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  • Author: L. L. FRANCHI x
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T. G. BAKER and L. L. FRANCHI

It is well known that the sequence of nuclear changes which takes place during the differentiation of the oocyte is interrupted for a relatively lengthy period towards the end of meiotic prophase. This generally occurs with the onset of the diplotene phase, although in the primordial oocytes of some mammals it is superseded by the dictyate phase (see Baker & Franchi, 1967b). The meiotic division is normally only resumed shortly before ovulation, which indicates that for a particular oocyte the `resting' period may last from a few weeks to many years (Brambell, 1956; Franchi, Mandl & Zuckerman, 1962).

On the basis of histological observations, however, certain authors have claimed that the oocytes in the cow `rest' in the pachytene stage (Henricson & Rajakoski, 1959; Rajakoski, 1965; Erickson, 1966). They consider that the diplotene stage does not appear until the

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Julieta Aisemberg, María V Bariani, Claudia A Vercelli, Manuel L Wolfson and Ana M Franchi

The initial inactivation of prostaglandins (PGs) is mediated by 15-hydroxyprostaglandin dehydrogenase (15-PGDH). PGs are potent mediators of several biological processes, including inflammation and reproduction. In uterus, PGs play a key role in infection-induced pregnancy loss, in which concentration of this mediator increased. This process is accompanied with the induction of nitric oxide synthase expression and a marked increase in uterine levels of nitric oxide. There is no information concerning nitric oxide contribution to potential changes in PG catabolism, but experimental evidence suggests that nitric oxide modulates PG pathways. The specific objectives of the study were to evaluate the protein expression of HPGD (15-PGDH) and to characterize the nitric oxide-dependent regulation of this enzyme in a model of lipopolysaccharide (LPS)-induced embryonic resorption. Results show that LPS decreased HPGD protein expression and augmented PGE synthase activity; therefore, PGE2 levels increased in uterus in this inflammatory condition. Just as LPS, the treatment with a nitric oxide donor diminished HPGD protein expression in uterine tissue. In contrast, the inhibition of nitric oxide synthesis both in control and in LPS-treated mice increased 15-PGDH levels. Also, we have found that this enzyme and PGE2 levels are not modulated by peroxynitrite, an oxidant agent derived from nitric oxide. This study suggests that LPS and nitric oxide promote a decrease in the ability of the uterus for PG catabolism during bacterially triggered pregnancy loss in mice.

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Fernando Correa, Manuel L Wolfson, Paula Valchi, Julieta Aisemberg and Ana María Franchi

The endocannabinoid system (eCS), is a complex system, comprising the main endogenous ligands anandamide and 2-arachidonoyl glycerol, the cannabinoid receptors CB1 and CB2 and the biosynthetic and degrading enzymes. Cumulative evidence shows that the eCS plays an important role in reproduction, from egg fertilization to parturition. Therefore, alterations in this system, either by recreation/therapeutic use of cannabis or deregulation of the endogenous cannabinoids, might lead to adverse pregnancy outcomes, including retardation in embryo development, poor blastocyst implantation, inhibition of decidualization, miscarriage and compromised placentation. Nevertheless, the molecular mechanisms by which the eCS participates in different stages of pregnancy remain poorly understood. In this review, we will examine the evidence from animal and human studies to support the role of the eCS in implantation, early-to-late pregnancy and placentation as well as the difficulties of targeting this system for treatment of female infertility.