For a long time, superoxide generation by an NADPH oxidase was considered as an oddity only found in professional phagocytes. Over the last years, six homologs of the cytochrome subunit of the phag...

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The NOX Family of ROS-Generating NADPH Oxidases: Physiology and Pathophysiology

Prostanoids are the cyclooxygenase metabolites of arachidonic acid and include prostaglandin (PG) D2, PGE2, PGF2α, PGI2, and thromboxne A2. They are synthesized and released upon cell stimulation and act on cells in the vicinity of their synthesis to exert their actions. Receptors mediating the actions of prostanoids were recently identified and cloned. They are G protein-coupled receptors with seven transmembrane domains. There are eight types and subtypes of prostanoid receptors that are encoded by different genes but as a whole constitute a subfamily in the superfamily of the rhodopsin-type receptors. Each of the receptors was expressed in cultured cells, and its ligand-binding properties and signal transduction pathways were characterized. Moreover, domains and amino acid residues conferring the specificities of ligand binding and signal transduction are being clarified. Information also is accumulating as to the distribution of these receptors in the body. It is also becoming clear for some types of ...

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Prostanoid Receptors: Structures, Properties, and Functions

Review article: free radicals, antioxidants and human disease: where are we now?

Free radicals, antioxidants, and human disease: where are we now?

PRL is an anterior pituitary hormone that, along with GH and PLs, forms a family of hormones that probably resulted from the duplication of an ancestral gene. The PRLR is also a member of a larger family, known as the cytokine class-1 receptor superfamily, which currently has more than 20 different members. PRLRs or binding sites are widely distributed throughout the body. In fact, it is difficult to find a tissue that does not express any PRLR mRNA or protein. In agreement with this wide distribution of receptors is the fact that now more than 300 separate actions of PRL have been reported in various vertebrates, including effects on water and salt balance, growth and development, endocrinology and metabolism, brain and behavior, reproduction, and immune regulation and protection. Clearly, a large proportion of these actions are directly or indirectly associated with the process of reproduction, including many behavioral effects. PRL is also becoming well known as an important regulator of immune function. A number of disease states, including the growth of different forms of cancer as well as various autoimmune diseases, appear to be related to an overproduction of PRL, which may act in an endocrine, autocrine, or paracrine manner, or via an increased sensitivity to the hormone. The first step in the mechanism of action of PRL is the binding to a cell surface receptor. The ligand binds in a two-step process in which site 1 on PRL binds to one receptor molecule, after which a second receptor molecule binds to site 2 on the hormone, forming a homodimer consisting of one molecule of PRL and two molecules of receptor. The PRLR contains no intrinsic tyrosine kinase cytoplasmic domain but associates with a cytoplasmic tyrosine kinase, JAK2. Dimerization of the receptor induces tyrosine phosphorylation and activation of the JAK kinase followed by phosphorylation of the receptor. Other receptor-associated kinases of the Src family have also been shown to be activated by PRL. One major pathway of signaling involves phosphorylation of cytoplasmic State proteins, which themselves dimerize and translocate to nucleus and bind to specific promoter elements on PRL-responsive genes. In addition, the Ras/Raf/MAP kinase pathway is also activated by PRL and may be involved in the proliferative effects of the hormone. Finally, a number of other potential mediators have been identified, including IRS-1, PI-3 kinase, SHP-2, PLC gamma, PKC, and intracellular Ca2+. The technique of gene targeting in mice has been used to develop the first experimental model in which the effect of the complete absence of any lactogen or PRL-mediated effects can be studied. Heterozygous (+/-) females show almost complete failure to lactate after the first, but not subsequent, pregnancies. Homozygous (-/-) females are infertile due to multiple reproductive abnormalities, including ovulation of premeiotic oocytes, reduced fertilization of oocytes, reduced preimplantation oocyte development, lack of embryo implantation, and the absence of pseudopregnancy. Twenty per cent of the homozygous males showed delayed fertility. Other phenotypes, including effects on the immune system and bone, are currently being examined. It is clear that there are multiple actions associated with PRL. It will be important to correlate known effects with local production of PRL to differentiate classic endocrine from autocrine/paracrine effects. The fact that extrapituitary PRL can, under some circumstances, compensate for pituitary PRL raises the interesting possibility that there may be effects of PRL other than those originally observed in hypophysectomized rats. The PRLR knockout mouse model should be an interesting system by which to look for effects activated only by PRL or other lactogenic hormones. On the other hand, many of the effects reported in this review may be shared with other hormones, cytokines, or growth factors and thus will be more difficult to study. (ABSTRACT TRUNCATED)

Prolactin (PRL) and Its Receptor: Actions, Signal Transduction Pathways and Phenotypes Observed in PRL Receptor Knockout Mice

