Tail Temperature Research Articles

The Effect Combination of Leonurus japonicus Houtt, Eclipta prostrata L., and Pueraria lobata Ohwi Extract on Menopause Symptoms in an Ovariectomized Rat Model

Abstract Objectives Menopause causes ovarian hormone decline, followed by symptoms including weight gain, bone loss, hot flashes, and menopausal depression. We had a purpose that a combination of Leonurus japonicus Houtt, Eclipta prostrata L., and Pueraria lobata Ohwi (LEPE) would alleviate menopausal symptoms in an ovariectomized menopausal rat model. Methods Female rat underwent surgery to resect bilateral ovarian and were randomly assigned to five groups: (1) Sham, (2) Vehicle, negative control, (3) LEPE (100 mg/kg bw), (4) LEPE (200 mg/kg bw), and (5) Estradiol (E2, 3 μg/kg bw). LEPE was orally gavaged daily for 12 weeks. Results There is no effect on growth performance, including body weight and feed intake, or body composition, including lean mass and fat in tissue. LEPE did not cause hepatotoxicity (aspartate aminotransferase and alanine aminotransferase) and endocrine disturbance (estradiol, follicle-stimulating hormone levels, and uterine weight). Despite decreasing type I collagen (CTX-1), LEPE did not affect bone mineral density and osteocalcin. LEPE supplement reduced the tail temperature and increased the rectal temperature, improving menopause-associated vasomotor symptoms such as hot flashes and night sweat. Furthermore, LEPE relieved behavior related to menopausal depression, including in forced swimming and tail suspension tests. Conclusions These findings suggest that LEPE ameliorates menopausal symptoms via improving menopause-associated vasomotor symptoms and depression behavior in a female rat model of surgical menopause. Funding Sources This research was funded by Nong Shim.

Posterior subthalamic nucleus (PSTh) mediates innate fear-associated hypothermia in mice

The neural mechanisms of fear-associated thermoregulation remain unclear. Innate fear odor 2-methyl-2-thiazoline (2MT) elicits rapid hypothermia and elevated tail temperature, indicative of vasodilation-induced heat dissipation, in wild-type mice, but not in mice lacking Trpa1–the chemosensor for 2MT. Here we report that Trpa1−/− mice show diminished 2MT-evoked c-fos expression in the posterior subthalamic nucleus (PSTh), external lateral parabrachial subnucleus (PBel) and nucleus of the solitary tract (NTS). Whereas tetanus toxin light chain-mediated inactivation of NTS-projecting PSTh neurons suppress, optogenetic activation of direct PSTh-rostral NTS pathway induces hypothermia and tail vasodilation. Furthermore, selective opto-stimulation of 2MT-activated, PSTh-projecting PBel neurons by capturing activated neuronal ensembles (CANE) causes hypothermia. Conversely, chemogenetic suppression of vGlut2+ neurons in PBel or PSTh, or PSTh-projecting PBel neurons attenuates 2MT-evoked hypothermia and tail vasodilation. These studies identify PSTh as a major thermoregulatory hub that connects PBel to NTS to mediate 2MT-evoked innate fear-associated hypothermia and tail vasodilation.

54 Relationships Between Heat Stress and Behavioral Responses with Reproductive Traits of Maternal-line Gilts

Abstract Heat stress (HS) during summer months can negatively affect reproductive efficiency and sow productivity. This study was designed to evaluate potential relationships between HS sensitivity and behavior with litter characteristics in replacement gilts. A total of 61 replacement gilts (108.8± 10.4 kg BW; 8 repetitions; 9d/repetition), were tested from February to May 2020 at the USDA-ARS Food Animal Behavior Laboratory in West Lafayette, IN. Pigs were housed (2/pen) in thermoneutral (TN; 22.6± 1.6⁰C) conditions and their behavior was recorded for 5 d. On d 6, gilts were subjected to an open field test and novel object test. Heart rate, number of escape attempts, and vocalizations were recorded during behavior testing. Vaginal temperature monitors were inserted to record body temperature (TB) every 15 min. Gilts were individually housed and exposed to cyclic HS (28.2± 0.97⁰C nighttime to 36.9± 1.9⁰C daytime; 46± 15.4% relative humidity) on d 7 to 9. Feed was provided ad libitum and feed intake was recorded daily. During the HS challenge, respiration rate (RR), skin (ear, shoulder, rump, and tail) temperature, and posture were recorded every 2 h from 0800 to 2000 h. Following the HS challenge, gilts were transported to the Purdue University swine farm, and gilts that displayed signs of estrus were artificially inseminated (253±29 d of age) between May and September 2020. At farrowing, litter characteristics were obtained and included total number of piglets born, total number of piglets born alive, average litter birth weight, total number of piglets weaned, and average weaning weight of the litter. Correlations between behavior, HS response, and litter characteristics were obtained using JMP 15 software. The preliminary analysis indicated no significant interactions (P < 0.05) between RR or TB with litter characteristics. However additional records are currently being collected, which might reveal important trends among the traits analyzed.

