The physical characteristics and behavior of the ATP-binding cassette (ABC) A1, A7, and apolipoprotein (apo) E knockout (KO) mice with lipid transport dysfunction were investigated. These KO mice exhibited adequate growth, and their body masses increased steadily. No remarkable changes were observed in their blood pressure and heart rate. However, there was a slight increase in the heart rate of the ABCA7 KO mice compared with that of the wild-type (WT) mice. ABCA1 and apoE KO mice showed hypo- and hyper-cholesterol concentrations in the plasma, respectively. With regard to the cerebrum, however, the weight of the ABCA1 KO mice was lighter than those of the other genotypes. Furthermore, the cholesterol, triglyceride and phospholipid concentrations, and fatty acid composition were generally similar. Compared with the WT mice, ABCA1 KO mice stayed for a shorter time in the closed arm of the elevated plus maze, and performed worse in the initial stage of the Morris water maze. To thermal stimuli, the ABCA1 and apoE KO mice showed hyper- and hypo-sensitivities, respectively. Only the response of the ABCA1 KO mice was significantly inhibited by pretreatment with indomethacin. A low concentration of the prostaglandin E metabolites was detected in the plasma of the ABCA1 KO mice. Thus, ABCA1 is thought to play a specific role in the neural function.

Crocetin (apo carotenoid dicarboxylic acid) is a common constituent of saffron. Its importance is well documented in Chinese medicine. Some studies have reported the inhibitory effect on inflammation in rats. The aim of the current experimental investigation to scrutinize the anti-inflammatory effect of Crocetin using the lipo polysaccharide (LPS) induced mouse macrophages (RAW 264.7) in vitro and complete Freund's adjuvant-induced arthritis model and to explore in vivo possible mechanism of action. RAW 264.7 macrophages were used for estimation of the effect of crocetin on the cyclooxygenase (COX-2), nitric oxide (NO)production, anti-inflammatory and along with pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and interleukin-10 (IL-10). Single intraperitoneal injection of complete freund's adjuvant (CFA) was used to induce arthritis. The rats were divided into different group and received the oral administration of crocetin in a dose-dependent manner with indomethacin till 28 days. The paw edema and body weight was estimated at regular interval of time. The biochemical parameters, hematological and pro-inflammatory cytokines such as tumor necrosis factor receptor 1 (TNF-R1), IL-6, and IL-1β, Vascular endothelial growth factor (VEGF); heme oxygenase-1/nuclear factor erythroid 2-related factor 2 (HO-1/Nrf-2) expression were estimated at end of the experimental study. Crocetin inhibited the COX-2 catalyzed prostaglandin (PGE2) and inducible nitric oxide synthase catalyzed NO production on RAW 264.7. The paw edema and body weight was significantly (P < 0.001) modulated by the Crocetin in a dose-dependent manner. Crocetin treatment increased the level of red blood cells (RBC), hemoglobin (Hb) and decreased level of white blood cells (WBC), erythrocyte sedimentation rate (ESR), alkaline phosphatase (ALP), serum glutamic pyruvic transaminase (SGPT), and serum glutamic-oxaloacetic transaminase (SGOT) parameters, with reduction of TNF-α, IL-6, and IL-1β.The protective effect of crocetin was substantiated with a reduction in expression of IL-6, IL-1β, VEGF, and TNF-R1, respectively. Crocetin also increased the HO-1/Nrf-2 and decreased the nuclear factor kappa-B (NF-κB) mRNA, protein expression. On the basis of the result, we can conclude that the reduction of HO-1/Nrf-2 expression, as well as inflammatory mediators, may be involved in the protective effect of Crocetin in the CFA model.

