GnRH analogs induce a LH peak and increase pregnancy per timed-AI in ewes

To date, there have been no studies testing the capacity of GnRH analogs and respective doses to induce a LH peak in sheep. In this sense, the present study aimed to evaluate the capacity of different synthetic forms and doses of GnRH in inducing LH release in sheep, and the effect of GnRH administration at timed artificial insemination (TAI) on pregnancy per timed-AI. In experiment 1, ewes (n = 40) received an intravaginal device (IVD) of medroxyprogesterone acetate (MPA; 60 mg) for 7 d and prostaglandin F2α analog on Day 5. On Day 7, the ewes were allocated randomly into one of eight groups (n = 5/group), which received a GnRH analog at a specific dose, as follows: lecirelin (12.5 or 25 μg), gonadorelin (50 or 100 μg), buserelin acetate (4.2 or 8.4 μg), or deslorelin (375 or 750 μg). Blood samples for LH determination were obtained at 0, 2, 4, and 6 h after GnRH and the IVDs were removed after the last blood collection. The maximal LH concentration induced by gonadorelin at doses of 50 μg and 100 μg (12.0 ± 2.4 ng/mL and 28.6 ± 7.1 ng/mL, respectively) was lower (P < 0.05) than serum LH induced by 8.4 μg of buserelin (78.9 ± 12.9 ng/mL), 375 μg and 750 μg of deslorelin (75.6 ± 7.4 ng/mL and 72.1 ± 10.6 ng/mL, respectively) and 12.5 μg and 25 μg of lecirelin (73.3 ± 17.8 ng/mL and 61.6 ± 5.9 ng/mL, respectively). However, the maximal LH concentration induced by 4.2 μg of buserelin (49.4 ± 5.9 ng/mL) was similar (P > 0.05) to the 100 μg of gonadorelin. The total release of LH (area under the curve - AUC) after treatment with 50 μg of gonadorelin (31.7 ± 5.9 ng h/mL) was lower (P < 0.05) than after other agonists. In a second experiment, 330 ewes were treated with IVD containing MPA for 7 d. Simultaneously with IVD removal, 250 μg of cloprostenol and 200 IU of eCG were administered. Then, ewes were assigned randomly to either no further treatment (control); or to receive 4.2 μg of buserelin acetate (GnRH group) at cervical TAI, which was performed with fresh semen 54 h after IVD withdrawal in all the animals. Higher pregnancy per timed-AI was observed for GnRH (50.3 %) compared to control (40.7 %). We conclude that buserelin acetate (8.4 μg), lecirelin (12.5 and 25 μg) and deslorelin (375 and 750 μg) induced a greater stimulatory effect on LH secretion than gonadorelin treatment. Furthermore, buserelin acetate treatment at TAI increased pregnancy per timed-AI in ewes previously treated with MPA and eCG.

Effect of Topical Prostaglandin F2α Analogs on Selected Oxidative Stress Parameters in the Tear Film

Background and Objectives: Topically administered antiglaucoma medications, especially those containing benzalkonium chloride (BAC), may cause local adverse effects and compromise ocular surface. The aim of the study was to assess the effect of topical prostaglandin F2α analogs (PGAs): preservative-free latanoprost, BAC-preserved latanoprost, preservative-free tafluprost, and BAC-preserved bimatoprost, on selected oxidative stress parameters in the tear film. Materials and Methods: The patients were divided into five groups: group C (n = 25) control group—subjects who did not use topical antiglaucoma medications, group L (n = 22)—patients using topical preservative-free latanoprost, group L+BAC (n = 25)—patients using topical BAC-preserved latanoprost, group T (n = 19)—patients using topical preservative-free tafluprost, and group B+BAC (n = 17)—patients using topical BAC-preserved bimatoprost. The oxidative stress markers in the tear film samples were evaluated: total protein (TP) concentration, advanced oxidation protein products (AOPP) content, total sulfhydryl (-SH) groups content, the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as Total Oxidant Status (TOS), Total Antioxidant Response (TAR), and Oxidative Stress Index (OSI). Results: The TP concentrations in the groups L, L+BAC, and B+BAC were statistically significantly higher in comparison with group C. The SOD and CAT activities in the groups L+BAC and B+BAC were statistically significantly higher when compared to group C. As compared to group C, AOPP and TOS were statistically significantly higher in all the study groups. OSI was found to be statistically significantly higher in the groups L+BAC, T, and B+BAC in comparison with group C. Conclusion: Use of topical PGAs by the patients with ocular hypertension or primary open-angle glaucoma is associated with increased oxidative stress in the tear film which is additionally exacerbated by the presence of BAC in the formulation.

Meibomian gland dropout rate as a method to assess meibomian gland morphologic changes during use of preservative-containing or preservative-free topical prostaglandin analogues

PURPOSE

To investigate the usefulness of meibomian gland (MG) dropout rate in the evaluation of MG morphological change associated with the use of prostaglandin for glaucoma treatment through the association between MG and the ocular surface parameters and medication duration and presence of preservative.

METHODS

This cross-sectional study was conducted on 88 eyes of 88 patients who were diagnosed with glaucoma and used only Tafluprost as treatment. The patients were divided into four "user" groups: 1) 23 patients used preservative-free (PF) Tafluprost for 6 months; 2) 21 patients used preservative-containing (PC) Tafluprost for 6 months; 3) 23 patients used PF-Tafluprost for 24 months; 4) 21 patients used PC-Tafluprost for 24 months. Ocular surface parameters and the MG condition, including MG dropout rate and meiboscale, were evaluated. Multiple regression was used to identify associations.

RESULTS

There were significant differences in age (p = 0.003), tear breakup time (p = 0.016), lid margin abnormality (p = 0.016), expressibility (p = 0.039), meiboscale (p<0.001), and MG dropout rate (p<0.001) among the 4 groups. MG dropout rate and meiboscale showed significant differences in all post hoc analyses, except for the comparison between the PF-Tafluprost and PC-Tafluprost 6-month user groups. Medication duration, preservative status, and meiboscale were significantly correlated with MG dropout rate (p<0.001, p = 0.024, p<0.001, respectively). In the 6-month user group, preservative status significantly correlated with MG dropout rate (p = 0.015). However, in the 24-month user group, meiboscale was the only parameter significantly associated with MG dropout rate (p<0.001).

CONCLUSION

MG dropout rate in patients using Tafluprost showed a significant correlation with medication duration and preservative status. This result indicates MG dropout rate reflects MG morphologic change associated with prostaglandin.

Preperimetric Glaucoma Prospective Observational Study (PPGPS): Design, baseline characteristics, and therapeutic effect of tafluprost in preperimetric glaucoma eye

Purpose

There is no consensus on the diagnosis or treatment policy for Preperimetric Glaucoma (PPG) because the pathogenesis of PPG is not clear at this time. Preperimetric Glaucoma Prospective Observational Study (PPGPS) is a first multicenter, prospective, observational study to clarify the pathogenesis of PPG. This article indicates study design, patient baseline characteristics, and analysis focused on optic nerve head (ONH) blood flow in PPG, as well as the intraocular pressure (IOP) -lowering effect and ONH blood flow-improving effects of Tafluprost.

Method

In this study, 122 eyes from 122 subjects (mean age: 53.1 ± 14.3) newly diagnosed as PPG were enrolled. The circumpapillary retinal nerve fiber layer thickness (cpRNFLT) was evaluated with optical coherence tomography (OCT). The ONH blood flow was measured with laser speckle flowgraphy. The therapeutic effect of Tafluprost was evaluated at Month 0 (ONH blood flow-improving effect) and Month 4 (IOP-lowering effect).

Results

The untreated IOP, cpRNFLT, and baseline Mean deviation (MD) value was 16.4 ± 2.5 mmHg, 80.4 ± 8.2 μm, and -0.48 ± 1.29 dB, respectively. In the site-specific visual field evaluation using the sector map, there was no appreciable site-specific visual field defect in the eye with PPG. The inferior region of cpRNFLT in 4-quadrant OCT sector analysis and 6 o’clock region in 12-o’clock OCT sector analysis was the highest rate of abnormality in PPG eyes. Topical administration of Tafluprost significantly reduced IOP from 16.4 ± 2.5 mmHg at baseline to 14.5 ± 2.3 mmHg at Month 4 (P < 0.001, paired t-test). In the linear regression analysis, there was a significant relationship between the increase of ONH blood flow and baseline value.

Conclusion

PPGPS is a first prospective study focusing on the pathology of PPG. This study is expected to elucidate the pathology of PPG, with evidence useful for determining a treatment strategy for PPG.

A Novel Convergent Synthesis of the Potent Antiglaucoma Agent Tafluprost

Tafluprost (AFP-168, 5) is a unique 15-deoxy-15,15-difluoro-16-phenoxy prostaglandin F₂α (PGF_2α) analog used as an efficacious ocular hypotensive agent in the treatment of glaucoma and ocular hypertension, as monotherapy, or as adjunctive therapy to β-blockers. A novel convergent synthesis of 5 was developed employing Julia–Lythgoe olefination of the structurally advanced prostaglandin phenylsulfone 16, also successfully applied for manufacturing of pharmaceutical grade latanoprost (2), travoprost (3) and bimatoprost (4), with an aldehyde ω-chain synthon 17. The use of the same prostaglandin phenylsulfone 16, as a starting material in parallel syntheses of all commercially available antiglaucoma PGF_2α analogs 2–5, significantly reduces manufacturing costs resulting from its synthesis on an industrial scale and development of technological documentation. Another key aspect of the route developed is deoxydifluorination of a trans-13,14-en-15-one 30 with Deoxo-Fluor. Subsequent hydrolysis of protecting groups and final esterification of acid 6 yielded tafluprost (5). The main advantages are the preparation of high purity tafluprost (5) and the application of comparatively cheap reagents. The preparation and identification of two other tafluprost acid derivatives, tafluprost methyl ester (32) and tafluprost ethyl amide (33), are also described.

