Sustained delivery of latanoprost by thermosensitive chitosan-gelatin-based hydrogel for controlling ocular hypertension.

Glaucoma is an irreversible ocular disease that may lead to progressive visual field loss and eventually to blindness with inadequately controlled intraocular pressure (IOP). Latanoprost is one of the most potent ocular hypotensive compounds, the current first-line therapy in glaucoma. However, the daily instillation required for efficacy and undesirable side-effects are major causes of treatment adherence failure and persistence in glaucoma therapy. In the present study, we developed an injectable thermosensitive chitosan/gelatin/glycerol phosphate (C/G/GP) hydrogel as a sustained-release system of latanoprost for glaucoma treatment. The latanoprost-loaded C/G/GP hydrogel can gel within 1min at 37°C. The results show a sustained release of latanoprost from C/G/GP hydrogel in vitro and in vivo. The latanoprost-loaded C/G/GP hydrogel showed a good in vitro and in vivo biocompatibility. A rabbit model of glaucoma was established by intravitreal injection of triamcinolone acetonide. After a single subconjunctival injection of latanoprost-loaded C/G/GP hydrogel, IOP was significantly decreased within 8days and then remained at a normal level. The results of the study suggest that latanoprost-loaded C/G/GP hydrogel may have a potential application in glaucoma therapy.

Indirect sympatholytic actions at ß-adrenoceptors account for the ocular hypotensive actions of cannabinoid receptor agonists.

Intraocular pressure (IOP) is the primary risk factor for glaucoma, a blinding eye disease. Cannabinoid agonists have long been known to decrease IOP, suggesting they may be useful in glaucoma treatment. However, the specific mechanism by which cannabinoids generate this ocular hypotensive effect remains unknown. The current evidence suggests the cannabinoids reduce IOP through actions at cannabinoid 1 (CB(1)) receptors within the eye, and adrenergic receptors (ARs) may also contribute to this action of cannabinoids. Considering this, the present study aimed to elucidate the mechanism behind the ocular hypotensive properties of cannabinoids through the use of mice genetically lacking either cannabinoid receptors or ßARs. Cannabinoid agonists, ßAR antagonists, and ßAR agonists decreased IOP in wild-type mice and CB(2)(-/-) mice. In contrast, none of these compounds were found to reduce IOP in ßAR(-/-) or CB(1)(-/-) mice. Desensitization of the ßARs and depletion of catecholamines in wild-type mice also eliminated the ability of the cannabinoid agonist (R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl]-1-naphthalenylmethanone mesylate (WIN 55,212-2) to reduce IOP, strongly implicating a role for both ßARs and catecholamines in the ocular hypotensive properties of cannabinoids. Finally, CB(1) receptors were shown to colocalize with tyrosine hydroxylase, a marker for adrenergic neurons. Taken together, these findings suggest that ßARs are required for the ocular hypotensive properties of cannabinoids, and cannabinoids reduce IOP by acting as indirect sympatholytics and inhibiting norepinephrine release within the eye.

Effectiveness of ophthalmic solution preservatives: a comparison of latanoprost with 0.02% benzalkonium chloride and travoprost with the sofZia preservative system.

BACKGROUND: Although in vitro and in vivo laboratory studies have suggested that benzalkonium chloride (BAK) in topical ophthalmic solutions may be detrimental to corneal epithelial cells, multiple short- and long-term clinical studies have provided evidence supporting the safety of BAK. Despite the conflicting evidence, BAK is the most commonly used preservative in ophthalmic products largely due to its proven antimicrobial efficacy. This study was designed to characterize the antimicrobial performance of two commonly used topical ocular hypotensive agents that employ different preservative systems: latanoprost 0.005% with 0.02% BAK and travoprost 0.004% with sofZia, a proprietary ionic buffer system. METHODS: Each product was tested for antimicrobial effectiveness by European Pharmacopoeia A (EP-A) standards, the most stringent standards of the three major compendia, which specify two early sampling time points (6 and 24 hours) not required by the United States Pharmacopeia or Japanese Pharmacopoeia. Aliquots were inoculated with between 10(5) and 10(6) colony-forming units of the test organisms: Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans and Aspergillus brasiliensis. Sampling and enumeration were conducted at protocol-defined time points through 28 days. RESULTS: BAK-containing latanoprost met EP-A criteria by immediately reducing all bacterial challenge organisms to the test sensitivity and fungal challenges within the first six hours while the preservative activity of travoprost with sofZia did not. Complete bacterial reduction by travoprost with sofZia was not shown until seven days into the test, and fungal reduction never exceeded the requisite 2 logs during the 28-day test. Travoprost with sofZia also did not meet EP-B criteria due to its limited effectiveness against Staphylococcus aureus. Both products satisfied United States and Japanese pharmacopoeial criteria. CONCLUSIONS: Latanoprost with 0.02% BAK exhibited more effective microbial protection than travoprost with sofZia using rates of microbial reduction, time to no recovery for all challenges and evaluation against EP-A criteria as measures. The rapid and complete reduction of all microbial challenges demonstrates that antimicrobial activity of latanoprost with 0.02% BAK exceeds that of travoprost with sofZia preservative system in these products and provides a more protective environment in the event of contamination and subsequent exposure to microorganisms during use.

