Promising alternative clinical uses of prostaglandin F2α analogs: beyond the eyelashes.

Prostaglandin F2α analogs, commonly prescribed for glaucoma treatment, have been shown to induce side effects such as cutaneous hypertrichosis and hyperpigmentation. Therefore, these medications have theoretic applications in the treatment of alopecia and disorders of hypopigmentation. We reviewed the literature to find original studies assessing the use of prostaglandin F2α analogs in these settings. Studies and reports were analyzed in regards to androgenic alopecia, alopecia areata, chemotherapy-induced alopecia, vitiligo, and hypopigmented scarring. Based on the results of these studies, and consideration of pathophysiologic mechanism, the most promising applications for prostaglandin F2α analogs include androgenic alopecia, chemotherapy-induced alopecia, and alopecia areata concurrently treated with corticosteroids.

Mechanisms of intracellular calcium homeostasis in developing and mature bovine corpora lutea.

Although calcium (Ca(2+)) is accepted as an intracellular mediator of prostaglandin F2 alpha (PGF2alpha) actions on luteal cells, studies defining mechanisms of Ca(2+) homeostasis in bovine corpora lutea (CL) are lacking. The increase in intracellular Ca(2+) concentration ([Ca(2+)]i) induced by PGF2alpha in steroidogenic cells from mature CL is greater than in those isolated from developing CL. Our hypothesis is that differences in signal transduction associated with developing and mature CL contribute to the increased efficacy of PGF2alpha to induce a Ca(2+) signal capable of inducing regression in mature CL. To test this hypothesis, major genes participating in Ca(2+) homeostasis in the bovine CL were identified, and expression of mRNA, protein, or activity, in the case of phospholipase Cbeta (PLCbeta), in developing and mature bovine CL was compared. In addition, we examined the contribution of external and internal Ca(2+) to the PGF2alpha stimulated rise in [Ca(2+)]i in LLCs isolated from developing and mature bovine CL. Three differences were identified in mechanisms of calcium homeostasis between developing and mature CL, which could account for the lesser increase in [Ca(2+)]i in response to PGF2alpha in developing than in mature CL. First, there were lower concentrations of inositol 1,4,5-trisphosphate (IP3) after similar PGF2alpha challenge, indicating reduced phospholipase C beta (PLCbeta) activity, in developing than mature CL. Second, there was an increased expression of sorcin (SRI) in developing than in mature CL. This cytoplasmic Ca(2+) binding protein modulates the endoplasmic reticulum (ER) Ca(2+) release channel, ryanodine receptor (RyR), to be in the closed configuration. Third, there was greater expression of ATP2A2 or SERCA, which causes calcium reuptake into the ER, in developing than in mature CL. Developmental differences in expression detected in whole CL were confirmed by Western blots using protein samples from steroidogenic cells isolated from developing and mature CL. Localization of these genes in steroidogenic luteal cells was confirmed by immunohistochemistry. Therefore, it is concluded that the cellular mechanisms that allow PGF2alpha to induce a calcium signal of greater magnitude in mature than in developing CL involve 1) greater PLCbeta activity with enhanced generation of IP3, 2) an enhanced Ca(2+) release from the ER via unrestrained RYR2 due to a decrease in SRI expression, and 3) a reduction in calcium reuptake to the ER due to lower expression of ATP2A2. Accordingly, the increase in [Ca(2+)]i induced by PGF2alpha in mature large steroidogenic cells had less dependency from extracellular calcium than in those isolated from immature CL.

Arachidonic acid supplementation enhances in vitro skeletal muscle cell growth via a COX-2-dependent pathway.

