including poikilothermia, exposure to high ambient temperatures, heavy exercise (vigorous dancing), vasoconstriction, dehydration, and delayed initiation of sweating and diuresis. It is concluded that recreational and clinical MDMA-users should refrain from concomitant drinking of alcoholic beverages to reduce the risk for adverse health incidents when using MDMA.

A review of the role of ethanol-induced adipose tissue dysfunction in alcohol-associated liver disease

Alcohol-associated liver disease (AALD) encompasses a spectrum of liver diseases that includes simple steatosis, steatohepatitis, fibrosis, and cirrhosis. The adverse effects of alcohol in liver and the mechanisms by which ethanol (EtOH) promotes liver injury are well studied. Although liver is known to be the primary organ affected by EtOH exposure, alcohol's effects on other organs are also known to contribute significantly to the development of liver injury. It is becoming increasingly evident that adipose tissue (AT) is an important site of EtOH action. Both AT storage and secretory functions are altered by EtOH. For example, AT lipolysis, stimulated by EtOH, contributes to chronic alcohol-induced hepatic steatosis. Adipocytes secrete a wide variety of biologically active molecules known as adipokines. EtOH alters the secretion of these adipokines from AT, which include cytokines and chemokines that exert paracrine effects in liver. In addition, the level of EtOH-metabolizing enzymes, in particular, CYP2E1, rises in the AT of EtOH-fed mice, which promotes oxidative stress and/or inflammation in AT. Thus, AT dysfunction characterized by increased AT lipolysis and free fatty acid mobilization and altered secretion of adipokines can contribute to the severity of AALD. Of note, moderate EtOH exposure results in AT browning and activation of brown adipose tissue which, in turn, can promote thermogenesis. In this review article, we discuss the direct effects of EtOH consumption in AT and the mechanisms by which EtOH impacts the functions of AT, which, in turn, increases the severity of AALD in animal models and humans.

Hot weather and heat extremes: health risks

Hot ambient conditions and associated heat stress can increase mortality and morbidity, as well as increase adverse pregnancy outcomes and negatively affect mental health. High heat stress can also reduce physical work capacity and motor-cognitive performances, with consequences for productivity, and increase the risk of occupational health problems. Almost half of the global population and more than 1 billion workers are exposed to high heat episodes and about a third of all exposed workers have negative health effects. However, excess deaths and many heat-related health risks are preventable, with appropriate heat action plans involving behavioural strategies and biophysical solutions. Extreme heat events are becoming permanent features of summer seasons worldwide, causing many excess deaths. Heat-related morbidity and mortality are projected to increase further as climate change progresses, with greater risk associated with higher degrees of global warming. Particularly in tropical regions, increased warming might mean that physiological limits related to heat tolerance (survival) will be reached regularly and more often in coming decades. Climate change is interacting with other trends, such as population growth and ageing, urbanisation, and socioeconomic development, that can either exacerbate or ameliorate heat-related hazards. Urban temperatures are further enhanced by anthropogenic heat from vehicular transport and heat waste from buildings. Although there is some evidence of adaptation to increasing temperatures in high-income countries, projections of a hotter future suggest that without investment in research and risk management actions, heat-related morbidity and mortality are likely to increase.

Case of Severe Accidental Hypothermia Cardiac Arrest in a Subtropical Climate and Review of Management

A patient was brought to the hospital with severe accidental hypothermia due to cold exposure associated with acute alcohol intoxication. Initial bladder core temperature was 21°C (70°F). The patient was agitated and combative with altered mental status and suffered rescue collapse during transport. Initial rhythm was ventricular fibrillation and we initiated a standard advanced cardiac life support (ACLS) protocol with rewarming measures. The patient received 28 mg of epinephrine and 13 shocks. Active and passive rewarming were initiated without extracorporeal rewarming. The patient achieved return of spontaneous circulation (ROSC) at a core temperature of 23.8°C (74.8°F). Patient was discharged 15 days later neurologically intact with no organ damage. The clinical management and implications for further research in severe accidental hypothermia management are discussed. In patients with severe accidental hypothermia (defined as <30°C or <86°F) in cardiac arrest, the optimal rewarming technique, use of epinephrine, and time when defibrillation should be attempted remain controversial. In our patient, the patient achieved ROSC in less than 2 hours with standard ACLS procedures despite a minimal increase in core temperature (21°C to 23.8°C or 70°F to 73.9°F).

Alcohol Sensitivity as an Endophenotype of Alcohol Use Disorder: Exploring Its Translational Utility between Rodents and Humans

Alcohol use disorder (AUD) is a complex, chronic, relapsing disorder with multiple interacting genetic and environmental influences. Numerous studies have verified the influence of genetics on AUD, yet the underlying biological pathways remain unknown. One strategy to interrogate complex diseases is the use of endophenotypes, which deconstruct current diagnostic categories into component traits that may be more amenable to genetic research. In this review, we explore how an endophenotype such as sensitivity to alcohol can be used in conjunction with rodent models to provide mechanistic insights into AUD. We evaluate three alcohol sensitivity endophenotypes (stimulation, intoxication, and aversion) for their translatability across human and rodent research by examining the underlying neurobiology and its relationship to consumption and AUD. We show examples in which results gleaned from rodents are successfully integrated with information from human studies to gain insight in the genetic underpinnings of AUD and AUD-related endophenotypes. Finally, we identify areas for future translational research that could greatly expand our knowledge of the biological and molecular aspects of the transition to AUD with the broad hope of finding better ways to treat this devastating disorder.

Nonexperimental Xenobiotics: Unintended Consequences of Intentionally Administered Substances in Terrestrial Animal Models

Review of the use of nonexperimental xenobiotics in terrestrial animal models and the potential unintended consequences of these compounds, including drug-related side effects and adverse reactions.