Cogent evidence points to the involvement of neurosteroids in the regulation of dopamine (DA) neurotransmission and signaling, yet the neurobiological bases of this link remain poorly understood. We previously showed that inhibition of 5α-reductase (5αR), a key neurosteroidogenic enzyme, attenuates the sensorimotor gating deficits induced by DA receptor activation, as measured by the prepulse inhibition (PPI) of the acoustic startle reflex. To extend these findings, the present study was aimed at the assessment of the role of other key neurosteroidogenic enzymes in PPI, such as 17α-hydroxylase/C17,20 lyase (CYP17A1), 3α- and 3β-hydroxysteroid dehydrogenase (HSD), in Sprague-Dawley rats. The PPI deficits induced by the DAergic non-selective agonist apomorphine (APO, 0.25mg/kg, SC) were dose-dependently attenuated by the selective CYP17A1 inhibitor abiraterone (ABI, 10-50mg/kg, IP) in a fashion akin to that of the 5αR inhibitor finasteride (FIN, 100mg/kg, IP). These systemic effects were reproduced by intracerebroventricular injection of ABI (1 μg/1 μl), suggesting the involvement of brain CYP17A1 in PPI regulation. Conversely, the PPI disruption induced by APO was not significantly affected by the 3α- and 3β-HSD inhibitors indomethacin and trilostane. Given that CYP17A1 catalyzes androgen synthesis, we also tested the impact on PPI of the androgen receptor (AR) antagonist flutamide (10mg/kg, IP). However, this agent failed to reverse APO-induced PPI deficits; furthermore, AR endogenous ligands testosterone and dihydrotestosterone failed to disrupt PPI. Collectively, these data highlight CYP17A1 as a novel target for antipsychotic-like action, and suggest that the DAergic regulation of PPI is modulated by androgenic neurosteroids, through AR-unrelated mechanisms.

Particulate matter (PM) induces oxidative stress and cardiovascular adverse health effects, but the mechanistic link between the two is unclear. We hypothesized that PM enhanced oxidative stress in vascular endothelial cells and investigated the enzymatic sources of reactive oxygen species and their effects on mitogen-activated protein kinase (MAPK) activation and vasoconstriction. We measured the production of extracellular H2O2, activation of extracellular signal-regulated kinases1/2 (ERK1/2) and p38 MAPKs in human pulmonary artery endothelial cells (HPAEC) treated with urban particles (UP; SRM1648), and assessed the effects of H2O2 on vasoconstriction in pulmonary artery ring and isolated perfused lung. Within minutes after UP treatment, HPAEC increased H2O2 production that could be inhibited by diphenyleneiodonium (DPI), apocynin (APO), and sodium azide (NaN3). The water-soluble fraction of UP as well as its two transition metal components, Cu and V, also stimulated H2O2 production. NaN3 inhibited H2O2 production stimulated by Cu and V, whereas DPI and APO inhibited only Cu-stimulated H2O2 production. Inhibitors of other H2O2-producing enzymes, including Nomega-methyl-L-argnine, indomethacin, allopurinol, cimetidine, rotenone, and antimycin, had no effects. DPI but not NaN3 attenuated UP-induced pulmonary vasoconstriction and phosphorylation of ERK1/2 and p38 MAPKs. Knockdown of p47phox gene expression by small interfering RNA attenuated UP-induced H2O2 production and phosphorylation of ERK1/2 and p38 MAPKs. Intravascular administration of H2O2 generated by glucose oxidase increased pulmonary artery pressure. We conclude that UP induce oxidative stress in vascular endothelial cells by activating NAD(P)H oxidase and the mitochondria. The endothelial oxidative stress may be an important mechanism for PM-induced acute cardiovascular health effects.

