I wonder, is this the key to the Omega-3&6 "essentiality" in
reproduction?
Taka

PPAR Res. 2008;2008:732303.

The role of peroxisome proliferator-activated receptors in the
development and physiology of gametes and preimplantation embryos.

Huang JC.

Division of Reproductive Endocrinology and Infertility, Department of
Obstetrics, Gynecology and Reproductive Sciences, University of Texas
Medical School at Houston, 6431 Fannin Street, Houston, TX 77030, USA.

In several species, a family of nuclear receptors, the peroxisome
proliferator-activated receptors (PPARs) composed of three isotypes,
is expressed in somatic cells and germ cells of the ovary as well as
the testis. Invalidation of these receptors in mice or stimulation of
these receptors in vivo or in vitro showed that each receptor has
physiological roles in the gamete maturation or the embryo
development. In addition, synthetic PPAR gamma ligands are recently
used to induce ovulation in women with polycystic ovary disease. These
results reveal the positive actions of PPAR in reproduction. On the
other hand, xenobiotics molecules (in herbicides, plasticizers, or
components of personal care products), capable of activating PPAR, may
disrupt normal PPAR functions in the ovary or the testis and have
consequences on the quality of the gametes and the embryos. Despite
the recent data obtained on the biological actions of PPARs in
reproduction, relatively little is known about PPARs in gametes and
embryos. This review summarizes the current knowledge on the
expression and the function of PPARs as well as their partners,
retinoid X receptors (RXRs), in germ cells and preimplantation
embryos. The effects of natural and synthetic PPAR ligands will also
be discussed from the perspectives of reproductive toxicology and
assisted reproductive technology.
PMID: 18354728

J Endocrinol. 2006 May;189(2):199-209.

Peroxisome proliferator-activated receptors in reproductive tissues:
from gametogenesis to parturition.

Froment P, Gizard F, Defever D, Staels B, Dupont J, Monget P.
INSERM U.418, UMR Communications Cellulaire et Différenciation,
Hôpital Debrousse, 29 rue Soeur Bouvier, 69322 Lyon, France.

Peroxisome proliferator-activated receptors (PPARalpha, PPARbeta/delta
and PPARgamma) are a family of nuclear receptors that are activated by
binding of natural ligands, such as polyunsaturated fatty acids or by
synthetic ligands. Synthetic molecules of the glitazone family, which
bind to PPARgamma, are currently used to treat type II diabetes and
also to attenuate the secondary clinical symptoms frequently
associated with insulin resistance, including polycystic ovary
syndrome (PCOS). PPARs are expressed in different compartments of the
reproductive system (hypothalamus, pituitary, ovary, uterus and
testis). Conservative functions of PPARs in mammalian species could be
suggested through several in vivo and in vitro studies, especially in
the ovary and during placental development. Several groups have
described a strong expression of PPARgamma in ovarian granulosa cells,
and glitazones modulate granulosa cell proliferation and
steroidogenesis in vitro. All these recent data raise new questions
about the biologic actions of PPARs in reproduction and their use in
therapeutic treatments of fertility troubles such as PCOS or
endometriosis. In this review, we first describe the roles of PPARs in
different compartments of the reproductive axis (from male and female
gametogenesis to parturition), with a focus on PPARgamma. Secondly, we
discuss the possible molecular mechanisms underlying the effect of
glitazones on PCOS. Like other 'insulin sensitizer' molecules, such as
metformin, glitazones may in fact act directly on ovarian cells.
Finally, we discuss the eventual actions of PPARs as mediators of
environmental toxic substances for reproductive function.
PMID: 16648288

Am J Reprod Immunol. 2007 Sep;58(3):289-310.

Peroxisome proliferator-activated receptors: new players in the field
of reproduction.

Toth B, Hornung D, Scholz C, Djalali S, Friese K, Jeschke U.
Department of Obstetrics and Gynecology, Ludwig-Maximilians-
University, Grosshadern, Munich, Germany.

Peroxisome proliferator-activated receptors (PPAR) are members of the
nuclear hormone receptor superfamily. Synthetic ligands to one family
member, PPARgamma, are currently widely used as treatment for chronic
diseases such as diabetes type II and other insulin resistances, e.g.
as seen in polycystic ovary syndrome (PCOS). Moreover, novel
approaches employing knock-out mice demonstrated that PPARgamma seems
to play a key role in placental and fetal development. This review
describes recent insights into the role of PPARs in human reproduction
with specific reference to infertility, placental maturation and fetal
development as well as disturbed pregnancy. Further, we highlight the
current knowledge on synthetic ligands to PPARgamma used as a
treatment in women with PCOS.
PMID: 17681045