Advantages of Efficacy and Safety of Fixed-Dose Tafluprost/Timolol Combination Over Fixed-Dose Latanoprost/Timolol Combination

Purpose

To compare the safety and efficacy of fixed-dose tafluprost/timolol combination (Taf/T-FDC) with those of fixed-dose latanoprost/timolol combination (Lat/T-FDC) by measuring the intraocular pressure (IOP)-lowering effect, ocular pharmacokinetics, and ocular surface toxicity.

Methods

The IOP-lowering effect of Taf/T-FDC and Lat/T-FDC in ocular normotensive monkeys was evaluated at 4 and 8 h after instillation in study A, at 12, 14, 16, and 18 h after instillation in study B, and at 24, 26, 28, and 30 h after instillation in study C. Drug penetration into the eye was evaluated by measuring the concentrations of timolol, tafluprost acid (active metabolic form of tafluprost), and latanoprost acid (active metabolic form of latanoprost) using liquid chromatography coupled with tandem mass spectrometry after single instillation of Taf/T-FDC or Lat/T-FDC to Sprague Dawley rats. Cytotoxicity following 1–30 min exposure of SV40-transformed human corneal epithelial cells to Taf/T-FDC or Lat/T-FDC was analyzed using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assays. Undiluted and 10-fold diluted solutions of each FDC were evaluated.

Results

The IOP-lowering effect of Taf/T-FDC was almost equivalent to that of Lat/T-FDC at 4–8 h after instillation. The peak IOP reduction of Taf/T-FDC and Lat/T-FDC was observed at 8 h after instillation, and there is no difference between the two. The difference between them was observed at 24–30 h after instillation, and Taf/T-FDC demonstrated a significantly greater IOP-lowering effect than Lat/T-FDC at 24–30 h after instillation. The IOP-lowering effect of Taf/T-FDC was sustained up to 30 h after instillation, while that of Lat/T-FDC had almost disappeared at 28 h after instillation. Timolol concentrations in aqueous humor after Taf/T-FDC instillation were higher than those after Lat/T-FDC instillation (C_max, 3870 ng/mL vs 1330 ng/mL; AUC_inf, 3970 ng·h/mL vs 1250 ng·h/mL). The concentrations of tafluprost acid and latanoprost acid in aqueous humor after instillation of Taf/T-FDC and Lat/T-FDC, respectively, were similar to those after instillation of mono-preparations of tafluprost and latanoprost, respectively. The cytotoxic effect of Taf/T-FDC to the human corneal epithelial cells was significantly lower than that of Lat/T-FDC at all evaluated time points in both undiluted and 10-fold diluted FDCs.

Conclusion

Taf/T-FDC provides increased IOP-lowering effect duration and lower potential ocular surface toxicity than Lat/T-FDC.

A concept for the control of kidney production of erythropoietin involving prostaglandins and cyclic nucleotides

Our hypothesis is that PGs released within the kidney play a role in the modulation of kidney production of Ep. PGs release probably at medullary and/or cortical sites following erythropoietic stimuli such as hypoxic hypoxia, anemic hypoxia, and ischemic hypoxia induced by renal artery constriction increase kidney production of Ep. PGs which are released probably activate a renal cortical adenylate cyclase thereby enhancing the production of intracellular cAMP. This initiates the cascade of events resulting in the production and/or secretion of Ep by the kidney. The endoperoxide analogs and PGE2 have been found to produce a dose-related and Ep-dependent increase in radioiron incorporation into newly formed red blood cells of exhypoxic polycythemic mice. Indomethacin, a potent PG cyclo-oxygenase inhibitior, attenuates Ep production and the appearance of PGE in the renal venous effluent of animals exposed to hypoxic hypoxia and renal artery constriction. Arachidonic acid (C20:4) and PGE2 infusion into the posthypoxic isolated perfused dog kidney produced a significant elevation in Ep titers in the perfusate. The increase in Ep production caused by arachidonate is blocked by indomethacin. It has been previously reported that PGs of the E series stimulate cAMP formation in several tissues. We have found that not only are renal cortical cAMP levels significantly elevated in rats following exposure to hypobaric hypoxia but that dibutyryl cAMP administration produces an increase in hematocrit and circulating red cell mass in normal mice. Our data thus far strongly support the hypothesis that the renal PGs and the cyclic nucleotides are intimately involved in the pharmacologic and/or pathophysiologic control of Ep production. Further work is necessary to determine whether the PGs and cyclic nucleotides are involved in the day-to-day control of Ep production by the mammalian kidney.

[Tafluprost--a novel prostaglandin F2alpha analogue]

The review provides a brief history of the evolution of ophthalmic containers: from glass vials to plastic bottles with obligatory preservatives and, finally, to preservative-free polypropylene single-use single-dose tubes. A brief characteristic of benzalkonium chloride, the most commonly used preservative, including mechanisms of its antiseptic activity and ocular toxicity is given. The problem of ocular surface damage, especially in glaucoma patients, due to the long-term use of preserved eye drops, is discussed. Pharmacodynamics of tafluprost, the first commercially available preservative-free single-dose prostaglandin analogue, is described. Operating characteristics of experimental preclinical studies and the first three phases of clinical trials of tafluprost are provided. Post-approval studies of the comparative efficacy and tolerability of the new drug are analyzed and its prospects for clinical use are assessed.

New drug update: 2012

Five new drugs that are used for medical problems often experienced by the elderly have been selected for consideration in this review. The uses and most important properties of these agents are considered, and a rating for each new drug is determined. The rating is based on a comparison of the new drug with related drugs already marketed. Advantages, disadvantages, and other important information regarding the new drug are identified and used as the basis for determining the rating.

Tafluprost: a novel prostaglandin analog for treatment of glaucoma

OBJECTIVE

The objective of this review is to evaluate the safety and efficacy of tafluprost, a fluoroprostaglandin receptor analog, for reduction of intraocular pressure in open angle glaucoma and ocular hypertension.

METHODS

A search of published literature was performed on the PubMed database using the search term "tafluprost." The literature search identified 48 publications, including clinical and preclinical studies, from 2003 to 2011. From these ressults, articles available in the English language and in full text were selected and systematically reviewed by the authors.

RESULTS

Recent studies have shown that tafluprost is an effective IOP-lowering medication. Evidence based medicine also reveals that tafluprost is safe and well-tolerated. Preservative-free tafluprost is as potent as the preserved formulation, but with fewer and milder ocular surface side effects.

CONCLUSION

Since its introduction in 2008, initial studies have demonstrated that preserved and preservative-free tafluprost formulations have proven efficacy and safety in the treatment of glaucoma and ocular hypertension. Larger studies with longer follow-up are needed to assess long-term safety, efficacy, and tolerability compared with other prostaglandin analogs used for treating glaucoma.

Response of the rabbit isolated testicular capsule at hypothermic and hyperthermic temperatures to norepinephrine, acetylcholine and prostaglandin F2 alpha

Spontaneous contractions of the adult rabbit isolated testicular capsule were found to be influenced by moderate hyperthermic and hypothermic temperature changes. The decrease in testicular capsular spontaneous contractions resulting from an exposure to 32, 40 and 42 degrees C have been shown to be influenced by the addition of NE, ACh and PGF2 alpha. Of the three neurohumoral agents studied, NE was found to cause the greatest increase and re-initiation of testicular capsular tone during both hypothermia and hyperthermia. These data indicate that endogenous levels of neurohumoral agents may play an important role in the maintenance of testicular capsular tone during exposure to hyperthermic or hypothermic conditions.

Effects of prostaglandins on the smooth muscle of the urinary tract

A short review is given of the effects of prostaglandins on the smooth muscle of the bladder, urethra and ureter. In several animal species and in man, prostaglandins of the E and F types contract the detrusor. The contractions develop slowly and are not affected by tetrodotoxin, phenoxybenzamine, or atropine, suggesting a direct effect on the smooth muscle cell. However, evidence is also available suggesting a role of the prostaglandins as modulators of transmitter release in the bladder. In animals as well as in man, urethral smooth muscle is contracted by prostaglandin F2alpha, but relaxed by prostaglandins E1 and E2. The smooth muscle of the ureter seems to react similarly, but published results vary. The detailed mode of action, and the role of prostaglandins in the control of activity in urinary tract smooth muscle remain to be established.

[Receptors involved in the mechanism of action of topical prostaglandines]

Hypotensive effect to prostaglandins analogs (latanoprost, travoprost, tafluprost) means to increase uveoscleral outflow by action to FP receptors who generated extracellular matrix changes and intermuscular spaces changes. Syntetic prostamides analogs (bimatoprost) have a particulary action with a receptors most and intensive studied. The bimatoprost effect is the consequences to preferated stimulations on the specific receptors who have action only the tissue with prostaglandins activity is important to specify what the bimatoprost have dual effect: to uveoscleral outflow and classic outflow by increase hidraulic conductivity.

