Facilitation of colonic T cell immune responses is associated with an exacerbation of dextran sodium sulfate-induced colitis in mice lacking microsomal prostaglandin E synthase-1.

Background: Microsomal prostaglandin E synthase-1 (mPGES-1) is a key enzyme that acts downstream of cyclooxygenase and plays a major role in inflammation by converting prostaglandin (PG) H to PGE. The present study investigated the effect of genetic deletion of mPGES-1 on the development of immunologic responses to experimental colitis induced by dextran sodium sulfate (DSS), a well-established model of inflammatory bowel disease (IBD).

Methods: Colitis was induced in mice lacking mPGES-1 (mPGES-1 mice) and wild-type (WT) mice by administering DSS for 7 days.

Prostaglandin F2α Facilitates Platelet Activation by Acting on Prostaglandin E2 Receptor Subtype EP3 and Thromboxane A2 Receptor TP in Mice.

Platelets play an important role in both physiological hemostasis and pathological thrombosis. Thromboxane (TX) A and prostaglandin (PG) I are well known as a potent stimulator and an inhibitor of platelet function, respectively. Recently, PGE has also been reported to regulate platelet function via PGE receptor subtypes.

Cyclooxygenase-2 is acutely induced by CCAAT/enhancer-binding protein β to produce prostaglandin E and F following gonadotropin stimulation in Leydig cells.

Cyclooxygenase 2 (COX-2) is an inducible rate-limiting enzyme for prostanoid production. Because COX-2 represents one of the inducible genes in mouse mesenchymal stem cells upon differentiation into Leydig cells, we investigated COX-2 expression and production of prostaglandin (PG) in Leydig cells. Although COX-2 was undetectable in mouse testis, it was transiently induced in Leydig cells by human chorionic gonadotropin (hCG) administration.

Prostaglandin I suppresses the development of diet-induced nonalcoholic steatohepatitis in mice.

Nonalcoholic steatohepatitis (NASH) is a hepatic manifestation of metabolic syndrome. Although the prostaglandin (PG)I receptor IP is expressed broadly in the liver, the role of PGI-IP signaling in the development of NASH remains to be determined. Here, we investigated the role of the PGI-IP system in the development of steatohepatitis using mice lacking the PGI receptor IP [IP-knockout (IP-KO) mice] and beraprost (BPS), a specific IP agonist.

Cigarette Smoke Extract Inhibits Platelet Aggregation by Suppressing Cyclooxygenase Activity.

The results of studies that were performed to determine whether cigarette smoking affects platelet function have been controversial, and the effects of nicotine- and tar-free cigarette smoke extract (CSE) on platelet function remain to be determined. The aim of this study was to determine the effect of CSE on platelet aggregation and to clarify the mechanism by which CSE affects platelet function. CSE inhibited murine platelet aggregation induced by 9,11-dideoxy-9α,11α-methanoepoxy-prosta-5Z,13E-dien-1-oic acid (U-46619), a thromboxane (TX) A receptor agonist, and that induced by collagen with respective IC values of 1.

Diethylstilbestrol administration inhibits theca cell androgen and granulosa cell estrogen production in immature rat ovary.

Diethylstilbestrol (DES), a strong estrogenic compound, is well-known to affect the reproductive system. In this study, we investigated the effects of DES administration on gonadotropin levels and ovarian steroidogenesis in prepubertal rats. DES treatment acutely reduced serum LH levels, followed by a reduction in the expression of various steroidogenesis-related genes in theca cells.

11-Ketotestosterone Is a Major Androgen Produced in Human Gonads.

Context: 11-ketotestosterone (11-KT) is a novel class of active androgen. However, the detail of its synthesis remains unknown for humans.

Objective: The objective of this study was to clarify the production and properties of 11-KT in human.

Thromboxane A2 is Involved in Itch-associated Responses in Mice with Atopic Dermatitis-like Skin Lesions.

To investigate the mechanisms underlying itching in atopic dermatitis, we examined whether thromboxane (TX) A2, an arachidonic acid metabolite, is involved in spontaneous scratching, an itch-related response, in NC mice with atopic dermatitis-like skin lesions. The TXA2 receptor (TP) antagonist ONO-3708 inhibited the spontaneous scratching. The mRNA expression of TX synthase (TXSyn) distributed mainly in epidermis and the concentration of TXB2, a metabolite of TXA2, were increased in lesional skin.

The novel prostaglandin I2 mimetic ONO-1301 escapes desensitization in an antiplatelet effect due to its inhibitory action on thromboxane A2 synthesis in mice.

ONO-1301 [(E)-[5-[2-[1-phenyl-1-(3-pyridyl)methylidene-aminooxy]ethyl]-7,8-dihydronaphthalene-1-yloxy]acetic acid] is a novel prostaglandin (PG) I2 mimetic with inhibitory activity on the thromboxane (TX) A2 synthase. Interestingly, ONO-1301 retains its inhibitory effect on platelet aggregation after repeated administration, while beraprost, a representative agonist for the PGI2 receptor (IP), loses its inhibitory effect after repeated administration. In the present study, we intended to clarify the mechanism by which ONO-1301 escapes desensitization of an antiplatelet effect.

