2-MPPA,a selective glutamate carboxypeptidase II inhibitor,attenuates morphine tolerance but not dependence in C57/Bl mice

Rationale and objectives We have recently reported that conditioned morphine reward and tolerance to its antinociceptive effect, but not expression of morphine dependence, were attenuated by 2-(phosphonomethyl)pentanedioic acid (2-PMPA), a prototypic inhibitor of glutamate carboxipeptidase II (GCP II), which is an enzyme responsible for the supply of glutamate. In the present study, we investigated in more detail the effects of GCP II inhibition on opioid dependence and tolerance to its antinociceptive effect in C57/Bl mice using a novel GCP II inhibitor.Results The treatment with 2-(3-mercaptopropyl)pentanedioic acid (2-MPPA; 60 but not 10 or 30 mg/kg) prevented the development of morphine tolerance without affecting acute morphine antinociception. 2-MPPA at 30 and 60 mg/kg did not prevent the development of dependence induced by 10 and 30 mg/kg of morphine. The study on opioid withdrawal syndrome, i.e., expression of opioid dependence, demonstrated that 2-MPPA potentiated jumping behavior and teeth chattering but attenuated chewing and ptosis. None of these opioid withdrawal signs were affected by 2-MPPA in morphine nondependent mice. Pretreatment with the mGluR II antagonist LY341495 (1 mg/kg) reversed the 2-MPPA-induced increase or decrease in opioid withdrawal signs in morphine-dependent mice. 2-MPPA (60 mg/kg) administered for 7 days with morphine did not affect brain concentration of this opiate.Conclusions The present findings suggest complex effects of GCP II inhibition on morphine dependence and tolerance and imply a role of mGluR II in the actions of 2-MPPA.     

Neuroprotection mediated by glutamate carboxypeptidase II (NAALADase) inhibition requires TGF-beta.

Inhibition of glutamate carboxypeptidase (GCP) II (EC 3.4.17.21), also termed N-acetylated alpha-linked acidic dipeptidase (NAALADase), has been shown to protect against ischemic injury presumably via decreasing glutamate and increasing N-acetyl-aspartyl-glutamate (NAAG). NAAG is a potent and selective mGlu3 receptor agonist. Activation of glial mGlu3 receptors has been shown to protect against NMDA toxicity by releasing transforming growth factors, TGF-betas. We hypothesized that GCP II inhibition could be neuroprotective also via TGF-betas, due to increased NAAG. To verify this, Enzyme-Linked Immunosorbent Assays (ELISAs) were performed on media from both control and ischemic cultures treated with the GCP II inhibitor, 2-(phosphonomethyl)-pentanedioic acid (2-PMPA). We found that 2-PMPA attenuated ischemia-induced declines in TGF-beta. To further assess the role of TGF-betas in 2-PMPA-mediated neuroprotection, a neutralizing antibody to TGF-beta (TGF-beta Ab) was used. In both in vitro and in vivo models of cerebral ischemia, TGF-beta Ab reversed the neuroprotection by 2-PMPA. Antibodies to other growth factors had no effect. Data suggests that neuroprotection by GCP II inhibition may be partially mediated by promoting TGF-beta release.     

N-substituted glutamyl sulfonamides as inhibitors of glutamate carboxypeptidase II (GCP2)

Glutamate carboxypeptidase II (GCP2) is a membrane-bound cell-surface peptidase which is implicated in several neurological disorders and is also over-expressed in prostate tumor cells. There is a significant interest in the inhibition of GCP2 as a means of neuroprotection, while GCP2 inhibition as a method to treat prostate cancer remains a topic of further investigation. The key zinc-binding functional group of the well-characterized classes of GCP2 inhibitors (phosphonates and phosphoramidates) is tetrahedral and negatively charged at neutral pH, while glutamyl urea class of inhibitors possesses a planar and neutral zinc-binding group. This study introduces a new class of GCP2 inhibitors, N-substituted glutamyl sulfonamides, which possess a neutral tetrahedral zinc-binding motif. A library containing 15 secondary sulfonamides and 4 tertiary (N-methyl) sulfonamides was prepared and evaluated for inhibitory potency against purified GCP2 enzyme activity. While most inhibitors lacked potency at 100 μm, short alkyl sulfonamides exhibited promising low micromolar potency, with the optimal inhibitor in this series being glutamyl N-(propylsulfonamide) (2g). Lastly, molecular docking was used to develop a model to formulate an explanation for the relative inhibitory potencies employed for this class of inhibitors.     

