Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
REGULATION OF GROWTH-HORMONE (GH) GENE-EXPRESSION AND SECRETION DURING PREGNANCY AND LACTATION IN THE RAT - ROLE OF INSULIN-LIKE GROWTH-FACTOR-I, SOMATOSTATIN, AND GH-RELEASING HORMONE
Autore:
ESCALADA J; SANCHEZFRANCO F; VELASCO B; CACICEDO L;
Indirizzi:
INST SALUD CARLOS III,CTR INVEST CLIN,SERV ENDOCRINOL,C SINESIO DELGADO 10 MADRID 28029 SPAIN INST SALUD CARLOS III,CTR INVEST CLIN,SERV ENDOCRINOL MADRID 28029 SPAIN HOSP RAMON Y CAJAL E-28034 MADRID SPAIN
Titolo Testata:
Endocrinology
fascicolo: 8, volume: 138, anno: 1997,
pagine: 3435 - 3443
SICI:
0013-7227(1997)138:8<3435:ROG(GA>2.0.ZU;2-E
Fonte:
ISI
Lingua:
ENG
Soggetto:
MESSENGER-RIBONUCLEIC-ACID; ANTERIOR-PITUITARY CELLS; IGF-BINDING-PROTEINS; SOMATOMEDIN-C; ADULT-RAT; DIFFERENTIAL EXPRESSION; TISSUE DISTRIBUTION; NEGATIVE FEEDBACK; RECEPTOR; SERUM;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
51
Recensione:
Indirizzi per estratti:
Citazione:
J. Escalada et al., "REGULATION OF GROWTH-HORMONE (GH) GENE-EXPRESSION AND SECRETION DURING PREGNANCY AND LACTATION IN THE RAT - ROLE OF INSULIN-LIKE GROWTH-FACTOR-I, SOMATOSTATIN, AND GH-RELEASING HORMONE", Endocrinology, 138(8), 1997, pp. 3435-3443

Abstract

GH appears to play an important metabolic role during late pregnancy and in lactation maintenance. In this study, pregnant (days 8, 15, and20 of gestation) and postpartum (days 3 and 8 postpartum, including lactating and nonlactating dams) Wistar rats were used to investigate pituitary GH gene expression and hormone secretion, and the potential alterations of the major signals regulating GH secretion and action [somatostatin (SS) and GH-releasing hormone (GHRH), GH receptor (GH-R), and insulin-like growth factor-I (IGF-I)]. GH and SS messenger RNA (mRNA) were quantitated by Northern blot, and both IGF-I and GH-R mRNA were analyzed by the ribonuclease protection assay technique. Pituitary IR-GH content and GH mRNA increased at midpregnancy. IR-GH content was decreased in lactating rats. Plasma GH levels progressively increased during pregnancy, whereas no significant alterations were shown duringlactation. Elevated GH levels persisted during lactation. Levels at this time were higher in nonsuckling compared with suckling dams. LiverGH-R mRNA progressively decreased during pregnancy, but it remained unchanged during lactation. Plasma IGF-I and liver IR-IGF-I constantly decreased during pregnancy, and no significant modifications were seeneither in suckling or in nonsuckling animals. IGF-I mRNA accumulationin the liver decreased during pregnancy. After delivery, a progressive decrease of liver IGF-I mRNA occurred. At the hypothalamic level, a progressive increase in the IR-SS content was found during pregnancy, with no SS mRNA modification. After delivery, a higher hypothalamic IR-SS content was found in lactating than in nonlactating rats, with no changes in SS mRNA levels. Hypothalamic IR-IGF-I also showed a progressive increase during pregnancy with no significant alterations during lactation. Hypothalamic IR-GHRH presented a nonsignificant mild increase during pregnancy with no modifications during lactation. In the pituitary, IR-IGF-I content progressively increased during gestation, reaching its highest concentration at day 20. During lactation, pituitaryIGF-I did not change. In summary, our data show that the mechanisms of the increase in plasma GH levels occurring during pregnancy include an increase in GH gene expression in the pituitary, a decrease in SS secretion from the hypothalamus, an increase in IR-IGF-I content in thehypothalamus and in the pituitary, and a significant decrease in circulating IGF-I. Plasma and liver IR-IGF-I and IGF-I mRNA in the liver decreased throughout gestation due to a lower GH-R gene expression in the liver. This state of GH resistance with a higher GH/IGF-I ratio could be important in providing supplementary nutrients to the fetus. During lactation, GH and its regulatory machinery did not show important modifications.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/11/20 alle ore 07:11:15