Efficacy and safety levels of preserved and preservative-free tafluprost are equivalent in patients with glaucoma or ocular hypertension: results from a pharmacodynamics analysis

PURPOSE

Tafluprost is a new prostaglandin F(2alpha) (PGF(2alpha)) derivative in development for the treatment of glaucoma. Tafluprost is the first PGF(2alpha) analogue with a preservative-free formulation.

METHODS

This randomized, investigator-masked, multicentre, crossover phase III study evaluated the pharmacodynamics and safety of preserved and preservative-free tafluprost 0.0015% eyedrops administered for 4 weeks in 43 patients with open-angle glaucoma or ocular hypertension. The primary variable was change from baseline in overall diurnal intraocular pressure (IOP) at 4 weeks. Adverse events and other safety parameters were also analysed.

RESULTS

Decreased IOP was clearly observed with both formulations at week 1 and was sustained until week 4. The overall treatment difference (preservative-free versus preserved formulations) at week 4 was 0.01 mmHg (95% confidence interval - 0.46 to 0.49; p = 0.96). There were no unexpected safety-related findings. Both formulations were well tolerated and most adverse events were ocular and mild in severity.

CONCLUSIONS

THE reduction in IOP achieved by preservative-free tafluprost is equivalent to that obtained with the preserved formulation. The preservative-free formulation was generally well tolerated.

Relaxing effect and mechanism of tafluprost on isolated rabbit ciliary arteries

Our objective was to determine if tafluprost, a newly synthesized antiglaucoma drug, can relax precontracted rabbit ciliary arteries, and if so, to elucidate the underlying mechanism. We used isometric tension recordings of smooth muscle contractions and fluorescence photometry to monitor the change of intracellular free calcium concentration ([Ca(2+)](i)) in isolated rabbit ciliary artery segments. Tafluprost induced a concentration-dependent relaxation in rabbit ciliary arteries precontracted with a high-K solution. The amplitude of relaxation induced by tafluprost was unchanged by 100 microM L-NAME, 10 microM indomethacin, denudation of vascular endothelium, 30 microM thapsigargin, or 100 microM ouabain. In Ca(2+)-free solution, 30 microM tafluprost did not decrease the amplitude of contraction induced by 1 microM histamine or the amplitude of the [Ca(2+)](i) increase induced by 10 microM histamine. The mechanism of tafluprost-induced relaxation was different from diltiazem, a voltage-dependent Ca(2+) channel blocker. However, in thapsigargin-pretreated preparations incubated in Ca(2+)-free solution, tafluprost attenuated the capacitative increase of [Ca(2+)](i) upon Ca(2+) reintroduction to the extracellular medium. Thus, we conclude that tafluprost relaxed isolated rabbit ciliary artery segments precontracted with a high-K solution. The relaxing mechanism was not dependent on endothelial-derived factors, and not affected by the intracellular Ca(2+) cycles or the Ca(2+) extrusion component of the extracellular Ca(2+) cycles. Relaxation of rabbit ciliary artery smooth muscle by tafluprost may be due, at least in part, to inhibition of capacitative Ca(2+) entry from the extracellular space.

Prostaglandin receptors in the airways

An analysis of the effects of some natural prostaglandins and of synthetic analogues with more selective actions points to the existence of several receptors for prostaglandins in the airways. Three effects have been studied: the contraction and relaxation of bronchial smooth muscle in vitro and the cough elicited by inhalation of prostaglandin aerosols by the conscious cat. From the rank orders of potency of a group of prostaglandins and analogues, from tachyphylaxis induced by continued exposure to a single species and from antagonism by indomethacin or mefenamic acid, three prostaglandin receptors have been distinguished: (1) for contraction (chi receptor) and (2) for relaxation (psi receptor) of bronchial smooth muscle, and (3) for cough (omega receptor). The natural prostaglandins tested stimulated to different extents each of these three receptors; but synthetic analogues with selective actions on only one or two receptors were identified. It seems likely that (1) prostaglandins or thromboxanes not yet tested will interact with these receptors, (2) other receptors for these substances may be distinguished in the airways, (3) the receptors so far distinguished may also be found in other sites, and (4) the receptor categories described may be subdivisible.

Dilatation of the uterine cervix

Dilatation of the cervix at parturition necessitates changes in the physical characteristics of cervical collagen and glycosaminoglycans which are probably hormone-dependent. The infusion of prostaglandin F2alpha (PGF2alpha) into the arterial blood supply to uterus and cervix of sheep pregnant for about 125 days resulted in cervical dilatation after 24 hours but this response was inconsistent; one factor affecting the response appeared to be the progesterone status, low circulating progesterone being associated with dilatation. Preliminary experiments in goats in which pregnancy is terminated by removal of the corpora lutea at day 125, subject to modification by the administration of progesterone, indomethacin or PGF2alpha, support the view that PGF2alpha evokes softening and dilatation of the cervix but that this is blocked by progesterone.

The role of prostaglandins in parturition, with special reference to the rat

The evidence which suggests a role for prostaglandins in parturition is reviewed, with special reference to experimental observations on the rat. The pregnant uterus can both synthesize and metabolize prostaglandins. The biosynthetic capacity of the rat uterus increases as pregnancy proceeds. This increase, which is especially marked during the last few days of pregnancy, may be oestrogen-controlled. During pregnancy the tissue levels of the major prostaglandin-metabolizing enzyme, 15-hydroxyprostaglandin dehydrogenase (EC 1.1.1.141) is greatly increased. This may prevent aberrant production of prostaglandins from terminating the pregnancy prematurely. The capacity for prostaglandin metabolism begins to fall (perhaps under hormonal control) as the expected day of delivery approaches; this, coupled with an augmented biosynthesis, produces a net increase in uterine prostaglandins which contribute to the process of parturition by causing a decrease in progesterone concentration, increasing the muscular tone of the uterus, and altering uterine haemodynamics. Agents which block either prostaglandin synthesis or metabolism delay or accelerate the parturition process in the rat.

Role of eicosanoids of the contralateral kidney in maintenance of two-kidney, one-clip renovascular hypertension in rats

OBJECTIVE

To elucidate the role of the eicosanoids prostaglandin E(2) (PGE(2)), 6-keto-prostaglandin F(1a) (PGF(1a)) and thromboxane B(2) (TXB(2)) in the maintenance of two-kidney, one-clip renovascular hypertension in rats.

MATERIAL AND METHODS

The right renal artery was constricted by a silver clip in 63 male Sprague-Dawley rats to induce hypertension, while a sham operation was performed in 17 control rats. Six months after the induction of hypertension, nephrectomy of the clipped kidney was performed. Nephrectomy was followed by a period of high sodium intake. Blood pressure and eicosanoid excretion were measured before and after nephrectomy of the clipped kidney, as well as during high sodium intake.

RESULTS

During the chronic phase of Goldblatt hypertension, the amount of vasoconstrictive TXB(2) excreted by the contralateral kidney increased compared to that in the controls, whereas PGE(2) excretion was unaffected. Eicosanoid excretion before and after removal of the clipped kidney did not differ between post-Goldblatt hypertensive and post-Goldblatt normotensive animals. During the period of high sodium intake, PGE(2) excretion increased only in control rats, being unaltered in Goldblatt hypertensive rats.

CONCLUSIONS

In the chronic phase of two-kidney, one-clip renovascular hypertension, the contralateral kidney of post-Goldblatt hypertensive and post-Goldblatt normotensive rats excretes more vasoconstrictive thromboxane in comparison to controls, whereas excretion of vasodilatory prostaglandin is not elevated. However, increased TXB(2) excretion and the absence of an increase in PGE(2) excretion from the contralateral kidney do not appear to be important for the maintenance of high blood pressure in this model of renovascular hypertension.

A Comparative, Placebo-Controlled Study of Prostanoid Fluoroprostaglandin-Receptor Agonists Tafluprost and Latanoprost in Healthy Males

OBJECTIVE

The aim of this study was to determine the safety, tolerability, and pharmaco-dynamics of a novel prostanoid fluoroprostaglandin (FP)-receptor agonist, tafluprost (AFP-168), in healthy males.

METHODS

This was a phase I study in healthy males 18-45 years of age (N = 49). Participants were randomized to receive 1 of 4 eye drops: tafluprost 0.0025% or 0.005%, latanoprost 0.005%, or a placebo, administered once-daily for 7 days, with 1 drop per eye. Safety and tolerability assessments and intraocular pressure (IOP) measurements were performed at defined intervals.

RESULTS

Tafluprost was generally well tolerated. No serious adverse events were reported and no participants withdrew owing to an adverse event. IOP decreased over time, compared with baseline, in all 4 treatment groups. Treatment with tafluprost 0.005% resulted in a significantly greater reduction in IOP, compared with either latanoprost 0.005% or a placebo, at various time points during treatment. Ocular hyperemia and photophobia were more common with tafluprost 0.0025% or 0.005%, compared with latanoprost 0.005%.