The detrimental effects of ultraviolet B (UVB) irradiation have been connected with the enhanced generation of reactive oxygen species (ROS) by UVB. However, the exact source of ROS produced by UVB has not been clearly revealed yet. In this study, we determined the source of ROS production and its role in the UVB-induced activation of nuclear factor (NF)-kappaB in HaCaT human keratinocytes. UVB irradiation generated ROS in a dose-dependent manner, and this was significantly inhibited by diphenylene iodonium (DPI), apocynin (Apo) and neopterine (Neo), inhibitors of the NADPH oxidase, and indomethacin (Indo), a cyclooxygenase (COX) inhibitor, but not by the mitochondrial electron transport inhibitors and other cytosolic enzyme inhibitors. In addition, these inhibitors of the NADPH oxidase and COX significantly blocked the UVB irradiation-induced nuclear translocation of NF-kappaB. These results suggest that the NADPH oxidase and COX may be major sources for the UVB-induced ROS generation, and play an essential role in the activation of NF-kappaB which is involved in the expression of a variety of genes induced by UVB in HaCaT cells. These results further suggest that these enzymes may be good targets for the preventive strategy of UVB-induced skin injury.

Prostanoids have been implicated in the transcriptional control of several genes. Since prostanoid synthesis inhibitors are commonly used in subjects with coronary heart disease we studied the effect of cyclooxygenase (COX) inhibition on apolipoprotein AI (apoAI) expression in a human hepatoma cell line (HepG2) transfected with full-length apoAI promoter attached to the chloramphenicol acetyl transferase (CAT) reporter gene. To control for transfection efficiency, the cells were cotransfected with the plasmid pCMV.SPORT-beta-gal containing the beta-galactosidase gene driven by the cytomegalovirus promoter. Treatment of these cells with varying concentrations of indomethacin (INDO, 0, 50, 100, and 300 micromol/L) resulted in a dose-dependent decrease in apoAI promoter activity (% acetylation corrected for beta-galactosidase activity: were 46.1 +/- 2.6, 29.9 +/- 1.2, 25.2 +/- 2.9, and 17.2 +/- 2.8, respectively, P <.001). INDO treatment did not cause significant changes in beta-galactosidase activity. A similar reduction in apoAI promoter activity was found after treating the cells with 50 micromol/L acetylsalicylic acid (ASA) (31.8 +/- 1.8%, P <.001), suggesting that the effect of INDO is related to COX inhibition rather than a peculiar effect of INDO. Nuclear run-off assays indicated that treatment of cells with 50 micromol/L INDO resulted in 31.4% reduction in apo A1 transcription rate (P <.0002). Northern blot analysis of RNA from HepG2 cells treated with 50 micromol/L of INDO for 72 hours showed that the apoAI mRNA concentration relative to G3PDH mRNA was 4,043.0 +/- 84.6 and 3,064.0 +/- 49.8 in control and INDO-treated cells, respectively (P <.0006). Kinetic studies of apoAI mRNA in HepG2 cells indicated that the half-life of apoAI mRNA was not significantly altered with 50 micromol/L INDO treatment. Apo AI mRNA half-life was 25.3 hours in control cells and 26.9 hours in INDO-treated cells. Western blot analysis of culture media of HepG2 cells treated with 50 micromol/L of INDO for 72 hours showed a significant reduction in apoAI protein (6,760.0 +/- 318.1 v 4,773.0 +/- 112.0 arbitrary units, P <.004). Treatment of cells with either arachidonic acid (COX substrate) or various prostanoids including prostaglandin I(2), thromboxane B(2), (+/-)5-HETE, or (+/-)12-HETE did not significantly alter apoAI promoter activity. However, prostaglandin E(1) and E(2) at the highest concentration tested (50 nmol/L) significantly repressed apoAI promoter activity. COX activity measurements in HepG2 cells verified the efficacy of COX inhibition by INDO. It is concluded that COX inhibition with INDO or ASA downregulates apoAI expression at the transcriptional level. This effect could not be attributed to either arachidonic acid excess or to a deficiency in various prostanoids tested.