Ocular hypotensive activity of BOL-303259-X, a nitric oxide donating prostaglandin F2α agonist, in preclinical models.

The aim of the study was to investigate the ocular hypotensive activity of a nitric oxide (NO)-donating latanoprost, BOL-303259-X, following topical administration. The effect of BOL-303259-X (also known as NCX 116 and PF-3187207) on intraocular pressure (IOP) was investigated in monkeys with laser-induced ocular hypertension, dogs with naturally-occurring glaucoma and rabbits with saline-induced ocular hypertension. Latanoprost was used as reference drug. NO, downstream effector cGMP, and latanoprost acid were determined in ocular tissues following BOL-303259-X administration as an index of prostaglandin and NO-mediated activities. In primates, a maximum decrease in IOP of 31% and 35% relative to baseline was achieved with BOL-303259-X at doses of 0.036% (9 µg) and 0.12% (36 µg), respectively. In comparison, latanoprost elicited a greater response than vehicle only at 0.1% (30 µg) with a peak effect of 26%. In glaucomatous dogs, IOP decreased from baseline by 44% and 10% following BOL-303259-X (0.036%) and vehicle, respectively. Latanoprost (0.030%) lowered IOP by 27% and vehicle by 9%. Intravitreal injection of hypertonic saline in rabbits increased IOP transiently. Latanoprost did not modulate this response, whereas BOL-303259-X (0.036%) significantly blunted the hypertensive phase. Following BOL-303259-X treatment, latanoprost acid was significantly elevated in rabbit and primate cornea, iris/ciliary body and aqueous humor as was cGMP in aqueous humor. BOL-303259-X lowered IOP more effectively than latanoprost presumably as a consequence of a contribution by NO in addition to its prostaglandin activity. The compound is now in clinical development for the treatment of glaucoma and ocular hypertension.

Effects of induced parturition in goats on immunoglobulin G and chitotriosidase activity in colostrum and plasma and on plasma concentrations of prolactin.

The effect of induction of parturition with a PGF(2)α analog on plasma concentration of prolactin (PRL) and its effects on colostrum concentration of IgG and chitotriosidase (ChT) activity were studied in 16 pregnant Majorera goats. Treated goats, those in which parturition was induced, had greater concentrations of PRL than control goats 24 h before parturition (P < 0.05) and 48 h after parturition (P < 0.05). Control goats had greater concentrations of PRL than treated goats 96 h after parturition (P < 0.05). Plasma concentration of IgG did not differ between groups during the experimental period, but colostrum concentrations of IgG were greater in control goats than in treated goats at parturition (P < 0.05). Plasma ChT activity decreased during the period 72 h before parturition to 24 h after parturition in control and treated goats. Time evolution after partum affected the colostrum ChT activity, being greater at parturition than after parturition in both groups (P < 0.05). In summary, concentration of IgG in colostrum is slightly diminished if parturition is induced. Induction of parturition causes an early increase in PRL, which is most likely responsible for preterm suppression of IgG transport into mammary secretions.

A model-based meta-analysis of the effect of latanoprost chronotherapy on the circadian intraocular pressure of patients with glaucoma or ocular hypertension.

Several reports have demonstrated that the efficacy of latanoprost is influenced by the time of dosing. This model-based meta-analysis validates previous findings that evening dosing is superior to morning dosing and predicts the optimal time for dosing, based on the quantitative assessment of baseline and latanoprost-treated 24-h circadian intraocular pressure (IOP) curves. The results confirm the importance of the time of dosing as a factor that influences the extent of reduction in IOP and underline the need to take this factor into consideration in the design of glaucoma trials and therapy.