Cardiac Arrest Secondary to Accidental Hypothermia: The Physiology Leading to Hypothermic Arrest

Cardiac arrest secondary to accidental hypothermia is rare in the United Kingdom. However, some evidence suggests that it is under-reported; furthermore, recognizing hypothermia as the cause of death is difficult in the postmortem setting. Urban and rural residents are exposed to cold winter conditions both at home and while undertaking recreational activities. Understanding the physiology underpinning hypothermic cardiac arrest is crucial in order to make informed clinical decisions in regard to triage and management by air ambulance services and in prevention of this rare presentation. This article discusses the epidemiology and pathophysiology of accidental hypothermic to explain how personnel can survive after 8 hours 40 minutes of cardiac arrest.

Brown fat activation mitigates alcohol-induced liver steatosis and injury in mice

Chronic alcohol consumption causes liver injury, inflammation and fibrosis, thereby increasing morbidity and mortality. Paradoxically, modest drinking is believed to confer metabolic improvement, but the underlying mechanism remains elusive. Here, we have identified a novel hepatoprotective brain/brown adipose tissue (BAT)/liver axis. Alcohol consumption or direct alcohol administration into the brain stimulated hypothalamic neural circuits and sympathetic nerves innervating BAT, and dramatically increased BAT uncoupling protein 1 (Ucp1) expression and activity in a BAT sympathetic nerve-dependent manner. BAT and beige fat oxidized fatty acids to fuel Ucp1-mediated thermogenesis, thereby inhibiting lipid trafficking into the liver. BAT also secreted several adipokines, including adiponectin that suppressed hepatocyte injury and death. Genetic deletion of Ucp1 profoundly augmented alcohol-induced liver steatosis, injury, inflammation and fibrosis in male and female mice. Conversely, activation of BAT and beige fat through cold exposure suppressed alcoholic liver disease development. Our results unravel an unrecognized brain alcohol-sensing/sympathetic nerve/BAT/liver axis that counteracts liver steatosis and injury.

Web-based hypothermia information: a critical assessment of Internet resources and a comparison to peer-reviewed literature

AIMS

Hypothermia is a medical condition characterized by a drop in core body temperature, and it is a considerable source of winter weather-related vulnerability in mid-/high-latitude areas. Heat vulnerability research, including assessments of internet-based resources, is more thoroughly represented in the peer-reviewed literature than cold-related vulnerability research. This study was undertaken to summarize available web-based hypothermia information, and then determine its scientific validity compared to the peer-reviewed literature.

METHODS

This research takes a similar approach used by Hajat et al. for web-based heat vulnerability research, and utilizes this framework to assess hypothermia information found on the internet. Hypothermia-related search terms were used to obtain websites containing hypothermia information, and PubMed (medical literature search engine) and Google Scholar were used to identify peer-reviewed hypothermia literature. The internet information was aggregated into categories (vulnerable populations, symptoms, prevention), which were then compared to the hypothermia literature to determine the scientific validity of the web-based guidance. The internet information was assigned a Strength of Recommendation Taxonomy (SORT) grade (developed by the American Academy of Family Practitioners) of A, B, or C based on the peer-reviewed evidence.

RESULTS

Overall, 25 different pieces of guidance within the three categories were identified on 49 websites. Guidance concerning hypothermia symptoms most frequently appeared on websites, with six symptoms appearing on 50% or greater of websites. No piece of guidance within the vulnerable population categories appeared on greater than 60% of the websites, and prevention-related guidance was characterized by varied SORT grades.

CONCLUSIONS

Hypothermia information on the internet was not entirely congruent with the information within the peer-reviewed medical literature. Several suggestions for improving web-based hypothermia resources include clearly listing sources for users to see and eliminating guidance with lower SORT grades and replacing with evidence-based information.

Circadian phase determines effects of repeated ethanol vapor exposure and withdrawal on body temperature and activity rhythms of male mice

BACKGROUND

Physiological responses to acute ethanol (EtOH) injection depend critically on the timing of their administration. Whether daily timing modulates effects of longer intoxication intervals characteristic of alcohol-dependent humans remains unknown. The present work examines time-of-day effects during EtOH exposure and withdrawal measured by locomotor activity (ActLoc ) and body temperature (Tb ) across multiple rounds of EtOH exposure/withdrawal.

METHODS

Two groups of C57BL/6J mice (n = 8 per group), implanted with radio-telemeters, were entrained to opposite light-dark periods (14:10 LD cycle) so that their rest/activity cycles were 12 hours apart. Under a 2-hour skeleton photoperiod animals were simultaneously exposed to 3 daily cycles of EtOH vapor inhalation (14 hours EtOH on) and withdrawal (10 hours EtOH off). During this time, air-only control groups (n = 4 per group) matched for entrainment were handled in a comparable manner. After the third cycle of EtOH vapor, the animals were left undisturbed for 11 days to recover. The 14-day protocol was repeated 3 additional times.

RESULTS

During intoxication, mice exposed to EtOH in the subjective night exhibited greater hypothermia and more overall disruptions in the Tb and ActLoc rhythms. Acute withdrawal induced hypothermia during the subjective night and hyperthermia during the subjective day. Animals in both phases demonstrated significant disruptions in ActLoc during withdrawal. ActLoc had little effect on Tb during EtOH exposure, but it significantly influenced Tb during acute withdrawal.

CONCLUSIONS

The physiological responses of both EtOH exposure and withdrawal differ as a function of time of day. These findings suggest that controlling for the circadian phase of exposure and/or withdrawal may mitigate the severity of symptomatic withdrawal.