Arachidonic acid (AA) is the metabolic precursor to a diverse range of downstream bioactive lipid mediators. A positive or negative influence of individual eicosanoid species [e.g., prostaglandins (PGs), leukotrienes, and hydroxyeicosatetraenoic acids] has been implicated in skeletal muscle cell growth and development. The collective role of AA-derived metabolites in physiological states of skeletal muscle growth/atrophy remains unclear. The present study aimed to determine the direct effect of free AA supplementation and subsequent eicosanoid biosynthesis on skeletal myocyte growth in vitro. C2C12 (mouse) skeletal myocytes induced to differentiate with supplemental AA exhibited dose-dependent increases in the size, myonuclear content, and protein accretion of developing myotubes, independent of changes in cell density or the rate/extent of myogenic differentiation. Nonselective (indomethacin) or cyclooxygenase 2 (COX-2)-selective (NS-398) nonsteroidal anti-inflammatory drugs blunted basal myogenesis, an effect that was amplified in the presence of supplemental free AA substrate. The stimulatory effects of AA persisted in preexisting myotubes via a COX-2-dependent (NS-389-sensitive) pathway, specifically implying dependency on downstream PG biosynthesis. AA-stimulated growth was associated with markedly increased secretion of PGF(2α) and PGE(2); however, incubation of myocytes with PG-rich conditioned medium failed to mimic the effects of direct AA supplementation. In vitro AA supplementation stimulates PG release and skeletal muscle cell hypertrophy via a COX-2-dependent pathway.

Characterization of a rabbit kidney prostaglandin F(2{alpha}) receptor exhibiting G(i)-restricted signaling that inhibits water absorption in the collecting duct.

PGF(2alpha) is the most abundant prostaglandin detected in urine; however, its renal effects are poorly characterized. The present study cloned a PGF-prostanoid receptor (FP) from the rabbit kidney and determined the functional consequences of its activation. Nuclease protection assay showed that FP mRNA expression predominates in rabbit ovary and kidney. In situ hybridization revealed that renal FP expression predominates in the cortical collecting duct (CCD). Although FP receptor activation failed to increase intracellular Ca(2+), it potently inhibited vasopressin-stimulated osmotic water permeability (L(p), 10(-7) cm/(atm.s)) in in vitro microperfused rabbit CCDs. Inhibition of L(p) by the FP selective agonist latanoprost was additive to inhibition of vasopressin action by the EP selective agonist sulprostone. Inhibition of L(p) by latanoprost was completely blocked by pertussis toxin, consistent with a G(i)-coupled mechanism. Heterologous transfection of the rabbit FPr into HEK293 cells also showed that latanoprost inhibited cAMP generation via a pertussis toxin-sensitive mechanism but did not increase cell Ca(2+). These studies demonstrate a functional FP receptor on the basolateral membrane of rabbit CCDs. In contrast to the Ca(2+) signal transduced by other FP receptors, this renal FP receptor signals via a PT-sensitive mechanism that is not coupled to cell Ca(2+).

The yin and yang of corpus luteum-derived endothelial cells: balancing life and death.

A dense network of capillaries irrigates the corpus luteum (CL) allowing an intricate cross talk between luteal steroiodgenic and endothelial cell (EC) types. Indeed, luteal endothelial cells (LEC) play pivotal roles throughout the entire CL life-span. Microvascular endothelial cells are locally specialized to accommodate the needs of individual tissues, therefore unraveling the characteristics of LEC is imperative in CL physiology. Numerous studies demonstrated that endothelium-derived endothelin-1 (ET-1) is upregulated by the luteolytic hormone-prostaglandin F2alpha (PGF2alpha) and functions as an important element of the luteolytic cascade. To have a better insight on its synthesis and action, members of ET system (ET-1, ET converting enzyme -ECE-1 and ET(A) and ET(B) receptors) were quantified in LEC. The characteristic phenotype of these cells, identified by high ET-1 receptor expression (both ET(A), ET(B)) and low ET-1 and ECE-1 levels, was gradually lost during culture suggesting that luteal microenvironment sustains the selective phenotype of its resident endothelial cells. Proper vascularization and endothelial cell activity per se are essential for normal CL function. Therefore, factors affecting vascular growth are expected to play major role in the regulation of luteal function. Concomitantly with the angiogenic process, luteal PGF2alpha and its receptors (PGFR) are induced and maintained during most of the CL life-span, suggesting a possible role of PGF2alpha in LEC proliferation and function. Dispersed LEC expressed PGFR and incubation with the prostaglandin stimulated mitogen-activated protein kinase (MAPK) signaling cascade. PGF2alpha activated p42/44 MAPK phosphorylation also in long-term cultured LEC. In this cell type, PGF2alpha increased cell number, 3H-Thymidine incorporation and cell survival. Additionally, PGF2alpha rapidly and transiently stimulated the expression of immediate-early response genes, i.e. c-fos and c-jun mRNA, further suggesting a mitogenic effect for this prostaglandin in LEC. These data imply that PGF2alpha may assume different and perhaps opposing roles depending on luteal microenvironment.