Spatially resolved measurements of RF accelerated deuterons at JET

An understanding of fast (supra-thermal) ion behavior is of great importance in tokamak physics and is a subject studied from both theoretical and experimental perspectives. This paper investigates the spatial energy and density distributions of RF accelerated deuterons using the neutron camera at the tokamak JET. Using the 19 liquid scintillator detectors available in the neutron camera system, we obtain spatial information that cannot be accessed with a single sightline. We present a spectroscopic analysis method in which a spatially resolved model of the fast ion distribution is fitted to the pulse height spectra from all 19 detectors simultaneously. The fast ion distribution is parameterized in such a way that the density, energy, and pitch-angle parts are uncoupled. The energy part is composed of a Maxwellian distribution, characterized by an ‘RF tail temperature,’ and the spatial dependence is modeled as a two-dimensional Gaussian distribution on the poloidal plane of the tokamak. From this parameterized model, we can calculate the spectrum of fusion born neutrons originating from reactions involving RF accelerated deuterons, and by fitting this model to the measured neutron camera pulse height spectra, we obtain an estimate of the spatially resolved distribution of the fast deuterons. The method has been applied to three JET pulses using different RF heating schemes and is shown to identify several features of the fast ion distribution produced in the various scenarios. Hence, this method is able to provide quantitative information about the fast ion distribution resulting from different heating schemes, and can also be useful, e.g., to validate simulation results from RF modeling codes.

Combined Extract of Leonurus japonicus Houtt, Eclipta prostrata L., and Pueraria lobata Ohwi Improved Hot Flashes and Depression in an Ovariectomized Rat Model of Menopause.

Menopause leads to ovarian hormone loss, which causes symptoms such as weight gain, hot flashes, and depression. Exploring nutraceuticals is important for treating menopausal symptoms that extensively impact women’s quality of life. We hypothesized that a combination of Leonurus japonicus Houtt, Eclipta prostrata L., and Pueraria lobata Ohwi (LEPE) would alleviate menopausal symptoms in an ovariectomized menopausal rat model. Bilateral ovariectomy was performed and animals were assigned to five groups: (1) Sham, (2) Vehicle, (-) Control, (3) LEPE (100 mg/kg bw), (4) LEPE (200 mg/kg bw), and (5) Estradiol (3 μg/kg bw). LEPE was orally administered daily for 12 weeks. LEPE supplementation did not affect growth performance (body weight and feed intake) or body composition (lean mass and fat in tissue). LEPE did not cause deviations in aspartate aminotransferase, alanine aminotransferase, estradiol, and follicle-stimulating hormone levels, indicating no hepatotoxicity or endocrine disturbance. LEPE decreased type I collagen (CTX-1) but did not affect bone mineral density or osteocalcin. LEPE decreased tail temperature and increased rectal temperature, improving menopause-related vasomotor symptoms. Furthermore, LEPE ameliorated depression-related behavior, including in forced swimming and tail suspension tests. Thus, LEPE may improve menopausal symptoms by enhancing vasomotor symptoms and depression in an ovariectomized rat menopause model.

Synthesis of Schiff base-based cationic Gemini surfactants and evaluation of their effect on in-situ AgNPs preparation: Structure, catalytic, and biological activity study