Hypothermia and Fever after organophosphorus poisoning in humans--a prospective case series

There have been many animal studies on the effects of organophosphorus pesticide (OP) poisoning on thermoregulation with inconsistent results. There have been no prospective human studies. Our aim was to document the changes in body temperature with OP poisoning. A prospective study was conducted in a rural hospital in Polonnaruwa, Sri Lanka. We collected data on sequential patients with OP poisoning and analyzed 12 patients selected from 53 presentations who had overt signs and symptoms of OP poisoning and who had not received atropine prior to arrival. All patients subsequently received specific management with atropine and/or pralidoxime and general supportive care. Tympanic temperature, ambient temperature, heart rate, and clinical examination and interventions were recorded prospectively throughout their hospitalization. Initial hypothermia as low as 32°C was observed in untreated patients. Tympanic temperature increased over time from an early hypothermia (<35°C in 6/12 patients) to later fever (7/12 patients >38°C at some later point). While some of the late high temperatures occurred in the setting of marked tachycardia, it was also apparent that in some cases fever was not accompanied by tachycardia, making excessive atropine or severe infection an unlikely explanation for all the fevers. In humans, OP poisoning causes an initial hypothermia, and this is followed by a period of normal to high body temperature. Atropine and respiratory complications may contribute to fever but do not account for all cases.

Alcohol, athletic performance and recovery

Alcohol consumption within elite sport has been continually reported both anecdotally within the media and quantitatively in the literature. The detrimental effects of alcohol on human physiology have been well documented, adversely influencing neural function, metabolism, cardiovascular physiology, thermoregulation and skeletal muscle myopathy. Remarkably, the downstream effects of alcohol consumption on exercise performance and recovery, has received less attention and as such is not well understood. The focus of this review is to identify the acute effects of alcohol on exercise performance and give a brief insight into explanatory factors.

Assessing the role of the medial preoptic area in ethanol-induced hypothermia

Administration of ethanol produces hypothermia. The preoptic area/anterior hypothalamus (POA/AH) contains warm- and cold-sensitive neurons that are important for temperature regulation. The present study evaluated the effect of ethanol on Fos immunoreactivity (Fos-ir) in the medial preoptic area (MPOA) and the effect of lesions to the MPOA on ethanol-induced hypothermia. Rats receiving 1.5-g/kg ethanol showed an increase in Fos-ir in the MPOA. However, lesions to the MPOA did not affect core body temperature. These findings indicate that ethanol increases neural activity in the MPOA, but this increased activity does not influence ethanol-induced changes in core body temperature.

Hypothermia in the geriatric population

Hypothermia is common in the geriatric population and its significance perhaps under-recognized. Hypothermia is associated with substantial morbidity and fatality, but to some extent is preventable provided caregivers and providers of healthcare to older adults adopt preventive measures to lower its occurrence. Hypothermia occurs in both cold and warm settings; its pathogenesis involves alterations in the age-related physiology of thermoregulation, along with a variable combination of environmental factors, disease processes and medications, many of which are recognizable. Once diagnosed, treatment must be prompt and aggressive, and must consider several options for rewarming. Education of healthcare providers regarding early recognition of hypothermia and a better understanding of preventive and treatment measures will undoubtedly lower complications of hypothermia in affected elderly.

The role of protein kinase A in acute ethanol-induced neurobehavioral actions in rats

BACKGROUND

cAMP-dependent protein kinase (PKA) signaling pathways are involved in the regulation of ethanol-induced sedative effects in knockout mouse models. In the present study, we examined the role of PKA on the behavioral action caused by ethanol in Sprague Dawley rats.

METHODS

A loss of righting reflex (LORR) test was used to study the acute sedative effects of intraperitoneally injected ethanol. Rotarod performance was used to study the motor impairment caused by ethanol. Convulsions induced by intracerebroventricular (ICV) N-methyl-d-aspartate (NMDA) were used to evaluate ethanol's effect on NMDA receptors. Western blot analysis was used to assay protein levels for NR1 and phosphoserine 897 on NR1 subnuits.

RESULTS

ICV pretreatment with H-9 (a nonspecific PK inhibitor) or KT 5720 (a specific PKA inhibitor) dose-dependently attenuated ethanol-induced sleeping time as assessed by LORR. ICV KT 5720 did not reduce ketamine or pentobarbital-induced sleeping time. Pretreatment with forskolin (an activator of adenylyl cyclase) or chelerythrine (a selective PKC inhibitor) had no effect on ethanol-induced LORR. Ethanol-induced motor impairment was also attenuated after pretreatment with KT 5720. Ethanol significantly inhibited NMDA-induced convulsions; the inhibitory effects of ethanol were reduced by prior ICV KT 5720, which had no significant effects on the levels of phosphoserine 897 on NMDA NR1 subunits in the several brain areas we examined.

CONCLUSIONS

Our results suggest that the PKA pathway may participate in ethanol-induced neurobehavioral changes and that NMDA receptors may be involved in the PKA regulation of ethanol's actions.

Alcohol and football

The use of alcohol is often intimately associated with sport, and the association is particularly strong in football. As well as providing a source of energy, alcohol (ethanol) has metabolic, cardiovascular, thermoregulatory, and neuromuscular actions that may affect exercise performance. Its actions on the central nervous system, however, result in decrements in skill and behavioural changes that may have adverse effects on performance. There is also evidence of dose-dependent decrements in aerobic capacity. Although the mechanisms are not well understood, the aftermath of alcohol use (hangover) may also adversely affect performance for many hours after intoxication. Alcohol intoxication may adversely affect the player's dietary choices by displacing carbohydrate from the diet at a time when restoration of glycogen stores should be a priority.

