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- Title
Induction of ovulation in sheep using a novel recombinant gonadotropin with dual (LH and FSH) activity.
- Authors
Lemke, E. P.; Adams, B. M.; Boime, I.; Adams, T. E.
- Abstract
The biopotency of a dually active chimeric gonadotropin was evaluated using prepuberal ewe lambs. This novel gonadotropin is a monomeric glycoprotein produced by CHO cells transfected with a construct that incorporates the coding regions of the α, hLHβ, and hFSHβ subunits into a single gene (FSHβ-CTP-LHβ-CTP-α, where CTP represents the sequence encoding the C-terminal portion of hCG). Lambs (bwt = 45 ± 2 kg) received (iv) 0, 5, 10 or 20 IU/kg of the dually-active chimera (n = 6 lambs/group) at the beginning of experimentation (day 0). Follicle development and subsequent activity of corpora lutea were assessed by monitoring serum concentrations of estradiol (E2) and progesterone (P4), respectively. Ovulation rate was determined by laparoscopy on day 9. Basal serum concentrations of E2 and P4 were maintained in control animals receiving vehicle alone. Conversely, serum levels of E2 were increased (P < 0.05) above basal concentrations within 24 h of chimera administration and peak levels were noted 3-5 days thereafter. The magnitude and duration of E2 secretion varied among treatment groups in a dose-dependent manner (P < 0.05). Serum P4 was increased (P < 0.05) above basal levels by day 4 in all groups receiving the dually active gonadotropin. Ovulation rate in groups receiving 0, 5, 10 or 20 IU/kg was 0.2 ± 0.1, 2.2 ± 0.7, 1.6 ± 0.5, 1.2 ± 0.4 ova/lamb, respectively. Persistent follicular activity was also noted at laparoscopy, most prominently in animals receiving the highest dose of the chimeric protein. Collectively these observations indicate that this recombinant gonadotropin is active in sheep. The chimera stimulates growth and maturation of ovarian follicles and concurrent E2 synthesis. This suggests that both the LH and FSH activities of the gonadotropin are functionally expressed. We postulate that the prolonged physiological response induced by the chimera is due to the unique pattern of glycosylation characteristic of this novel gonadotropin. Supported by the USDA (NRI Grant 5-35203-16274).
- Subjects
UNITED States. Dept. of Agriculture; GONADOTROPIN; INDUCED ovulation; CORPUS luteum; OVARIAN follicle; SHEEP; CHIMERIC proteins
- Publication
Journal of Animal Science, 2006, Vol 84, p208
- ISSN
0021-8812
- Publication type
Article