Effects of acceleration on thermoregulatory responses of unanesthetized rats

1977 ◽  
Vol 42 (1) ◽  
pp. 74-79 ◽  
Author(s):  
C. A. Fuller ◽  
J. M. Horowitz ◽  
B. A. Horwitz
Keyword(s):  
Rapid Decrease ◽  
Mechanical Forces ◽  
Slow Recovery ◽  
Environmental Conditioning ◽  
Thermoregulatory Responses ◽  
Initial Drop ◽  
Thermoregulatory System ◽  
Colonic Temperature ◽  
Induced Changes ◽  
The Brain

Upon exposure of rats to 2 G environments (achieved by centrifugation), there occurred a rapid decrease in colonic temperature (Tco) followed, after about 50 min, by a slow recovery toward precentrifugation levels. The initial drop in Tco was accompanied by decreases in hypothalamic and spinal cord temperatures and increases in tail temperature (Tta). In contrast to this anomalous response (i.e., increased heat loss (manifested by increased Tta) despite decreasing temperature at spinal and hypothalamic thermoreceptor areas) the return toward normal Tco appeared to involve appropriate thermoregulatory responses. The initial fall in Tco was decreased in magnitude by inverting the rat during acceleration, thereby suggesting that mechanical forces acting on the brain may underlie this temperature decrease. Exposure to cold during centrifugation allowed further examination of the thermoregulatory system. Unlike the initial acceleration-induced changes, the cold-evoked fall in Tco was not accompanied by increasing Tta and was modified by the environmental conditioning of the rats. These results are consistent with the view that exposure to 2 G adversely affects the thermoregulatory ability of rats challenged by cold.

Changes in the Cortex Neurons in Single and Fractional Gamma Radiation

2021 ◽  
Vol 66 (4) ◽  
pp. 18-24
Author(s):  
I. Ushakov ◽  
Vladimir Fyodorov
Keyword(s):  
Nervous System ◽  
Cerebral Cortex ◽  
Radiation Exposure ◽  
Comparative Assessment ◽  
Male Rats ◽  
Fractionated Irradiation ◽  
Radiation Induced ◽  
Post Radiation ◽  
Induced Changes ◽  
The Brain

Purpose: Comparative assessment of radiation-induced changes in neurons of the cerebral cortex after a single and fractionated exposure to ionizing radiation in doses of 0.1 – 1.0 Gy. Material and methods. The study was carried out in compliance with the rules of bioethics on 180 white outbred male rats at the age of 4 months. by the beginning of the experiment, exposed to a single or fractionated exposure to γ-quanta of 60Co in total doses of 0.1; 0.2; 0.5 and 1.0 Gy. Neuromorphological and histochemical methods were used to assess morphometric and tinctorial parameters of nerve cells, as well as changes in the content of protein and nucleic acids in neurons in the early and late periods of the post-radiation period. Using one-way analysis of variance, a comparative assessment of neuromorphological indicators under various modes of radiation exposure is given. Results: In the control and irradiated animals throughout their life, undulating changes in the indicators of the state of the neurons of the brain occur with a gradual decrease by the end of the experiment. Despite a number of features of the dynamics of neuromorphological parameters, these irradiation regimes do not cause functionally significant changes in the neurons of the cortex. However, in some periods of the post-radiation period, the changes under the studied irradiation regimes were multidirectional and did not always correspond to age control. Significant differences in the response of neurons to these modes of radiation exposure in the sensory and motor areas of the cerebral cortex have not been established. Conclusion: No functionally significant radiation-induced changes in neurons were found either with single or fractionated irradiation. At the same time, different modes of irradiation in general caused the same type of changes in neurons. However, in some periods of observation, changes in neuromorphological parameters under the studied irradiation regimes were not unidirectional and differed from age control, which indicates a possible risk of disturbances in the functioning of the nervous system against the background of other harmful and dangerous factors.

Signaling the brain in systemic inflammation: which vagal branch is involved in fever genesis?

1998 ◽  
Vol 275 (1) ◽  
pp. R63-R68 ◽  
Author(s):  
Christopher T. Simons ◽  
Vladimir A. Kulchitsky ◽  
Naotoshi Sugimoto ◽  
Louis D. Homer ◽  
Miklos Székely ◽  
...  
Keyword(s):  
Vagal Afferents ◽  
Male Wistar Rats ◽  
Food Retention ◽  
Maximal Rise ◽  
Fever Response ◽  
Colonic Temperature ◽  
Postsurgical Recovery ◽  
The Brain ◽  
Bladder Urine

Recent evidence has suggested a role of abdominal vagal afferents in the pathogenesis of the febrile response. The abdominal vagus consists of five main branches (viz., the anterior and posterior celiac branches, anterior and posterior gastric branches, and hepatic branch). The branch responsible for transducing a pyrogenic signal from the periphery to the brain has not as yet been identified. In the present study, we address this issue by testing the febrile responsiveness of male Wistar rats subjected to one of four selective vagotomies: celiac (CBV), gastric (GBV), hepatic (HBV), or sham (SV). In the case of CBV, GBV, and HBV, only the particular vagal branch(es) was cut; for SV, all branches were left intact. After the postsurgical recovery (26–29 days), the rats had a catheter implanted into the jugular vein. On days 29–32, their colonic temperature (Tc) responses to a low dose (1 μg/kg) of Escherichia colilipopolysaccharide (LPS) were studied. Three days later, the animals were subjected to a 24-h food and water deprivation, and the effectiveness of the four vagotomies to induce gastric food retention, pancreatic hypertrophy, and impairment of the portorenal osmotic reflex was assessed by weighing the stomach and pancreas and measuring the specific gravity of bladder urine, respectively. Stomach mass, pancreas mass, and urine density successfully separated the four experimental groups into four distinct clusters, thus confirming that each type of vagotomy had a different effect on the indexes measured. The Tc responses of SV, CBV, and GBV rats to LPS did not differ and were characterized by a latency of ∼40 min and a maximal rise of 0.7 ± 0.1, 0.6 ± 0.1, and 0.9 ± 0.2°C, respectively. The fever response of the HBV rats was different; practically no Tc rise occurred (0.1 ± 0.2°C). The HBV appeared to be the only selective abdominal vagotomy affecting the febrile responsiveness. We conclude, therefore, that the hepatic vagus plays an important role in the transduction of a pyrogenic signal from the periphery to the brain.