Carcinogenic organic pollutants pose a threat to human health and the environment; therefore, appropriate solutions are required for their removal. In this study, three hybrid systems composed of surfactants and silver nanoparticles (AgNPs) were prepared based on three cationic Gemini surfactants exhibiting different hydrophobic tail lengths. The AgNPs were synthesized by a photochemical reduction method using sunlight as a surplus source of a reducing agent. The reaction was conducted in the presence of previously synthesized cationic Gemini surfactants as capping agents. It was found that surfactants with longer hydrophobic tails induced the formation of AgNPs displaying a smaller particle size, more uniform structure, and higher stability in solution compared to those prepared using surfactants with shorter hydrophobic tails. The results were confirmed by ultraviolet-visible (UV–Vis) spectroscopy, transmission electron microscopy (TEM), and dynamic light scattering (DLS). The surface behavior of the amphiphilic surfactants and their hybrid systems with AgNPs was investigated at 25, 45, and 65 °C by performing surface tension measurements. It was determined that increasing the hydrophobic tail length and temperature resulted in increased micellization. Moreover, grafting the synthesized cationic Gemini surfactants with AgNPs enhanced the surface parameters. The synthesized surfactant–AgNPs hybrid systems showed good catalytic activity in converting carcinogenic p-nitrophenol (p-NP) into less toxic p-aminophenol (p-AP) in the presence of NaBH4 as the reducing agent. The effect of the chain length variation on the catalytic performance of AgNPs was studied for the first time. Overall, combination of the synthesized cationic Gemini surfactants with AgNPs led to a significant enhancement in the biological performance.

Sensory neurons expressing calcitonin gene-related peptide α regulate adaptive thermogenesis and diet-induced obesity

ObjectivesHeat-sensory neurons from the dorsal root ganglia (DRG) play a pivotal role in detecting the cutaneous temperature and transmission of external signals to the brain, ensuring the maintenance of thermoregulation. However, whether these thermoreceptor neurons contribute to adaptive thermogenesis remains elusive. It is also unknown whether these neurons play a role in obesity and energy metabolism. MethodsWe used genetic ablation of heat-sensing neurons expressing calcitonin gene-related peptide α (CGRPα) to assess whole-body energy expenditure, weight gain, glucose tolerance, and insulin sensitivity in normal chow and high-fat diet-fed mice. Exvivo lipolysis and transcriptional characterization were combined with adipose tissue-clearing methods to visualize and probe the role of sensory nerves in adipose tissue. Adaptive thermogenesis was explored using infrared imaging of intrascapular brown adipose tissue (iBAT), tail, and core temperature upon various stimuli including diet, external temperature, and the cooling agent icilin. ResultsIn this report, we show that genetic ablation of heat-sensing CGRPα neurons promotes resistance to weight gain upon high-fat diet (HFD) feeding and increases energy expenditure in mice. Mechanistically, we found that loss of CGRPα-expressing sensory neurons was associated with reduced lipid deposition in adipose tissue, enhanced expression of fatty acid oxidation genes, higher exvivo lipolysis in primary white adipocytes, and increased mitochondrial respiration from iBAT. Remarkably, mice lacking CGRPα sensory neurons manifested increased tail cutaneous vasoconstriction at room temperature. This exacerbated cold perception was not associated with reduced core temperature, suggesting that heat production and heat conservation mechanisms were engaged. Specific denervation of CGRPα neurons in intrascapular BAT did not contribute to the increased metabolic rate observed upon global sensory denervation. ConclusionsTaken together, these findings highlight an important role of cutaneous thermoreceptors in regulating energy metabolism by triggering counter-regulatory responses involving energy dissipation processes including lipid fuel utilization and cutaneous vasodilation.

Comparison of Tympanic and Tail Temperatures in Angus and Brahman Steers

In cattle, core body temperature can be used as an important indicator of heat stress level. However, accurately recording core body temperature can be difficult and labor intensive. The objectives of the current study were 1) to compare the recorded tympanic and tail body temperature measurements in steers and 2) to determine the body temperature change of Angus and Brahman steers in a hot and humid environment. Data was analyzed using a repeated measure model where repeated measures were hourly tympanic and tail temperatures and their difference for individual steers during the day of the experiment. There was a significant breed effect (P=0.01), hour (P<0.0001) and breed by hour interaction (P<0.0001) for the tympanic temperature. Brahman steers, which are known to have superior thermotolerance, maintained a lower body temperature than the Angus steers during the afternoon under grazing conditions. In the Brahman steers there was only a minimal increase in the body temperature throughout the day, an evidence of the thermotolerance ability of the breed. In the Angus steers, which experienced an increase in their body temperature from hour to hour with a peak around 1600 hour; there was a significant difference between the tympanic and tail temperature during the times when the body temperature as measured by the tympanic recordings was the highest (1300 to 1700 hour). Our results indicate that the tympanic temperature can be used to accurately and continuously monitor core body temperature in a natural environment for up to several days and without disturbing the animal.

