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Submitted on 1 Jan 1975

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LUTEOLYSIS INDUCED BY PROSTAGLANDIN F2αCOMPARED WITH NATURAL LUTEOLYSIS INTHE EWE. AN ULTRASTRUCTURAL STUDY

Marie Corteel

To cite this version:Marie Corteel. LUTEOLYSIS INDUCED BY PROSTAGLANDIN F2α COMPARED WITH NAT-URAL LUTEOLYSIS IN THE EWE. AN ULTRASTRUCTURAL STUDY. Annales de biologie ani-male, biochimie, biophysique, 1975, 15 (2), pp.175-180. �hal-00896943�

https://hal.archives-ouvertes.fr/hal-00896943https://hal.archives-ouvertes.fr

LUTEOLYSIS INDUCED

BY PROSTAGLANDIN F2α COMPAREDWITH NATURAL LUTEOLYSIS IN THE EWE

AN ULTRASTRUCTURAL STUDY

Marie CORTEEL

Station de Physiologie de la Reproduction,Centre de Recherches de Tours, I. N. R. A., .,

37380 Nouzilly (France)

SUMMARY

Normal ovine luteolysis shows a series of transformations of luteal cell ultrastructures andultimate disappearance of organnelles. In order to know if infusion of PGF2&dquo; into the uterinevein at mid cycle induces the same luteolysis, an ultrastructural study was performed. It showedrapid disappearance of dense bodies and later appearance of numerous lipid droplets. In theseexperimental conditions, the blood supply seemed to be altered as shown among other obser-vations by scattered dead cells in the corpus luteum. With previous observations and others itis thought that PGF2! induces the release of dense bodies and inhibits the progesterone synthesischain but does not mimic natural luteolvsis in this experiment.

INTRODUCTION

Arguments in favour of an induction of natural luteolysis by PGF2« have accu-mulated since 1970. The ultrastructural transformations occurring in the corpusluteum of the ewe at the end of the oestrous cycle have been described (BjERSiNGet al., zg!o ; CoR2!!r&dquo; 1975).

By infusing pharmacological doses of prostaglandin in the uterine vein, luteo-lysis may be obtained at mid-cycle. The purpose of this work is an attempt to ans-wer the ,follow·ing question : « does luteolysis induced by exogenous prostaglandinmimic natural luteolysis ? » To our knowledge, such a comparison has been madeonly once in the pseudopregnant rabbit (Ko!RirrG and KrRTOIV, 1973). The firstultrastructural study of the effect of PGF2« was performed in the pseudo-pregnant

rat but without reference to normal luteolysis (OKAMURA et al., i9!2). In a studyin the Rhesus-Monkey (KiRTO:s and Ko!Rrrrc, 1973) PGF2

The only corpus luteum studied at H,2, observed macroscopically in a longitu-dinal section, showed two distinct areas : the deep part was white (devoid of bloodsupply) and the upper part was still pale pink. Upon observation with the electronmicroscope, the cells of the samples belonging to the deeper area were regressed andshrunk, the intercellular spaces were large and filled with collagen. This part of thecorpus luteum looked like the old corpus luteum on the first or second day of thefollowing cycle (Pl. 3 (2)), but its cells had less myelin-like structures. The cells ofthe apical area had the appearance of luteal cells on the nth day of the cycle withdense bodies persisting in the cells as well as being expelled (PI. 3 (3)).

DISCUSSION

In this study we have used only one dose of PGF2«, only two hours of infusionand only one route of administration i. e. through the uterine vein. The differencesobserved suggest some hypotheses about the luteolytic action of exogenous PGF2«when infused in the uterine vein.

