Cold exposure, starvation and their combined effects on circulating aldosterone and corticosterone concentrations in self-selecting Sprague-Dawley rats

The differential effects of insulin-induced hypoglycemia and cold exposure on adrenal medullary epinephrine (Epi) and norepinephrine (NE) cells were investigated in male Sprague-Dawley rats. In rats fasted overnight, insulin produced a marked hypoglycemia that resulted in a 70% decrease in adrenal medullary Epi content 3 h after the insulin was administered. No change in NE content was observed. Plasma Epi concentration was increased markedly after insulin, with a smaller increment in NE. In contrast, exposure to a 4 degrees C environment selectively reduced adrenal NE content, with the effect reaching statistical significance at 18 h. Cold exposure also led to a significant rise in plasma NE but not Epi. Both insulin-induced hypoglycemia and cold exposure significantly elevated adrenal dopamine, indicating that catecholamine synthesis was stimulated. Further evidence of enhanced catecholamine formation was the observation that inhibition of synthesis with alpha-methyl-p-tyrosine (AMT) greatly augmented the ability of insulin-induced hypoglycemia to selectively reduce adrenal medullary Epi content. Similarly, in cold-exposed animals, AMT pretreatment accelerated the NE depletion so that a significant decline was observed at 3 h. These results support the conclusion that the two major populations of adrenal catecholamine-secreting cells may be preferentially stimulated by different stressors. Moreover, augmented synthetic activity functions to maintain catecholamine stores in both Epi- and NE-secreting cells.

Download Full-text

Effect of prolonged cold exposure on the glycolytic enzymes of liver and muscle

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1960.198.2.375 ◽

1960 ◽

Vol 198 (2) ◽

pp. 375-380 ◽

Cited By ~ 12

Author(s):

John P. Hannon ◽

David A. Vaughan

Keyword(s):

Muscle Tissue ◽

Cold Exposure ◽

Liver Tissue ◽

Glycolytic Enzymes ◽

Hexose Monophosphate ◽

Sprague Dawley ◽

Cold Effect ◽

Sprague Dawley Rats ◽

Free Glucose ◽

Muscle Phosphorylase

Liver and muscle tissue from male Sprague-Dawley rats, exposed to 5 ± 1°C for 3–4 weeks, were assayed for the activities of selected glycolytic enzymes. When compared to control animals maintained at 25 ± 1°C, the cold-exposed animals showed an increase in liver glucose-6-phosphatase, an increase in liver and muscle glucokinase, a decrease in glucose-6-phosphate and 6-phosphogluconic dehydrogenase in both liver and muscle, and an increase in the rate of pyruvate formation from 3-phosphoglycerate in liver tissue. Assays of liver and muscle phosphoglucomutase, total liver and muscle phosphorylase and phosphorylase a and b in muscle failed to show any cold effect. The results indicate the cold-exposed rat has the enzyme capacities for: an increased utilization of free glucose, an increased glycogenolysis either to free glucose to pyruvate and an increased gluconeogenesis. They also indicate a decreased hexose monophosphate shunt activity. Little evidence could be found to indicate an epinephrine-induced activation of phosphorylase in the cold-exposed animals.

Download Full-text

Independent and combined effects of Bisphenol A and Diethylhexyl Phthalate on gestational outcomes and offspring development in Sprague-Dawley rats

Chemosphere ◽

10.1016/j.chemosphere.2020.128307 ◽

2021 ◽

Vol 263 ◽

pp. 128307

Author(s):

Josephine Bou Dagher ◽

Coral K. Hahn-Townsend ◽

Amrita Kaimal ◽

Maryam Al Mansi ◽

Joseph E. Henriquez ◽

...

Keyword(s):

Bisphenol A ◽

Combined Effects ◽

Sprague Dawley ◽

Diethylhexyl Phthalate ◽

Offspring Development ◽

Sprague Dawley Rats

Download Full-text

Combined Effects of Acute Cerebrovascular Ischemia and Myocardial Infarction in Arteriosclerotic, Male Sprague-Dawley Rats

Angiology ◽

10.1177/000331977702800907 ◽

1977 ◽

Vol 28 (9) ◽

pp. 624-643 ◽

Cited By ~ 3

Author(s):

Bernard C. Wexler

Keyword(s):

Myocardial Infarction ◽

Combined Effects ◽

Sprague Dawley ◽

Sprague Dawley Rats

Download Full-text

Effect of prolonged cold exposure on the gross blood composition of the rat

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1959.197.5.1008 ◽

1959 ◽

Vol 197 (5) ◽

pp. 1008-1012 ◽

Cited By ~ 13

Author(s):

John P. Hannon ◽

David W. Young

Keyword(s):

Blood Glucose ◽

Specific Gravity ◽

Plasma Protein ◽

Cold Exposure ◽

Plasma Lipids ◽

Total Plasma ◽

Sprague Dawley ◽

Nonprotein Nitrogen ◽

Protein Levels ◽

Sprague Dawley Rats

One month's cold exposure (5 ± 1 °C) of male Sprague-Dawley rats induced a slight, but significant, increase in hemoglobin levels but had no effect on the hematocrit. Fasting for 24 hours, although not altering the hemoglobin concentrations of either the control or the cold-exposed animals, did produce a slight lowering of the hematocrit. Cold exposure also resulted in a plasma dilution as indicated by a significant increase in plasma water, and significant decreases in plasma specific gravity and plasma protein levels. Fasting superimposed a further reduction in plasma protein levels under both control and cold-exposed conditions. The levels of blood glucose and total plasma lipids were unaltered by cold exposure but each was significantly reduced by fasting. Significant increases in the nonprotein nitrogen, phospholipid, cholesterol and ketone levels were observed in cold-exposed, nonfasted animals. Superimposed on these changes, fasting produced a decrease in the levels of nonprotein nitrogen and phospholipids and an increase in the level of ketones. It had no effect on the level of cholesterol. Fasting of the cold-exposed animals led to greater reductions in plasma nonprotein nitrogen and phospholipids and a smaller increase in blood ketones as compared to controls.

Download Full-text