Influence of preeclampsia or maternal intake of omega-3 fatty acids on the vasoactive effect of prostaglandin F-two-alpha in human umbilical arteries.

The vasoactive effect of prostaglandin F(2alpha) (PGF(2alpha)) was studied in in vitro perfused human umbilical arteries following maternal dietary supplementation with omega-3 fatty acids or in pregnancies complicated by a moderate degree of preeclampsia. In most preparations PGF(2alpha) induced a biphasic pressure response with a transient dilatation followed by a constrictory response. The pressure increase was significant in both groups, but no significant differences in the constrictory response or in the proportions of preparations displaying dilatatory responses were observed when compared to appropriate control groups. In conclusion, neither preeclampsia nor dietary supplementation with cod-liver oil had any significant effect on the vasoactive response to PGF(2alpha) in umbilical cord arteries.

F(2)-isoprostanes mediate high glucose-induced TGF-beta synthesis and glomerular proteinuria in experimental type I diabetes.

BACKGROUND: The recently discovered arachidonic acid derivatives, isoprostanes, are increased in pathological conditions associated with oxidative stress, such as diabetes. No role has yet been described for isoprostanes during the development of diabetic nephropathy. Cell culture in high ambient glucose has been used as a model in elucidating cellular mechanisms underlying diabetic nephropathy. Among the growth factors involved in the effect of high glucose, transforming growth factor-beta (TGF-beta) has been described as playing a key role in the development of nephropathy. METHODS: Streptozotocin-induced diabetic rats were supplemented in their diet with the antioxidant vitamin E (1000 U/kg diet). Blood and urine samples were taken to determine renal function and isoprostane concentration, as determined by gas chromatography/mass spectrometry. Glomerular mesangial and endothelial cells were cultured in high ambient glucose to determine the synthesis of isoprostanes and the role of isoprostanes in high glucose-induced synthesis of TGF-beta. RESULTS: Streptozotocin-induced diabetic rats had marked increases in plasma levels and urinary excretion rates of F(2)-isoprostanes. Dietary supplementation with vitamin E normalized (plasma) and reduced (urine) isoprostane levels and, surprisingly, improved proteinuria and blood urea nitrogen (BUN) levels. High ambient glucose increased F(2)-isoprostane synthesis in glomerular endothelial and mesangial cells in culture. Incubation of glomerular cells with F(2)-isoprostanes stimulated the production of TGF-beta. CONCLUSIONS: Increased F(2)-isoprostane synthesis during diabetes appears to be responsible in part for the increase in renal TGF-beta, a well-known mediator of diabetic nephropathy.

Antihypertensive actions of methylripariochromene A from Orthosiphon aristatus, an Indonesian traditional medicinal plant.