Superoxide (O(2)(-)), hydrogen peroxide (H(2)O(2)), and lipid peroxides are generated in luteal tissue during natural and prostaglandin-induced regression in the rat, and this response is associated with reversible depletion of ascorbic acid Reactive oxygen species immediately uncouple the luteinizing hormone receptor from adenylate cyclase and inhibit steroidogenesis by interrupting transmitochondrial cholesterol transport The cellular origin of oxygen radicals in regressing corpora lutea is predominantly from resident and infiltrated leukocytes, notably neutrophils Reactive oxygen species are also produced within the follicle at ovulation and, like the corpus luteum, leukocytes are the major source of these products Antioxidants block the resumption of meiosis, whereas the generation of reactive oxygen induces oocyte maturation in the follicle Although oxygen radicals may serve important physiologic roles within the ovary, the cyclic production of these damaging agents over years may lead to an increased cumulative risk of ovarian pathology that would probably be exacerbated under conditions of reduced antioxidant status

Oxidative Stress and the Ovary

Free radicals and reactive oxygen species play a number of significant and diverse roles in reproductive biology. In common with other biological systems, mechanisms have evolved to minimize the damaging effects that these highly reactive molecules can have on reproductive integrity. Conversely, however, recent findings illustrate the constructive roles that oxygen radicals and reactive oxygen species play in a number of important junctures in the development of germ cells and the obligate endocrine support they receive for the successful propagation of the species. Specifically addressed in this review are some aspects of sperm development and action, the uterine environment, oocyte maturation and ovulation, and corpus luteum function and regression.

Oxygen radicals and reactive oxygen species in reproduction.

The relationship between follicular fluid steroid concentration and successful fertilization of human oocytes in vitro

The hypothesis that hydrogen peroxide generation occurs in the corpora lutea of superovulated rats during luteolysis was tested using a peroxide-dependent inhibitor of catalase, 3-amino-l,2,4-triazole (AT). Luteal regression was induced during midpseudopregnancy by injection of 500 jig prostaglandin F2n (PGF2n) 1 h before administration of AT (0.1 g/ kg, ip) and was confirmed by progesterone analysis of peripheral blood serum. Within groups of both PGF2a-treated and untreated control rats, other rats also received ethanol (0.2 g/kg, ip), which prevents hydrogen peroxide-mediated inhibition of catalase by AT. Diluted homogenates of ovaries removed 1 h after AT administration were assayed for catalase activity by measuring the decrease in absorbance at 240 nm for 30 sec after the addition of hydrogen peroxide (10 mM). Ethanol-sensitive catalase inhibition by AT was significantly higher (47.9 ± 3.38%) in samples from PGF2a-treated groups than in controls (23.1 ± 4.82%; P < 0.01; n = 9). Similar increases in ...

In Vivo Generation of Hydrogen Peroxide in the Rat Corpus Luteum during Luteolysis

Background: Patients with trophoblastic diseases produce ordinary and irregular forms of human chorionic gonadotropin (hCG; e.g., nicked hCG, hCG missing the b-subunit C-terminal segment, hyperglycosylated hCG, and free b subunit) that are recognized to differing extents by automated immunometric hCG (or hCGb) assays. This has led to low or false-negative results and misdiagnosis of persistent disease. False-positive hCG immunoreactivity has also been detected, leading to needless therapy for trophoblastic diseases. Here we compare seven commonly used hCG assays. Methods: Standards for five irregular forms hCG produced in trophoblastic diseases, serum samples from 59 patients with confirmed trophoblastic diseases, and serum samples from 12 women with previous falsepositive hCG results (primarily in the Abbott AxSYM assay) were blindly tested by commercial laboratories in the Beckman Access hCGb, the Abbott AxSYM hCGb, the Chiron ACS:180 hCGb, the Baxter Stratus hCG test, the DPC Immulite hCG test, the Serono MAIAclone hCGb tests, and in the hCGb RIA. Results: Only the RIA and the DPC appropriately detected the five irregular hCG standards. Only the Beckman, DPC, and Abbott assays gave results similar to the RIA in the patients with confirmed trophoblastic diseases (values within 25% of RIA in 49, 49, and 54 of 59 patients, respectively). For samples that were previously found to produce false-positive hCG results, no false-positive results were detected with the DPC and Chiron tests (5 samples, median 10 IU/L) in

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Harold R. Behrman

Papers

Oxidative Stress and the Ovary

Oxygen radicals and reactive oxygen species in reproduction.

The relationship between follicular fluid steroid concentration and successful fertilization of human oocytes in vitro

In Vivo Generation of Hydrogen Peroxide in the Rat Corpus Luteum during Luteolysis

Utility of Commonly Used Commercial Human Chorionic Gonadotropin Immunoassays in the Diagnosis and Management of Trophoblastic Diseases