The effect of alcohol on athletic performance

The use of alcohol is often intimately associated with sport. As well as providing a source of energy, alcohol (ethanol) has metabolic, cardiovascular, thermoregulatory, and neuromuscular actions that may affect exercise performance. Strength is minimally affected, and performance impairments depend on the dose of alcohol and subject habituation to alcohol intake, exercise duration, environmental conditions, and other factors. Central nervous system function is impaired at high doses, resulting in decrements in cognitive function and motor skill, as well as behavioral changes that may have adverse effects on performance. Effects may persist for hours after intoxication.

Effects of genetic and procedural variation on measurement of alcohol sensitivity in mouse inbred strains

Mice from eight inbred strains were studied for their acute sensitivity to ethanol as indexed by the degree of hypothermia (HT), indexed as the reduction from pre-injection baseline of their body temperature. Two weeks later, mice were tested for their loss of righting reflex (LRR) after a higher dose of ethanol. The LRR was tested using the "classical" method of watching for recovery in animals placed on their backs in a V-shaped trough and recording duration of LRR. In a separate test, naive animals of the same strains were tested for HT repeatedly to assess the development of rapid (RTOL) and chronic tolerance (CTOL). We have recently developed a new method for testing LRR that leads to a substantial increase in the sensitivity of the test. Strains also have been found to differ in the new LRR test, as well as in the development of acute functional tolerance (AFT) to this response. In addition, our laboratory has periodically published strain difference data on the older versions of the HT and LRR responses. The earlier tests used some of the exact substrains tested currently, while for some strains, different substrains (usually, Nih versus Jax) were tested. We examined correlations of strain means to see whether patterns of strain differences were stable across time and across different test variants assessing the same behavioral construct. HT strain sensitivity scores were generally highly correlated across a 10-23 years period and test variants. The CTOL to HT was well-correlated across studies, and was also genetically similar to RTOL. The AFT, however, was related to neither RTOL nor CTOL, although this may be because different phenotypic end points were compared. The LRR data, which included a variant of the classical test, were not as stable. Measures of LRR onset were reasonably well correlated, as were those taken at recovery (e.g., duration). However, the two types of measures of LRR sensitivity to ethanol appear to be tapping traits that differ genetically. Also, the pattern of genetic correlation between HT and LRR initially reported in 1983 was not seen in current and contemporaneous studies. In certain instances, substrain seems to matter little, while in others, substrains differed a great deal. These data are generally encouraging about the stability of genetic differences.

Tolerance and withdrawal in goldfish exposed to ethanol

Acute ethanol exposure decreases regulated body temperature. Tolerance and dependence develop with continued exposure. Removal of ethanol following chronic exposure produces withdrawal. There is little information on the time course for the development of tolerance and disagreement about the presence of a rebound effect on body temperature during withdrawal. For tolerance, we monitored the selected temperature [T(sel)] of goldfish [Carassius auratus] for 8 h while they were exposed to one of three doses of ethanol. During the period from 90 to 150 min post-exposure, T(sel) was: control: 24.1+/-0.07 degrees C; 0.4% ethanol: 21.9+/-0.09 degrees C; 0.8% ethanol: 21.3+/-0.05 degrees C; 1.1% ethanol: 18.4+/-0.10 degrees C. The difference between control and experimental T(sel) decreased by the following amounts for the final 1.5 h in the gradient: 0.4% ethanol: 2.60+/-0.12 degrees C; 0.8% ethanol: 1.58+/-0.09 degrees C; 1.1% ethanol: 4.08+/-0.12 degrees C. At all 3 doses, tolerance proceeded in a stepwise manner rather than continuously. Temperature regulation during withdrawal was evaluated by maintaining the goldfish in 0.8% ethanol for three days and subsequently monitoring T(sel) in an ethanol-free temperature gradient for 36 h. During withdrawal there was no evidence for an effect on T(sel); experimental and control values were nearly identical.

Effects of combining ethanol (EtOH) with gamma-hydroxybutyrate (GHB) on the discriminative stimulus, locomotor, and motor-impairing functions of GHB in mice

RATIONALE

Gamma-hydroxybutyrate (GHB) is a drug of abuse that is often coabused with ethanol (EtOH) and has been implicated as a date rape agent in conjunction with EtOH. Much information is lacking regarding the manner in which GHB interacts with EtOH.

OBJECTIVE

This study was designed to further characterize the behavioral effects of GHB alone and in combination with EtOH in male Swiss-Webster mice.

METHODS

The effects of GHB (0.1-1.0 g/kg) and EtOH (2.0-5.0 g/kg) alone, as well as the effects of GHB in combination with EtOH, were examined using an automated locomotor activity procedure, a functional observational battery (FOB) and a GHB drug discrimination procedure.

RESULTS

GHB decreased, whereas EtOH had little effect on locomotor activity. In the FOB, EtOH dose-dependently decreased activity in combination with 0.3 g/kg GHB. Alone, each drug had little effect on the righting reflex, but combining ineffective doses of GHB and EtOH significantly impaired righting. GHB and EtOH decreased forelimb grip strength. Combinations of ineffective doses of GHB and EtOH decreased forelimb grip strength when given together. GHB and EtOH impaired inverted screen performance, and EtOH increased the impairing effects of low, but not high, doses of GHB. GHB and EtOH increased hind limb splay, and EtOH increased the effects of 0.1 and 0.3 g/kg GHB on splay. GHB and EtOH decreased body temperature, and EtOH augmented the temperature-decreasing effects of GHB. EtOH produced less than 50% GHB-like discriminative stimulus effects, and GHB failed to alter the GHB-like discriminative stimulus effects of EtOH.