In order to investigate the consequences of stress susceptibility on vascular function, the authors assessed the respective contributions of nitric oxide (NO), prostanoids, and endothelium-derived hyperpolarizing factor to the vascular tone in rats with a constitutionally determined high and low susceptibility to behavioral stressors. In mesenteric resistance arteries mounted in a small vessel myograph and precontracted with l-phenylephrine hydrochloride (phenylephrine), the NO-synthase inhibitor N omega-nitro-l-arginine (l-NOARG, 100 microM) elicited a smaller increase of vascular tone in apomorphine-susceptible (APO-SUS) rats (P < 0.01). Addition of indomethacin (10 microM), in the presence of l-NOARG, resulted in a smaller decrease of vascular tone in APO-SUS rats (P < 0.01). Although acetylcholine-induced relaxation in phenylephrine-precontracted arteries was not different (P > 0.1), the individual components contributing to this relaxation were. In arteries precontracted with 125 mM K+, and incubated with indomethacin, acetylcholine-induced relaxation was not significantly different (pEC(50) and E(max): P > 0.1). Sensitivity (pEC(50): P < 0.05) and maximum relaxation (E(max): P < 0.001) to sodium nitroprusside, in the presence of 125 mM K+, was more pronounced in APO-SUS rats. In phenylephrine-precontracted arteries, in the presence of l-NOARG and indomethacin, maximum relaxation to ACh was reduced in APO-SUS rats (E(max): P < 0.05). This study showed that in rats with a high susceptibility to stressors, the contribution of NO to vascular tone was decreased as was the ratio of vasoconstrictor and vasodilator cyclooxygenase products in alpha-adrenergic precontracted arteries. End-organ sensitivity to NO was greater in APO-SUS rats, possibly due to up-regulation. Moreover, the contribution of endothelium-derived hyperpolarizing factor to acetylcholine-induced vasodilation was reduced in APO-SUS rat arteries.

High serum lipoprotein(a) (Lp(a)) is a risk factor for vascular disorders. Our preliminary observations suggest that, in some patients with coronary heart disease with high serum Lp(a) levels, administration of aspirin reduced Lp(a) levels. Therefore, we aimed to analyze the effects of aspirin on the production of apo(a), the expression of apolipoprotein(a) (apo(a)) mRNA and the transcriptional activity of apo(a) gene promoter. Aspirin (5 mM) reduced the apo(a) levels in culture medium of human hepatocytes and suppressed apo(a) mRNA expression to 73% and 85% of the controls, respectively. Aspirin also reduced the transcriptional activity of apo(a) gene transfected into HepG2 hepatoma cells in a dose-dependent manner, with a maximal effect at 5 mM (44.3 +/- 1.5% of the control). Sodium salicylate (5 mM) also reduced apo(a) gene transcription, whereas indomethacin (10 microM) had no effect. Deletion analysis of apo(a) gene promoter showed that promoter region extending from -30 to +138 is critical for the effect of aspirin. Furthermore, enhanced production, mRNA expression, and gene transcription of apo(a) by interleukin-6 were also inhibited by aspirin. These results demonstrate that aspirin reduces apo(a) production from hepatocytes via reduction of the transcriptional activity of apo(a) gene with suppression of apo(a) mRNA expression. The suppression of apo(a) production by aspirin may at least in part play a role in the anti-atherogenic effect of aspirin in vascular disorders.

The mechanism of the hypolipidemic effect of n-3 fatty acids was studied using isolated rat hepatocytes maintained in culture. EPA and DHA caused a significant reduction in the incorporation of 3[H]-leucine into apoB associated with the VLDL produced by hepatocytes in culture when compared to that in presence of palmitic acid. Presence of indomethacin, an inhibitor of cyclo-oxygenase reversed the effect of EPA on VLDL synthesis while diethyl carbamazine an inhibitor of lipoxygenase did not show any effect suggesting that the effect of EPA may be mediated through prostaglandins. This was further tested by invivo experiments where animals were fed fish oil containing diet with and without aspirin, which inhibits formation of prostaglandins. The incorporation of 3[H]-leucine into apo B and 14[C]-acetate into cholesterol of VLDL produced by hepatocytes from aspirin treated animals were significantly high. The reversal of the effect of n-3 fatty acids by agents which inhibit the formation of prostaglandin suggests that the n-3 fatty acids may exert their effect on VLDL production by liver cells through prostaglandins.

