EFFECT OF THE EXPOSURE TO COLD ON THE EXTRATHYROIDAL CONVERSION OF L-THYROXINE TO TRIIODO-L-THYRONINE, AND ON INTRAMITOCHONDRIAL α-GLYCEROPHOSPHATE DEHYDROGENASE ACTIVITY IN THYROIDECTOMIZED RATS ON L-THYROXINE

1975 ◽  
Vol 78 (3) ◽  
pp. 481-492 ◽  
Author(s):  
J. Bernal ◽  
F. Escobar del Rey
Keyword(s):  
Dehydrogenase Activity ◽  
Paper Chromatography ◽  
Cold Exposure ◽  
Isotopic Equilibrium ◽  
Glycerophosphate Dehydrogenase ◽  
Exposure To Cold ◽  
Constant Dose ◽  
And Control

ABSTRACT Thyroidectomized rats have been injected daily with 125I labelled L-thyroxine (T4*) and, once isotopic equilibrium was attained, divided into cold-exposed (4–10°C) and control (21–24°C) groups, the daily T4* administration being continued till the end of the experiment. Fourteen days after onset of cold exposure, the total I* of different organs and of the carcass was determined and the tissues submitted to extraction and paper chromatography for the separation of T4 and T4-derived I-containing compounds. The activity of intramitochondrial α-glycerophosphate dehydrogenase (α-GPD) was measured in kidneys and liver. It was found that the total amount of I* was intensely decreased in all samples from cold-exposed animals. The proportion of this I* which was non-extractable was the same, in all tissues, for cold-exposed and control rats. The % of extractable tissue radioactivity in the form of T4 was decreased, and that found as T4-derived T3 was increased, in all samples from cold-exposed animals. The T3/T4 ratio was increased more than two-fold in all tissues studied. The concentration of T4 decreased significantly in all tissues, whereas the concentration of T3 in tissues of cold-exposed rats did not decrease. It actually increased in kidneys and lungs, and remained the same in liver and carcass. Despite the decrease in the concentration of T4 in the kidneys, α-GPD activity was increased in this tissue, where the concentration of T3 was increased. No change in the α-GPD activity was found for the liver, where the concentration of T3 was the same for cold-exposed and control rats. Thus, it appears likely that the conversion of T4 to T3 is increased by the exposure to cold of thyroidectomized rats on a constant dose of T4. α-GPD activity in a given tissue appears to be more closely related to the concentration of T3, than to that of T4.

EFFECT OF CHRONIC CORTISONE TREATMENT AND COLD EXPOSURE ON THE ZINC CONTENT AND THE SUCCINIC DEHYDROGENASE ACTIVITY OF THE ADRENAL GLAND

1964 ◽  
Vol 42 (1) ◽  
pp. 127-132
Author(s):  
Jacques Dunnigan
Keyword(s):  
Adrenal Gland ◽  
Dehydrogenase Activity ◽  
Cold Exposure ◽  
Chronic Treatment ◽  
Zinc Concentration ◽  
Succinic Dehydrogenase ◽  
Zinc Content ◽  
Transient Increase ◽  
Succinic Dehydrogenase Activity ◽  
Exposure To Cold

Chronic treatment, with cortisone (5 mg/day) results in a dramatic increase in the zinc concentration in the adrenals. The treatment produces an atrophy of the gland without affecting its total zinc content. This fact accounts for the increase in the zinc concentration.Zinc determinations on fat-free adrenals confirm that, as a result of atrophy, zinc is retained; and show that the site of retention is the proteic part of the gland. Exposure to cold produces hypertrophy of the gland, but no change in the total zinc content, resulting in a decrease in the zinc concentration.Adrenal succinic dehydrogenase (S.D.) activity is decreased with cortisone treatment. Cold exposure produces a transient increase in the S.D. activity.Thus, there is no relationship between S.D. activity and zinc content in the adrenals.

Tolerance of estrogen-treated rats to acute cold exposure

1979 ◽  
Vol 47 (1) ◽  
pp. 59-66 ◽  
Author(s):  
M. J. Fregly ◽  
D. L. Kelleher ◽  
D. J. Black
Keyword(s):  
Oxygen Consumption ◽  
Cold Exposure ◽  
Previous Experiment ◽  
Female Rats ◽  
Control Group ◽  
Maximal Rate ◽  
Acute Cold Exposure ◽  
Exposure To Cold ◽  
Rate Of Oxygen Consumption ◽  
Rate Of Cooling

Female rats treated chronically with ethynylestradiol (36 micrograms/kg per day) alone, and in combination with the progestational agent, norethynodrel (253 micrograms/kg per day), cooled significantly faster than controls when lightly restrained and exposed to air at 5 degrees C. Rate of cooling of rats given only norethynodrel was similar to that of the control group. In other studies, rate of oxygen consumption was determined for all groups during acute exposure to cold (14 degrees C). All estrogen-treated groups achieved the same maximal rate of oxygen consumption as control and norethynodrel-treated groups during cold exposure, but cooled significantly faster. Two groups of female rats were treated chronically with ethynylestradiol at two separate doses (36 and 61 micrograms/kg per day). An untreated group served as controls. Rate of oxygen consumption of all animals were measured during restraint and exposure to cold (18 degrees C). The estrogen-treated groups again achieved the same maximal rate of oxygen consumption as the control group, but also cooled significantly faster despite the fact that the cold stress was less severe than in the previous experiment. That estrogen-treated rats cooled faster than controls in both studies despite achieving a maximal rate of heat production which did not differ from controls suggests that reduced cold tolerance of estrogen-treated rats may be related to increased heat loss.