CONCLUSIONS

Tafluprost eye drops 0.0025% and 0.005% were generally well tolerated and safe. Tafluprost 0.005% reduced IOP more than placebo or latanoprost 0.005%. Therefore, tafluprost looks promising for further investigation.

Vasoactive Peptides in the Luteolytic Process Activated by PGF2alpha in Pseudopregnant Rabbits at Different Luteal Stages1

To study the role of endothelial factors in luteal function, the dynamic profiles of genes for endothelin 1 (EDN1), its receptor subtypes, EDNRA and EDNRB, and angiotensin converting enzyme (ACE) were examined in corpora lutea (CL) obtained from rabbits on Days 4 and 9 of pseudopregnancy after prostaglandin (PG) F2alpha analogue (alfaprostol) treatment. The cell type distribution of EDN1 in the ovaries and its mechanisms of actions in vitro and in vivo were also studied. Positive immunostaining for EDN1 was localized in the luteal and endothelial cells, in granulosa cells of the follicles, and in the ovarian epithelium. The basal mRNA levels for EDNRA, EDNRB, and ACE were lower (P </= 0.01) in Day-4 CL than in Day-9 CL, whereas those for EDN1 did not differ between these two time-points. On Day 4, the luteal EDN1, EDNRA, EDNRB, and ACE mRNA levels were similarly increased two-fold (P </= 0.01) 1.5 h after alfaprostol injection, and did not show further changes in the subsequent 24 h. On Day 9, alfaprostol challenge transiently up-regulated (P </= 0.01) the luteal ACE transcripts at 1.5 h, and those of EDN1 at 1.5 h and 3 h, whereas the EDNRA and EDNRB transcript levels remained unchanged during the course of luteal regression. EDN1 decreased (P </= 0.01) progesterone release and increased (P </= 0.01) PGF2alpha secretion and NOS activity via the PLC/PKC pathway in Day-9 CL, but not in Day-4 CL, cultured in vitro. EDN1-induced, but not alfaprostol-induced luteolysis, was blocked by cotreatment in vivo with the ACE antagonist captopril. These findings support the hypothesis that PGF2alpha regulates luteolysis through intraluteal activation of the renin-angiotensin/EDN1 systems in CL that have acquired luteolytic competence.

Physiological and pathological observations on rat middle cerebral arteries and human AVM tissue cultures following single high-dose gamma irradiation

In vitro isometric myograph and histopathological studies were performed on rat middle cerebral arteries (MCAs) to explore changes in contractile capacity following experimental Gamma Knife radiosurgery. Right MCAs were treated with 25 Gy and 50 Gy at the 50% isodose line, while contralateral vessels received 15 Gy and 20 Gy at the 20% isodose region. Survival period varied from 3 to 18 months. Reduction in contractile capacity of irradiated normal rat MCAs was detected but their lumina remained patent. In another study, we investigated human AVM tissue cultures in order to detect genetic and phenotypic modifications contributing to vessel occlusion after irradiation. In culture, the proliferation index decreased considerably following 15-, 20-, 25- or 50-Gy irradiation at the 5th posttreatment day and remained depressed during the observation period of 14 days. P53, p21Waf-1 and mdm-2 mRNA contents were elevated significantly after irradiation, indicating enhanced apoptosis. Immunohistochemistry revealed vigorous vimentin positivity in the nonirradiated control AVM cultures, which gradually decreased by the time in the irradiated specimens. Smooth muscle alpha-actin positivity was prominent in the irradiated cultivated samples, suggesting transformation of resting fibroblasts onto activated myofibroblastic elements with contractile capacity. This transformation process was confirmed by the appearance of TGF-Beta in the irradiated AVM cell lines also. These data support the hypothesis that one of the contributing factors to AVM shrinkage and obliteration after radiosurgery might be fibrocyte-myofibroblastic cell transformation in the vessel wall.

The IOP-lowering effects and mechanism of action of tafluprost in prostanoid receptor-deficient mice

AIM

To clarify the intraocular pressure (IOP)-lowering profile of tafluprost, a newly synthesised prostaglandin F(2alpha) analogue, in mice.

METHODS

C57BL/6J, and EP1, EP2, EP3 and postaglandin F (FP) receptor-deficient wild-type (WT), EP1KO, EP2KO, EP3KO and FPKO, respectively mice were bred and acclimatised under a 12-h (6:00-18:00) light-dark cycle. To evaluate effects of tafluprost (0.002%) on IOP at night, a single 3 microl drop of tafluprost solution was applied topically at 18:00 once into one eye in each mouse. IOP was measured 3 h after the application with a microneedle method. To clarify whether endogenous prostaglandin is concerned with the tafluprost-induced IOP reduction, we applied 0.1% diclofenac Na, a cyclo-oxygenase inhibitor or PBS 30 min before the application of tafluprost in WT and EP3KO mice and measured IOP 3 h after the tafluprost application. We also determined whether animals responded predictably to 0.1% bunazosin HCl, a drug known to increase uveoscleral outflow.

RESULTS

3 h after the application of 0.0015% tafluprost, mean (SEM) IOP reductions were 25.8 (2.1)% 26.3 (0.8)% 24.2 (1.4)% 16.5 (1.7)% and -0.9 (1.5)% in WT, EP1KO, EP2KO, EP3KO and FPKO mice, respectively. IOP reductions in EP3KO and FPKO mice were significantly smaller than in WT mice. Pretreatment with diclofenac Na significantly attenuated the IOP lowering effect of tafluprost in WT mice but not in EP3KO mice. Bunazosin HCl lowered IOP significantly in all genotypes by the same amount.

CONCLUSION

We conclude that tafluprost lowers IOP through the prostanoid FP receptor. A part of ocular hypotensive effect of tafluprost is attributed to FP receptor-mediated prostaglandin production acting through the prostanoid EP3 receptor.

Gap junctional connexin 37 is expressed in sheep ovaries

The objective of current study was to evaluate the expression of Cx37 in ovarian follicles and in corpora lutea (CL) during the estrous cycle in sheep. Ovine Cx37 was cloned and characterized to design speciesspecific probe and primers. In Exp. 1, ovaries were collected on d 13, 14, 15, and 16 of the estrous cycle, or from FSH-induced ewes at 0, 2, 4, 8, 12, 24, and 48 h after hCG treatment on d 15 of the estrous cycle. In Exps. 2 and 3, CL were collected on d 5, 10, and 15 of the estrous cycle, or at 0, 4, 8, 12, and 24 h after prostaglandin F2alpha (PGF2alpha)-induced luteal regression on d 10 of the estrous cycle, respectively. Ovarian tissues (e.g., granulosa cells, theca cells, ovarian follicles, and /or CL) were used for Cx37 immunostaining followed by image analysis or for determination of Cx37 mRNA expression by real-time RT-PCR. We demonstrated that (1) Cx37 protein was expressed in granulosa and cumulus oocyte complex compartments, ovarian blood vessels, and on the luteal cell borders, (2) expression of Cx37 mRNA was greater in granulosa than in theca cells of preovulatory follicles, (3) Cx37 mRNA expression in granulosa but not theca cells was affected by hCG treatment, (4) Cx37 protein and mRNA expression were dependent on the stage of luteal development, and (5) Cx37 expression changed during PGF2alpha- induced luteal regression. Thus, Cx37 may play a role in follicular development and ovulation as well as in luteal tissue growth, differentiation, and regression.

Endogenous prostaglandins regulate spontaneous contractile activity of uterine strips isolated from non-pregnant pigs

Myometrial strips isolated from non-pregnant pigs show spontaneous contractile activity. In the present study, the involvement of endogenous prostaglandins in regulation of uterine spontaneous contraction was investigated using mechanical, immunohistochemical and biochemical approaches. Immunohistochemical study and Western blot analysis for immunoreactive cyclooxygenase (COX) indicated that COX-1 but not COX-2 was expressed predominantly in the myometrium of non-pregnant pigs in a muscle layer-dependent manner (longitudinal muscle>circular muscle). Pretreatment of uterine strips with indomethacin and selective COX-1 inhibitors (SC-560 and FR122047) significantly reduced both the amplitude and frequency of spontaneous contraction in the longitudinal muscle, but inhibition by COX inhibitors was negligible in the circular muscle. On the other hand, CAY10404, a COX-2 inhibitor, did not change the spontaneous contraction in either of the muscle layers. Pretreatment with SC-560 reduced myometrial PGF(2alpha) and PGE(2) levels. Contractile FP and EP(3) receptors were expressed in a muscle layer-dependent manner (longitudinal muscle>circular muscle), similar to the expression pattern of COX-1. In conclusion, endogenous prostaglandins produced by COX-1 regulate spontaneous contractile activity of non-pregnant porcine uterine longitudinal muscle selectively due to the heterogeneous expression of contractile prostanoid receptors and COX-1.

