| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Regular Article |
a School of Animal and Microbial Sciences, University of Reading, Whiteknights, Reading RG6 6AJ, United Kingdom
b School of Biological and Molecular Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom
ABSTRACT
The relationship between follicle growth and plasma inhibin A, FSH, LH, estradiol (E), and progesterone was investigated during the normal bovine estrous cycle and after treatment with steroid-free bovine follicular fluid (bFF) to arrest follicle development. In the first study, four heifers were monitored over three prostaglandin (PG)-synchronized cycles. Blood was collected every 2–8 h, and ovaries were examined daily by ultrasonography. Inhibin A was measured using a modified enzyme-linked immunosorbent assay that employed a new monoclonal antibody against the
subunit of bovine inhibin. Plasma inhibin A (
50 pg/ml before luteolysis) rose steadily during the induced follicular phase (P < 0.05) to a peak (125 pg/ml) coincident with the preovulatory E/LH/FSH surge. After ovulation, inhibin A fell sharply (P < 0.05) to a nadir (55 pg/ml) coincident with the secondary FSH rise. During the next 3 days, inhibin A increased to approximately 90 pg/ml in association with growth of the new dominant follicle (DF). Plasma E also rose twofold during this period, whereas FSH fell by approximately 50%. Inhibin A was negatively correlated with FSH (r = -0.37, P < 0.001) and positively correlated with E (r = 0.49, P < 0.0001). Observations on eight cycles (two cycles/heifer), in which growth of the ovulatory DF was monitored from emergence to ovulation, showed that the first-wave DF (DF1) ovulated in three cycles and the second-wave DF (DF2) in five cycles. After PG, plasma inhibin A and E increased similarly in both groups, with concomitant falls in FSH. In the former group, the restricted ability of DF1 to secrete both inhibin A and E was restored after luteolysis. Results indicate that dynamic changes in the secretion of both E and inhibin A from the DF contribute to the fall in FSH during the follicular phase and to the generation and termination of the secondary FSH surge, both of which play a key role in follicle selection. In the second study, bFF (two dose levels) was administered to heifers (n = 3–4) for 60 h starting from the time of DF1 emergence. Both doses suppressed FSH (P < 0.05) and blocked DF1 growth to the same extent (P < 0.01), although inhibin A levels were only marginally raised by the lower dose (not significant compared to controls). The high bFF dose raised (P < 0.001) inhibin A to supraphysiological levels (1 ng/ml). A large "rebound" rise in FSH occurred within 1 day of stopping both treatments, even though the inhibin A level in the high-dose bFF group was still approximately threefold higher than that in controls. This indicates that desensitization of gonadotropes to inhibin negative feedback is a contributory factor, together with reduced ovarian output of E, in generation of the post-bFF rebound in FSH.
First decision: 7 August 2000.
1 Supported by Biotechnology and Biological Sciences Research Council and Ministry of Agriculture, Fisheries and Food.
2 Correspondence. FAX: 44 118 931 0180; p.g.knight{at}reading.ac.uk
This article has been cited by other articles:
|
|
 |
|
  J.J. Ireland, A.E. Zielak-Steciwko, F. Jimenez-Krassel, J. Folger, A. Bettegowda, D. Scheetz, S. Walsh, F. Mossa, P.G. Knight, G.W. Smith, et al. Variation in the Ovarian Reserve Is Linked to Alterations in Intrafollicular Estradiol Production and Ovarian Biomarkers of Follicular Differentiation and Oocyte Quality in Cattle Biol Reprod, May 1, 2009; 80(5): 954 - 964. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. R Kayani, C. Glister, and P. G Knight Evidence for an inhibitory role of bone morphogenetic protein(s) in the follicular-luteal transition in cattle Reproduction, January 1, 2009; 137(1): 67 - 78. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Veiga-Lopez, W. Ye, D.J. Phillips, C. Herkimer, P.G. Knight, and V. Padmanabhan Developmental Programming: Deficits in Reproductive Hormone Dynamics and Ovulatory Outcomes in Prenatal, Testosterone-Treated Sheep Biol Reprod, April 1, 2008; 78(4): 636 - 647. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. S. Burns, F. Jimenez-Krassel, J. L.H. Ireland, P. G. Knight, and J. J. Ireland Numbers of Antral Follicles During Follicular Waves in Cattle: Evidence for High Variation Among Animals, Very High Repeatability in Individuals, and an Inverse Association with Serum Follicle-Stimulating Hormone Concentrations Biol Reprod, July 1, 2005; 73(1): 54 - 62. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J M Haughian, O J Ginther, K Kot, and M C Wiltbank Relationships between FSH patterns and follicular dynamics and the temporal associations among hormones in natural and GnRH-induced gonadotropin surges in heifers Reproduction, January 1, 2004; 127(1): 23 - 33. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Webb, P. C. Garnsworthy, J.-G. Gong, and D. G. Armstrong Control of follicular growth: Local interactions and nutritional influences J Anim Sci, January 1, 2004; 82(13_suppl): E63 - 74. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P.J.M. Hendriksen, B.M. Gadella, P.L.A.M. Vos, E. Mullaart, T.A.M. Kruip, and S.J. Dieleman Follicular Dynamics Around the Recruitment of the First Follicular Wave in the Cow Biol Reprod, December 1, 2003; 69(6): 2036 - 2044. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. Sisco, L. J. Hagemann, A. N. Shelling, and P. L. Pfeffer Isolation of Genes Differentially Expressed in Dominant and Subordinate Bovine Follicles Endocrinology, September 1, 2003; 144(9): 3904 - 3913. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. Jimenez-Krassel, M. E. Winn, D. Burns, J. L. H. Ireland, and J. J. Ireland Evidence for a Negative Intrafollicular Role for Inhibin in Regulation of Estradiol Production by Granulosa Cells Endocrinology, May 1, 2003; 144(5): 1876 - 1886. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K.I. Parker, D.M. Robertson, N.P. Groome, and K.L. Macmillan Plasma Concentrations of Inhibin A and Follicle-Stimulating Hormone Differ Between Cows with Two or Three Waves of Ovarian Follicular Development in a Single Estrous Cycle Biol Reprod, March 1, 2003; 68(3): 822 - 828. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Tanaka, H. Taniyama, N. Tsunoda, C. B. Herath, R. Nakai, H. Shinbo, N. Nagamine, Y. Nambo, S.-i. Nagata, G. Watanabe, et al. Localization and Secretion of Inhibins in the Equine Fetal Ovaries Biol Reprod, January 1, 2003; 68(1): 328 - 335. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Kaneko, J. Noguchi, K. Kikuchi, J. Todoroki, and Y. Hasegawa Alterations in Peripheral Concentrations of Inhibin A in Cattle Studied Using a Time-Resolved Immunofluorometric Assay: Relationship with Estradiol and Follicle-Stimulating Hormone in Various Reproductive Conditions Biol Reprod, July 1, 2002; 67(1): 38 - 45. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M.A. Beg, D.R. Bergfelt, K. Kot, and O.J. Ginther Follicle Selection in Cattle: Dynamics of Follicular Fluid Factors During Development of Follicle Dominance Biol Reprod, January 1, 2002; 66(1): 120 - 126. [Abstract] [Full Text]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