CONCLUSIONS

Overall, EtOH increased the effects of GHB on several gross measures of behavior and only partially occasioned the discriminative stimulus properties of GHB.

Effects of ethanol on the induction of uncoupling protein-1 (UCP1) mRNA in the mouse brown adipose tissue

Expression of uncoupling protein-1 (UCP1) is increased by cold acclimation and overfeeding, and reduced in fasting and genetic obesity. It is known that the mitochondrial UCP1 in the brown adipose tissue (BAT) is an important key molecule for non-shivering thermogenesis. On the other hand, ethanol (EtOH) alters thermoregulation in humans and laboratory animals. However, the relationship between EtOH intake and UCP1 expression is not yet clear. Accordingly, the present study employed the technique of real-time quantitative polymerase-chain reaction (PCR) to investigate the effects of EtOH (0.5 or 2.0 g/kg) on the expression of UCP1 mRNA in the mouse BAT. Control mice were injected with the same volume of physiological saline intraperitoneally (IP). IP injection of EtOH (0.5 g/kg) caused a decrease and an increase of the expression of BAT UCP1 mRNA at 1 and 4 hours, respectively. Treatment with EtOH (2.0 g/kg) caused an increases of the expression of BAT UCP1 mRNA at both 2 and 4 hours. BAT UCP1 mRNA levels in both groups increased at 4 hours after EtOH administration. The levels of UCP1 mRNA returned to the control levels by 8 hours after EtOH administration. The expression of BAT UCP1 mRNA was upregulated following EtOH administration, although a lower dose of EtOH initially reduced the expression of UCP1 mRNA in BAT. These findings suggest that EtOH-induced UCP1 mRNA expression in BAT reflects an alteration of the set point of thermogenesis.

Biochemical background of ethanol-induced cold susceptibility

The process of cooling is always associated with the depletion of energetic reserves and burning the ketone bodies covers the tissues' needs. Ethanol shows antiketonaemic effects changing the cellular redox potential, inhibiting beta-oxidation of fatty acids, stimulating the release of insulin and inhibiting the release of its antagonist. The aim of the study was to determine whether the cooling process of the organism in the presence of ethanol intoxication may be related to inhibition of the physiological mechanism of ketogenesis induced by hypothermia. The study involved the 67 autopsy cases from 1996 to 2002, in which the circumstances of death indicated the effects of overcooling. This was confirmed on the basis of the data from the Prosecutor's Offices. Then, the chromatograms of autopsy blood alcohol determinations were analyzed and the acetone levels recorded. The analysis supported the hypothesis that the severity of ketosis is inversely proportional to the blood ethanol concentration. Furthermore, it demonstrated that signs of prolonged cold exposure were less frequently observed in unsober persons (frostbites, gastric hemorrhages). Increased sensitivity of intoxicated individuals to cold may be related not only to the dilation of the peripheral vessels, inhibition of shivering thermogenesis caused by muscle relaxation, central nervous system depression and behavioral factors but also to the antiketonaemic effects of ethanol.

Orally administered ethanol: transepidermal pathways and effects on the human skin barrier

Ethanol intake is associated with a variety of skin diseases. The aim of the present study was (1) to identify the pathways of release of orally administered ethanol through the skin, and (2) to investigate the effects of a single oral dose of ethanol on the penetration of topically applied substances into the skin. Ethanol evaporation via the skin was measured using the new technique of ion mobility spectrometry (IMS). Transepidermal water loss (TEWL) and skin surface temperature were simultaneously measured before and after ethanol consumption. Measurements were performed on skin sites with different stratum corneum (SC) thickness, and density of follicles and sweat glands. These appendages were selectively sealed to investigate their participation in ethanol evaporation. The penetration of a topically applied UV filter substance was studied before and after ethanol consumption after removing the SC with adhesive tape. Ethanol evaporation was measured within 5 min of consumption, while the skin surface temperature remained nearly constant. The sealing of the appendages did not have a significant effect on ethanol evaporation. On the forehead, a higher TEWL value was measured than on the forearm. On both skin sites, an increase in TEWL was observed after ethanol ingestion. No influence of orally administered ethanol on the penetration of the topically applied UV filter substance was observed. The results indicate that ethanol evaporation occurs via the lipid layers without a significant effect on the penetration of the topically applied substance.

Assessment of heat production, heat loss, and core temperature during nitrous oxide exposure: a new paradigm for studying drug effects and opponent responses

Studies using core temperature (T(c)) have contributed greatly to theoretical explanations of drug tolerance and its relationship to key features of addiction, including dependence, withdrawal, and relapse. Many theoretical accounts of tolerance propose that a given drug-induced psychobiological disturbance elicits opponent responses that contribute to tolerance development. This proposal and its theoretical extensions (e.g., conditioning as a mechanism of chronic tolerance) have been inferred from dependent variables, such as T(c), which represent the summation of multiple underlying determinants. Direct measurements of determinants could increase the understanding of opponent processes in tolerance, dependence, and withdrawal. The proximal determinants of T(c) are metabolic heat production (HP) and heat loss (HL). We developed a novel system for simultaneously quantifying HP (indirect calorimetry), HL (direct gradient layer calorimetry), and T(c) (telemetry) during steady-state administrations of nitrous oxide (N(2)O), an inhalant with abuse potential that has been previously used to study acute and chronic tolerance development to its hypothermia-inducing property. Rats were administered 60% N(2)O (n = 18) or placebo gas (n = 16) for 5 h after a 2-h placebo baseline exposure. On average, N(2)O rapidly but transiently lowered HP and increased HL, each by approximately 16% (P < 0.001). On average, rats reestablished and maintained thermal equilibrium (HP = HL) at a hypothermic T(c) (-1.6 degrees C). However, some rats entered positive heat balance (HP > HL) after becoming hypothermic such that acute tolerance developed, i.e., T(c) rose despite continued drug administration. This work is the first to directly quantify the thermal determinants of T(c) during administration of a drug of abuse and establishes a new paradigm for studying opponent processes involved in acute and chronic hypothermic tolerance development.