The effects of ovarian function on estrus synchronization with PGF in dairy cows

Milk progesterone concentration (P4), milk yield, milk composition, ovarian structures and pregnancy status were studied in 108 cows treated with two doses of PGF 14 days apart and inseminated at fixed time (TAI) 80-82 h later. The synchronization protocol was started at 70+/-1.4 days after parturition. Milk P4 profiles revealed that anestrus, failure of luteolysis following treatment with PGF and failure to ovulate following luteolysis were the main reasons for low pregnancy rate with TAI. Anestrous cows had a higher percentage of milk fat (P<0.05) and higher fat to protein ratio (P<0.01), and cows that did not undergo luteolysis had higher milk yield (P<0.05) and lower percentage of milk protein (P<0.05) than cows that responded to PGF treatment. Cows that did not undergo luteolysis and cows that did not ovulate following luteolysis had lower milk P4 during the luteal phase preceding the second PGF injection (P<0.01 and P<0.05, respectively). Pregnancy rates 24 and 47 days after TAI in cows that responded as expected to the synchronization treatment were 62% and 54%, respectively. Pregnancy was precluded in non-responsive cows. The largest follicle at the time of TAI in cows experiencing late embryonic mortality was smaller (P=0.02) than in cows that successfully maintained pregnancy. Results suggest that a primary reason for low pregnancy rate in dairy cows after administration of PGF and TAI is inappropriate ovarian function prior to, or following treatment.

Dissecting why superovulation and embryo transfer usually work on some farms but not on others

Bovine embryo transfer is a well-established commercial industry that is often associated with veterinary practices. Practitioners offering embryo transfer services may possess a very high standard of technical expertise; however, success in the production of embryos and the impregnation of recipients cannot be achieved unless the cattle are healthy and maintained in a well-managed cattle operation. In addition to appropriate gonadotropin treatments of donor cattle, the use of highly fertile semen, known to have been properly stored and handled is required for success. Recipient cattle must be managed with the same attention to detail as donors. Traditionally, PGF has been used for the synchronization of recipients. However, PGF is limited in its effectiveness early and late in the bovine estrus cycle. Recipient estrus synchronization with progesterone releasing intravaginal inserts has been successful and high pregnancy rates have resulted following embryo transfer.

Effect of prostaglandins against alloxan-induced diabetes mellitus

Previously, we observed that alloxan-induced in vitro cytotoxicity and apoptosis in an insulin secreting rat insulinoma, RIN, cells was prevented by prior exposure to prostaglandin (PG) E(1), PGE(2), PGI(2), PGF(1)(alpha), and PGF(3)(alpha) (P<0.05 compared to alloxan), whereas thromboxane B(2) (TXB(2)) and 6-keto-PGF(1)(alpha) were ineffective. In an extension of these studies, we now report that prior intraperitoneal administration of PGE(1), PGE(2), PGF(1)(alpha), and PGF(3)(alpha) prevented alloxan-induced diabetes mellitus in male Wistar rats, whereas PGI(2), TXB(2), and 6-keto PGF(1)(alpha) were not that effective. PGE(1), PGE(2), PGF(1)(alpha), and PGF(3)(alpha) not only attenuated chemical-induced diabetes mellitus but also restored the antioxidant status to normal range in red blood cells and pancreas. These results suggest that PGE(1), PGE(2), PGF(1)(alpha), and PGF(3)(alpha) can abrogate chemically induced diabetes mellitus in experimental animals and attenuate the oxidant stress that occurs in diabetes mellitus.

Prostaglandin analogues and mouse intraocular pressure: effects of tafluprost, latanoprost, travoprost, and unoprostone, considering 24-hour variation

PURPOSE

To establish a mouse model for the pharmacological analysis of antiglaucoma drugs, considering the effect of variations in IOP during 24 hours on the drugs' effects, and to evaluate the effect of a newly developed FP agonist, tafluprost, on mouse IOP, in comparison with three clinically available prostaglandin (PG) analogues.

METHODS

Inbred adult ddY mice were bred and acclimatized under a 12-hour light-dark cycle. With mice under general anesthesia, a microneedle method was used to measure IOP. A single drop of 3 muL of either drug or vehicle solution was topically applied once into one eye in each mouse, in a blinded manner, with the contralateral, untreated eye serving as the control. IOP reduction was evaluated by the difference in IOP between the treated and untreated eyes in the same mouse. First, to determine the period feasible for demonstrating a larger magnitude of ocular hypotensive effect, the 24-hour diurnal variation in mouse IOP was measured, and 0.005% latanoprost was applied at the peak or trough time of variation in 24-hour IOP. The time point of the most hypotensive effect was selected for further studies, to evaluate the effects of PG analogues. Second, mice received tafluprost (0.0003%, 0.0015%, 0.005%, or 0.015%), latanoprost (0.001%, 0.0025%, or 0.005%), travoprost (0.001%, 0.002%, or 0.004%), or isopropyl unoprostone (0.03%, 0.06%, or 0.12%), and each corresponding vehicle solution. IOP was then measured at 1, 2, 3, 6, 9, and 12 hours after drug administration. The ocular hypotensive effects of the other three PG analogues were compared with that of tafluprost. All experiments were conducted in a masked study design.

RESULTS

The IOP in the untreated mouse eye was higher at night than during the day. Latanoprost significantly lowered IOP at night (21.4%), compared with the IOP in the untreated contralateral eye 2 hours after administration. The maximum IOP reduction was 20.2% +/- 2.0%, 18.7% +/- 2.5%, and 11.2% +/- 1.8% of that in the untreated eye 2 hours after administration of 0.005% tafluprost, 0.005% latanoprost, and 0.12% isopropyl unoprostone, respectively, whereas it was 20.8% +/- 4.6% at 6 hours with 0.004% travoprost (n = 7 approximately 17). The order of ocular hypotensive effects of three clinically used PG analogues in mice was comparable to that in humans. Area under the curve (AUC) analysis revealed dose-dependent IOP reductions for each PG analogue. Tafluprost 0.005% decreased IOP more than 0.005% latanoprost at 3, 6, and 9 hours (P = 0.001-0.027) or 0.12% unoprostone at 2, 3, and 6 hours (P = 0.0004-0.01).

CONCLUSIONS

The 24-hour variation in mouse eyes should be taken into consideration when evaluating the reduction of IOP. The mouse model was found to be useful in evaluating the pharmacological response to PG analogues. A newly developed FP agonist, 0.005% tafluprost, lowered normal mouse IOP more effectively than did 0.005% latanoprost.

Effect of prostaglandins against alloxan-induced cytotoxicity to insulin secreting insulinoma RIN cells in vitro

In the present study, we studied the effect of various prostaglandins (PGs) on alloxan-induced cytotoxicity to rat insulinoma (RIN) cells. Of all the PGs tested, PGE(1), PGE(2), PGI(2), PGF(1 alpha), and PGF(3 alpha) protected RIN cells from alloxan-induced cytotoxicity (P<0.05 compared to alloxan), whereas thromboxane B(2) and 6-keto-PGF(1 alpha) were not effective. PGE(1) induces a statistically significant increase in the activities of superoxide dismutase and glutathione peroxidase and decrease in lipid peroxides in alloxan-treated RIN cells (P<0.001). PGE(1) restored nitric oxide/lipid peroxide ratio to normalcy, suggesting that PGE(1) suppresses oxidant stress induced by alloxan in RIN cells in vitro. Furthermore, PGE(1) prevented DNA damage and apoptosis induced by alloxan. These results indicate that PGE(1) prevents alloxan-induced cytotoxicity to RIN cells in vitro.

Pharmacological characteristics of AFP-168 (tafluprost), a new prostanoid FP receptor agonist, as an ocular hypotensive drug

To evaluate the pharmacological characteristics of AFP-168 (tafluprost), a new prostaglandin (PG) F(2alpha) derivative, we examined its receptor-binding affinities, intraocular pressure (IOP)-lowering effect, effects on aqueous humor dynamics, and stimulating effect on melanogenesis. The receptor-binding profile for AFP-172, a carboxylic acid of AFP-168, was determined by measuring muscle contractions in an organ bath, inhibition of platelet aggregation, and competitive binding of a radio-labelled ligand. For the IOP-measurement study, ocular normotensive and laser-induced ocular hypertensive cynomolgus monkeys were used, and IOP was measured using a pneumatonograph. For the studies of aqueous humor dynamics, IOP (Goldmann applanation tonometry), fluorophotometry, two-level constant pressure perfusion, and isotope dilution and accumulation techniques were used in ocular normotensive monkeys. The melanin contents in the medium and in the cell bodies of cultured B16-F0 melanoma cells were measured. The affinity for the FP receptor shown by AFP-172 (Ki : 0.4 nm) was 12 times that of PhXA85 ( Ki : 4.7 nm), a carboxylic acid of latanoprost. A single application of AFP-168 at 0.0025% significantly lowered IOP in both ocular normotensive and hypertensive monkeys (3.1 and 11.8 mmHg, respectively, p < 0.01) and latanoprost at 0.005% significantly lowered IOP (2.1 mmHg, p < 0.01 and 9.5 mmHg, p = 0.059 respectively). Once daily instillation of AFP-168 at 0.001, 0.0025, or 0.005% for 5 days in normotensive monkeys significantly reduced IOP not only for a few hours, but also at the drug-trough time 24hr after application. Latanoprost at 0.005% also reduced IOP, but not at the drug-trough time. AFP-168 decreased IOP mainly by increasing uveoscleral outflow by 65% (p < 0.05) and, as sometimes seen with other prostanoids, also increased total outflow facility (33% increase, p < 0.05). In cultured B16-F0 melanoma cells, AFP-172 (100 microM) did not stimulate melanogenesis, but PhXA85 (100 microM) did. These findings indicate that AFP-168 has a high affinity for the prostanoid FP receptor, has potent IOP-lowering effects in both ocular normotensive and hypertensive monkeys that exceed those of latanoprost, and has less stimulating effect on melanogenesis in melanoma cells.