Latanoprost protects rat retinal ganglion cells from apoptosis in vitro and in vivo.

We investigated whether latanoprost has a direct anti-apoptotic effect in retinal ganglion cell (RGC) line and RGCs in the rat. RGC-5 cells were induced to undergo apoptosis by serum deprivation and exogenous glutamate. The level of cell death with or without latanoprost acid was monitored by an XTT assay and by immunocytochemistry with activated caspase-3. Changes in the level of intracellular calcium ([Ca(2+)]i) were measured with fluo-4 fluorescence. The XTT assay revealed that latanoprost acid increased RGC-5 cell viability. Latanoprost acid significantly reduced caspase-3 positive cells and suppressed [Ca(2+)]i evoked by glutamate. U0126, a mitogen-activated protein/extracellular signal-regulated kinase 1 and 2 inhibitor, partially blocked the rescue effect of latnanoprost acid (p=0.013). In vivo, rat RGCs were degenerated by optic nerve crush. After topical instillation of latanoprost for 7days, RGCs labeled with fluorogold were significantly. Retinal flatmounts were subjected to terminal dUTP nick end labeling (TUNEL) staining to detect apoptotic cells. TUNEL-positive cells were significantly decreased in eyes with topically instilled latanoprost (p=0.015). These data suggest that latanoprost has an neuroprotective ability in RGCs.

Comparative efficacy of pilocarpine, timolol and latanoprost in experimental models of glaucoma.

Intraocular pressure (IOP)-lowering effects of investigational antiglaucoma drugs often need comparison with existing drugs, but detailed data showing comparative efficacy of antiglaucoma drugs with different mechanism of action has not been reported so far. This study was designed to establish baseline information of the IOP-lowering effect of three currently used antiglaucoma drugs in three experimental models in rabbits, so that they act as a benchmark for the efficacy evaluation of the future experimental antiglaucoma drugs. The IOP-lowering effect of single-drop application of pilocarpine, timolol and latanoprost was studied in normotensive, water loading and steroid-induced models of glaucoma in rabbits. The noncontact tonometer was used for the first time to estimate IOP in rabbits. The peak IOP-lowering effect of pilocarpine, timolol and latanoprost in normotensive rabbit eye was 18.23%, 20% and 22.56%, respectively. In water-loading model, the maximum protection against the rise in IOP was shown by latanoprost (40.27%), followed by timolol (31.39%) and pilocarpine (28.91%). In steroid-pretreated rabbit eyes, peak IOP-lowering effects of pilocarpine, timolol and latanoprost were 25.65%, 34.21% and 35.06%, respectively. Therefore, the latanoprost was found to be most effective in all three models followed by timolol and pilocarpine. The results of this study can be used for future preclinical investigations for the assessment of IOP-lowering activity of potential antiglaucoma drugs.

Prostanoid- and interleukin-1-induced primary genes in cementoblastic cells.

BACKGROUND: Cementum is a key component of a functional periodontal organ. However, regenerating lost cementum is difficult and often incomplete. Identifying molecular mediators of cementoblast differentiation and function should lead to better targeted treatment for periodontitis. Prostaglandins increase mineralization of murine cementoblastic OCCM cells and alveolar bone formation, whereas the cytokine interleukin-1 (IL-1) inhibits alveolar bone formation. We hypothesized that differentially induced primary genes in OCCM cells may mediate anabolic and catabolic responses. Our objective was to identify primary genes differentially induced by the synthetic prostanoid fluprostenol and IL-1 in cementoblastic cells. METHODS: Confluent OCCM cells were pretreated with the protein synthesis inhibitor cycloheximide followed by fluprostenol or IL-1 for 1.5 hours. cDNA generated from each group was used for cDNA subtraction hybridization to identify differentially induced genes. Preferential gene induction was verified by Northern blot analysis. RESULTS: Thirteen fluprostenol- and seven IL-1-regulated genes were identified. Among the fluprostenol-induced genes was mitogen-activated protein (MAP) kinase phosphatase 1 (MKP1), a negative regulator of MAP kinase signaling. To verify the cDNA subtraction hybridization results, OCCM cells were treated with fluprostenol or prostaglandin F2 (PGF2), and MKP1 mRNA levels were determined. The 0.001 to 1 microM fluprostenol and 0.01 to 1 microM PGF2 significantly induced MKP1 mRNA levels, which peaked at 1 hour of treatment and returned to baseline at 2 hours. CONCLUSIONS: Fluprostenol enhanced, whereas IL-1 inhibited, OCCM mineralization. Using cDNA subtraction hybridization, we identified primary genes that correlate with the observed anabolic and catabolic responses. These findings further our understanding of cementoblast function and suggest that differentially induced genes may mediate cementum formation and resorption.

