Relationship of oestrus synchronization method, circulating hormones, luteinizing hormone and prostaglandin F-2α receptors and luteal progesterone concentration to premature luteal regression in superovulated sheep
Ewes were treated with exogenous follicle-stimulating hormone (FSH) and oestrus was synchronized using either a dual prostaglandin F-2α (PGF-2α) injection regimen or pessaries impregnated with medroxy progesterone acetate (MAP). Natural cycling ewes served as controls. After oestrus or AI (Day 0), c...
Saved in:
Published in | Journal of reproduction & fertility Vol. 93; no. 1; p. 19 |
---|---|
Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
England
Society for Reproduction and Fertility
01.09.1991
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | Ewes were treated with exogenous follicle-stimulating hormone (FSH) and oestrus was synchronized using either a dual prostaglandin
F-2α (PGF-2α) injection regimen or pessaries impregnated with medroxy progesterone acetate (MAP). Natural cycling ewes served
as controls. After oestrus or AI (Day 0), corpora lutea (CL) were enucleated surgically from the left and right ovaries on
Days 3 and 6, respectively. The incidence of premature luteolysis was related ( P < 0·05) to PGF-2α treatment and occurred in 7 of 8 ewes compared with 0 of 4 controls and 1 of 8 MAP-exposed females. Sheep
with regressing CL had lower circulating and intraluteal progesterone concentrations and fewer total and small dissociated
luteal cells on Day 3 than gonadotrophin-treated counterparts with normal CL. Progesterone concentration in the serum and
luteal tissue was higher ( P < 0·05) in gonadotrophin-treated ewes with normal CL than in the controls; but luteinizing hormone (LH) receptors/cell were
not different on Days 3 and 6. There were no apparent differences in the temporal patterns of circulating oestradiol-17β,
FSH and LH. High progesterone in gonadotrophin-treated ewes with normal CL coincided with an increase in total luteal mass
and numbers of cells, which were primarily reflected in more small luteal cells than in control ewes. Gonadotrophin-treated
ewes with regressing CL on Day 3 tended ( P < 0·10) to have fewer small luteal cells and fewer ( P < 0·05) low-affinity PGF-2α binding sites than sheep with normal CL. By Day 6, luteal integrity and cell viability was absent
in ewes with prematurely regressed CL. These data demonstrate that (i) the incidence of premature luteal regression is highly
correlated with the use of PGF-2α; (ii) this abnormal luteal tissue is functionally competent for 2–3 days after ovulation,
but deteriorates rapidly thereafter and (iii) luteal-dysfunctioning ewes experience a reduction in numbers of small luteal
cells without a significant change in luteal mass by Day 3 and, overall, have fewer low-affinity PGF-2α binding sites.
Keywords: sheep; superovulation; premature luteal regression; prostaglandin F-2α; receptor |
---|---|
ISSN: | 1470-1626 0022-4251 1741-7899 |
DOI: | 10.1530/jrf.0.0930019 |