Does an Energy Drink Modify the Effects of Alcohol in a Maximal Effort Test?

BACKGROUND

There are popular reports on the combined use of alcohol and energy drinks (such as Red Bull and similar beverages, which contain caffeine, taurine, carbohydrates, etc.) to reduce the depressant effects of alcohol on central nervous system, but no controlled studies have been performed. The main purpose of this study was to verify the effects of alcohol, and alcohol combined with energy drink, on the performance of volunteers in a maximal effort test (cycle ergometer) and also on physiological indicators (oxygen uptake, ventilatory threshold, respiratory exchange rate, heart rate, and blood pressure), biochemical variables (glucose, lactate, insulin, cortisol, ACTH, dopamine, noradrenaline, and adrenaline), and blood alcohol levels.

METHODS

Fourteen healthy subjects completed a double-blind protocol made up of four sessions: control (water), alcohol (1.0 g/kg), energy drink (3.57 ml/kg Red Bull), and alcohol + energy drink, each 1 week apart. The effort test began 60 min after drug or control ingestion, and the dependent variables were measured until 60 min after the test.

RESULTS

Heart rate at the ventilatory threshold was higher in the alcohol and alcohol + energy drink sessions in comparison with control and energy drink sessions. Although in comparison to the control session, the peak oxygen uptake was 5.0% smaller after alcohol ingestion, 1.4% smaller after energy drink, and 2.7% smaller after the combined ingestion, no significant differences were detected. Lactate levels (30 min after drug ingestion, 30 and 60 min after the effort test) and noradrenaline levels (30 min after the effort test) were higher in the alcohol and alcohol + energy drink sessions compared with the control session.

CONCLUSIONS

The performance in the maximal effort test observed after alcohol + energy drink ingestion was similar to that observed after alcohol only. No significant differences between alcohol and alcohol + energy drink were detected in the physiological and biochemical parameters analyzed. Our findings suggest that energy drinks, at least in the tested doses, did not improve performance or reduce alterations induced by acute alcohol ingestion.

Influence of ethanol on thermoregulation: mapping quantitative trait loci

The genetic basis for the effects of ethanol on thermoregulation was investigated by utilizing recombinant inbred mouse strains from C57BL/6J and DBA/2J progenitor strains. Changes in core body temperature (T(c)) and the degree of fluctuation of T(c) were monitored in male mice following the administration of ethanol in an environment with cyclic changes in ambient temperature (T(a)). Changes in T(c) were utilized to assess ethanol-induced effects on regulated T(c), whereas fluctuations in T(c) were utilized to assess thermoregulatory disruption. Ethanol was administered intraperitoneally at 1.5, 2.5, and 3.5 g/kg for all strains. Change in T(c) and increase in tail temperature were also evaluated at 2.5 g/kg ethanol in a constant T(a) of 26 degrees C. Associations between the measured physiological responses and previously mapped genetic markers were used to identify quantitative trait loci (QTLs). This established probable chromosome locations for a number of genes for the responses. To our knowledge, this is the first report of QTLs that underlie changes in regulation as well as the disruption of a physiological regulatory system.

Sensitivity and tolerance to ethanol in mouse lines selected for ethanol-induced hypothermia

Within-family selective breeding techniques have been used to create two lines of mice to be insensitive (HOT) and two lines to be sensitive (COLD) to the hypothermic effects of an acute 3.0-g/kg ethanol (EtOH) injection. Previous studies have found HOT mice to be relatively resistant to the development of tolerance to this effect, whereas COLD mice readily develop tolerance. The breeding program is currently in selected Generation 52, and the HOT and COLD mice differ by about 10 degrees C (average of both replicates) in their selected hypothermic response. Starting with selection Generation 20, separate lines of mice were inbred from the HOT-2 and COLD-2 selected lines, while selection continued for the original two replicate lines of HOT and COLD mice. To assess whether different dose treatments would produce differential tolerance development in the HOT and COLD selected lines, we administered different dose regimens across 5 days to HOT and COLD mice. The COLD mice developed tolerance while the HOT mice did not, regardless of total EtOH administered. In a separate study, we administered EtOH (3.0 g/kg) to mice for 3 days to assess a shorter tolerance paradigm. We also present here responses to the selection dose of 3.0-g/kg EtOH in the inbred HOT (IHOT-2) and COLD (ICOLD-2) mice tested after 41 generations of brother-sister mating. In addition, we report recent attempts to find doses of EtOH that would produce an equivalent initial hypothermic response in each of the six lines (HOT-1, COLD-1, HOT-2, COLD-2, ICOLD-2, and IHOT-2). When doses were selected to produce similar initial hypothermic sensitivity, tolerance was tested by giving three daily doses and examining the attenuation of the hypothermic response on the third day. All three COLD lines developed significant tolerance, while the HOT lines did not. The HOT and COLD mice provide a genetic model to study mechanisms mediating acute EtOH-induced hypothermia as well as tolerance development.