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+).

New fluoroprostaglandin F(2alpha) derivatives with prostanoid FP-receptor agonistic activity as potent ocular-hypotensive agents.

To find new prostanoid FP-receptor agonists possessing potent ocular-hypotensive effects with minimal side effects, we evaluated the agonistic activities of newly synthesized prostaglandin F(2alpha) derivatives for the prostanoid FP-receptor both in vitro and in vivo. The iris constrictions induced by the derivatives and their effects on melanin content were examined using cat isolated iris sphincters and cultured B16 melanoma cells, respectively. The effects of derivative ester forms on miosis and intraocular pressure (IOP) were evaluated in cats and cynomolgus monkeys, respectively. Of these derivatives, 6 out of 12 compounds were more potent iris constrictors, with EC(50) values of 0.6 to 9.4 nM, than a carboxylic acid of latanoprost (EC(50)=13.6 nM). A carboxylic acid of latanoprost (100 microM) significantly increased the melanin content of cultured B16 melanoma cells, but some 15,15-difluoro derivatives, such as AFP-157 and AFP-172, did not. Topically applied AFP-168, AFP-169 and AFP-175 (isopropyl ester, methyl ester and ethyl ester forms, respectively, of AFP-172) induced miosis in cats more potently than latanoprost. AFP-168 (0.0005%) reduced IOP to the same extent as 0.005% latanoprost (for at least 8 h). These findings indicate that 15,15-difluoroprostaglandin F(2alpha) derivatives, especially AFP-168, have more potent prostanoid FP-receptor agonistic activities than latanoprost. Hence, AFP-168 may be worthy of further evaluation as an ocular-hypotensive agent.

Human lens epithelial cell damage and stimulation of their secretion of chemical mediators by benzalkonium chloride rather than latanoprost and timolol.

OBJECTIVE: To investigate the effects of latanoprost, timolol maleate, and benzalkonium chloride on cell damage and induction of the secretion of chemical mediators of stress and wound healing by human lens epithelial cells in culture. METHODS: Cells from a human lens epithelial cell line (SRA01/04) were cultured in Dulbecco minimum essential medium supplemented with 5% fetal bovine serum. The amounts of latanoprost (50 micro g/mL), timolol maleate (5 mg/mL), or benzalkonium chloride (200 micro g/mL) used in eyedrops, and x10 to x1000 dilutions thereof, were added to the medium. After 7 days' culture, cell morphological changes were assessed using phase-contrast microscopy, and cell-free culture supernatants were collected for prostaglandin E2 (PGE2), interleukin 1alpha (IL-1alpha), and interleukin 6 (IL-6) iodine I 125 radioimmunoassay, enzyme-linked immunosorbent assay, and chemiluminescent enzyme immunoassay, respectively. RESULTS: All cells that were cultured with the concentrations of latanoprost, timolol, or benzalkonium chloride used in eyedrops detached from the culture dish and died within 3 days. At a x10 dilution of latanoprost or timolol or a x100 dilution of benzalkonium chloride, no proliferation or elongation of the cells was observed. Secretions of PGE2, IL-1alpha, and IL-6 at x10 dilutions of latanoprost or timolol were 3 to 77 times higher than in controls, whereas they were 190 to 305 times higher at a x180 dilution of benzalkonium chloride. The amounts of these soluble mediators in culture supernatants depended on the dose of latanoprost, timolol, or benzalkonium chloride added. CONCLUSION: Our results indicate that benzalkonium chloride, used as the preservative in eyedrops containing latanoprost or timolol, is the agent most damaging to lens epithelial cells and most strongly stimulates the expression of soluble chemical mediators in these cells.

Ocular hypotensive FP prostaglandin (PG) analogs: PG receptor subtype binding affinities and selectivities, and agonist potencies at FP and other PG receptors in cultured cells.

