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Titolo:
CIRCANNUAL ALTERATIONS IN THE CIRCADIAN-RHYTHM OF MELATONIN SECRETION
Autore:
THRUN LA; MOENTER SM; OCALLAGHAN D; WOODFILL CJI; KARSCH FJ;
Indirizzi:
UNIV MICHIGAN,DEPT BIOL,REPROD SCI PROGRAM,300 N INGALLS BLDG,RM 1101SW ANN ARBOR MI 48109 UNIV MICHIGAN,DEPT BIOL,REPROD SCI PROGRAM ANN ARBOR MI 48109 UNIV MICHIGAN,DEPT PHYSIOL,REPROD SCI PROGRAM ANN ARBOR MI 48109 NATL UNIV IRELAND UNIV COLL DUBLIN,FAC VET MED DUBLIN 4 IRELAND
Titolo Testata:
Journal of biological rhythms
fascicolo: 1, volume: 10, anno: 1995,
pagine: 42 - 54
SICI:
0748-7304(1995)10:1<42:CAITCO>2.0.ZU;2-B
Fonte:
ISI
Lingua:
ENG
Soggetto:
LUTEINIZING-HORMONE; GROUND-SQUIRRELS; REPRODUCTIVE REFRACTORINESS; SUPRACHIASMATIC NUCLEI; PROLACTIN SECRETION; BREEDING-SEASON; ESTROUS-CYCLE; LH-SECRETION; SUFFOLK EWE; PHOTOPERIOD;
Keywords:
CIRCANNUAL; CIRCADIAN; MELATONIN; LUTEINIZING HORMONE; REPRODUCTION; EWE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
34
Recensione:
Indirizzi per estratti:
Citazione:
L.A. Thrun et al., "CIRCANNUAL ALTERATIONS IN THE CIRCADIAN-RHYTHM OF MELATONIN SECRETION", Journal of biological rhythms, 10(1), 1995, pp. 42-54

Abstract

To determine if a circadian rhythm known to be functionally related to the reproductive axis varies on a circannual basis, we monitored thecircadian secretion of melatonin at monthly intervals for 2 years in four ovariectomized, estradiol-implanted ewes held in a constant short-day photoperiod. Prior to the study, ewes had been housed in a short-day (8L:16D) photoperiod for 4 years and were exhibiting circannual reproductive rhythms as assessed by serum luteinizing hormone (LH) levels. Three of the four sheep showed unambiguous deviations from the expected nocturnal melatonin secretion at two different times approximately 1 year apart. Nocturnal rises in melatonin, which usually last the duration of the dark phase, were delayed by 3-14 h or were missing. Altogether, five of the seven melatonin alterations observed in these three ewes occurred during the nadir of the circannual LH cycle. In the remaining ewe, we did not observe an altered melatonin secretory pattern during this period, and this ewe also failed to show a high amplitude circannual cycle of LH. The results provide evidence for a circannual change in the circadian rhythm of melatonin secretion. This alteration in melatonin secretion may serve as a ''functional'' change in daylength, and thereby may influence the expression of the circannual reproductive rhythm of sheep held in a fixed photoperiod for an extended time.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 02/12/20 alle ore 07:50:01