Search results for "Body temperature"

CB(1) signaling in forebrain and sympathetic neurons is a key determinant of endocannabinoid actions on energy balance

2010

The endocannabinoid system (ECS) plays a critical role in obesity development. The pharmacological blockade of cannabinoid receptor type 1 (CB(1)) has been shown to reduce body weight and to alleviate obesity-related metabolic disorders. An unsolved question is at which anatomical level CB(1) modulates energy balance and the mechanisms involved in its action. Here, we demonstrate that CB(1) receptors expressed in forebrain and sympathetic neurons play a key role in the pathophysiological development of diet-induced obesity. Conditional mutant mice lacking CB(1) expression in neurons known to control energy balance, but not in nonneuronal peripheral organs, displayed a lean phenotype and res…

Diurnal Rhythm of the Muscular Performance of Elbow Flexors During Isometric Contractions

1996

The influence of time of day on elbow flexion torque was studied. Thirteen physical education students, 7 males and 6 females, made maximal and submaximal isometric contractions at 90 degrees of elbow flexors using a dynamometer. The torque developed was measured on each contraction. The myoelectric activity of the biceps muscle was also measured at the same time by surface electromyography (EMG) and quantified from the root mean square (RMS) activity. Torque and surface EMGs were measured at 6:00, 9:00, 12:00, 15:00, 18:00, 21:00, and 24:00 h over the same day. Oral temperature before each test session was measured on each occasion after a 30-min rest period. We observed a diurnal rhythm i…

Temperature Measurement by Diffusion-Weighted Imaging

2021

Diffusion-weighted imaging (DWI) thermometry is a magnetic resonance-based imaging tool that allows the noninvasive measurement of brain core temperature. Although only applicable to cerebrospinal fluid, it is thought to be potentially useful in assessing the thermal pathophysiology of the brain in both patients and healthy subjects. The objective of this article is to provide a concise but thorough review of the basic physical principles and the principal applications of DWI thermometry as a potential method to elucidate the pathophysiology of several brain diseases and neurologic syndromes.

Scientific Reports

2019

Anthropogenic climate change ranks among the major global-scale threats to modern biodiversity. Extinction risks are known to increase via the interactions between rapid climatic alterations and environmentally-sensitive species traits that fail to adapt to those changes. Accumulating evidence reveals the influence of ecophysiological, ecological and phenological factors as drivers underlying demographic collapses that lead to population extinctions. However, the extent to which life-history traits influence population responses to climate change remains largely unexplored. The emerging 'cul-de-sac hypothesis' predicts that reptilian viviparity ('live-bearing' reproduction), a 'key innovati…

Relationship between skin temperature and muscle activation during incremental cycle exercise.

2015

While different studies showed that better fitness level adds to the efficiency of the thermoregulatory system, the relationship between muscular effort and skin temperature is still unknown. Therefore, the present study assessed the relationship between neuromuscular activation and skin temperature during cycle exercise. Ten physically active participants performed an incremental workload cycling test to exhaustion while neuromuscular activations were recorded (via surface electromyography - EMG) from rectus femoris, vastus lateralis, biceps femoris and gastrocnemius medialis. Thermographic images were recorded before, immediately after and 10 min after finishing the cycling test, at four …

Changes of peroxisomal fatty acid metabolism during cold acclimatization in hibernating jerboa (Jaculus orientalis)

2003

Abstract Jerboa (Jaculus orientalis) is a deep hibernator originating from sub-desert highlands and represents an excellent model to help to understand the incidence of seasonal variations of food intake and of body as well as environmental temperatures on lipid metabolism. In jerboa, hibernation processes are characterized by changes in the size of mitochondria, the number of peroxisomes in liver and in the expression of enzymes linked to fatty acid metabolism. In liver and kidney, cold acclimatization shows an opposite effect on the activities of the mitochondrial acyl-CoA dehydrogenase (–50%) and the peroxisomal acyl-CoA oxidase (AOX) (+50%), while in brown and white adipose tissues, bot…

Understanding Cannabinoid Psychoactivity with Mouse Genetic Models

2007

Marijuana and its main psychotropic ingredient Δ9-tetrahydrocannabinol (THC) exert a plethora of psychoactive effects through the activation of the neuronal cannabinoid receptor type 1 (CB1), which is expressed by different neuronal subpopulations in the central nervous system. The exact neuroanatomical substrates underlying each effect of THC are, however, not known. We tested locomotor, hypothermic, analgesic, and cataleptic effects of THC in conditional knockout mouse lines, which lack the expression of CB1 in different neuronal subpopulations, including principal brain neurons, GABAergic neurons (those that release γ aminobutyric acid), cortical glutamatergic neurons, and neurons expres…

Insights on the use of thermography in human physiology practical classes

2018

Analyzing the electrophysiological effects of local epicardial temperature in experimental studies with isolated hearts

2008

As a result of their modulating effects upon myocardial electrophysiology, both hypo- and hyperthermia can be used to study the mechanisms that generate or sustain cardiac arrhythmias. The present study describes an original electrode developed with thick-film technology and capable of controlling regional temperature variations in the epicardium while simultaneously registering its electrical activity. In this way, it is possible to measure electrophysiological parameters of the heart at different temperatures. The results obtained with this device in a study with isolated and perfused rabbit hearts are reported. An exploration has been made of the effects of local temperature changes upon…

THERMOREGULATION CONSTRAINS EFFECTIVE WARNING SIGNAL EXPRESSION

2009

Evolution of conspicuous signals may be constrained if animal coloration has nonsignaling as well as signaling functions. In aposematic wood tiger moth (Parasemia plantaginis) larvae, the size of a warning signal (orange patch on black body) varies phenotypically and genetically. Although a large warning signal is favored as an antipredator defense, we hypothesized that thermoregulation may constrain the signal size in colder habitats. To test this hypothesis, we conducted a factorial rearing experiment with two selection lines for larval coloration (small and large signal) and with two temperature manipulations (high and low temperature environment). Temperature constrained the size and br…