Radioimmunoassay of Serum Concentrations of Melatonin in Sheep Exposed to Different Lighting Regimens

Journal Article · Sun Feb 01 04:00:00 EST 1976 · Endocrinology

DOI:https://doi.org/10.1210/endo-98-2-482· OSTI ID:4019219

ROLLAG, M. D.; NISWENDER, G. D.

A specific and sensitive double-antibody radioimmunoassay for melatonin (N-acetyl-5-methoxytryptamine) was developed. The least detectable concentration of melatonin standard was 10 pmolar (2.3 pg/tube) with 50 percent inhibition resulting when the concentration was 100 pmolar (23 pg/tube). Inhibition curves obtained with increasing quantities of melatonin or increasing quantities of chloroform extracts of ovine sera were parallel. Concentrations of melatonin could be accurately determined when 31 to 1000 pg were added to 1 ml ovine serum. Serum samples with melatonin concentrations of 1000 pg/ml, 500 pg/ml and 75 pg/ml had intra-assay coefficients of variation of 9.1 percent, 8.6 percent, and 17.4 percent, respectively. The respective inter-assay coefficients of variation were 22.7 percent, 18.1 percent, and 37.1 percent. Ewes exposed to a 12 h light:12 h dark lighting regimen demonstrated a circadian rhythm in serum concentrations of melatonin. Concentrations ranged from 10 to 30 pg/ml during periods of light to 100 to 300 pg/ml during periods of dark. During exposure to continuous light, the circadian rhythm was abolished and concentrations of melatonin were maintained at 10 to 50 pg/ml. When exposed to conditions of continuous dark the circadian rhythm persisted. A precipitous drop in serum concentrations of melatonin resulted when ewes experiencing peak melatonin concentrations were exposed to light. Concentrations returned to peak levels when the lights were turned off 3.5 h later. (auth)

• Research Organization: Colorado State Univ., Fort Collins
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-026387
• OSTI ID: 4019219
• Journal Information: Endocrinology, Journal Name: Endocrinology Journal Issue: 2 Vol. 98; ISSN 0013-7227
• Country of Publication: United States
• Language: English

Related Subjects

*MELATONIN-- RADIOIMMUNOASSAY
550601* --Biomedical Sciences
Basic Studies--Medicine-- Unsealed Radionuclides in Diagnostics
ANTIBODIES
IMMUNE SERUMS
N48830* --Life Sciences--New Tracer Techniques--Other
SHEEP
TRITIUM COMPOUNDS
VISIBLE RADIATION