Natural prostaglandins (PGs) such as PGD2, PGE2, PGF2(2alpha), and PGI2 exhibited the highest affinity for their respective cognate receptors, but were the least selective agents when tested in receptor binding assays. Travoprost acid ([+]-fluprostenol) was the most FP-receptor-selective compound, exhibiting a high affinity (Ki = 35 +/- 5 nM) for the FP receptor, and minimal affinity for DP (Ki = 52,000 nM), EP1 (Ki = 9540 nM), EP3 (Ki = 3501 nM), EP4 (Ki = 41,000 nM), IP (Ki > 90,000 nM), and TP (Ki = 121,000 nM) receptors. Travoprost acid was the most potent PG analog tested in FP receptor functional phosphoinositide turnover assays in the following cell types: human ciliary muscle (EC50 = 1.4 nM), human trabecular meshwork (EC50 = 3.6 nM), and mouse fibroblasts and rat aortic smooth muscle cells (EC50 = 2.6 nM). Although latanoprost acid exhibited a relatively high affinity for the FP receptor (Ki = 98 nM), it had significant functional activity at FP (EC50 = 32-124 nM) and EP1 (EC50 = 119 nM) receptors. Bimatoprost acid was less selective, exhibiting a relatively high affinity for the FP (Ki = 83 nM), EP1 (Ki = 95 nM), and EP3 (Ki = 387 nM) receptors. Bimatoprost acid exhibited functional activity at the EP1 (EC50 = 2.7 nM) and FP (EC50 = 2.8-3.8 nM in most cells) receptors. Bimatoprost (nonhydrolyzed amide) also behaved as an FP agonist at the cloned human FP receptor (EC50 = 681 nM), in h-TM (EC50 = 3245 nM) and other cell types. Unoprostone and S-1033 bound with low affinity (Ki = 5.9 microM to > 22 microM) to the FP receptor, were not selective, but activated the FP receptor. In conclusion, travoprost acid has the highest affinity, the highest FP-receptor-selectivity, and the highest potency at the FP receptor as compared to the other ocular hypotensive PG analogs known so far, including free acids of latanoprost, bimatoprost, and unoprostone isopropyl ester.

Source and site of action of anti-luteolytic interferon in red deer (Cervus elaphus): possible involvement of extra-ovarian oxytocin secretion in maternal recognition of pregnancy.

Six conceptuses were collected from red deer hinds on day 22 after synchronization of oestrus with intravaginal progesterone-releasing devices (removal of device = day 0). Within 24 h of culture in vitro, the supernatant from five of six conceptuses showed detectable antiviral activity. Interferon alpha (IFN-alpha) receptors were identified by immunohistochemistry on the luminal surface of the endometrium, in the neurohypophysis and paraventricular hypothalamus, but not in the ovaries of the hinds from which the conceptuses were collected. Another 16 intact hinds were synchronized as above. Injection of 4 mg IFN i.m. twice a day on days 13-15 had no effect on cloprostenol-induced oxytocin secretion on day 15 and did not prevent cloprostenol-induced luteal regression. Sixteen ovariectomized hinds received a protocol of steroid treatment to mimic ovarian hormone secretion during the normal oestrous cycle. On day 16, hinds showed undulant oxytocin secretion that showed a degree of temporal association with uterine PGF2 alpha release. Treatment with 4 mg IFN-alpha I 1 twice a day on days 13-16 had no effect on this spontaneous oxytocin secretion, but reduced the magnitude of cloprostenol-induced oxytocin secretion on day 17 (P < 0.05). These results indicate that red deer conceptuses secrete an anti-luteolytic IFN to which the endometrium expresses a receptor during early pregnancy. The presence of IFN receptors in the hypothalamus and posterior pituitary and the IFN-induced suppression of extra-ovarian oxytocin secretion provides tentative evidence of an involvement of the central nervous system in maternal recognition of pregnancy in deer.

Cloning and expression of a cDNA for the human prostanoid FP receptor.

A cDNA clone coding for a functional human prostanoid FP receptor has been isolated from a uterus cDNA library. The human FP receptor consists of 359 amino acid residues with a predicted molecular mass of 40,060, and has the seven putative transmembrane domains characteristic of G-protein-coupled receptors. Challenge of Xenopus oocytes expressing the FP receptor with 10 nM of either prostaglandin (PG) F2 alpha or the selective FP-receptor agonist fluprostenol resulted in an elevation in intracellular Ca2+. Radioreceptor binding studies using membranes prepared from mammalian COS cells transfected with the FP receptor cDNA showed that the rank order of potency for prostaglandins and prostaglandin analogs in competition for [3H]PGF2 alpha specific binding sites was as predicted for the FP receptor, with PGF2 alpha approximately fluprostenol > PGD2 > PGE2 > U46619 > iloprost. In summary, we have cloned the human prostanoid FP receptor which is functionally coupled to the Ca2+ signalling pathway.

