Characterization of midbrain component of the trigger for arousal from hibernation

1976 ◽  
Vol 230 (2) ◽  
pp. 368-375 ◽  
Author(s):  
AL Beckman ◽  
E Satinoff ◽  
TL Stanton
Keyword(s):  
Body Temperature ◽  
Ambient Temperature ◽  
Reticular Formation ◽  
Functional Organization ◽  
Ground Squirrels ◽  
Anterior Hypothalamus ◽  
Midbrain Reticular Formation ◽  
Citellus Lateralis ◽  
Arousal Mechanism

The ability of the midbrain reticular formation (MRF) to trigger arousal from hibernation and to change body temperature (Tb) during euthermia was tested in golden-mantled ground squirrels (Citellus lateralis). During hibernation (ambient temperature 5-6 degrees C) microinjections of cholinomimetic compounds (acetylcholine and carbachol) triggered full arousal or produced transient increases in Tb in 15 out of 19 tests; MRF microinjections of norepinephrine (NE) and 5-hydroxytryptamine (5-HT), at the same concentrations that produced full arousal when microinjected into the preoptic/anterior hypothalamus (PO/AH) area in previous experiments, has no effect on Tb in 13 out of 16 tests. In experiments on euthermic ground squirrels tested at an ambient temperature of 25 degrees C, MRF microinjections of acetylcholine raised Tb, whereas the monoamines had no significant effects. These results show that cholinoceptive neurons in the MRF can trigger arousal from hibernation and increase Tb during euthermia. The failure of NE and 5-HT to produce any significant effects at the same doses that were reported to be effective in the PO/AH indicates that the functional organization of the MRF portion of the arousal mechanism is different from that reported for the PO/AH.

Changes in CNS responsiveness during hibernation

1976 ◽  
Vol 231 (3) ◽  
pp. 810-816 ◽  
Author(s):  
AL Beckman ◽  
TL Stanton
Keyword(s):  
Reticular Formation ◽  
Ground Squirrels ◽  
Progressive Change ◽  
Midbrain Reticular Formation ◽  
Citellus Lateralis ◽  
Early Portion ◽  
Stimulation Of

The ability of the midbrain reticular formation (MRF) to produce thermogenic responses and to trigger arousal from hibernation was tested during successive quarters of individual hibernation bouts. Golden-mantled ground squirrels (Citellus lateralis) were implanted with bilateral cannula guides into the MRF. Single, bilateral, 1-mul injections of acetylcholine (ACh) at concentrations of 50, 100, or 200 mug/mul were delivered in each quarter of the same bout or in selected quarters of different bouts. The results show that the magnitude of thermogenic responses evoked by ACh stimulation of the MRF was depressed during the early portion of the bout and increased as time in the bout elapsed. Furthermore, the magnitude of responses evoked during hibernation was depressed in comparison to those evoked during euthermia, indicating the influence of inhibition on the responsiveness of the CNS during hibernation. We suggest that during hibernation, a progressive change in responsiveness of the CNS, perhpas focused in the MRF, controls the duration of each hibernation bout.

THE EFFECT OF TEMPERATURE AND PHOTOPERIOD ON THE YEARLY HIBERNATING BEHAVIOR OF CAPTIVE GOLDEN-MANTLED GROUND SQUIRRELS (CITELLUS LATERALIS TESCORUM)

1963 ◽  
Vol 41 (6) ◽  
pp. 1103-1120 ◽  
Author(s):  
Eric T. Pengelley ◽  
Kenneth C. Fisher
Keyword(s):  
High Temperature ◽  
Body Temperature ◽  
Ground Squirrels ◽  
The Body ◽  
Effect Of Temperature ◽  
Cyclic Variation ◽  
Ambient Temperatures ◽  
Lighting Conditions ◽  
Citellus Lateralis ◽  
Specific Stage

The state of torpidity (hibernation), the food consumption, and the weight of a number of C. lateralis were recorded daily, weekly, and weekly, respectively, for periods up to 2 years. At ambient temperatures of 32° F, 70° F, and 95–100° F and under constant lighting conditions, all animals displayed an approximately 1-year cyclic variation in weight which roughly paralleled the consumption of food. Under these constant conditions of light and temperature the animals subjected to 32° F and 70° F hibernated, i.e., their body temperature dropped nearly to the ambient and they became torpid. The body temperature of animals kept at 95–100° F could not drop and these animals did not become torpid.Hibernation could not be induced by removal of food but was greatly prolonged if food was not present in the cages at the time the whole hibernation period was ending. The onset of hibernation could be changed only slightly by changing the day lengths. Hibernation was possible only at a specific stage of the weight cycle. The length of the weight cycle was shortened by exposure to an ambient temperature of 95–100° F. By manipulation of the length of the exposure to the high temperature it was possible to have animals hibernating in summer and active in winter. It was not possible to produce a similar shift in the phase of the weight cycle, and hence of hibernation, by changing the lighting conditions.

