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Effect of gonadotropin-releasing hormone (GnRH) pulse frequency on serum and pituitary concentrations of luteinizing hormone and follicle-stimulating hormone, GnRH receptors, and messenger ribonucleic acid for gonadotropin subunits in cows.
- Source :
-
Endocrinology [Endocrinology] 1997 Feb; Vol. 138 (2), pp. 594-601. - Publication Year :
- 1997
-
Abstract
- Thirty-two nutritionally anestrous cows were used to determine the effect of the frequency of exogenous GnRH pulses on ovarian follicular growth, serum concentrations of LH and FSH, and concentrations of LH, FSH, GnRH receptors (GnRH-R), messenger RNA (mRNA) for GnRH-R, and mRNA for gonadotropin subunits in the pituitary. Cows were randomly assigned to one of four treatments: 2 micrograms GnRH infused (i.v.) continuously during 1 h, 2 micrograms GnRH infused during 5 min once every hour, 2 micrograms GnRH infused during 5 min once every fourth hour, or saline (control) for 13 days. Infusion of GnRH every hour increased LH concentrations in serum (P < 0.05), but FSH concentrations were not affected by GnRH infusion. Luteal activity (LA) was assessed by the presence of corpora lutea and/or serum progesterone greater than 1 ng/ml. Six of eight cows infused with GnRH every hour had LA by day 13, whereas only 25% of cows infused either continuously or with a pulse every fourth hour had LA by day 13. None of the control cows had LA during the experiment (P < 0.01). Concentrations of LH and FSH in the pituitary were significantly reduced when GnRH was infused hourly or continuously. Concentrations of common alpha and FSH beta mRNA were not influenced by treatment. However, continuous infusion of GnRH decreased (P < 0.05) LH beta mRNA subunit. Concentrations of GnRH-R (P < 0.1) and GnRH-R mRNA (P < 0.05) were reduced when GnRH was infused continuously. We concluded that pulsatile secretion of LH is necessary for follicular growth and LA in beef cattle, and GnRH treatment differentially regulates LH and FSH gene transcription and serum concentrations of LH and FSH in cattle.
- Subjects :
- Animals
Corpus Luteum physiology
Estradiol blood
Female
Follicle Stimulating Hormone blood
Follicle Stimulating Hormone genetics
Luteinizing Hormone blood
Luteinizing Hormone genetics
Ovarian Follicle physiology
Periodicity
Pituitary Gland, Anterior drug effects
Progesterone blood
RNA, Messenger metabolism
Receptors, LHRH genetics
Cattle
Follicle Stimulating Hormone metabolism
Gonadotropin-Releasing Hormone administration & dosage
Luteinizing Hormone metabolism
Pituitary Gland, Anterior metabolism
Receptors, LHRH metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0013-7227
- Volume :
- 138
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- Endocrinology
- Publication Type :
- Academic Journal
- Accession number :
- 9002991
- Full Text :
- https://doi.org/10.1210/endo.138.2.4938