Comparison of spectrofluorometric and competitive protein-binding methods for the measurement of plasma corticosteroids

Sarin, Raj K.; Connell, Gerald M.; Linfoot, John A.

doi:10.1016/0003-2697(71)90209-0

Cited by 15 publications

(6 citation statements)

References 17 publications

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“…We feel that the discrepancy between present and pre viously reported results could be explained by the relative insensitivity of the fluorometric assay when measuring low concentrations of the hormone [4,14]. It appears that this assay is unable to detect minute changes in serum corti costerone concentration while being adequate for detec tion of changes in the much greater concentration of adre nal corticosterone of the neonate in response to stress.…”

Section: Discussioncontrasting

confidence: 48%

“…observation]. Similar comparisons have been noted in the mouse [4] and in man [14], leading to the conclusion that the CPB assay is more sensitive than the fluorometric analysis, particularly when measuring serum corticosterone concentrations of less than 10 /ig/100 ml [4,14]. Since the question of sensitivity may be critical to an analysis of the refractory period, the present study was designed to re examine the responsiveness of the neonatal rat to ether stress and exogenous ACTH.…”

mentioning

confidence: 93%

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Maturation of Adrenal Stress Responsiveness in the Rat

Schoenfeld¹,

Leathem²,

Rabii³

1980

Neuroendocrinology

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Serum and adrenal corticosterone was measured by competitive protein-binding radioassay in rats subjected to saline injection, ACTH administration or ether fumes. Groups of rats were tested at 5, 7, 9, 11, 13, 15, 20 and 25 days of age and measurement of hormone level was made either before treatment, to obtain basal values, or 15 min after treatment. Furthermore, the time-course of corticosterone release after ether was determined in 9- and 15-day-old rats. Neonatal rats responded to ether exposure, ACTH administration or saline injection with a significant rise in serum and adrenal corticosterone concentration above basal levels as early as 5 days of age. By 9 days of age, response to stress was qualitatively the same as that of the 25-day-old rat. The time course of adrenal responsiveness to ether stress was similar in 9- and 15-day-old rats, both age groups showing significant increases in hormone concentration by 15 min. These results contradict the concept of the ‘stress non-responsive period’ which was promoted by previous studies based on the nuorometric analysis of corticosterone.

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Section: Discussioncontrasting

confidence: 48%

mentioning

confidence: 93%

Maturation of Adrenal Stress Responsiveness in the Rat

Schoenfeld¹,

Leathem²,

Rabii³

1980

Neuroendocrinology

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“…We believe that the higher values obtained by these authors may be attributed to the analytical methods they used. The competitive protein-binding method used in the present study is quite specific and is not susceptible to artifacts introduced by diet or disease states, whereas this is not true for the widely used fluorometric methods (Sarin et al, 1971). …”

Section: Resultsmentioning

confidence: 97%

Blood Analyses of Wolf Pups and Their Ecological and Metabolic Interpretation

Seal

Mech

Ballenberghe

1975

Journal of Mammalogy

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“…The plasma concentrations of corticosterone measured were found to be lower than those pre¬ viously reported in young rats, using spectrofluorometric techniques (Haltmeyer, Denenberg, Thatcher & Zarrow, 1966;Bartova, 1968). However, it has been shown that the competitive protein-binding assay provides a more accurate estimate of plasma corticosteroid values than the spectrofluorometric assay, particularly in the case of very low levels (Sarin, Connell & Linfoot, 1971). The present finding that the onset of closure (days 18-20) is associated with a marked increase in plasma corticosterone levels, provides further evidence for the implication of the adrenal cortex in the maturation of the small intestine.…”

mentioning

confidence: 87%

Adrenocortical Hormones and Absorption of Macromolecules by the Small Intestine of the Young Rat

Daniels¹,

Hardy²,

Malinowska³

et al. 1972

Journal of Endocrinology

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The villous epithelial cells of the terminal part of the rat small intestine readily absorb maternal antibodies and certain other macromolecules up to the 18th day after birth. Between 18 and 21 days, however, these cells are progressively replaced by more mature cells, and the uptake of macromolecules declines to zero (Clarke & Hardy, 1969a, b). This process has been termed 'closure'.Closure can be induced at least 9 days before the normal time by the administration of deoxycorticosterone acetate or cortisone acetate (Halliday, 1959). Furthermore, bilateral adrenalectomy at 15-18 days after birth has been shown to delay the time of closure (Daniels & Hardy, 1971). These results suggest that the functional development of the adrenal cortex may determine the maturation of the small intestine with respect to its ability to absorb macromolecules.In order to investigate further the possible role of the adrenal gland in the mechanism of closure, normal plasma adrenocortical steroid levels were measured in young rats during the first 28 days after birth, and were related to intestinal polyvinyl pyrrolidone (PVP) uptake. CFY rats (Carworth, Europe) were used in all experiments and were maintained at 20°C in a lighting regime of 14 h light/24 h. On the day of the experiments rats were fed a solution of 125I-labelled PVP of mean molecular weight 160000 (Clarke & Hardy, 1969a, 6). Four hours after feeding, the rats were killed by decapitation and a blood sample was taken immediately from the severed neck for the estimation of plasma corticosteroids. The PVP uptake by the small intestine was then measured as described by Clarke & Hardy (1969a). Steroids were measured in 0-1 ml plasma from individual animals by a modification of the competitive protein-binding technique (Murphy, 1967), after preliminary separation on Sephadex LH 20. Figure 1 shows that low cortisol concentrations persisted throughout the observed period. However, corticosterone concentration remained fairly constant only until day 16. From day 18 to 19 there was an almost twofold increase in concentration and the mean level then remained between 5 and 7 /ig/100 ml until day 22. Thereafter, the mean concentration continued to increase up to about 15/tg/100ml on day 28. The increased plasma corticosterone level between days 19 and 22 correlates closely with a decrease in the absorption of PVP between days 18 and 22 (Fig. 1). The plasma concentrations of corticosterone measured were found to be lower than those pre¬ viously reported in young rats, using spectrofluorometric techniques (Haltmeyer,

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Comparison of spectrofluorometric and competitive protein-binding methods for the measurement of plasma corticosteroids

Cited by 15 publications

References 17 publications

Maturation of Adrenal Stress Responsiveness in the Rat

Maturation of Adrenal Stress Responsiveness in the Rat

Blood Analyses of Wolf Pups and Their Ecological and Metabolic Interpretation

Adrenocortical Hormones and Absorption of Macromolecules by the Small Intestine of the Young Rat

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