Average Cortisol Concentration Research Articles

Corticosteroids of the peccary ( Dicotyles tajacu)

Cortisol and cortisone were tentatively identified as the principal corticosteroids present in the plasma of the male collared peccary ( Dicotyles tajacu). On the basis of colorimetric assays the average cortisol concentration was estimated to be 7.5 μg/100 ml of plasma. Cortisol, cortisone, and dehydrocorticosterone were tentatively identified in the extracts of whole adrenal glands from the collared peccary.

Serum corticotrophin, plasma cortisol and urinary excretion of 17-ketogenic steroids in the elderly (age group: 66-94 years).

ABSTRACT The serum corticotrophin concentrations was determined in 28 elderly subjects (70–94 years) by the radioimmunochemical double-antibody-technique. In 5 elderly subjects, the corticotrophin concentration was studied throughout the 24-hour period. The plasma cortisol concentration was determined by means of a double-isotope-derivative technique in 69 elderly subjects (66–94 years). In 10 elderly and 8 younger subjects the concentration was checked throughout the 24-hour period. The urinary excretion of 17-ketogenic steroids was determined in a total of 80 elderly subjects (66–94 years). For comparison corticotrophin and cortisol measurements in young volunteers assayed by identical methods were used and partly carried out in cooperation with other investigators. At 8 a. m. the average corticotrophin concentration was 101.8 ± 55.0 (sd) pg/ml of serum and the average cortisol concentration was 15.0 ± 4.60 (sd) μg/100 ml of plasma. No significant age or sex variation could be detected. With regard to both hormones, the circadian variations were marked with parallel changes in the concentrations of corticotrophin and cortisol. The highest concentration was measured in the morning and the lowest in the evening. The urinary excretion of 17-ketogenic steroids showed a tendency to decrease with increasing age. The regression equation for females was ȳx = −0.07x + 11.42, for males ȳx = −0.22x + 26.59.

The effects of hypophysectomy in the rainbow trout Salmo gairdnerii (Rich.) with special reference to the pituitary-interrenal axis

A method for the hypophysectomy of rainbow trout ( Salmo gairdnerii) is desribed. Hypophysectomy resulted in a marked atrophy of the interrenal and thyroid tissue, a cessation of spermatogenesis, and an absence of proliferation of the integument. The plasma cortisol concentration in sham hypophysectomized fish averaged 8.1 μg/100 ml. One day after hypophysectomy the cortisol concentration averaged 3.6 μg/100 ml. Plasma samples taken from 2 to 17 days after hypophysectomy had an average cortisol concentration of 1.6 μg/100 ml. Stress caused a significant increase in the plasma cortisol concentration of control fish, but not of hypophysectomized fish. Sham operated trout injected with dexamethasone 1 mg/kg intraperitoneally 20 hours prior to blood sampling had a plasma cortisol concentration identical to that of uninjected hypophysectomized fish. These data indicate that interrenal function in S. gairdnerii is under pituitary control and that a negative feedback mechanism probably operates between the interrenal and the pituitary.