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Titolo:
NONCLASSICAL SECRETORY DYNAMICS OF LH REVEALED BY HYPOTHALAMOHYPOPHYSEAL PORTAL SAMPLING OF SHEEP
Autore:
MIDGLEY AR; MCFADDEN K; GHAZZI M; KARSCH FJ; BROWN MB; MAUGER DT; PADMANABHAN V;
Indirizzi:
UNIV MICHIGAN,REPROD SCI PROGRAM,300 N INGALLS BLDG,RM 1101 ANN ARBORMI 48109 UNIV MICHIGAN,NATL CTR INFERTIL RES ANN ARBOR MI 48109 UNIV MICHIGAN,BIOENGN PROGRAM ANN ARBOR MI 48109 UNIV MICHIGAN,DEPT PHYSIOL ANN ARBOR MI 48109 UNIV MICHIGAN,DEPT PEDIAT ANN ARBOR MI 48109 UNIV MICHIGAN,DEPT BIOSTAT ANN ARBOR MI 48109
Titolo Testata:
Endocrine
fascicolo: 2, volume: 6, anno: 1997,
pagine: 133 - 143
SICI:
1355-008X(1997)6:2<133:NSDOLR>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
GONADOTROPIN-RELEASING-HORMONE; PITUITARY VENOUS-BLOOD; LUTEINIZING-HORMONE; OVARIECTOMIZED EWES; MARE; DECONVOLUTION; ESTRADIOL; PATTERNS; PROGESTERONE; ALGORITHMS;
Keywords:
GONADOTROPINS; REPRODUCTION; GNRH; LUTEINIZING HORMONE; DECONVOLUTION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
38
Recensione:
Indirizzi per estratti:
Citazione:
A.R. Midgley et al., "NONCLASSICAL SECRETORY DYNAMICS OF LH REVEALED BY HYPOTHALAMOHYPOPHYSEAL PORTAL SAMPLING OF SHEEP", Endocrine, 6(2), 1997, pp. 133-143

Abstract

Continuous withdrawal of hypophyseal portal blood from unrestrained sheep has permitted detailed assessments of the pulsatile secretion of gonadotrophin-releasing hormone (GnRH). To determine if this blood canalso be used to characterize the secretory dynamics of pituitary hormones, patterns of luteinizing hormone (LH) in the hypophyseal portal blood of ovariectomized ewes was compared with previous patterns of GnRH and peripheral LH. Hypophyseal portal blood and jugular vein blood were collected every 5 min from six ovariectomized ewes over 6-12 h. Hypophyseal portal blood contained GnRH-associated, sharply defined LH pulses that were much larger than in the periphery. Pulses of secreted LH (hypophyseal portal LH less peripheral LH) showed much faster ratesof rise and fall than peripheral and followed pulses of GnRH by an average of 1.26 min. In contrast to pulses in jugular blood, secreted LHpulses often reached a relatively unchanging interpulse nadir-plateauand thereby approached closely algorithm-estimated, extrapolated baselines. The interpulse baseline concentrations of secreted LH (99.6 ng/mL) in hypophyseal portal blood were 31-fold higher than those for jugular LH (3.23 ng/mL). These elevated concentrations also exceeded meanjugular peak concentrations (11.1 ng/mL) and, thus, primarily must represent newly secreted LH. The non-Gaussian profiles of th is secretedLH were substantially more complex than the inputs predicted from jugular LH measurements by deconvolution. Furthermore, regardless of the analytical approach, estimations of the mass of secreted LH in each pulse did not correlate well with inputs predicted by deconvolution or Kushler-Brown pulsefit analysis of corresponding pulses in jugular blood (r(2) ranging 0.40-0.48). Among alternative explanations is the possibility of heterogeneity in concentrations of GnRH in the portal vessels and variable distribution within the hypophysis. in summary, assay of hypophyseal portal blood obtained directly from the pituitary provides a method for direct assessment of secretory responses to hypothalamic peptides, and thereby serves as an unmatched method for studying the dynamics of LH secretion in vivo. With this approach, LH is revealed to be secreted as complex, non-Gaussian pulses that are far more sharply defined than those in the periphery, include non-GnRH-dependent, secretory components that cannot be predicted by deconvolution and arefollowed by periods of relatively constant, basal secretion.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 27/11/20 alle ore 22:26:00