A global test of Allen’s rule in rodents

AbstractAimWe test whether geographical variation in the length of appendages in rodent species follows predictions of Allen's rule (a positive relationship between appendage length and temperature) at a broad taxonomic scale (order Rodentia). We also test whether the applicability of this rule varies based on the unit of analysis (species or assemblage), the appendage examined (tail, hind foot, ear), body size, occupied habitat, geographical range size, life mode and saltatorial ability.LocationWorld‐wide.Time periodCurrent.Major taxa studiedRodents (order Rodentia).MethodsWe assembled data on the morphology, ecology and phylogeny for ≤ 2,212 rodent species, representing c. 86% of all the described rodent species and c. 95% of the described genera. We tested the predicted Allen's rule associations among size‐corrected appendage lengths and both latitudinal and climatic variables (temperature and precipitation). We applied a cross‐species approach based on phylogenetic regressions and a cross‐assemblage approach based on spatial regressions in equal‐area 1.5° grid cells.ResultsSupport for Allen's rule was greatest for the tail and was stronger across assemblages than across species. We detected a negative relationship between tail length and (absolute) latitude, which was accounted for by a positive association between tail length and temperature of the coldest month. This association was greatest in desert species. In addition, we observed a negative relationship between ear length and precipitation.Main conclusionsIn rodents, Allen's rule is confirmed only for tails, and this association seems to be driven by adaptation to the cold, rather than warm temperatures. Habitat type seems to influence conformity to this rule. Conformity to Allen's rule is likely to be the result of complex evolutionary trade‐offs between temperature regulation and other essential species traits.

Involvement of brainstem noradrenergic system in cutaneous heat loss during exercise

The involvement of brainstem noradrenergic system in thermoregulation during exercise was evaluated by assessing the neuronal activation of A1, A2, locus coeruleus (LC) during exercise. Male Wistar rats weighing 280−330 g were used in the present study. Ninety minutes after exercise bout until fatigue, animals were anaesthesiated and brain removed and processed immunohistochemically for Fos protein and tyrosine hydroxylase in A1, A2 and LC and for Fos in POA subregions. Core and tail temperature were recorded during all running period by telemetry system. Heat storage rate (HSR, cal.min−1), maximum tail vasoconstriction (°C) and vasodilatation threshold (°C) were calculated and correlated with Fos expression in all nuclei studied. Fos expression in LC correlated inversely with maximum tail skin vasoconstriction (r = −0.787, p < 0.03) and HSR (r = −0.834, p < 0.02) and positively to time to fatigue (r = 0.862, p < 0.01). A1 nucleus showed an inverse correlation with tail skin vasodilatation threshold (r = −0.861, p < 0.01). Fos expression in LC correlated inversely with Fos expression in the median (MnPO, r = −0.909, p < 0.01) and medial preoptic nucleus (MPOM, r = −0.942, p < 0.05). Our results bring further evidences that noradrenergic neurons from LC and A1 nuclei are involved in cutaneous heat loss mechanisms during exercise. LC nucleus probably modulates the sympathetic tonus of tail artery and integrates the central network LC / POA that could represent an important circuitry of temperature regulation during exercise. Also, noradrenergic neurons from A1 nucleus could be involved in cutaneous heat loss during exercise by modulating of vasodilatation threshold.

The contribution of the mouse tail to thermoregulation is modest.

Understanding mouse thermal physiology informs the usefulness of mice as models of human disease. It is widely assumed that the mouse tail contributes greatly to heat loss (as it does in rat), but this has not been quantitated. We studied C57BL/6J mice after tail amputation. Tailless mice housed at 22°C did not differ from littermate controls in body weight, lean or fat content, or energy expenditure. With acute changes in ambient temperature from 19 to 39°C, tailless and control mice demonstrated similar body temperatures (Tb), metabolic rates, and heat conductances and no difference in thermoneutral point. Treatment with prazosin, an α1-adrenergic antagonist and vasodilator, increased tail temperature in control mice by up to 4.8 ± 0.8°C. Comparing prazosin treatment in tailless and control mice suggested that the tail's contribution to total heat loss was a nonsignificant 3.4%. Major heat stress produced by treatment at 30°C with CL316243, a β3-adrenergic agonist, increased metabolic rate and Tb and, at a matched increase in metabolic rate, the tailless mice showed a 0.72 ± 0.14°C greater Tb increase and 7.6% lower whole body heat conductance. Thus, the mouse tail is a useful biomarker of vasodilation and thermoregulation, but in our experiments contributes only 5-8% of whole body heat dissipation, less than the 17% reported for rat. Heat dissipation through the tail is important under extreme scenarios such as pharmacological activation of brown adipose tissue; however, non-tail contributions to heat loss may have been underestimated in the mouse.