Effects of ambient temperature on metabolic rate, respiratory quotient, and torpor in an arctic hibernator

2000 ◽  
Vol 279 (1) ◽  
pp. R255-R262 ◽  
Author(s):  
C. Loren Buck ◽  
Brian M. Barnes
Keyword(s):  
Body Temperature ◽  
Metabolic Rate ◽  
Ambient Temperature ◽  
Respiratory Quotient ◽  
Brain Temperature ◽  
Core Body Temperature ◽  
Ground Squirrels ◽  
Spermophilus Parryii ◽  
Anterior Body ◽  
Arctic Ground Squirrels

Arctic ground squirrels ( Spermophilus parryii) overwinter in hibernaculum conditions that are substantially below freezing. During torpor, captive arctic ground squirrels displayed ambient temperature (Ta)-dependent patterns of core body temperature (Tb), metabolic rate (TMR), and metabolic fuel use, as determined by respiratory quotient (RQ). At Ta 0 to −16°C, Tb remained relatively constant, and TMR rose proportionally with the expanding gradient between Tb and Ta, increasing >15-fold from a minimum of 0.0115 ± 0.0012 ml O2 · g−1 · h−1. At Ta 0–20°C, Tbincreased with Ta; however, TMR did not change significantly from Tb 0 to 12°C, indicating temperature-independent inhibition of metabolic rate. The overall change in TMR from Tb 4 to 20° equates to a Q10 of 2.4, but within this range of Tb, Q10 changed from 1.0 to 14.1. During steady-state torpor at Ta 4 and 8°C, RQ averaged 0.70 ± 0.013, indicating exclusive lipid catabolism. At Ta −16 and 20°C, RQ increased significantly to >0.85, consistent with recruitment of nonlipid fuels. RQ was negatively correlated with maximum torpor bout length. For Ta values <0°C, this relationship supports the hypothesis that availability of nonlipid metabolic fuels limits torpor duration in hibernating mammals; for Ta values >0°C, hypotheses linked to body temperature are supported. Because anterior body temperatures differ from core, overall, the duration torpor can be extended in hibernating mammals may be dependent on brain temperature.

Crystallographic Characterization of Dislocation Loops in Irradiated Tungsten

1968 ◽  
Vol 26 ◽  
pp. 290-291
Author(s):  
Robert C. Rau
Keyword(s):  
Electron Microscope ◽  
Ambient Temperature ◽  
Dislocation Loops ◽  
Polycrystalline Specimen ◽  
Post Irradiation ◽  
Neutron Fluences

Previous work has shown that post-irradiation annealing, at temperatures near 1100°C, produces resolvable dislocation loops in tungsten irradiated to fast (E > 1 MeV) neutron fluences of about 4 x 1019 n/cm2 or greater. To crystallographically characterize these loops, tilting experiments were carried out in the electron microscope on a polycrystalline specimen which had been irradiated to 1.5 × 1021 n/cm2 at reactor ambient temperature (∼ 70°C), and subseouently annealed for 315 hours at 1100°C. This treatment produced large loops averaging 1000 Å in diameter, as shown in the micrographs of Fig. 1. The orientation of this grain was near (001), and tilting was carried out about axes near [100], [10] and [110].

scholarly journals A novel mouse model of heatstroke accounting for ambient temperature and relative humidity

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Kazuyuki Miyamoto ◽  
Keisuke Suzuki ◽  
Hirokazu Ohtaki ◽  
Motoyasu Nakamura ◽  
Hiroki Yamaga ◽  
...  
Keyword(s):  
Gene Expression ◽  
Body Temperature ◽  
Relative Humidity ◽  
Ambient Temperature ◽  
Core Body Temperature ◽  
Heat Exposure ◽  
Organ Damage ◽  
Core Body ◽  
The Impact ◽  
Treatment Water

Abstract Background Heatstroke is associated with exposure to high ambient temperature (AT) and relative humidity (RH), and an increased risk of organ damage or death. Previously proposed animal models of heatstroke disregard the impact of RH. Therefore, we aimed to establish and validate an animal model of heatstroke considering RH. To validate our model, we also examined the effect of hydration and investigated gene expression of cotransporter proteins in the intestinal membranes after heat exposure. Methods Mildly dehydrated adult male C57/BL6J mice were subjected to three AT conditions (37 °C, 41 °C, or 43 °C) at RH > 99% and monitored with WetBulb globe temperature (WBGT) for 1 h. The survival rate, body weight, core body temperature, blood parameters, and histologically confirmed tissue damage were evaluated to establish a mouse heatstroke model. Then, the mice received no treatment, water, or oral rehydration solution (ORS) before and after heat exposure; subsequent organ damage was compared using our model. Thereafter, we investigated cotransporter protein gene expressions in the intestinal membranes of mice that received no treatment, water, or ORS. Results The survival rates of mice exposed to ATs of 37 °C, 41 °C, and 43 °C were 100%, 83.3%, and 0%, respectively. From this result, we excluded AT43. Mice in the AT 41 °C group appeared to be more dehydrated than those in the AT 37 °C group. WBGT in the AT 41 °C group was > 44 °C; core body temperature in this group reached 41.3 ± 0.08 °C during heat exposure and decreased to 34.0 ± 0.18 °C, returning to baseline after 8 h which showed a biphasic thermal dysregulation response. The AT 41 °C group presented with greater hepatic, renal, and musculoskeletal damage than did the other groups. The impact of ORS on recovery was greater than that of water or no treatment. The administration of ORS with heat exposure increased cotransporter gene expression in the intestines and reduced heatstroke-related damage. Conclusions We developed a novel mouse heatstroke model that considered AT and RH. We found that ORS administration improved inadequate circulation and reduced tissue injury by increasing cotransporter gene expression in the intestines.