Prostacyclin stimulated integrin-dependent angiogenic effects of endothelial progenitor cells and mediated potent circulation recovery in ischemic hind limb model.

Background: Prostacyclin (PGI2) enhances angiogenesis, especially in cooperation with bone marrow (BM)-derived endothelial progenitor cells (EPCs). However, the mechanisms of PGI2 in EPC-mediated angiogenesis in vivo remain unclear. The purpose of this study was to clarify the role of PGI2 in EPC-mediated angiogenesis using BM-specific IP deletion mice.

17β-Estradiol is critical for the preovulatory induction of prostaglandin E(2) synthesis in mice.

Aromatase-deficient (ArKO) mice are totally anovulatory due to insufficient estrogen production. However, sequential administrations of high doses of 17β-estradiol (E2) and gonadotropins were found to induce ovulation in these mice. Here, we examined how the ovulatory stimulation for ArKO mice alters the expressions of genes related to prostaglandin (PG) E(2) metabolism and ovarian contents of PGE(2), as PGE(2) is one of the critical mediators of ovulatory induction.

The intrinsic prostaglandin E2-EP4 system of the renal tubular epithelium limits the development of tubulointerstitial fibrosis in mice.

Inflammatory responses in the kidney lead to tubulointerstitial fibrosis, a common feature of chronic kidney diseases. Here we examined the role of prostaglandin E(2) (PGE(2)) in the development of tubulointerstitial fibrosis. In the kidneys of wild-type mice, unilateral ureteral obstruction leads to progressive tubulointerstitial fibrosis with macrophage infiltration and myofibroblast proliferation.

Roles of prostanoids in the pathogenesis of cardiovascular diseases: Novel insights from knockout mouse studies.

Prostanoids consisting of prostaglandins (PGs) and thromboxanes (TXs) are produced from arachidonic acids, representative fatty acids contained in cell membrane, by the sequential actions of phospholipase A(2), cyclooxygenases and respective prostanoid synthases. Prostanoids are released outside of the cells immediately after biosynthesis and exert a wide range of actions in the body. These actions are mediated by their respective G protein-coupled receptors expressed in the target cells, which receptors include the DP, EP, FP, IP and TP receptors for PGD(2), PGE(2), PGF(2)α, PGI(2) and TXA(2), respectively.

Selective activation of the prostaglandin E2 receptor subtype EP2 or EP4 leads to inhibition of platelet aggregation.

The effect of selective activation of platelet prostaglandin (PG) E2 receptor subtype EP2 or EP4 on platelet aggregation remains to be determined. In platelets prepared from wild-type mice (WT platelets), high concentrations of PGE2 inhibited platelet aggregation induced by U-46619, a thromboxane receptor agonist. However, there was no significant change in the inhibitory effect of PGE2 on platelets lacking EP2 (EP2-/- platelets) and EP4 (EP4-/- platelets) compared with the inhibitory effect on WT platelets.

Roles of prostanoids in the pathogenesis of cardiovascular diseases.

The roles of prostanoids in the pathogenesis of cardiovascular diseases and in the development of pathological conditions have been examined using mice lacking the individual, specific prostanoid receptor. Prostaglandin (PG) I2 protected the heart from ischemia-reperfusion injury in a model of acute myocardial infarction. In addition, PGI2 suppressed the development of pressure overload-induced cardiac hypertrophy.

Prostaglandin I2 promotes recruitment of endothelial progenitor cells and limits vascular remodeling.

Objective: Endothelial progenitor cells (EPCs) play an important role in the self-healing of a vascular injury by participating in the reendothelialization that limits vascular remodeling. We evaluated whether prostaglandin I(2) plays a role in the regulation of the function of EPCs to limit vascular remodeling.

Methods And Results: EPCs (Lin(-)cKit(+)Flk-1(+) cells) were isolated from the bone marrow (BM) of wild-type (WT) mice or mice lacking the prostaglandin I(2) receptor IP (IP(-/-) mice).

Infected subdural hematoma.

A case is presented in which Escherichia coli seeded a pre-existing chronic subdural hematoma. A 77-year-old woman was admitted to our hospital because of lethargy, left hemiparesis and fever. Drainage through a burr hole was performed with the diagnosis of bilateral chronic subdural hematoma.

Prostaglandin I2 plays a key role in zymosan-induced mouse pleurisy.

Zymosan, the cell wall of Saccharomyces cerevisiae, induces innate immune responses involving prostanoid production and complement activation. However, the roles of prostanoids in zymosan-induced inflammation and their interaction with the complement system remain to be determined. To clarify these issues, we examined zymosan-induced pleurisy in mice lacking receptors for prostaglandin (PG) E(2) (EP(-/-) mice) or PGI(2) (IP(-/-) mice).

Doxorubicin induces apoptosis by activation of caspase-3 in cultured cardiomyocytes in vitro and rat cardiac ventricles in vivo.

Doxorubicin (DOX) is widely used to treat patients suffering from cancer, but the usage for patients is limited because of the dose-dependent cardiotoxicity. We hypothesized that DOX induces apoptosis through caspase activation in cardiomyocytes, and we examined this hypothesis using both rat primary cultured cardiomyocytes and rat hearts from an animal model. Cardiomyocytes were treated with DOX for 24 h.