Blood Flow: A Mediator of Ovarian Function1

Niswender, Gordon D.; Reimers, T. J.; Diekman, M A; Nett, T. M.

doi:10.1095/biolreprod14.1.64

Cited by 265 publications

(139 citation statements)

References 70 publications

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“…This result suggests that the route for uterine or exogenous PGF2α to the CL (blood vessels) plays a crucial role in inducing a rapid functional luteolysis. The intramuscular injection of PGF2α has been shown to induce an acute decrease in the blood flow into the CL [12], which triggers and accelerates the whole cascade of functional luteolysis. On the other hand, the present model using the MDS excluded the effect of PGF2α on the vasoconstriction of the arterioles in the CL.…”

Section: Discussionmentioning

confidence: 99%

Direct Effect of PGF2.ALPHA., TPA and lonophore A23187 on Progesterone Release from Microdialyzed Corpus Luteum inthe Cow.

Ohtani

Kobayashi

Miyamoto

1999

Journal of Reproduction and Development

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Abstract. There is general agreement that prostaglandin F2α (PGF2α) is a physiological luteolysin in the cow. Contrary to this fact, PGF2α has been shown to stimulate the progesterone (P) release from luteal cells in vitro, through the activation of intracellular protein kinase C (PKC) and free calcium ion (Ca 2+ ). To examine the possibility that an essential factor or function(s) may be lost through the process of preparing cells from the corpus luteum (CL), we evaluated the direct effect of PGF2α, TPA and ionophore A23187 on local P release within the CL in the cow, by utilizing in vivo microdialysis system (MDS). Normal cyclic Holstein cows (n=4) were superovulated with FSH and the PGF2α analogue, and on Day 8 after estrus, they were surgically implanted with the MDS (cutoff Mr=1000 kDa) into multiple CL (1-3 line/CL). The system was continuously perfused with Ringer's solution from immediately after the surgery. On Days 10-11, several CL were assigned to the control, PGF2α (10 -5 M), TPA (10 -5 M), A23187 (10 -5 M), PGF2α+A23187 and TPA+A23187. The stimulants were infused into the CL using the MDS for 6 h, and each line of the MDS was further perfused with Ringer's solution for 26 h. A 6-h infusion with PGF2α stimulated P release during infusion, but after infusion the P release was again stable around the baseline. A 6-h infusion with TPA or A23187 strongly stimulated the P release. Similarly, PGF2α+A23187 or TPA+A23187 stimulated the P release. During the last 8 h of the experiment, A23187 alone, PGF2α+A23187 or TPA+A23187 inhibited the P release, whereas TPA as well as PGF2α maintained the same level as in the control. The results indicate that the direct exposure of the microenvironment in the bovine CL to PGF2α in vivo does not result in the suppression of P release until 26 h after stimulation, and that the activation of cytosolic free calcium is more effective in inhibiting the P release than the stimulation of PKC during the following period. Thus, the results support the concept that PGF2α needs some local luteolytic intermediator(s) that may enhance the intracellular calcium concentration.

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Section: Discussionmentioning

confidence: 99%

Direct Effect of PGF2.ALPHA., TPA and lonophore A23187 on Progesterone Release from Microdialyzed Corpus Luteum inthe Cow.

Ohtani

Kobayashi

Miyamoto

1999

Journal of Reproduction and Development

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“…In rats (Wurtman 1964) and rabbits (Janson 1975) luteinizing hormone (LH) causes an increase in ovarian blood flow. However, it has been reported that, in sheep, LH treatment produces only a small increase in ovarian blood flow (Cook et al 1969;Niswender et al 1976) or has no significant effect (Hixon and Clegg 1969). On the other hand, a considerable amount of oestradiol-17 fJ is secreted by the ovaries at oestrus and this hormone is known to induce marked and prolonged increases in capillary blood flow within organs of the female genital tract (Brown et al 1974b;Brown and Mattner 1977).…”

Section: Introductionmentioning

confidence: 99%

Effects of Ovarian Hormones on Ovarian Capillary Blood Flow in Anoestrous Ewes

Brown¹,

Mattner²

1984

Aust. Jnl. Of Bio. Sci.

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The indicator fractionation technique with [86Rb ]rubidium chloride as the indicator was used to determine the relative blood flow (RBF) as a measure of capillary blood flow in the ovaries of conscious, hormonally treated, anoestrous ewes. Treatment of ewes with either progesterone only or oestradiol only had no effect on ovarian RBF, but treatment with oestradiol subsequent to progesterone caused a significant increase (P< 0.(01).Consequently, it appears that progesterone-induced sensitivity of the ovarian vasculature to the vasodilatory effects of oestradiol may be responsible for increased ovarian blood flow around oestrus in cyclic ewes.

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“…Experimental results have been divided. Studies in the ewe by Niswender et al (42) and Nett et al (43) indicate that PGF2a administration during the mid-luteal phase of the cycle results in hemodynamic changes in the ovary bearing the corpus luteum which are similar to those seen during normal luteolysis. On the other hand, several studies failed to support the hypothesis: (1) mechanical reduction of blood flow to the sheep ovary during the mid-luteal phase of the cycle did not induce luteolysis (44); (2) pora lutea transplanted to the rabbit kidney capsule, thus ruling out the possibility of hemodynamic effects upon the ovarian vein (46).…”

Section: Luteolytic Controlmentioning

confidence: 92%

Basic mechanisms of ovarian endocrine function

Schomberg¹

1978

Environ Health Perspect

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This review outlines the current understanding of ovarian endocrine development and regulation with both physiological and biochemical background to provide a framework applicable to problems concerning environmental agents and ovarian endocrine function. Two approaches are used. First, the endocrine regulation of foUicle development and corpus luteum function is considered in the classical sense, i.e., viewing these structures as gonadotropin-responsive units undergoing a programmed sequence of development and differentiation. Secondly, a relatively new area of ovarian physiology concerned with intra-ovarian regulation is explored, since this area holds potential for exploration of the direct effects of toxicological or environmental agents upon gonadal endocrine cells. Follicle DevelopmentGonadotropin-Independent and Dependent StagesThe stages of follicular maturation have been classified in a variety of ways by several different investigators, depending upon the degree of detail necessary (1, 2). For purposes of this discussion, distinction need only be made between the following: (1) the primordial follicle stage, characterized by an immature ovum surrounded by a single layer of flattened or disc-shaped granulosa cells; (2) the primary follicle stage, characterized by a transition in granulosa cell morphology to the cuboidal form followed by an increase in the number of granulosa cell layers (In the rat, oocyte growth is complete by the four-layer granulosa cell stage); and (3) Follicle development in most species, with the notable exception of the human (3), is thought to be independent of gonadotropic support up to the

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Blood Flow: A Mediator of Ovarian Function1

Cited by 265 publications

References 70 publications

Direct Effect of PGF2.ALPHA., TPA and lonophore A23187 on Progesterone Release from Microdialyzed Corpus Luteum inthe Cow.

Direct Effect of PGF2.ALPHA., TPA and lonophore A23187 on Progesterone Release from Microdialyzed Corpus Luteum inthe Cow.

Effects of Ovarian Hormones on Ovarian Capillary Blood Flow in Anoestrous Ewes

Basic mechanisms of ovarian endocrine function

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