Acute dependence on, but not tolerance to, heroin and morphine as measured by respiratory effects in rhesus monkeys

Acute dependence on and tolerance to heroin and morphine were assessed in rhesus monkeys using measures of respiration. Respiratory frequency (f) and minute volume (V(e)) were measured in monkeys breathing air or 5% CO(2) in air using a pressure-displacement plethysmograph. Cumulative doses of naltrexone (0.0001-1.0 mg/kg, i.m) did not alter these parameters in untreated monkeys. Twenty-four hours after a cumulative dose of heroin (1 mg/kg, i.m.), naltrexone produced an increase in both f and V(e) when monkeys were breathing air or 5% CO(2). Following 1 to 3 days of treatment with heroin (0.5 mg/kg/day, i.m.) or morphine (16 mg/kg/day, i.m.), naltrexone produced an increase in f and V(e) that was related to the dose of naltrexone and the number of days of agonist administration. Two days following termination of heroin administration, naltrexone-induced respiratory stimulation declined and had disappeared completely by the fifth day. In tolerance studies, heroin (0.032-0.5 mg/kg, i.m.) and morphine (1-16 mg/kg, i. m.) were injected cumulatively each day for three consecutive days. These drugs suppressed f and V(e) to nearly the same extent on day 3 as they had on day 1 of administration. These results suggest that dependence to morphine and heroin can be measured under conditions of acute 1 to 3 day administration conditions in primates using f and V(e) as reliable and quantitative indicators of opioid withdrawal. Under these conditions, tolerance does not occur.     

Alteration of spinal protein kinase C expression and kinetics in morphine, but not clonidine, tolerance.

Antinociceptive synergism between spinally administered morphine and clonidine decreases to an additive interaction in morphine- and clonidine-tolerant mice. Spinally administered protein kinase C (PKC) inhibitors also decrease the synergism to addition. To determine whether chronic morphine or clonidine treatment alters spinal PKC activity, the present studies measured PKC activity and expression of PKC isoform proteins in spinal cord cytosol and membrane fractions. Mice were treated for 4 days with either placebo pellets, morphine pellets, s.c. saline, or s.c. clonidine. Morphine pellet-implanted mice were tolerant to morphine-induced tail flick antinociception, but not cross-tolerant to clonidine. Clonidine-pretreated mice were tolerant to clonidine, but not cross-tolerant to morphine. Induction of morphine tolerance produced a 2-fold lower Km value for PKC (8.24 +/- 1.67 microM in placebo pellet vs 4.43 +/- 1.24 microM in morphine pellet) in cytosol, but not membrane fractions from spinal cord. Vmax values were not different. No difference in Km or Vmax values was found between proteins from saline- and clonidine-pretreated animals. Immunoreactive cPKCalpha, betaI, and gamma isoforms decreased 14, 26, and 17%, respectively, in cytosol from morphine-tolerant animals. No difference in PKC isoforms was found in the membranes or in fractions from clonidine-tolerant mice. Morphine tolerance, but not clonidine tolerance, enhanced PKC activity while decreasing protein expression.     

The dopamine D3/2 agonist 7-OH-DPAT attenuates the development of morphine tolerance but not physical dependence in rats