Contribution of the mouse tail to heat dissipation

Mice are widely used to study obesity and diabetes. Since there are big differences in thermal physiology between mice and humans, understanding these differences is important for using mice predictively to model human disease. Heat dissipation is limited in mice, as they do not routinely use evaporative heat loss. The mouse tail contributes to non‐evaporative heat loss, as it has no hair, a large surface to volume ratio, and dense vascularization. The rat tail has been reported to dissipate ~20 % of body heat, but we are unaware of a similar analysis for mice. Scaling and other considerations suggest that the mouse tail is relatively less effective for heat dissipation. Here, we used tailless mice to quantitate the capacity of the mouse tail to dissipate heat.C57BL/6J mice had their tails amputated shortly after birth and were compared to littermate controls. Total energy expenditure (TEE) was determined by indirect calorimetry or estimated from energy balance. Core body temperature (Tb) was measured using intraperitoneal radiotelemetry probes, surface temperature was measured by infrared thermography, and body composition was measured by magnetic resonance spectroscopy (EchoMRI).Tailless mice did not differ from controls in body weight, lean or fat content, or TEE (22 °C). Tb of tailless and control mice was not different at ambient temperatures (Ta) of 22 °C, 31 °C, or 34°C. We reasoned that a Scholander‐type of analysis (of TEE vs Ta, over a wide Ta range) might detect subtle differences in thermal physiology. However, no differences were observed in Tb or TEE between tailless and control mice. To maximize the need for heat dissipation, brown adipose tissue thermogenesis was activated by treatment at 30 °C with CL316243, a β3‐adrenergic receptor agonist. This treatment increased TEE from 0.263 ± 0.011 kcal/h to 0.490 ± 0.033 kcal/h and Tb from 36.0± 0.2 °C 37.5 ± 0.3 °C in controls. Both parameters increased more in tailless mice; TEE from 0.264 ±0.016 kcal/h to 0.557 ± 0.032 kcal/h and Tb from 36.1 ± 0.2 °C to 38.3 ± 0.2 °C, indicating that the tail does contribute to heat dissipation under heat stress conditions. The tail is normally vasoconstricted at 22 °C. To enhance tail heat dissipation, peripheral vasodilation was achieved using prazosin, an α1‐adrenergic receptor antagonist, which increased tail temperature from 23.7 ± 0.9 °C to 29.1 ± 1.9 °C and increased heat loss by 10 % in control mice. In tailless mice, the increase in total heat loss after prazosin treatment was reduced to 5 %. Thus, in this experiment, the tail contributed 5 % of total heat dissipation (0.02 kcal/h), equal to 9 % of the BMR.These results demonstrate that the mouse tail contribution to heat dissipation is detectable under conditions of heat stress, however the contribution is modest. Experimentally, the tail is an accessible indicator of the heat status of the mouse. Understanding the tail’s role in mouse thermal biology enriches and informs the use of the mouse as a model organism for studying energy homeostasis, diabetes, and obesity.Support or Funding InformationZIA DK075063

Effect of heat-sensitive moxibustion at "Zhongwan" (CV 12) on serum GH and PG in chronic atrophic gastritis rats