Apoptosis induced by an antibody to CD95/APO-1/FAS in the colon carcinoma cells COLO 205 and HT-29 is suppressed by the phorbol ester TPA. Inhibition is much more effective in COLO 205 than in HT-29 cells. The TPA effect is abrogated by the protein kinase C (PKC)-specific inhibitor Go6983 indicating a role of PKC in this process. Bryostatin 1, unlike TPA, is unable to suppress apoptosis, but inhibits the TPA-induced suppression of apoptosis. TPA also inhibits indomethacin-induced apoptosis in COLO 205 cells. COLO 205 and HT-29 cells contain the PKC isoenzymes alpha, beta(II) delta, epsilon, eta, mu and zeta. Expression and activity of PKC alpha are at least 5 times higher in COLO 205 than in HT-29 cells. This correlates with the fact that inhibition of CD95-mediated apoptosis by TPA is more prominent in COLO 205 than in HT-29 cells. Thus, these findings suggest that PKC alpha has an important role in the TPA-induced inhibition of apoptosis.

The steady state tryptophan fluorescence of apo-human cyclooxygenase-2 (hCox-2) is quenched approximately 40%-50% by the slow binding inhibitors diclofenac, indomethacin, ketoprofen, NS-398, and DuP-697. The effects of these inhibitors on tryptophan fluorescence are both time and concentration dependent. Addition of each inhibitor results in a rapid fluorescence decrease, followed by a slower time dependent quenching. The slow, time dependent loss of fluorescence follows first-order kinetics, the rate constants for the process increasing with inhibitor concentration in a saturation-type manner. The rapid fluorescence loss also increases with increasing inhibitor concentration in the same manner. These results are consistent with the initial formation of a rapid equilibrium complex of enzyme and inhibitor (EI), followed by the slower formation of a tightly bound enzyme-inhibitor complex (EI*). The fluorescence of the EI complex is not significantly different from that of the EI* complex. The kinetic parameters of each inhibitor derived for this process (Ki and kon) are close to those obtained by determination of the rate constants for the onset of enzyme inhibition, thereby linking the fluorescence changes with inhibitor binding. The reversible inhibitors ibuprofen and docosahexaenoic acid do not quench the protein fluorescence but do decrease both the rate of the slow fluorescence loss and the magnitude of the initial rapid fluorescence decrease caused by the slow binding inhibitors, consistent with their competitive behavior. ASA-acetylated apo-hCox-2 shows the same fluorescence-quenching behavior in the presence of most of the above inhibitors. However, acetylation apparently blocks the binding of diclofenac, whereas the affinity of ibuprofen is increased. The effects of the collisional quenching agents iodide and acrylamide on both the native and inhibited enzyme are small (< 20% quenching at 0.3 M), showing that inhibitor binding does not result in an increased solvent accessibility of protein tryptophans. The cause of the inhibitor-induced quenching of the intrinsic apo-hCox-2 fluorescence is likely energy transfer to the bound inhibitor. Calculations based on the inhibitor-tryptophan distances in ovine Cox-1 indicate that the distances are within the required range for significant quenching to occur.

