Graduate Thesis Or Dissertation
 

In Vivo and In Vitro effects of a cyclopropenoid fatty acid on progesterone synthesis by the ovine corpus luteum

Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/1c18dh99t

Descriptions

Attribute NameValues
Creator
Abstract
  • Two experiments were conducted to examine the effect of a cyclopropenoid fatty acid on luteal cell function. In Exp. 1, 12 mature ewes were mated to a fertile ram, assigned to two groups (n = 6/group) and laparotomized on day 18 of gestation. Ewes with corpora lutea (CL) in both ovaries were unilaterally ovariectomized while ewes with a CL in one ovary only were allowed to remain intact. An extract of Sterculia foetida seeds (1.09 mg), consisting of a mixture of fatty acid methyl esters including 750 ug of sterculic acid (SA), or 1.09 mg oleic acid methyl ester (OA) was injected into the artery supplying the ovary bearing CL. Jugular blood was collected on day 18 before surgery and daily thereafter until day 30 of gestation or until detected estrus, whichever occurred first. Sera were assayed for progesterone (P₄) by radioimmunoassay. In Exp. 2, 12 mature ewes were laparotomized on day 10 of the estrous cycle and CL were removed, weighed and sliced for incubation. Corpora lutea from two ewes were pooled for each incubation. Slices of CL were preincubated in medium containing 145 ng/ml of S. foetida extract (100 ng/ml sterculic acid methyl ester) or 145 ng/ml oleic acid methyl ester (control) for 90 min. Then, slices of tissue were washed and reincubated in fresh medium containing 25 ug 22(R)- hydroxycholesterol/ml (0.079 nM final concentration) or 25 ug 5-pregnen-3βol-20-one/m1 (0.084 nM final concentration) for 120 min. Tissue plus medium were analyzed for P₄. Injection of SA or OA on day 18 of gestation caused a reduction in serum concentrations of P4 within 24 h, after which concentrations of steroid remained low and relatively constant in control and those SA-treated ewes that remained pregnant until day 30 of gestation. Three of six ewes that were injected with SA exhibited estrus within 3 to 5 days after treatment. Serum concentrations of P₄ of SA-treated ewes differed from those of OA-injected control ewes (P<0.01). Luteal tissue subjected to SA or OA in vitro did not differ in ability to synthesize P₄ during subsequent incubation in the absence of precursor substrate (incubated controls). Relative to respective incubated controls, P₄ synthesis by tissue previously exposed to SA or OA was not altered by incubation in the presence of 22(R)-hydroxycholesterol. Presence of 5-pregnen-3βol-20-one (pregnenolone) in the medium significantly increased P₄ synthesis by luteal tissue preincubated with SA or OA compared with that of controls. However, response of SA-treated tissue was markedly less than that of tissue exposed to OA (P<0.05). Results of this study suggest that $A can cause regression of CL in 50% of pregnant ewes. Apparently, the luteolytic effect of SA may be caused by its ability to interfere in the conversion of pregnenolone to P₄ by 3β- hydroxysteroid dehydrogenase.
Resource Type
Date Available
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Publisher
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome) using ScandAll PRO 1.8.1 on a Fi-6770A in PDF format. CVista PdfCompressor 5.0 was used for pdf compression and textual OCR.
Replaces

Relationships

Parents:

This work has no parents.

In Collection:

Items

Thumbnail Title Date Uploaded Visibility Actions
file details TumbelakaLigayaITA1991.pdf 2017-08-04 Public Download