To observe the effect of heat-sensitive moxibustion at "Zhongwan" (CV 12) on serum growth hormone (GH) and pepsinogen (PG) in chronic atrophic gastritis (CAG) rats, and to explore the potential mechanism of heat-sensitive moxibustion for CAG. A total of 66 male SD rats were randomized into a blank group (12 rats) and a model establishment group (54 rats). No intervention was given in the blank group. Rats in the model establishment group were intervented with compound pathogeny method for 12 weeks to establish CAG model, which were further divided into a model group (11 rats), a vitacoenzyme group (11 rats) and a moxibustion group (22 rats). In the moxibustion group, suspending moxibustion was applied at "Zhongwan" (CV 12) for 40 min. After the intervention of moxibustion, 0.9% sodium chloride solution was given by gavage (2 mL·kg-1·d-1). According to the changes of tail temperature, rats in the moxibustion group were divided into a heat-sensitive moxibustion group (11 rats) and a non-heat-sensitive moxibustion group (8 rats). The vitacoenzyme group was given vitacoenzyme as the same dose by gavage. The intervention was adopted once a day for 28 days. Changes of body weight were observed among the groups. Expressions of serum GH, PGⅠand PGⅡwere detected by ELISA, and the ratio of PGⅠand PGⅡ (PGR) was calculated. The morphological changes of gastric mucosa were observed by macroscopy and light microscope. ①After modeling, the body weight of rats in the model establishment group was lower than the blank group (P<0.01). Compared with the model group, the body weight of rats in the vitacoenzyme group, the heat-sensitive moxibustion group and the non-heat-sensitive moxibustion group was increased after intervention (P<0.05), and there were no significant differences among the intervention groups (P>0.05). ②Under macroscopy and light microscope, gastric tissue of rats after modeling showed dark red and pale gastric mucosa, lower plica and mucosal congestion. The glands of lamina propria were atrophied or disappeared with sparse and disordered arrangement, in which, lymphoid follicles and inflammatory cells could be observed. After intervention, morphology of gastric mucosa was improved in the vitacoenzyme group, the heat-sensitive moxibustion group and the non-heat-sensitive moxibustion group. ③Compared with the blank group, the serum levels of GH, PGⅠ, PGⅡ and PGR were decreased in the model group (P<0.05, P<0.01). Compared with the model group, the serum levels of GH, PGⅠand PGⅡwere increased in the vitacoenzyme group, the heat-sensitive moxibustion group and the non-heat-sensitive moxibustion group (P<0.05, P<0.01), the levels of PGR were increased without statistical difference (P>0.05). Compared with the vitacoenzyme group and the non-heat-sensitive moxibustion group, the serum levels of GH and PGⅠwere increased in the heat-sensitive moxibustion group (P<0.05). Heat-sensitive moxibustion at "Zhongwan" (CV 12) can improve the morphology of gastric mucosa in chronic atrophic gastritis rats, its mechanism may be related to the up-regulation of serum GH and PGⅠ.

The Dorsomedial Hypothalamus Is Involved in the Mediation of Autonomic and Neuroendocrine Responses to Restraint Stress.

We hypothesized that dorsomedial hypothalamus (DMH) modulates autonomic and neuroendocrine responses in rats at rest and when subjected to restraint stress (RS). Male Wistar rats were used, and guide cannulas were bilaterally implanted in the DMH for microinjection of vehicle or the nonspecific synaptic blocker CoCl2 (1 mM/100 nl). A polyethylene catheter was inserted into the femoral artery for the recording of arterial pressure and heart rate (HR). Tail temperature was measured using a thermal camera. The session of RS started 10 min after DMH treatment with vehicle or CoCl2. Under home-cage condition, the pretreatment of DMH with CoCl2 increased baseline blood pressure (BP), and heart rate (HR) without affecting the tail temperature. In addition, it decreased plasma vasopressin levels without affecting plasma corticosterone and oxytocin contents. When rats pretreated with CoCl2 were exposed to RS, the RS-evoked cardiovascular were similar to those observed in vehicle-treated animals; however, because cobalt pretreatment of the DMH increased baseline BP and HR values, and the RS-evoked cardiovascular responses did not exceed those observed in vehicle-treated animals, suggesting a possible celling limit, the possibility that DMH is involved in the modulation of RS-evoked cardiovascular responses cannot be certainly excluded. Nonetheless, the pretreatment of DMH with CoCl2 blocked the reduction in tail temperature caused by RS. The DMH pretreatment with CoCl2 did not modify the RS-evoked increase in plasma corticosterone and oxytocin contents. In conclusion, the present data suggest the involvement of DMH in the maintenance of BP, HR, and vasopressin release under the rest conditions at the home-cage. Furthermore, indicate that DMH is an important thermoregulatory center during exposure to RS, regulating tail artery vasoconstriction.

