Search Results
You are looking at 1 - 2 of 2 items for
- Author: S L Monfort x
- Refine by access: All content x
Search for other papers by S. L. Monfort in
Google Scholar
PubMed
Search for other papers by J. L. Brown in
Google Scholar
PubMed
Search for other papers by D. E. Wildt in
Google Scholar
PubMed
ABSTRACT
Episodic and seasonal rhythms of cortisol secretion were evaluated in six adult Eld's deer (Cervus eldi thamin) stags. Plasma cortisol was measured in serial blood samples collected via remote catheterization every 10 min for 10 h within 2 weeks of the summer solstice (21 June), autumn equinox (22 September), winter solstice (21 December) and spring equinox (20 March), and in weekly blood samples collected from sedated stags. Cortisol was secreted episodically at a rate of approximately 0·6 peaks/h. Based on quantitative peak detection analyses of each 10-h data series, no overall seasonal differences (P>0·05) were detected in the number of peaks (mean range, 5·7–6·2), maximal peak height (mean range, 30·1–40·8 nmol/l), mean peak height as per cent increase (mean range, 158–168%), mean interval between peaks (mean range, 80·1–88·6 min), mean peak width (mean range, 55·1–65·1 min) and mean peak area under the curve (mean range, 675–816 nmol/l min). Based on weekly blood sampling, spring cortisol concentrations were elevated (P<0·05) compared with summer and autumn concentrations. However, when mean cortisol concentrations derived from the 10-h quarterly data sets were analysed, no seasonal differences (P>0·05) were detected. The present study represents the first detailed confirmation of episodic cortisol secretion in any cervid. Results (1) indicate that Eld's deer stags lack a distinct seasonal rhythm of cortisol secretion and (2) clearly illustrate the need for frequent blood sampling in fully conscious individuals to ensure accurate assessment of adrenal status in cervids.
Journal of Endocrinology (1993) 138, 41–49
Search for other papers by S A Cavigelli in
Google Scholar
PubMed
Search for other papers by S L Monfort in
Google Scholar
PubMed
Search for other papers by T K Whitney in
Google Scholar
PubMed
Search for other papers by Y S Mechref in
Google Scholar
PubMed
Search for other papers by M Novotny in
Google Scholar
PubMed
Search for other papers by M K McClintock in
Google Scholar
PubMed
The circadian glucocorticoid rhythm provides important information on the functioning of the hypothalamic-pituitary-adrenal axis in individuals. Frequent repeated blood sampling can limit the kinds of studies conducted on this rhythm, particularly in small laboratory rodents that have limited blood volumes and are easily stressed by handling. We developed an extraction and assay protocol to measure fecal corticosterone metabolites in repeated samples collected from undisturbed male and female adult Sprague–Dawley rats. This fecal measure provides a non-invasive method to assess changes in corticosterone within a single animal over time, with sufficient temporal acuity to quantify several characteristics of the circadian rhythm: e.g. the nadir, acrophase, and asymmetry (saw-tooth) of the rhythm. Males excreted more immunoreactive fecal corticoids than did females. Across the estrous cycle, females produced more fecal corticoids on proestrus (the day of the preovulatory luteinizing hormone surge) than during estrus or metestrus. These results establish a baseline from which to study environmental, psychological, and physiological disturbances of the circadian corticosterone rhythm within individual rats.