Effects of lifelong ethanol consumption on rat sympathetic neurons

In this experiment we studied the effects of aging and lifelong ethanol consumption on rat peripheral sympathetic neurons. The aim was to find out the possible differences in the vulnerability to ethanol-induced neuronal degeneration between rats of both genders, or between the alcohol-avoiding (ANA) and the alcohol-preferring (AA) lines of rat. The superior cervical ganglia (SCG) of 40 male and 41 female AA and ANA rats were analyzed. The ethanol-exposed groups had 12% ethanol as the only available fluid from 3 to 24 months of age. The young (3 months) and old (24 months) control groups had water instead. SCG neuronal density, volume, and total neuron number were measured by unbiased morphometric methods. No gender difference was seen in either the volume of the SCG or in the SCG neuron number. The volume of the ganglion was significantly increased with age, but the total neuron number did not change. Neuronal density was significantly decreased with age, but lifelong ethanol consumption induced no further decrease. SCG neuron number in the ethanol-exposed groups did not differ from the age-matched or young control groups, but a significant negative correlation (r = -0.70, p<0.01) was seen between individual ethanol consumption and the number of SCG neurons in the female rats. The amount of lipopigment in the SCG was increased in the ethanol-exposed male rats. These results suggest that the peripheral sympathetic neurons are rather resistant to ethanol-induced degeneration, and that no major gender or line differences exist in this respect.

Poikilothermia syndrome

Poikilothermia syndrome is a rare cause of intrinsic thermoregulatory failure. Patients with this syndrome regulate body temperature poorly, if at all. Recently, a patient was referred to us who had clinical evidence of poikilothermia syndrome, as well as long-standing multiple sclerosis. Computerized tomography and magnetic resonance scanning failed to identify a hypothalamic lesion. The patient was gradually warmed to sweating, and then cooled to vasoconstriction and shivering. The core-temperature thresholds triggering each defence were calculated, after compensating for the changes in skin temperature. The calculated sweating threshold was 38.3 degrees C (normal: 37.0 +/- 0.3 degrees C). The vasoconstriction threshold was 34.4 degrees C (normal: 36.4 +/- 0.3 degrees C). The sweating-to-vasoconstriction interthreshold range was thus approximately 4 degrees C, which is between 10 and 20 times the normal value. The shivering threshold was 31.8 degrees C (normal: 35.6 +/- 0.3 degrees C). The vasoconstriction-to-shivering range was thus approximately 2.5 degrees C which is more than twice the normal value. The pattern of thermoregulatory failure in this patient resembled that resulting from general anaesthesia.

Ethanol, body temperature and thermoregulation

1. The effects of ethanol on body temperature (Tb) and on the regulator of Tb are reviewed. 2. The first section considers how ethanol affects cellular function and how temperature modifies these effects. 3. The next section reviews the effects of ethanol on Tb, covering both disruptive effects and effects on regulatory elements. 4. The final section covers recent work that has made use of genetic techniques to elucidate specific aspects of how ethanol affects temperature regulation.

The threshold for thermoregulatory vasoconstriction during nitrous oxide/sevoflurane anesthesia is reduced in the elderly

Elderly patients become more hypothermic during surgery, shiver less postoperatively, and take longer to rewarm than younger patients. Similarly, the vasoconstriction threshold (triggering core temperature) is reduced approximately 1 degree C in elderly patients during nitrous oxide/isoflurane anesthesia. Accordingly, we tested the hypothesis that the vasoconstriction threshold in the elderly is also reduced approximately 1 degree C during nitrous oxide and sevoflurane anesthesia. Eleven young patients aged 30-50 yr and 14 elderly patients aged 60-80 yr were anesthetized with nitrous oxide (50%) and sevoflurane (1%). Mean skin temperature was calculated from four sites. Fingertip blood flow was estimated using forearm minus fingertip skin-temperature gradients, with a gradient of 0 degree C identifying onset of vasoconstriction. The distal esophageal temperature triggering onset of vasoconstriction identified the threshold for this thermoregulatory defense. The data from five patients who did not vasoconstrict at minimum core temperatures of 33-34 degrees C were eliminated, leaving 10 patients in each group. The vasoconstriction threshold was significantly less in the elderly (35.0 +/- 0.8 degrees C) than in younger patients (35.8 +/- 0.3 degrees C), despite similar mean skin temperatures (mean +/- SD, P < 0.01, Student's t-test). Age dependence of thermoregulatory vasoconstriction during nitrous oxide/sevoflurane anesthesia is similar to that previously observed during nitrous oxide/isoflurane anesthesia.

Ethanol-induced hypothermia in rats is antagonized by dexamethasone

The effect of dexamethasone on ethanol-induced hypothermia was investigated in 3.5-month old male Wistar rats (N = 10 animals per group). The animals were pretreated with dexamethasone (2.0 mg/kg, i.p.; volume of injection = 1 ml/kg) 15 min before ethanol administration (2.0, 3.0 and 4.0 g/kg, i.p.; 20% w/v) and the colon temperature was monitored with a digital thermometer 30, 60 and 90 min after ethanol administration. Ethanol treatment produced dose-dependent hypothermia throughout the experiment (-1.84 +/- 0.10, -2.79 +/- 0.09 and -3.79 +/- 0.15 degrees C for 2.0, 3.0 and 4.0 g/kg ethanol, respectively, 30 min after ethanol) but only the effects of 2.0 and 3.0 g/kg ethanol were significantly antagonized (-0.57 +/- 0.09 and -1.25 +/- 0.10, respectively, 30 min after ethanol) by pretreatment with dexamethasone (ANOVA, P < 0.05). These results are in agreement with data from the literature on the rapid antagonism by glucocorticoids of other effects of ethanol. The antagonism was obtained after a short period of time, suggesting that the effect of dexamethasone is different from the classical actions of corticosteroids.