Hydralazine (HDZ), a p.o. effective antihypertensive drug, was evaluated for its genotoxic effects in both rodent and human cultured cells and in the intact rat. Dose-dependent amounts of DNA fragmentation, as measured by the alkaline elution technique, and of DNA repair synthesis, as revealed by autoradiography, were produced in primary cultures of metabolically competent rat hepatocytes by subtoxic HDZ concentrations ranging from 0.32 to 1.0 mM. A similar potency in inducing DNA repair synthesis was displayed by HDZ in primary cultures of hepatocytes from four human donors. A modest reduction of both DNA fragmentation (-13%) and DNA repair (approximately -50%) was observed in hepatocytes obtained from rats pretreated with indomethacin in order to reduce prostaglandin synthetase activity. In contrast, neither in rat nor in human hepatocytes, differences in N-acetyltransferase activity resulted in meaningful changes of the same end points. V79 cells, which are essentially deficient of monooxygenases catalyzing the biotransformation of xenobiotics, were as sensitive as hepatocytes to the DNA-damaging activity of HDZ. Moreover, after exposure to 0.1 to 0.3 mM HDZ, a modest (2.1- to 2.8-fold), but significant, increase in the frequency of mutation to 6-thioguanine resistance was observed in V79 cells in the absence of a metabolic activation system. In rats, a single p.o. dose of 80 mg/kg produced a clastogenic effect in the liver, but not in the bone marrow, and the p.o. administration for 14 successive days of approximately 46 mg/kg/day increased the average diameter of liver basophilic foci initiated by diethylnitrosamine.(ABSTRACT TRUNCATED AT 250 WORDS)

We have recently reported that apolipoprotein A-IV (apo A-IV), a protein associated with lipoproteins, acts in the brain to inhibit gastric acid secretion. In the present study, we determined whether or not apo A-IV has an anti-ulcer action via the central nervous system using Sprague-Dawley rats. Intracisternal injection of apo A-IV dose-dependently (2.0-4.0 micrograms/rat) reduced the severity of gastric mucosal lesions induced by intravenous injection of 2-deoxy-D-glucose or subcutaneous administration of indomethacine. A higher dose (15 micrograms) of apo A-IV injected intraperitoneally failed to inhibit the development of gastric mucosal damage evoked by these ulcerogenic agents. These results suggest for the first time that apo A-IV has an anti-ulcer action through a central mechanism.

Derivatives of the potent antiinflammatory agent and cyclooxygenase inhibitor indomethacin were synthesized in which the carboxylic acid moiety was converted into reactive acylating agents. Indomethacin imidazole (indomethacin-IM) and indomethacin N-hydroxysuccinimide (indomethacin-NHS) inactivated both the cyclooxygenase and peroxidase activities when incubated with the apo form of purified prostaglandin endoperoxide synthase (PGH synthase) at a stoichiometry of 1:1. Treatment of the inactivated enzyme with hydroxylamine at neutral pH led to recovery of all peroxidase and about 50% of the cyclooxygenase activity. Hydroxylamine did not regenerate the cyclooxygenase activity of indomethacin-inactivated protein. Reconstitution of the apoprotein with heme protected against inactivation by indomethacin-NHS. Visible spectroscopy established that indomethacin-NHS-inactivated apoenzyme had a reduced capacity to bind heme. Indomethacin-NHS also substantially protected the apoenzyme from cleavage at the trypsin-sensitive Arg277 site. Incubation of [2-14C]indomethacin-NHS with PGH synthase led to incorporation of radioactivity into the protein, but no adduct was detected by reversed-phase HPLC, suggesting it was unstable to the chromatographic conditions. Incubation of indomethacin-NHS with apoprotein followed by HPLC analysis led to the formation of greater amounts of the hydrolysis product indomethacin than did similar treatment of holoprotein. The results suggest that indomethacin-IM and indomethacin-NHS covalently and selectively label PGH synthase near the heme binding site, leading to loss of both catalytic activities of the enzyme.

