Back to Search
Start Over
Effects of bovine follicular fluid and passive immunization against gonadotropin-releasing hormone (GnRH) on messenger ribonucleic acid for GnRH receptor and gonadotropin subunits in ovariectomized ewes.
- Source :
-
Biology of reproduction [Biol Reprod] 1997 Jun; Vol. 56 (6), pp. 1537-43. - Publication Year :
- 1997
-
Abstract
- In cultured ovine pituitary cells, inhibin increases concentrations of mRNA encoding GnRH receptor and numbers of GnRH receptors. The objective of this study was to test the hypothesis that inhibin increases concentrations of ovine GnRH receptor mRNA in vivo. Ovariectomized ewes were used to eliminate effects of endogenous ovarian hormones, and passive immunization against GnRH was employed to avoid possible confounding influences of GnRH on GnRH receptor gene expression. Two groups of ewes (n = 5/group) were treated with 50 ml GnRH antiserum on Days 0 and 3 of the experiment. One group of immunized ewes received 10 ml charcoal-extracted bovine follicular fluid (bFF) as a source of inhibin every 8 h for 48 h on Days 4-6 of the experiment. A third group of ewes was not passively immunized and was treated only with bFF, and control ewes received no treatments. Anterior pituitary glands were collected from all ewes on Day 6. Passive immunization against GnRH, alone or in combination with treatment with bFF, decreased mean concentrations of LH (p < 0.01) and LH pulse amplitude (p < 0.001). In ewes treated only with GnRH antiserum, number of LH pulses was also reduced (p < 0.03). Circulating concentrations of FSH tended to be lower (p = 0.06) in passively immunized ewes compared to controls. Treatment with bFF, alone or in combination with GnRH antiserum, reduced circulating concentrations of FSH (p < 0.02) and amounts of FSHbeta subunit mRNA (p < 0.001) to less than 30% and 10% of control values, respectively. Despite effects of bFF on concentrations of FSHbeta mRNA and secretion of FSH, concentrations of GnRH receptor mRNA were similar among controls, ewes treated with bFF alone, and passively immunized ewes treated with bFF. Passive immunization against GnRH did not affect concentrations of GnRH receptor mRNA but resulted in a reduction (p < 0.05) in amount of LHbeta mRNA. Treatment with bFF did not affect amounts of either alpha subunit or LHbeta subunit mRNA except when combined with treatment with antiserum, when amounts of both alpha and LHbeta subunit mRNA were reduced (p < 0.05). These results do not support the hypothesis that inhibin increases concentrations of GnRH receptor mRNA in the ewe, and they provide evidence that inhibin is not an acute regulator of ovine GnRH receptor gene expression in vivo.
- Subjects :
- Animals
Cattle
Female
Follicle Stimulating Hormone blood
Follicle Stimulating Hormone genetics
Follicle Stimulating Hormone metabolism
Gene Expression drug effects
Gonadotropin-Releasing Hormone immunology
Immunization, Passive
Inhibins pharmacology
Luteinizing Hormone blood
Luteinizing Hormone genetics
Luteinizing Hormone metabolism
Ovariectomy
Ovary physiology
Pituitary Gland, Anterior drug effects
Pituitary Gland, Anterior metabolism
Protein Conformation
Receptors, LHRH metabolism
Sheep
Vaccination
Follicular Fluid metabolism
Gonadotropin-Releasing Hormone antagonists & inhibitors
RNA, Messenger genetics
RNA, Messenger metabolism
Receptors, LHRH genetics
Subjects
Details
- Language :
- English
- ISSN :
- 0006-3363
- Volume :
- 56
- Issue :
- 6
- Database :
- MEDLINE
- Journal :
- Biology of reproduction
- Publication Type :
- Academic Journal
- Accession number :
- 9166707
- Full Text :
- https://doi.org/10.1095/biolreprod56.6.1537