PERINATAL THYROID FUNCTION IN THE RAT

1966 ◽  
Vol 52 (3) ◽  
pp. 375-382 ◽  
Author(s):  
Warner H. Florsheim ◽  
Marjorie A. Faircloth ◽  
Nancy L. Corcorran ◽  
Paul Rudko
Keyword(s):  
Dehydrogenase Activity ◽  
Thyroid Function ◽  
Hormone Secretion ◽  
Late Gestation ◽  
Pituitary Hormone ◽  
Radioiodine Uptake ◽  
Glycerophosphate Dehydrogenase ◽  
Thyroid Glands ◽  
Developing Rat

ABSTRACT Thyroid function in the developing rat was measured during late gestation and the first 3 weeks of life. Radioiodine uptake showed a marked peak immediately after birth. Thyroidal hormone stores dropped to stable levels by the 4th day of life and an increase in hepatic α-glycerophosphate dehydrogenase activity suggested increased hormone secretion about the time of birth. Monoiodotyrosine in the thyroid glands declined sharply just before birth but recovered its prenatal level by the 3rd day of life. The data may indicate a discharge of pituitary TSH at birth followed by a period of pituitary hormone repletion. Hypothalamic influences upon the thyroid - pituitary axis appear to be of little importance in perinatal life.

Separation of simian virus 40 large-T-antigen-transforming and origin-binding functions from the ability to block differentiation

1988 ◽  
Vol 8 (3) ◽  
pp. 1380-1384 ◽  
Author(s):  
V Cherington ◽  
M Brown ◽  
E Paucha ◽  
J St Louis ◽  
B M Spiegelman ◽  
...  
Keyword(s):  
Dehydrogenase Activity ◽  
Adipocyte Differentiation ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Lipid Binding ◽  
T Antigen ◽  
Large T Antigen ◽  
Wild Type ◽  
Glycerophosphate Dehydrogenase ◽  
Triglyceride Accumulation

Wild-type simian virus 40 large T antigen is very effective at blocking adipocyte differentiation in 3T3-F442A cells as assayed by triglyceride accumulation, induction of glycerophosphate dehydrogenase activity, and expression of mRNAs for glycerophosphate dehydrogenase, the adipocyte serine protease adipsin, and the putative lipid-binding protein adipocyte P2. Point mutants defective for either origin-specific DNA binding or transformation blocked differentiation as completely as wild type.

Cold-Induced Skin Disorders

1996 ◽  
Vol 1 (2) ◽  
pp. 119-130
Author(s):  
H.L. Kim ◽  
Y. Bo-Abbas ◽  
Lyn C. Guenther
Keyword(s):  
Cold Exposure ◽  
Clinical Presentation ◽  
Heterogeneous Group ◽  
Current Understanding ◽  
Cold Climates ◽  
Skin Disorders ◽  
Cold Temperatures ◽  
Exposure To Cold

Background: Humans are commonly exposed to extremes in temperature. Fortunately, our skin behaves as an anatomic and physiologic barrier during these periods. Exposure to cold temperatures may result in a variety of symptoms and disorders. Objective: Our current understanding of the pathophysiology, clinical presentation, and therapies of cold-induced skin disorders are reviewed. Methods: Studies, reviews, and book chapters that contained information on cold-induced skin disorders were reviewed. Conclusion: Cold-induced skin disorders are a heterogeneous group of disorders that cause great morbidity, particularly in cold climates. These entities can be classified as physiologic or pathologic responses to freezing or nonfreezing cold exposure.

scholarly journals Changes in rat pituitary POMC mRNA after exposure to cold or a novel environment, detected by in situ hybridization.

1991 ◽  
Vol 39 (6) ◽  
pp. 843-852 ◽  
Author(s):  
P Wu ◽  
G V Childs
Keyword(s):  
Cold Exposure ◽  
Color Image ◽  
Fold Increase ◽  
Male Rats ◽  
Image Analysis System ◽  
Frozen Sections ◽  
Novel Environment ◽  
Pomc Mrna ◽  
Exposure To Cold

Plasma adrenocorticotropin (ACTH) levels increase after acute cold exposure. The purpose of this study was to determine if there were parallel changes in pituitary proopiomelanocortin (POMC) mRNA. Male rats were exposed to cold (3-5 degrees C) or a novel environment for 15 or 30 min. Others were unstressed. POMC mRNAs in frozen sections or dissociated cells were hybridized with a photobiotinylated oligonucleotide probe which was detected in situ by streptavidin-alkaline phosphatase. The percentage of area labeled for POMC mRNA was quantified by the Cue-3 color image analysis system. In frozen sections, 24-fold increases in the percentage of area labeled for POMC mRNA were evident in intermediate lobes (IL) 30 min after stress. No change was seen in anterior lobes (AL). If the ALs were dissociated, a 66-99% increase in percentage of labeled cells was detected 2-3 hr after the cold exposure. Fifteen min of cold stress (CS) also caused a 117% increase in the area of label for POMC mRNA per corticotrope. No change was seen after 30 min. Exposure to a novel environment caused a 73% increase in the percentage of area labeled for POMC mRNA per AL corticotrope and an 11-fold increase in the IL. These results indicate that both AL corticotropes and IL melanotropes are stimulated by acute exposure to cold and novel environments.

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