In conscious renal artery-ligated rats, a high renin hypertensive rat model, DuP 753, a p.o. active nonpeptide angiotensin II (AII) receptor antagonist, decreased blood pressure at 0.1 to 3 mg/kg given i.v. or at 0.3 to 10 mg/kg given p.o. with an i.v. ED30 of given i.v. or at 0.3 to 10 mg/kg given p.o. with an i.v. ED30 of 0.78 mg/kg and a p.o. ED30 of 0.59 mg/kg. The antihypertensive efficacy of DuP 753 was similar to that of captopril. Unlike the peptide AII antagonist saralasin, DuP 753 did not cause a transient increase in blood pressure, suggesting absence of agonistic activity. At 3 mg/kg p.o., DuP 753 lowered blood pressure for at least 24 hr and did not change heart rate, suggesting a long duration of antihypertensive effect. At 3 mg/kg i.v., DuP 753 inhibited the pressor response to AII but not to norepinephrine or vasopressin. Pretreatment of renal artery-ligated rats with captopril, saralasin or propranolol, but not with prazosin, hydralazine or indomethacin, abolished or reduced the antihypertensive effect of DuP 753. In the deoxycorticosterone acetate hypertensive rat, a low renin model, DuP 753 did not lower blood pressure. These results suggest that DuP 753 is a p.o. active, antihypertensive agent in renal artery-ligated rats with a similar antihypertensive efficacy as captopril. The antihypertensive effect of DuP 753 is most likely related to the blockade of the vasoconstrictor effect of AII. Unlike saralasin, DuP 753 does not have agonistic activity.

The effect of Fe3+ bound lactoferrin (LF) on chemiluminescence (CL) generation in human monocytes in the presence and absence of opsonized zymosan was examined. Fe3+ bound LF (10(-6) or 10(-7) M) augmented the CL response in the presence but not the absence of zymosan. In contrast, Apo LF, Fe3+ bound transferrin and Fe3+ itself had no significant effect. It appears that the effect of LF on zymosan-induced chemiluminescence is dependent on iron and is receptor specific. The augmentation of CL by LF was inhibited by superoxide dismutase (SOD) and ETYA (fatty acid cyclooxygenase and lipoxygenase inhibitor), but not indomethacin (fatty acid cyclooxygenase inhibitor). Thus the enhancement of CL by LF depends on superoxide anion production and is related to the lipoxygenase pathway. The significance of this observation in terms of microbicidal or tumoricidal mechanisms remains to be determined.

The effect of prostaglandins (PGs) on apomorphine (apo)-induced circling was examined in unilaterally lesioned mice. Intraventricularly injected PGD2, PGE2, and PGF2 alpha at a dose of 1.0 nmole/g all inhibited apo-induced circling. When injected directly into the striatum, these same PGs also inhibited circling in a dose range of 0.01-0.1 nmole/g, while the PGE2 metabolite, 13,14-dihydro-15-keto-PGE2, was inactive at 0.1 nmole/g. For both routes of administration, PGF2 alpha appeared to be the most potent of the PGs tested. PGs administered alone by either route to unilaterally lesioned mice did not produce circling. Pretreatment with the PG synthetase inhibitor, indomethacin, caused the apo treated mice to circle at significantly higher rates than control animals. These results are the first report suggesting that within dopamine (DA)-mediated pathways PGs act at sites postsynaptic to the dopaminergic synapse.

The effect of intraventricularly (ivc) administered bradykinin (BRS) and activation of kininogenic enzymes of the cerebral tissue by kallikrein on dopaminergic system was investigated in tests of amphetamine (AMPH) and apomorphine (APO)-induced stereotypy and haloperidol (HAL)-induced catalepsy in rats receiving an inhibitor of prostaglandin synthetase, indomethacin (IND). The cerebral content of dopamine (DA), noradrenaline (NA) and homovanillic acid (HVA) was determined after some dosage schedules. In rats pretreated with IND the action of AMPH was potentiated and modulated by kinins (depending on the dose). IND prolonged the duration of APO-induced stereotypy and antagonized the action of low dose (1 mu g) of BRS, but potentiated the action of high doses (2 and 4 mu g) of BRS. IND potentiated the action of BRS on catalepsy induced by a low dose of HAL (0.75 mg/kg) but abolished the action of BRS on the catalepsy produced by a high dose of HAL (1.25 mg/kg). The results of biochemical investigation do not explain in full the behavioral changes.