Methylripariochromene A (MRC) was isolated from the leaves of Orthosiphon aristatus (Lamiaceae) and subjected to the examination of several pharmacological actions related to antihypertensive activity. The following four findings were revealed from the present study: 1) MRC caused a continuous decrease in systolic blood pressure and a decrease in heart rate after subcutaneous administration in conscious male SHRSP, 2) MRC exhibited the concentration-dependent suppression of contractions induced by high K+, l-phenylephrine or prostaglandin F2alpha in endothelium-denuded rat thoracic aorta, 3) MRC showed a marked suppression of contractile force without a significant reduction in the beating rate in isolated bilateral guinea pig atria, and 4) MRC increased urinary volume and the excretion of Na+, K+ and Cl- for 3 h after oral administration with a load of saline in fasted rats. These findings indicate that MRC possesses some actions related to a decrease in blood pressure, i.e. vasodilating action, a decrease in cardiac output and diuretic action. Furthermore, it is presumed that the traditional use of this plant in the therapy of hypertension may be partially supported by these actions with MRC.

Leptin stimulates prostaglandin E2 and F2alpha, but not nitric oxide production in neonatal rat hypothalamus.

Leptin, an adipocyte-derived 16 kDa polypeptide hormone, has been found to regulate food intake and thermogenesis by modulating stimulatory and inhibitory pathways in the feeding circuitry of the hypothalamus, among which corticotropin releasing hormone (CRH). Nitric oxide (NO) and prostaglandins have been shown to be involved in both CRH neurosecretion and feeding regulation. We have investigated the role of NO, prostaglandin E2 and prostaglandin F2alpha as mediators of the hypothalamic effects of leptin and their possible involvement in leptin-stimulated CRH secretion. Using primary cultures of neonatal (5- to 6-day-old) rat hypothalamic cells, we confirmed that leptin (0.1-10 nM) stimulates CRH secretion. This effect was not blocked by L-N(G)-nitro-methyl-arginine (L-NAME, 100 microM), a NO-synthase competitive inhibitor; and leptin did not stimulate NO production. Cyclooxygenase inhibition by indomethacin (10 microM) did not modify leptin-induced CRH secretion, while leptin stimulated prostaglandin E2, and prostaglandin F2alpha secretion. In conclusion, leptin-induced hypothalamic CRH secretion is not modulated by NO-synthase- or cyclooxygenase-mediated mechanisms; leptin does not stimulate NO production, but it stimulates prostaglandin E2 and F2alpha production, which could add to the growing list of mediators of leptin signaling in the hypothalamus.

[Role of neuropeptides and "pain substances" in the formation of humoral mechanisms of experimental and postoperative pain]. / Rol' neiropeptidov i "bolevykh substantsii" v formirovanii gumoral'nykh mekhanizmov éksperimental'noi i posleoperatsionnoi boli.

Humoral mechanisms of pain caused by different factors vary. The authors compare blood concentrations of "painful substances" in experimental dogs and in patients suffering from postoperative pain relieved by electroacupuncture for assessing the role of these substances: serotonin, histamine, prostaglandin F2 alpha (PGF), and neuropeptides beta-endorphine, methionine- and leucine-enkephalines. Serotonin, histamine, and PGF participated in the nociception process in an equal measure both in dogs and humans. Notable differences were observed for neuropeptides, which can be explained by species-specific differences and by probable contribution of other neuropeptides to mechanisms of experimental and postoperative pain.

Prostaglandin and tumor necrosis factor levels in early wound inflammatory fluid: effects of parenteral omega-3 and omega-6 fatty acid administration.