Differences between fast and slow explorers in short-term tail temperature responses to handling in a rodent of wild origin

Animals of different behavioral types typically show associated differences in their physiological stress response, including differential reactivity of the sympathetic nervous system. Infrared thermography offers the possibility to explore this link in a non-invasive way via the quantification of fine-scale changes in peripheral body temperature due to changes in cutaneous blood flow. We used this technique to investigate the association between exploration tendency, a behavioral trait frequently used to phenotype mammals and birds, and short-term thermal responses to challenge in a small rodent of wild origin, the mound-building mouse (Mus spicilegus). We applied a brief handling procedure consisting in the transfer of subjects into a small arena. This procedure led to a significant increase in subjects’ maximum peripheral body temperature (mainly reflecting the temperature of the eyes) and to significant decreases in maximum temperatures at different positions on the tail. Maximum peripheral body and tail temperatures showed significant individual-level consistencies in response to repeated applications of the handling procedure, suggesting stable individual differences in the animals’ sympathetic activity. We then compared the thermal responses to handling between ‘fast’ and ‘slow’ explorers, who were phenotyped through repeated open field and novel object tests. Fast explorers showed significantly lower tail temperatures than slow explorers shortly after handling, suggesting a stronger sympathetic reactivity in the former. Comparisons within sibling groups kept in different cages showed that the differences between explorer types were particularly pronounced during the first minute after handling, and increased in magnitude along the first millimeters distal to the tail base.

Demonstration by Infra-Red Imaging of a Temperature Control Defect in a Decompression Sickness Model Testing Minocycline.

The prevention, prognosis and resolution of decompression sickness (DCS) are not satisfactory. The etiology of DCS has highlighted thrombotic and inflammatory phenomena that could cause severe neurological disorders or even death. Given the immunomodulatory effects described for minocycline, an antibiotic in widespread use, we have decided to explore its effects in an experimental model for decompression sickness. 40 control mice (Ctrl) and 40 mice treated orally with 90 mg/kg of minocycline (MINO) were subjected to a protocol in a hyperbaric chamber, compressed with air. The purpose was to mimic a scuba dive to a depth of 90 msw and its pathogenic decompression phase. Clinical examinations and blood counts were conducted after the return to the surface. For the first time they were completed by a simple infrared (IR) imaging technique in order to assess feasibility and its clinical advantage in differentiating the sick mice (DCS) from the healthy mice (NoDCS). In this tudy, exposure to the hyperbaric protocol provoked a reduction in the number of circulating leukocytes. DCS in mice, manifesting itself by paralysis or convulsion for example, is also associated with a fall in platelets count. Cold areas ( < 25°C) were detected by IR in the hind paws and tail with significant differences (p < 0.05) between DCS and NoDCS. Severe hypothermia was also shown in the DCS mice. The ROC analysis of the thermograms has made it possible to determine that an average tail temperature below 27.5°C allows us to consider the animals to be suffering from DCS (OR = 8; AUC = 0.754, p = 0.0018). Minocycline modulates blood analysis and it seems to limit the mobilization of monocytes and granulocytes after the provocative dive. While a higher proportion of mice treated with minocycline experienced DCS symptoms, there is no significant difference. The infrared imaging has made it possible to show severe hypothermia. It suggests an modification of thermregulation in DCS animals. Surveillance by infrared camera is fast and it can aid the prognosis in the case of decompression sickness in mice.

Rats that are predisposed to excessive obesity show reduced (leptin-induced) thermoregulation even in the preobese state.

Both feeding behavior and thermogenesis are regulated by leptin. The sensitivity to leptin's anorexigenic effects on chow diet was previously shown to predict the development of diet‐induced obesity. In this study, we determined whether the sensitivity to leptin's anorexigenic effects correlates with leptin's thermogenic response, and if this response is exerted at the level of the dorsomedial hypothalamus (DMH), a brain area that plays an important role in thermoregulation. Based on the feeding response to injected leptin on a chow diet, rats were divided into leptin‐sensitive (LS) and leptin‐resistant (LR) groups. The effects of leptin on core body, brown adipose tissue (BAT) and tail temperature were compared after intravenous versus intra‐DMH leptin administration. After intravenous leptin injection, LS rats increased their BAT thermogenesis and reduced heat loss via the tail, resulting in a modest increase in core body temperature. The induction of these thermoregulatory mechanisms with intra‐DMH leptin was smaller, but in the same direction as with intravenous leptin administration. In contrast, LR rats did not show any thermogenic response to either intravenous or intra‐DMH leptin. These differences in the thermogenic response to leptin were associated with a 1°C lower BAT temperature and reduced UCP1 expression in LR rats under ad libitum feeding. The preexisting sensitivity to the anorexigenic effects of leptin, a predictor for obesity, correlates with the sensitivity to the thermoregulatory effects of leptin, which appears to be exerted, at least in part, at the level of the DMH.