TRIGEMINAL PROJECTIONS IN THE RETICULAR FORMATION OF THE PONS IN THE CAT

1962 ◽  
Vol 40 (1) ◽  
pp. 7-12
Author(s):  
J. M. Langlois ◽  
Guy Lamarche
Keyword(s):  
Reticular Formation ◽  
Trigeminal Nerve ◽  
Unit Activity ◽  
Functional Organization ◽  
Pontine Reticular Formation ◽  
Recording Unit ◽  
Spatial Convergence ◽  
The Face ◽  
High Degree ◽  
Stimulation Of

The projections of the trigeminal nerve in the pontine reticular formation of the cat have been investigated by recording unit activity, after physiological stimulation of the face, in 30 "encéphales isolés" preparations. No somatotopical arrangement was found but a high degree of spatial convergence onto pontine reticular units exists and a certain degree of functional organization was observed.

scholarly journals Characterization of moulds associated with processed garri stored for 40 days at ambient temperature in Makurdi, Nigeria

2014 ◽  
Vol 13 (5) ◽  
pp. 673-677 ◽  
Author(s):  
Aguoru ◽  
Onda ◽  
Victor Taghoghor Omoni ◽  
Innocent Okonkwo Ogbonna
Keyword(s):  
Ambient Temperature

Ambient temperature effects on physiological traits of white-tailed deer

1975 ◽  
Vol 53 (6) ◽  
pp. 679-685 ◽  
Author(s):  
J. B. Holter ◽  
W. E. Urban Jr. ◽  
H. H. Hayes ◽  
H. Silver ◽  
H. R. Skutt
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Energy Expenditure ◽  
Ambient Temperature ◽  
Temperature Effects ◽  
Temperature Changes ◽  
Wind Chill ◽  
Ambient Temperatures ◽  
Energy Equilibrium ◽  
Body Energy

Six adult white-tailed deer (Odocoileus virginianus borealis) were exposed to 165 periods of 12 consecutive hours of controlled constant ambient temperature in an indirect respiration calorimeter. Temperatures among periods varied from 38 to 0 (summer) or to −20C (fall, winter, spring). Traits measured were energy expenditure (metabolic rate), proportion of time spent standing, heart rate, and body temperature, the latter two using telemetry. The deer used body posture extensively as a means of maintaining body energy equilibrium. Energy expenditure was increased at low ambient temperature to combat cold and to maintain relatively constant body temperature. Changes in heart rate paralleled changes in energy expenditure. In a limited number of comparisons, slight wind chill was combatted through behavioral means with no effect on energy expenditure. The reaction of deer to varying ambient temperatures was not the same in all seasons of the year.

Body temperature regulation and oxygen consumption in young chicks fed thyroid hormone

1991 ◽  
Vol 69 (7) ◽  
pp. 1842-1847 ◽  
Author(s):  
Gregory K. Snyder ◽  
Joseph R. Coelho ◽  
Dalan R. Jensen
Keyword(s):  
Oxygen Consumption ◽  
Thyroid Hormone ◽  
Body Temperature ◽  
Ambient Temperature ◽  
Cold Exposure ◽  
Elevated Serum ◽  
Body Temperatures ◽  
Serum Thyroid Hormone ◽  
Regulate Body Temperature ◽  
Young Chicks

In chicks the ability to regulate body temperature to adult levels develops during the first 2 weeks of life. We examined whether the ability of young chicks to regulate body temperature is increased by elevated levels of the thyroid hormone 3,3′5-triiodothyronine. By 13 days following hatch, body temperatures of chicks were not significantly different from those expected for adult birds. Furthermore, at an ambient temperature of 10 °C, 13-day-old control chicks were able to maintain body temperature, and elevated serum thyroid hormone levels did not increase rates of oxygen consumption or body temperature above control values. Six-day-old chicks had body temperatures that were significantly lower than those of the 13-day-old chicks and were not able to regulate body temperature when exposed to an ambient temperature of 10 °C. On the other hand, 6-day-old chicks with elevated serum thyroid hormone had significantly higher rates of oxygen consumption than 6-day-old control chicks, and were able to maintain constant body temperatures during cold exposure. The increased oxygen consumption rates and improved ability to regulate body temperature during cold exposure were correlated with increased citrate synthase activity in skeletal muscle. Our results support the argument that thyroid hormones play an important role in the development of thermoregulatory ability in neonate birds by stimulating enzyme activities associated with aerobic metabolism.

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