The ocular effects of prostaglandins and the therapeutic potential of a new PGF2 alpha analog, PhXA41 (latanoprost), for glaucoma management.

In the early days of prostaglandin (PG) research, the infusion of large PG doses into rabbit eyes already traumatized by cannulation, led to the conclusion that PGs have a profound ocular hypertensive effect that is associated with a breakdown of the blood-aqueous barrier. In contrast, repeated topical application of PGs to nontraumatized eyes of several species other than rabbits has later been shown to yield a maintained ocular hypotensive effect, without barrier breakdown. Due to its excellent pharmacokinetic properties, the isopropyl ester form of PGF2 alpha (PGF2 alpha-IE) is a much more potent ocular hypotensive agent and appeared to be better suited for the management of glaucoma, than PGF2 alpha itself or any currently used glaucoma drug. However, even this prodrug caused clinically unacceptable foreign-body sensation and conjunctival hyperemia, which could be reduced, or eliminated, only by some modifications of the omega chain of PGF2 alpha-IE. One such analog, PhXA41, maintained highly significant IOP reduction in glaucoma patients even with once-daily application at the remarkably low concentration of 0.006%. Because PhXA41 reaches intraocular tissues and the systemic circulation in its de-esterified free-acid form, which is a good substrate for the PG transport system, it retains the most important pharmacokinetic advantages of topically applied PGF2 alpha-IE. However, its greatly reduced side effects give PhXA41 a clear therapeutic advantage over PGF2 alpha-IE, making it an effective new drug candidate for the long-term medical management of glaucoma.

Cardiovascular and sympathetic responses to PGF2 alpha injection into hypothalamic nuclei.

Injection of prostaglandin F2 alpha (1 nmol/rat) into the paraventricular, dorsomedial and posterior hypothalamic nuclei of halothane anesthetized rats elicited rapid increases of heart rate and blood pressure. The injection of this same dose of prostaglandin F2 alpha into the cerebroventricular system or intravenously had no effect on these parameters. The cardiovascular responses observed following prostaglandin F2 alpha injection into these hypothalamic nuclei were accompanied by increases in plasma levels of norepinephrine and epinephrine, with peak levels at the maximal cardiovascular response. This study suggests a possible role for prostaglandin F2 alpha in modulation of the cardiovascular system via specific hypothalamic nuclei.

[Steroid and nonsteroid postcoital contraceptives]. / Steroidnye i nesteroidnye kontratseptivy postkoital'nogo deistviia.

It has been shown experimentally that a combined use of estrogen-norsteroids prostaglandins and neurotropic substances during preimplantation period produces the most potent contraceptive effect. Analysis of the action mode of combined small doses of steroids, prostaglandins and neurotropic drugs suggests that the contraceptive action is underlain by the inhibitory effect on incretion produced by the luteinizing hormone, this effect being in its turn a reason for variation in the amount and condition of the developing fetuses.

Control of parturition in the sow using progesterone and prostaglandin.

The effect of progesterone and prostaglandin administration on the timing of farrowing was studied in three groups of 25 sows each. Progesterone treatment (100 mg/day) on days 112, 113 and 114 of gestation (group I) significantly prolonged the gestation length to 116.4 +/- 0.4 (mean +/- s.e.) days compared to the control sows (group III; 115.5 +/- 0.2; P less than 0.05). Administration of prostaglandin (200 micrograms Cloprostanol intramuscularly) on day 115 of gestation following progesterone treatment (group II) resulted in a gestation length of 116.0 +/- 0.1 days, with the sows farrowing 25.4 +/- 1.0 h after the prostaglandin injection. 80% of the sows farrowed between 0800 and 1700 h of day 116 of gestation. Plasma progesterone levels were maintained by the exogenous progesterone during treatment. At farrowing, higher levels of progesterone were observed in groups I and II compared to controls. Prostaglandin treatment did not significantly alter withdrawal of progesterone in progesterone treated sows, suggesting that the actions of exogenous prostaglandin is primarily on the myometrium and the cervix. Hormonal treatment in late pregnancy did not have any adverse effects on piglet viability and growth rate, or subsequent reproductive performances of sows. Lactation was initiated normally, and the concentrations of lactose, protein, fat, IgG, Na+, Ca2+ and K+ in colostrum and milk were similar in all groups during the first 5 days of lactation.