Monokines are important mediators of wound healing. Specifically, the proportions of proinflammatory (tumor necrosis factor and PGE2) and antiinflammatory (PGF2 alpha) monokines may modulate its early phases. Using a polyvinyl alcohol sponge model of rat wounding, the authors determined the temporal changes in the levels of monokines in wound inflammatory fluid, and examined whether dietary manipulation for 6 days with the precursors (omega 6 fatty acids) and inhibitors (fish oil omega 3 fatty acids) of the prostaglandin-2 series influenced monokine composition of wound fluid. For 3 days before the wounding, adult rats received isocaloric, isovolemic, and isonitrogenous total parenteral nutrition (TPN), in which lipids supplied either 35% (Intralipid [IL] or fish oil emulsion [FO]) or 8% (minimal essential fatty acid; EFA) of the total calories. Control rats received isocaloric enteral chow. The controls were studied at 24, 48, 72, and 96 hours, and the experimentals at 72 hours after wounding. Cell counts were performed, and cell-free fluid was analyzed for PGE2, PGF2 alpha, and TNF. In control rats, the total WBC count was highest at 24 to 48 hours, and decreased significantly by 96 hours. The percentage of mononuclear cells progressively increased throughout the 96 hours, and the total mononuclear cell count peaked at 72 hours. The TNF and prostaglandin levels were highest at 24 hours; these decreased rapidly by 72 hours. At all time-points, the levels of PGE2 remained higher than those of PGF2 alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

Prostaglandin F2 alpha stimulates cAMP phosphodiesterase via protein kinase C in cultured human granulosa cells.

To investigate the involvement of cyclic AMP phosphodiesterase in the antigonadotrophic actions of prostaglandin F2 alpha (PGF2 alpha), human granulosa cells were cultured in serum-supplemented medium for 72 h, treated for 30 min with cloprostenol or phorbol myristate acetate (PMA) and then exposed to human chorionic gonadotrophin (hCG) +/- isobutyl-methylxanthine (IBMX) for a further 4 h. In the absence of IBMX, cloprostenol and PMA inhibited hCG-stimulated progesterone production. However, in the presence of 0.5 mM IBMX, inhibition of phosphodiesterase prevented these antigonadotrophic effects. Phosphodiesterase activity was assessed by a novel direct assay performed on intact cells after 3 days of culture. PGF2 alpha, cloprostenol and 4 beta-PMA all enhanced cAMP degradation whilst an inactive phorbol ester (4 alpha-PMA) had no effect. Down-regulation of protein kinase C by 4 beta-PMA pre-treatment prevented the subsequent stimulation of phosphodiesterase activity by both cloprostenol and 4 beta-PMA. We conclude that the antigonadotrophic actions of PGF2 alpha in cultured human granulosa cells involve a stimulation of cAMP phosphodiesterase mediated via protein kinase C.

Chemical structural requirement in gingerol derivatives for potentiation of prostaglandin F2 alpha-induced contraction in isolated mesenteric veins of mice.

We have previously reported that (+/-)-[6]- and (+/-)-[8]-gingerols potentiate prostaglandin (PG) F2 alpha-induced muscle contraction, and that other gingerol-related derivatives do not necessarily produce the same effect. The moiety necessary for potentiation was therefore investigated. 1) (+/-)-[8]-Gingerol potentiated PGF2 alpha-induced contraction to a greater extent than (+/-)-[6]-gingerol and (+/-)-hexahydrocurcumine (HHC), but [6]-shogaol produced inhibition; 2) Noradrenaline (NA)-induced contraction was inhibited in the following order: [6]-shogaol greater than (+/-)-[8]-gingerol greater than [6]-gingerdione greater than (+/-)-[6]-gingerol greater than S-(+)-[6]-gingerdiacetate (GDA) greater than [6]-dehydrogingerdione (DHG), whereas (+/-)-HHC had no significant inhibitory action; 3) [6]-gingerdione had different effects on PGF2 alpha-induced contraction, indicating inhibition just after preparation of the solution, no effect apparent after 2 h, and potentiation after 5 h; 4) [6]-gingerdione showed a change in its chemical structure after 5 h as measured by the FeCl3 reaction, and ultraviolet and 1H nuclear magnetic resonance spectra. It was concluded that the aliphatic hydroxyl group present in gingerol derivatives is necessary for potentiation of PGF2 alpha- and the keto group for inhibition of NA-induced contraction.