Sensitivity to ethanol-induced ataxia in HOT and COLD selected lines of mice

Studies with inbred strains of mice have suggested that there may be a genetic correlation between strain sensitivities to the ataxic and hypothermic responses to ethanol (EtOH), which would suggest that some genes influence both responses. To test this hypothesis, EtOH sensitivity was determined in replicate lines of mice selectively bred for sensitivity (COLD) or resistance (HOT) to acute ethanol hypothermia. Several tests were used to index ataxia, related traits such as muscle strength, and locomotor activity. The screen test yielded a dose-dependent EtOH-induced decrease in performance that did not differ between the selected lines. Based on the dose-response characteristics of this task, 2.5 g/kg of EtOH was used as the test dose for the remaining experiments. Results from the fixed-speed rotarod and the grid test of motor incoordination also indicated no significant differences between HOT and COLD mice in sensitivity to EtOH impairment. When the selected lines were tested on an accelerating rotarod, COLD mice were impaired by the acute EtOH injection, but HOT mice were unaffected. COLD mice were more sensitive to EtOH-induced decrements in grip strength and locomotor activity. Overall, the results indicated that HOT and COLD mice were only differentially sensitive to EtOH in some tasks related to ataxia, suggesting that some genes must be associated uniquely with EtOH-induced hypothermia or ataxia. The mixed results from the various tests indicate that ataxia can best be conceived as a group of related complex behaviors that cannot be assessed adequately by the use of a single task and that ataxia-related behaviors are influenced by different groups of genes.

Alcohol and its variable effect on human thermoregulatory response to exercise in a warm environment

The aim of this study was to observe the effect of alcohol ingestion on body temperature and local sweat rate during endogenous and exogenous heat stress. After ingesting either alcohol (1.2 g alcohol/kg of body weight) or a placebo drink, 8 subjects exercised for 60 minutes at 45% VO2max in a warm environment (35 degrees C, 45% RH). Varying patterns of response were observed in these subjects, with no consistent effect on the thermoregulatory response seen. The absence of any significant change in skin and body temperature and in sweat rate suggests that the capacity of the body to struggle against exogenous and endogenous heat is not fundamentally altered by alcohol ingestion. The difference in individual response observed in our experiment is in accord with the previous lack of clearcut effect of alcohol reported in the literature.

Alcohol lowers the vasoconstriction threshold in humans without affecting core cooling rate during mild cold exposure

Elevated blood alcohol levels are often seen in hypothermia and hyperthermia related deaths, leading to the belief that alcohol renders humans poikilothermic. We examined the core temperature (Tco) thresholds for sweating, vasoconstriction and shivering as well as core cooling rates of seven subjects immersed in 28 degrees C water. On two separate days, subjects exercised on an underwater cycle ergometer to elevate Tco above the sweating threshold. They then rested and cooled until they shivered vigorously. Subjects drank orange juice (7 ml.kg-1) prior to immersion during the control trial and 1 ml.kg-1 absolute ethanol, added to orange juice in a 1:6 ratio, during the alcohol trial. Mean blood alcohol concentration (breath analysis) was 0.097 +/- 0.010 g% at the start of cooling and 0.077 +/- 0.008 g% at the end of the cooling period. Alcohol lowered the vasoconstriction threshold by 0.32 +/- 0.2 degrees C and elevated finger tip blood flow, but had no effect on thresholds for sweating and shivering or core cooling rate. Considering these minor effects it is unlikely that moderate alcohol consumption predisposes individuals to hypothermia or hyperthermia via impaired thermoregulation, but rather likely due to behavioral factors.

Influence of ethanol on circulation in surface-induced hypothermia and subsequent rewarming

Hypothermia and ethanol are often closely linked and in hypothermic accidents ethanol is often a contributing factor. To study the effects of ethanol on the circulation in hypothermic conditions, cardiac catheterization was carried out on 18 anaesthetized beagle dogs. They were divided into two groups. One gram of ethanol/kg of b.wt. diluted in saline was infused into the vena cava superior within 30 min to seven dogs. The dogs were then cooled between ice bags until the blood temperature in the ascending aorta was 25 degrees C and they were then rewarmed. The control group of 11 dogs was cooled and rewarmed without ethanol infusion. The heart rate first increased when cooling down to 33 degrees C and decreased thereafter in the control group. In the ethanol group heart rate increased during the ethanol infusion and remained high when cooling down to 33 degrees C and decreased thereafter. Heart rate was higher in the ethanol group throughout the experiments, and during rewarming the difference was significant. In the control group cardiac output first increased until a body temperature of 33 degrees C was achieved but then decreased. In the ethanol group cardiac output started to decrease after ethanol infusion. During rewarming there was a significantly higher cardiac output in the ethanol group, probably due to the higher heart rate. In the cardiac cycle the systolic period prolonged significantly (p < 0.001) in both groups when the body temperature decreased from 37 degrees C to 25 degrees C whereas the diastolic period remained quite stable. The contraction phase was also affected by the cooling. The changes in contraction force cannot be seen in dP/dt alone because dP/dt values first increased significantly when cooling from 37 degrees C to 33 degrees C but then decreased. Ejection fraction, systolic period, and the systemic vascular resistance increased despite the reduction of the dP/dt and thus we conclude that the contraction force is augmented in hypothermia. In the ethanol group the myocardium seems to be depressed due to ethanol. In the early phase of cooling heart rate increased but cardiac output decreased in the ethanol group, indicating the decreased ability of the heart to respond to cooling in the presence of ethanol. The time constant of exponential pressure fall (tau) increased linearly with cooling from 37 degrees C to 25 degrees C and recovered with rewarming in both groups. Changes in negative dP/dt coincided with the changes in the time constant of exponential isovolumic pressure fall. Ethanol did not influence relaxation. All the parameters we checked recovered to normal during rewarming.