Human Ciliary Muscle Cell Responses to FP-Class Prostaglandin Analogs: Phosphoinositide Hydrolysis, Intracellular Ca2+ Mobilization and MAP Kinase Activation

Phospholipase C induced phosphoinositide (PI) turnover, intracellular Ca(2+) ([Ca(2+)](i)) mobilization and mitogen-activated protein (MAP) kinase activation by FP-class prostaglandin analogs was studied in normal human ciliary muscle (h-CM) cells. Agonist potencies obtained in the PI turnover assays were: travoprost acid ((+)-fluprostenol; EC(50) = 2.6 +/- 0.8 nM) > bimatoprost acid (EC(50) = 3.6 +/- 1.2 nM) > (+/-)-fluprostenol (EC(50) = 4.3 +/- 1.3 nM) >> prostaglandin F(2 alpha) (PGF(2 alpha)) (EC(50) = 134 +/- 17 nM) > latanoprost acid (EC(50) = 198 +/- 83 nM) > S-1033 (EC(50) = 2930 +/- 1420 nM) > unoprostone (EC(50) = 5590 +/- 1490 nM) > bimatoprost (EC(50) = 9600 +/- 1100 nM). Agonist potencies in h-CM cells correlated well with those previously obtained for the cloned human ciliary body-derived FP receptor (r = 0.96, p< 0.001) and that present on h-TM cells (r = 0.94, p< 0.0001). Travoprost acid, PGF(2 alpha) and unoprostone also stimulated [Ca(2+)](i) mobilization in h-CM cells with travoprost acid being the most potent agonist. MAP kinase activity was stimulated in the h-CM cells with the following rank order of activity (at 100 nM): travoprost acid > PGF(2 alpha) > latanoprost acid > PGD(2) > bimatoprost > latanoprost = bimatoprost acid = fluprostenol > PGE(2) = S-1033 > unoprostone > PGI(2). The PI turnover, [Ca(2+)](i) mobilization and MAP kinase activation induced by several of these agonists was blocked by the FP receptor antagonist, AL-8810 (11 beta-fluoro-15-epiindanyl PGF(2 alpha)) (e.g. K(i) = 5.7 microM versus PI turnover). These studies have characterized the biochemical and pharmacological properties of the native FP prostaglandin receptor present on h-CM cells using three signal transduction mechanism assays and a broad panel of FP-class agonist analogs (including free acids of bimatoprost, travoprost and latanoprost) and the FP receptor antagonist, AL-8810.

Vasodilatory and electrophysiological actions of 8-iso-prostaglandin E2 in porcine coronary artery

We examined the effects of several E-ring and F-ring isoprostanes on mechanical and electrophysiological activity in porcine coronary artery. Several isoprostanes evoked concentration-dependent contractions, with 8-iso-PGE2 being the most potent (-log EC50 of 6.9 +/- 0.1); this excitatory effect has been described in detail elsewhere and was not examined further here. 8-iso-PGE2 evoked dose-dependent relaxations in tissues preconstricted with the thromboxane A2-agonist U46619 (10(-6) M), with a negative log EC50 of 6.0 +/- 0.1 (n = 5). 8-iso-PGE1 and 8-iso-PGF2 beta also evoked relaxations (albeit with lower potency), whereas the other F-ring isoprostanes (8-iso-PGF1 alpha, 8-iso-PGF1 beta, and 8-iso-PGF2 alpha) were largely ineffective in this respect. The potency and efficacy of 8-iso-PGE2 in reversing tone were not dependent upon the concentration of U46619 used to preconstrict the tissues (10(-8) to 10(-6) M), indicating a lack of U46619-induced functional antagonism of these responses. 8-iso-PGE2 was able to completely relax tissues that had been denuded of endothelium (as indicated by loss of responsiveness to bradykinin). 8-iso-PGE2-evoked relaxations were markedly reduced by elevating the K+ equilibrium potential using 30 mM KCl and abolished by 60 mM KCl; they were also sensitive to charybdotoxin (10(-7) M) but not to 4-aminopyridine (1 mM). 8-iso-PGE2 also caused membrane hyperpolarization and augmentation of outward K+ current. We conclude that 8-iso-prostaglandin E2 acts directly on the smooth muscle to increase K+ conductance, leading to membrane hyperpolarization and vasodilation.

The algogenic-induced nociceptive flexion test in mice: studies on sensitivity of the test and stress on animals

Recently we developed a new technique, known as peripheral nociception test or algogenic-induced nociceptive flexion (ANF) test, to study the in vivo signal transduction of pain at the peripheral nerve endings in mice. In the present report, we examined the sensitivity of the method to detect pain signal and the stresses induced by the test on experimental animals. In the algogenic-induced biting and licking (ABL) test, bradykinin could not induce significant biting-licking response even at a dose of 1nmol. It induced significant biting-licking response only at 10nmol. However, with the ANF test, 100fmol of bradykinin was enough to produce sharp and significant nociceptive flexion response. Similarly, substance P, ATP and ONO-54918-07, a stable prostaglandin I(2) agonist, induced nociceptive flexion response in ANF test at much lower doses than needed to induce biting-licking responses in ABL test. Next, we measured the plasma corticosterone level after different nociception tests, which is a measure of stress on animals due to experimental manipulations. However, no significant rise in corticosterone level was observed with ANF test. Altogether, these findings indicate that the ANF test is a highly sensitive and less stressful technique to study in vivo mechanisms of pain at the peripheral nerve ending.

Differential inhibition by botulinum neurotoxin A of cotransmitters released from autonomic vasodilator neurons

The role of the soluble NSF attachment protein receptor (SNARE) protein complex in release of multiple cotransmitters from autonomic vasodilator neurons was examined in isolated segments of guinea pig uterine arteries treated with botulinum neurotoxin A (BoNTA; 50 nM). Western blotting of protein extracts from uterine arteries demonstrated partial cleavage of synaptosomal-associated protein of 25 kDa (SNAP-25) to a NH2-terminal fragment of approximately 24 kDa by BoNTA. BoNTA reduced the amplitude (by 70-80%) of isometric contractions of arteries in response to repeated electrical stimulation of sympathetic axons at 1 or 10 Hz. The amplitude of neurogenic relaxations mediated by neuronal nitric oxide (NO) was not affected by BoNTA, whereas the duration of peptide-mediated neurogenic relaxations to stimulation at 10 Hz was reduced (67% reduction in integrated responses). In contrast, presynaptic cholinergic inhibition of neurogenic relaxations was abolished by BoNTA. These results demonstrate that the SNARE complex has differential involvement in release of cotransmitters from the same autonomic neurons: NO release is not dependent on synaptic vesicle exocytosis, acetylcholine release from small vesicles is highly dependent on the SNARE complex, and neuropeptide release from large vesicles involves SNARE proteins that may interact differently with regulatory factors such as calcium.

Opposite effect of prolactin and prostaglandin F(2 alpha) on the expression of luteal genes as revealed by rat cDNA expression array

It is well established that prolactin (PRL) sustains, while prostaglandin F(2 alpha) (PGF(2 alpha)) curtails, progesterone production by the rat corpus luteum (CL). We have previously shown that the actions of both molecules converge on the 20 alpha-HSD gene and control its expression in a dramatically opposed manner. In this investigation, we have found twelve more genes that are inversely regulated by PRL and PGF(2 alpha). In addition to 20 alpha-HSD, PGF(2 alpha) stimulated and PRL inhibited PGF(2 alpha)-receptor, phospholipase C delta(1) and TGF beta(1) expression. In contrast PRL stimulated and PGF(2 alpha) inhibited the LH receptor, 11 beta-HSD2, sterol carrier protein 2, mitochondrial glutathione S-transferase (GST), GST mu(2), inhibitory DNA-binding proteins 1, 2, and 3, and calcium binding protein 2. We have also identified new target genes for PRL and PGF(2 alpha). PGF(2 alpha) stimulated the expression of genes involved in cell signaling such as cell adhesion kinase-beta, ERK3, FRA2, IL-2 receptor, and 14-3-3 proteins. PGF(2 alpha) also up-regulated the expression of the sodium channel beta(1), Na/K ATPase, annexin IV, GST7pi, and P450 reductase. In contrast PGF(2 alpha) inhibited the expression of two genes involved in cell cycle: cyclin D2 and retinoblastoma related protein (Rb2/p130). It also inhibited genes involved in estradiol (P-450(AROM)) and cholesterol biosynthesis (HMG-CoA synthase), as well as genes involved in tissue remodeling: VEGF and TIMP3. PRL had a profound inhibitory effect on the expression of genes encoding the ADP-ribosylation factor 3, annexin V and c-jun, yet increased the expression of P450scc, 3beta-HSD, and SR-B1 (HDL-receptor), all genes involved in steroidogenesis. PRL also stimulated the expression of beta(2)-microglobulin, TIMP2, cytochrome c oxidase IV, cathepsin H and L, and copper-zinc superoxide dismutase as well as elongation factor SIII, heat shock protein-60 and mitochondrial ATP synthase-D. In conclusion, this investigation has revealed a "yin-yang" relationship between PRL and PGF(2 alpha) in regulating certain critical genes in the rodent CL, and has demonstrated novel regulation by these factors of other important genes involved in luteal function.