Suppression of norepinephrine-induced thermogenesis in brown adipose tissue by fasting

1983 ◽  
Vol 245 (6) ◽  
pp. E582-E586 ◽  
Author(s):  
M. Hayashi ◽  
T. Nagasaka
Keyword(s):  
Adipose Tissue ◽  
Oxygen Consumption ◽  
Thyroid Hormones ◽  
Brown Adipose Tissue ◽  
Plasma Levels ◽  
Interscapular Brown Adipose Tissue ◽  
Brown Adipose ◽  
Colonic Temperature ◽  
Induced Changes ◽  
Thermogenic Response

Fasting-induced changes in thermogenic responses to norepinephrine (NE, 4.0 micrograms X kg-1 X min-1 iv) were studied in anesthetized rats previously cold acclimated. The rats were divided into five groups at the end of 30–40 days of cold acclimation (5 degrees C). The five groups were kept for 5 days at 25 degrees C and fed (intact fed), fasted (intact fasted), fasted with daily treatment with thyroxine (T4, 2 micrograms/kg sc), thyroidectomized and fed, or thyroidectomized and fasted. In the intact fasted group, in which the weight of brown adipose tissue decreased, NE-induced increases in oxygen consumption, colonic temperature (T col), and temperature of the interscapular brown adipose tissue (TBAT) were markedly suppressed. The two thyroidectomized groups also showed a reduction in thermogenic response. In these three groups, TBAT was lower than Tcol throughout NE infusion. In the T4-treated fasted group, fasting-induced suppression of thermogenic response to NE was largely prevented. In the intact fed and the T4-treated fasted groups, TBAT attained higher values than Tcol during NE infusion. Plasma levels of thyroid hormones were significantly lower in the intact fasted group than in the intact fed or the T4-treated fasted group. These results suggest that fasting-induced suppression of the thermogenic response to NE is largely due to the reduced thermogenic response of brown adipose tissue to NE. The lowering of the levels of the thyroid hormones induced by fasting may be one of a number of causes of the reduction in the thermogenic response of brown adipose tissue.

Do Benzodiazepines Interfere with the Action of Electroconvulsive Therapy?

1992 ◽  
Vol 160 (4) ◽  
pp. 545-546 ◽  
Author(s):  
Samuel I. Cohen ◽  
Claire Lawton
Keyword(s):  
British Journal ◽  
Electroconvulsive Therapy ◽  
Chronic Administration ◽  
Depressed Woman ◽  
Induced Changes ◽  
The Brain

A 67-year-old anxious and depressed woman was withdrawn from a long-term course of a benzodiazepine and soon after was given ECT. This proved ineffective, but ECT given some months later was successful. It is suggested that the chronic administration of the benzodiazepine may have induced changes in the brain that interfered with ECT.British Journal of Psychiatry (1992), 160, 545–546

Ambient temperature modulates hypoxic-induced changes in rat body temperature and activity differentially

2001 ◽  
Vol 280 (4) ◽  
pp. R1190-R1196 ◽  
Author(s):  
B. Bishop ◽  
G. Silva ◽  
J. Krasney ◽  
H. Nakano ◽  
A. Roberts ◽  
...  
Keyword(s):  
Body Temperature ◽  
Ambient Temperature ◽  
Induced Responses ◽  
Brain Pathology ◽  
Level Of Activity ◽  
Time Courses ◽  
Induced Changes ◽  
Subsequent Rise ◽  
The Brain

When rats, acclimated to an ambient temperature (Ta) of 29°C, are exposed to 10% O2 for 63 h, the circadian rhythms of body temperature (Tb) and level of activity (La) are abolished, Tb falls to a hypothermic nadir followed by a climb to a hyperthermic peak, Laremains depressed (Bishop B, Silva G, Krasney J, Salloum A, Roberts A, Nakano H, Shucard D, Rifkin D, and Farkas G. Am J Physiol Regulatory Integrative Comp Physiol 279: R1378–R1389, 2000), and overt brain pathology is detected (Krasney JA, Farkas G, Shucard DW, Salloum AC, Silva G, Roberts A, Rifkin D, Bishop B, and Rubio A. Soc Neurosci Abstr 25: 581, 1999). To determine the role of Ta in these hypoxic-induced responses, Tb and La data were detected by telemetry every 15 min for 48 h on air, followed by 63 h on 10% O2 from rats acclimated to 25 or 21°C. Magnitudes and rates of decline in Tb after onset of hypoxia were inversely proportional to Ta, whereas magnitudes and rates of Tb climb after the hypothermic nadir were directly proportional to Ta. No hyperthermia, so prominent at 29°C, occurred at 25 or 21°C. The hypoxic depression of La was least at 21°C and persisted throughout the hypoxia. In contrast, Ta was a strong determinant of the magnitudes and time courses of the initial fall and subsequent rise in Tb. We propose that the absence of hyperthermia at 21 and 25°C as well as a persisting hypothermia may protect the brain from overt pathology.

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