i) It is known that high doses of this chemical compound have a vasoconstrictingeffect. Some authors have shown that in the ovary, the blood flow is reduced bylower pharmacological doses of infused PGF2

of the rough endoplasmic reticulum and there is an accumulation of lipid dropletsin numbers equal to or larger than the accumulation occurring at the last day inthe natural cycle. This suggests an inhibition of the progesterone synthesis chainby PGF21X. It is probably a reflection of the inhibition of cholesterol ester synthetaseor cholesterol esterase studied by BEHRMAN et ccl., (1971). In the normally function-ning corpus luteum the accumulation of cholesterol precursors is avoided by thefast turn-over of progesterone synthesis and secretion. Therefore lipid droplets donot accumulate. The progesterone synthesis inhibition provoked by PGF21X seemsto be incomplete and/or reversible below a given threshold. This would explain theineffectiveness of very low doses of PGF2«, the reappearance of dense bodies in somecells and even the resumption of activity of the apical part of the H; _ corpus luteumwithout any apparent abnormality of the cell in this region. A low dose of exogenousor endogenous PG as in the D12 corpus luteum (GoDmG, i9!3) would provoke abeginning of luteolysis i. e. a cc functional » luteolysis (BAIRD, 1975) eventually rever-sible ; a high or cumulated doses as in D,2 + D1; -!- DI6 of the cycle would provokea cc morphological » luteolysis that is irreversible with a large accumulation oflipid droplets, a transformation of all the ultrastructures and cell degeneration.

The observations reported here give rise to a discussion of the comparison bet-ween natural luteolysis and luteolysis provoked by PGF21X but with the dose usedand the route of administration chosen, we have not been able to mimic naturalluteolysis.

Colloque : Control of sexual cycles in donrcstic animalsOctobev !7-30, 1971, Xou:illy.

RÉSUMÉ

COMPARAISON DE LA I,UTEOI,YSE NATURELLE ET DE LA LUTËOLYSE INDUITEPAR I,A PROSTAGLANDINE k’2« CHEZ LA BREBIS.

ETUDE ULTRASTRUCTURALE

Une étude a été entreprise pour comparer les transformations des ultrastructures (les corpsjaunes de brebis dont la lutéolyse est induite par l’infusion de PGF2x dans la veine utérine, acelles des corps jaunes en lutéolyse naturelle. Elle montre, dans le cas de la lutëolyse provoquée,la disparition brutale des corps denses et vingt-quatre heures plus tard l’apparition d’un nombreexcessif de gouttelettes lipidiques. Il y a également une perturbation de la vascutarisation traduiteentre autres signes par des cellules mortes dispersées: dans le corps jaune. Ces observations ainsique d’autres décrites, font penser que la prostaglandine F20( entraîne la libération des corps denseset bloque la chaîne de synthèse de progestérone mais elle ne mime pas la lutéol°sc naturelle dan;ces conditions expérimentales.

REFERENCES

BAIRD D. T., SCARAMUZZI .11. C. 12., 1975. The role of pro,.-,tag]411(lills in .luteal ;egres>ion..4 n>i, 13iol.anint. 73ioch. Biophys., 15, 161-174.BEnxNtnN H. R., McDoNALD G. J., GREEP R. 0., 1971. llegulatioii of ovarian cholestero! ester- :

evidence for enzymatic sites of prostaglandin-induced loss of corpus luteum function. Lipids, 6, 791-796.BJERSING L., HAY M. 1&dquo;., MOOR R. 1B1., SHORT R. V., DEANL H. !V., 1970. &dquo;.Endocrine activity,

histochemistry and ultrastructure of ovine corpora lutea. I. IW rther I on< on regression at thehistochemistry and ultrastructure of ovine corpora lutea. I. Further observattons on regression at theend of the oestrous cycle. Z. Zellforsch., 111, 437-457. ’ ’

(attttsrLVSw _-1. Is, GILLIM S. W., 1969. The correlation of fine structure and function in steroid-secreting cells, with emphasis on those of the gonads. In The gonads, McKExrrs K. W. ed., North Hollandpublishing compagny, Amsterdam, 415-488.

CoarEEL BL, 1973. - Étude histologique de la transformation du follicule pr6ovulatoire en corps jaunechez la Brebis. I. Evolution des ultrastructures des cellules de la granulosa. Ann. Biol. anini. B och.Bto!Av.!., 13 (hors s6rie), 249-258.COI