Effects of prostaglandin F(2alpha)and carbachol on MAP kinases, cytosolic phospholipase A(2)and arachidonic acid release in cat iris sphincter smooth muscle cells

The signal transduction pathways initiated by Ca(2+)-mobilizing agonists, such as prostaglandin F(2alpha)(PGF(2alpha)) and carbachol (CCh), leading to activation of cytosolic phospholipase A(2)(cPLA(2)) and arachidonic acid (AA) release in a wide variety of tissues remain obscure. To further define the role of protein kinases in receptor mediated stimulation of cPLA(2)and consequently AA release we have investigated the role of mitogen-activated protein (MAP) kinases and protein kinase C (PKC) in PGF(2alpha)- and CCh-induced cPLA(2)phosphorylation and AA release in cat iris sphincter smooth muscle (CISM) cells. The cells were prelabeled with [(3)H]AA for 24 hr and incubated in the absence or presence of the agonist for 5-10 min as indicated. MAP kinases activities and cPLA(2)phosphorylation were determined in immunoprecipitates obtained by using anti-p38 MAP kinase and anti-cPLA(2)antibodies. We found that: (a) PGF(2alpha)and CCh increased p38 MAP kinase activity by 197 and 215%, respectively, and increased p42/p44 MAP kinase activity by 200 and 125%, respectively. (b) SB202190, a p38 MAP kinase specific inhibitor, inhibited PGF(2alpha)- and CCh-induced cPLA(2)phosphorylation by 92 and 85%, respectively, and AA release by 62 and 78%, respectively. (c) PD98059, a p42/p44 MAP kinase inhibitor, inhibited CCh-induced cPLA(2)phosphorylation by 70% and AA release by 71%, but had no effect on that of PGF(2alpha). (d) Inhibition of PKC activity by RO 31-8220 inhibited both PGF(2alpha)- and CCh-stimulation of p38 MAP kinase, p42/p44 MAP kinases and cPLA(2)phosphorylation. We conclude from these results that in CISM cells PGF(2alpha)-induced cPLA(2)phosphorylation and AA release is mediated through p38 MAP kinase, but not through p42/p44 MAP kinases, whereas that of CCh is mediated through both p38 MAP kinase and p42/p44 MAP kinases. These effects of PGF(2alpha)and CCh are regulated by the MAP kinases in a PKC-dependent manner. Studies aimed at elucidating the role of protein kinases in the coupling mechanism between the activation of PGF(2alpha)and muscarinic receptors, and the stimulation of cPLA(2)and AA release in the smooth muscles of the iris-ciliary body will provide important information about the role of protein kinases signaling pathways in smooth muscle function, as well as about the mechanism of the intraocular pressure-lowering effects of PGF(2alpha)and its analog, latanoprost, in glaucoma therapy.

Marked hypotensive and blood flow-increasing effects of a new lipo-PGE(1) (lipo-AS013) due to vascular wall targeting

Lipo-AS013 is being developed as an improved formulation of lipo-PGE(1), which is widely used in clinical practice in Japan and some Asian countries. We have previously reported that lipo-AS013, which is a lipid microsphere (LM) preparation of a chemically stable and lipophilic PGE(1) prodrug (AS013, Fig. 1), slowly releases small amounts of the active ingredient (AS013) in human plasma. In the present study, to estimate the vascular wall targeting ability and efficacy of lipo-AS013, we determined the hypotensive and blood flow-increasing effects of lipo-AS013, lipo-PGE(1), PGE(1)CD, and AS013. Lipo-AS013 was found to have longer-lasting hypotensive and blood flow-increasing effects than the other agents. The two LM preparations, lipo-PGE(1) and lipo-AS013, had a markedly stronger effect than PGE(1)CD and AS013 alone, demonstrating the benefit of drug delivery using LM. In spontaneously hypertensive rats (SHR), lipo-AS013 also had a significant hypotensive effect. To confirm vascular wall targeting by lipo-AS013, the localization of PGE(1) in the aorta and neovascular capillaries of rat was investigated by immunostaining. The results indicated that lipo-AS013 was more efficient at delivering the active ingredient (AS013) to the vessel wall. In conclusion, lipo-AS013 could supersede lipo-PGE(1) and PGE(1)CD in clinical use.

Excitatory and inhibitory actions of isoprostanes in human and canine airway smooth muscle

Isoprostanes are generated nonenzymatically during free radical-mediated lipid peroxidation, and are used clinically and experimentally as markers of oxidative stress. However, their biological effects are poorly understood. We examined the effects of seven different 8-isoprostanes in human and canine airway smooth muscles. In large order airways (carina) of the human, several isoprostanes evoked powerful contractions, with 8-iso-prostaglandin (PG) E(2), 8-iso-PGF(1 alpha), and 8-iso-PGF(2 alpha) being the most efficacious (and with logEC(50) values of 7.0, 5.9, and 6.2 microM, respectively). These contractions were sensitive to the prostanoid TP receptor antagonist ICI 192,605 (0.1-1 microM), but not the EP prostanoid receptor antagonist AH-6809 (50 microM), or the leukotriene receptor antagonists monteleukast or ICI 198,615 (both 1 microM). Qualitatively similar results were obtained in small order human airways (<2 mm o.d.), except that the isoprostanes were generally slightly less potent. None of the isoprostanes had any marked excitatory effect in canine airways. In carbachol-preconstricted tissues (pretreated with ICI 192,605 to block any potential contraction), several isoprostanes completely relaxed canine airways: 8-iso-PGE(1), 8-iso-PGE(2), and 8-iso-PGF(3 alpha) were the most potent, with logIC(50) values of 6.9, 6.9, and 5.7, respectively. Only 8-iso-PGF(3 alpha) relaxed human airways (logIC(50) = 4.9). Our results show that several 8-isoprostanes are highly biologically active in human and canine airways, evoking both excitatory and/or inhibitory effects, and that these effects are compound, species, and tissue dependent.

Exogenous hyaluronidase induces release of nitric oxide from the coronary endothelium

OBJECTIVE

Hyaluronidase, an endogenous enzyme that hydrolyzes mucopolysaccharides, has been shown to enhance myocardial protection when added to preservation solutions. In addition, hyaluronidase infusion reduces injury to ischemic myocardium. Endothelium-derived nitric oxide is an endogenous vasodilator that prevents leukocyte adhesion to the intima and inhibits platelet adhesion and aggregation in the coronary artery. Experiments were undertaken to determine whether the protective action of hyaluronidase could be mediated by the endogenous release of nitric oxide.

METHODS

Segments of coronary artery, with and without endothelium, were placed in organ chambers (25 mL) to measure isometric force. Blood vessel segments were contracted with prostaglandin F(2)(alpha) (2 x 10(-6) mol/L) and exposed to hyaluronidase (3-15 units).

RESULTS

Hyaluronidase induced vasodilation of arteries with intact endothelium but not of arteries without endothelium (n = 6, P<.05). Endothelium-dependent vasodilation to hyaluronidase was blocked by N(G)-monomethyl-L -arginine (10(-5) mol/L), an inhibitor of nitric oxide synthesis from L -arginine (n = 6, P<.05). Inhibition of vasodilation by N(G)-monomethyl-L -arginine was reversed by L -arginine (10(-4) mol/L) but not D -arginine (10(-4) mol/L; n = 6, each group). Vasodilation to hyaluronidase also was inhibited by hemoglobin (2 x 10(-6) mol/L), a scavenger of the nitric oxide radical (n = 6, P<.05).

CONCLUSIONS

Hyaluronidase induces the release of nitric oxide from the coronary endothelium. Because nitric oxide, an endogenous vasodilator, inhibits leukocyte adhesion to the intima in addition to inhibiting platelet adhesion and aggregation, stimulated production of endothelium-derived nitric oxide by exogenous hyaluronidase could be the mechanism of the protective action of hyaluronidase infusion.

Aging reduces the responsiveness of coronary arteries from male Wistar rats to the vasodilatory action of testosterone

This study was performed to examine whether aging affects the vasodilatory effects of testosterone in the coronary arteries of male rats. Isolated coronary arteries from young mature (3-4 months) and elderly (22-26 months) male Wistar rats were studied in a wire myograph. Contractile function and endothelial function were assessed by measuring vasomotor responses to 10-100 mmol/l KCl, 0.1 mmol/l prostaglandin F(2alpha) (PGF(2alpha)) and 10 micromol/l acetylcholine. Sensitivity to the vasodilatory effects of testosterone was assessed by constructing dose-response curves to concentrations between 1 micromol/l and 1 mmol/l testosterone dissolved in water in vessels maximally preconstricted with PGF(2alpha). The compliance characteristics of each vessel and serum testosterone levels from each animal were measured. Histological sections of myocardium were examined for differences in coronary artery morphology. Vessels from elderly animals were significantly more resistant to the vasodilatory effects of testosterone than vessels from young animals (P=0.001 by analysis of covariance). Vessels from elderly animals were also significantly less compliant (7.32+/-0.43 microm/mN, compared with 10.99+/-1.52 microm/mN in young animals; P=0.011), and the levels of circulating testosterone in elderly animals were lower, but not significantly so (2.04+/-0.63 nmol/l compared with 3.88+/-1.7 nmol/l; P=0.32). Vessels from elderly animals were less contractile in response to KCl than those from young animals (P=0.004 by analysis of covariance). There were no significant differences between the two groups in their responses to PGF(2alpha) or acetylcholine. Thus it is concluded that coronary arteries from elderly rats are significantly less sensitive to the vasodilatory effects of testosterone than those from young animals.