The Supraoptic Nucleus of the Hypothalamus Modulates Autonomic, Neuroendocrine, and Behavioral Responses to Acute Restraint Stress in Rats

Aims: Acute restraint stress (RS) has been reported to cause neuronal activation in the supraoptic nucleus of the hypothalamus (SON). The aim of the study was to evaluate the role of SON on autonomic (mean arterial pressure [MAP], heart rate [HR], and tail temperature), neuroendocrine (corticosterone, oxytocin, and vasopressin plasma levels), and behavioral responses to RS. Methods: Guide cannulas were implanted bilaterally in the SON of male Wistar rats for microinjection of the unspecific synaptic blocker cobalt chloride (CoCl₂, 1 mM) or vehicle (artificial cerebrospinal fluid, 100 nL). A catheter was introduced into the femoral artery for MAP and HR recording. Rats were subjected to RS, and it was studied the effect of microinjection of CoCl₂ or vehicle into the SON on pressor and tachycardic responses, drop in tail temperature, plasma oxytocin, vasopressin, and corticosterone levels, and anxiogenic-like effect induced by RS. Results: SON pretreatment with CoCl₂ reduced the RS-induced MAP and HR increase, without affecting the RS-evoked tail temperature decrease. Microinjection of CoCl₂ into areas surrounding the SON did not affect RS-induced increase in MAP and HR, reinforcing the idea that SON influences RS-evoked cardiovascular responses. Also, SON pretreatment with CoCl₂ reduced RS-induced increase in corticosterone and oxytocin, without affecting vasopressin plasma levels, suggesting its involvement in RS-induced neuroendocrine responses. Finally, the CoCl₂ microinjection into SON inhibited the RS-caused delayed anxiogenic-like effect. Conclusion: The results indicate that SON is an important component of the neural pathway that controls autonomic, neuroendocrine, and behavioral responses induced by RS.

Cinnamaldehyde application decreases tail temperature in ovariectomized rats with and without estradiol administration.

The aim of this study was to examine the effect of estradiol (E2) on the thermoregulatory responses induced by cinnamaldehyde, a component extracted from cinnamon at 16 °C or 27 °C. The thermoneutral and subneutral experiments were performed to evaluate the augmented effect of cinnamaldehyde by cold exposure and the effect of cinnamaldehyde itself. Ovariectomized rats were implanted with a silastic tube with or without E2 (E2(+) and E2(-) groups), and data loggers into the peritoneal cavity. After the application of 30% cinnamaldehyde or vehicle into the skin of the whole trunk of rats, the rats were exposed to 16 °C or 27 °C for 2 h. Body temperature (Tb) and tail temperature (Ttail) were measured using a data logger and thermography. After exposure, blood samples were obtained, and plasma catecholamine concentration were measured by high-performance liquid chromatography. In the E2(-) group exposed to 27 °C, the change in Tb in rats applied cinnamaldehyde was significantly lower than that of rats applied vehicle. The change in Ttail in rats applied cinnamaldehyde was significantly lower than that of rats applied vehicle in both E2(-) and E2(+) groups at 27°C and 16°C. Plasma catecholamine concentration at 27°C was not different among the groups. E2 might not affect thermoregulatory responses induced by cinnamaldehyde application; however, it decreased Ttail in female rats.

Bi-Maxwellian, slowing-down, and ring velocity distributions of fast ions in magnetized plasmas

We discuss analytical fast-ion velocity distribution functions which are useful for basic plasma modelling as illustrated for the tokamak ITER. The Maxwellian is by far the most widespread model for ions and electrons in tokamaks and stellarators. The bi-Maxwellian and the drifting (bi-)Maxwellian are extensions allowing for anisotropy and bulk plasma flow, respectively. For example, fast ions generated by wave heating in the ion cyclotron range of frequencies are often described by bi-Maxwellians or so-called tail temperatures. The ring distribution can serve as a basic building block for arbitrary distributions or as a bump-on-tail in stability studies. The isotropic slowing-down distribution is a good model for fusion α-particles. The anisotropic slowing-down distribution occurs for anisotropic particle sources as is typical for neutral beam injection. We physically motivate these distribution functions and present analytical models in various coordinate systems commonly used by theorists and experimentalists. We further calculate 1D projections of the distribution functions onto a diagnostic line-of-sight to gain insight into measurements relying on the Doppler shift.