Changes in the mechanisms involved in uterine contractions during pregnancy in guinea-pigs

1. The mechanisms involved in contraction in guinea-pig myometrium were compared at mid- and late pregnancy. Tension was recorded simultaneously with either membrane potential or cytoplasmic calcium ([Ca2+]i) in strips exposed briefly to prostaglandin F2alpha (PGF). 2. PGF-induced increases in tension were underpinned by action potentials followed by sustained depolarization and biphasic increases in [Ca2+]i at mid- (peak, 879 +/- 199 nM; sustained, 298 +/- 35 nM, n = 11) and late pregnancy (peak, 989 +/- 302 nM; sustained 178 +/- 33 nM, n = 8). 3. At mid- and late pregnancy, nifedipine (10-6 M) reduced (a) the PGF-induced increase in tension to 84 and 35 %, (b) the level attained during the depolarization by 2 and 12 mV and (c) the peak rise in [Ca2+]i to 42 and 17 %. The sustained rises in [Ca2+]i were resistant to nifedipine. 4. In Ca2+-free solution (containing 1 mM EGTA), PGF elicited an increase in tension that was 26 % of that in 2.5 mM Ca2+ and an increase in [Ca2+]i (24 % of the sustained level) at mid-pregnancy but no increase in tension or [Ca2+]i at term. 5. At both stages of pregnancy, PGF decreased the level of [Ca2+]i required to elicit increases in tension comparable to those evoked by high K+o. The slope of the tension-[Ca2+]i curves were steeper in mid- than in late pregnancy. 6. In conclusion, at mid-pregnancy, the contractile response of the guinea-pig myometrium to PGF involves Ca2+ influx through L-type voltage-operated Ca2+ channels (VOCCs) and by receptor-operated mechanisms, release of Ca2+ from intracellular stores, and an increase in the sensitivity of the contractile apparatus to Ca2+. At term the situation is different: a modest increase in the sensitivity of the contractile apparatus to Ca2+ persists and there is a major reliance on Ca2+ influx through VOCCs.

Design and synthesis of 13,14-dihydro prostaglandin F(1alpha) analogues as potent and selective ligands for the human FP receptor

The in vitro evaluation of a new class of potential bone anabolic agents for the treatment of osteoporosis is described. These compounds are potent and selective ligands for the human prostaglandin F receptor (hFP receptor). The compounds lack the olefin unsaturation required for potency in the natural ligand PGF(2)(alpha) yet retain binding affinity for the hFP receptor in the nanomolar to micromolar range. Removal of the alkenes also results in a better selectivity ratio for the hFP receptor over the other prostaglandin receptors tested. A rationale for the selectivity differences of various analogues, based on ligand docking experiments to a putative hFP receptor model, is also described.

Effects of some isoprostanes on the human umbilical artery in vitro

1. Cumulative concentration-effect curves for the selective prostanoid TP receptor agonist U46619 and six isoprostanes were constructed in the human isolated umbilical artery. 2. All compounds except 8-iso-PGF3 alpha produced concentration-dependent contractions. The contractile response to the isoprostanes increased with each cumulative addition up to a point, after which subsequent addition reduced the contraction below the previous level. This 'downturn' in the concentration-effect curve did not occur with U46619. 3. The potencies of the compounds tested were as follows (pEC50 +/- s.e.mean): U46619, 6.7 +/- 0.2; 8-iso-PGE2, 6.5 +/- 0.1; 8-iso-PGF2 alpha, 5.8 +/- 0.2; 8-iso-PGE1, 5.4 +/- 0.1; 8-iso-PGF1 alpha, 5.0 +/- 0.1; 8-iso-PGF2 beta > 4.8; 8-iso-PGF3 alpha >> 4.8 (n = 4-17). Neither 8-iso-PGF2 beta nor 8-iso-PGF3 alpha at 44 microM had a significant effect on cumulative concentration-effect curves to U46619. 4. The selective TP receptor antagonist GR32191 (0.1 microM) caused rightward shifts in the concentration-effect curves to all the active compounds. pA2 values for GR32191 against U46619, 8-iso-PGE2, 8-iso-PGF2 alpha, 8-iso-PGE1 were 7.6 +/- 0.2, 9 +/- 1, 8.2 +/- 0.3 and 7.7 +/- 0.3, respectively (n = 4). 5. Neither N omega-nitro-L-arginine methyl ester (100 microM) nor the selective DP receptor antagonist BW A868C (50 nM) affected the complex concentration-effect curve to 8-iso-PGE2 (n = 3). 6. Stable contractions to U46619 (1-3 microM) were unaffected by anandamide at concentrations up to 60 microM.

Effects of lysophosphatidic acid on proliferation and cytosolic Ca++ of human adult vascular smooth muscle cells in culture

Lysophosphatidic acid (LPA) is a lipid mediator generated by activated platelets and having various effects on numerous cell types. We investigated some effects of 1-oleyl LPA on vascular smooth muscle cells cultured from adult human normal arteries. At micromolar concentrations, LPA induced a mitogenic effect ([3H]-thymidine incorporation and cell proliferation) on quiescent cells, without an additional growth factor being required. This effect was equipotent to that of 10% fetal calf serum, and it was accompanied by early (5 minutes) and late (1-3 hours) phosphorylation of mitogenactivated protein kinase. LPA inhibited cell migration through collagen coated membranes, with or without platelet-derived growth factor BB as chemoattractant. LPA induced a typical biphasic Ca2+ signal response made up of a rapid first phase due to Ca2+ release from intracellular stores followed by a second wave due to external Ca2+ influx. These findings support the proposal that LPA released from activated platelets is a mediator for smooth muscle cell response at the site of vessel injury in humans.

Prostaglandin E2 and I2 regulate intercellular adhesion molecule-1 expression in interleukin-1 beta-stimulated human gingival fibroblasts

The present study investigated the effect of prostaglandin (PG) E2 and PGI2 on intercellular adhesion molecule-1 (ICAM-1) expression in interleukin-1 beta (IL-1 beta)-stimulated human gingival fibroblasts (HGF). IL-1 beta potently induced ICAM-1 expression in HGF and indomethacin, a cyclooxygenase inhibitor, enhanced ICAM-1 expression in the cells. These data showed that endogenous PGs generated by HGF stimulated with IL-1 beta downregulated ICAM-1 expression. IL-1 beta significantly increased the levels of PGE2 and, to a lesser extent, those of 6-keto-PGF1 alpha (a stable metabolite of PGI2) in the culture media of HGF. Indomethacin completely inhibited the production of PGE2 and 6-keto-PGF1 alpha in IL-1 beta-stimulated HGF. Exogenous PGE2 and carbacyclin (a stable derivative of PGI2) in the presence of indomethacin dose-dependently suppressed ICAM-1 expression in IL-1 beta-challenged HGF. Since PGE2 and PGI2 are known to elevate intracellular cyclic AMP (cAMP) levels, we examined the effect of dibutyryl cAMP, a cAMP analogue, and isobutylmethylxanthine, a phosphodiesterase inhibitor, on ICAM-1 expression. Both agents downregulated ICAM-1 expression in IL-1 beta-stimulated HGF. These results suggest that PGE2 and PGI2 downregulate ICAM-1 expression in IL-1 beta-stimulated HGF through a cAMP-dependent mechanism and that intracellular cAMP elevation in HGF may control inflammatory and immune responses in periodontal disease.

Different contractile properties between intralobar and extralobar pulmonary arteries of the rabbit

In pulmonary circulation, small muscular resistance arteries are known to have different receptor properties and sensitivity to neurotransmitters from those of large elastic conduit arteries. It is, however, not yet certain whether the different properties are primarily due to the diameter or the location of arteries. In the present study, we compared the contractile responses to various agonists among large extralobar (ELPA, diameter: 2-3 mm), large intralobar (ILPA, diameter: 2-3 mm), and small intralobar pulmonary arteries (SPA, diameter: 300-500 microm) of the rabbit. There were no differences in normalized dose-response curves to KCl among three groups. Half maximum doses (EC50 in mM) were 38.0+/-2.0 (n=8, mean+/-SEM) in ELPA, 36.9+/-2.4 (n=10) in ILPA, and 39.0+/-0.9 (n=12) in SPA. Responses to phenylephrine, epinephrine, histamine, serotonin, and PGF2alpha were normalized and expressed as a relative contraction against maximum tension to KCl. In ELPA, the contractile responses to various agents showed the following sequence: KCl>epinephrine>phenylephrine>serotonin>PGF2alpha>histamine. In ILPA and SPA, the sequence was: KCl>histamine>PGF2alpha>serotonin. There was little response to phenylephrine and epinephrine in ILPA and SPA. These results demonstrate that the difference of contractile responses between ELPA and ILPA was more prominent than that between ILPA and SPA, suggesting that the location is more important than the diameter itself in determining the characteristic contractile responses of pulmonary arteries.