RATIONALE: The dopamine (DA) D3/2 agonist 7-OH-DPAT attenuates the acute antinociceptive, discriminative stimulus, locomotor activating, and reinforcing effects of mu agonists (for example, morphine). OBJECTIVES: To examine the ability of 7-OH-DPAT to modulate the development of morphine tolerance and physical dependence in the rat. METHODS: Morphine antinociception was assessed using a warm water tail-withdrawal procedure before and following chronic treatment with morphine (15 mg/kg)/7-OH-DPAT (0.3-3.0 mg/kg). Physical dependence was assessed following naloxone-precipitated (1.0 mg/kg) withdrawal in rats treated chronically with morphine (15 and 7.5 mg/kg)/7-OH-DPAT (1.0-10 mg/kg). RESULTS: 7-OH-DPAT attenuated the antinociceptive effects of morphine in both morphine naive and tolerant rats. Additionally, morphine tolerance was attenuated by the coadministration of 7-OH-DPAT in a dose- and time-dependent manner. The magnitude of the attenuation obtained when morphine and 7-OH-DPAT were administered at the same time was similar to that obtained when administration of these drugs was separated by 6 h, indicating that 7-OH-DPAT did not alter morphine pharmacokinetics. In rats rendered tolerant to morphine, the subsequent coadministration of morphine/7-OH-DPAT failed to reverse morphine tolerance, but did attenuate its further development. The level of physical dependence (number and frequency of withdrawal signs) was greater in rats treated with 15 than 7.5 mg/kg morphine. Under both treatment conditions, physical dependence was not altered by 7-OH-DPAT. In morphine-dependent (15 mg/kg) rats, 7-OH-DPAT (3.0 and 10 mg/kg) failed to precipitate withdrawal. CONCLUSION: The D3/2 agonist 7-OH-DPAT can attenuate the antinociceptive effects of morphine in both acute and chronic preparations as well as the development of morphine tolerance. 7-OH-DPAT does not, however, alter morphine physical dependence.     

Extracellular signal-regulated kinase (ERK) inhibition does not prevent the development or expression of tolerance to and dependence on morphine in the mouse

The clinical use of opioids is limited by the development of tolerance and physical dependence. Opioid tolerance and dependence are believed to result from complex adaptations in the CNS, representing a form of neural plasticity. Extracellular signal-regulated kinases (ERKs) are involved in many forms of neural plasticity, and therefore could also be involved in the development of opioid tolerance and dependence. In this study, we investigated the effect of a systemically bioavailable MEK (ERK kinase) inhibitor, SL327, upon the development and the expression of tolerance to and dependence on morphine in mice. In tolerance and dependence development studies, two strains of mice were treated daily for 8 or 9 days with 5mg/kg morphine s.c. Tolerance development was assessed by tail flick latency. Withdrawal was then precipitated by subcutaneous injection of 2mg/kg naloxone s.c. and signs recorded. Co-administration of 50mg/kg SL327 i.p. prior to morphine administration had no effect on the development of tolerance or withdrawal signs. To study possible effects of ERK inhibition on the expression of tolerance and dependence, mice were implanted with 75mg morphine pellets s.c. Tolerance and dependence were assessed as previously described. An acute i.p. injection of 50mg/kg SL327 after 4 days of morphine exposure had no effect on the expression of either morphine tolerance or physical dependence. To verify that this dose of SL327 inhibited morphine-induced ERK modulation, mice received an acute i.p. injection of 50mg/kg SL327 prior to morphine administration, and sacrificed 30min later. Western blots demonstrated that SL327 did inhibit morphine-induced ERK modulation. Taken together, these data suggest that unlike many other observed forms of neural plasticity, the ERK signaling cascade is not involved in the development or expression of opioid tolerance and dependence.     

2-phosphonomethyl-pentanedioic acid (glutamate carboxypeptidase II inhibitor) increases threshold for electroconvulsions and enhances the antiseizure action of valproate against maximal electroshock-induced seizures in mice

This study examined the effect of 2-(phosphonomethyl)-pentanedioic acid (2-PMPA), a potent and selective inhibitor of glutamate carboxypeptidase II (GCP II), an enzyme releasing glutamate and N-acetyl-aspartate from synaptical terminals, on the electroconvulsive threshold in mice. Moreover, the influence of 2-PMPA on the anticonvulsant activities of four conventional antiepileptic drugs (carbamazepine, phenobarbital, phenytoin and valproate) was evaluated in the maximal electroshock-induced seizure test in mice. Results indicated that 2-PMPA (at a dose range of 50-200 mg/kg, i.p.) raised the electroconvulsive threshold in mice dose-dependently. Linear regression analysis of dose-response relationship between the doses of 2-PMPA and their corresponding threshold values allowed the calculation of threshold increasing dose by 20% (TID20), which was 109.2 mg/kg. Moreover, 2-PMPA administered i.p. at a constant dose of 150 mg/kg (the dose increasing the threshold for electroconvulsions) enhanced significantly the anticonvulsant action of valproate, by reducing its median effective dose (ED50) from 281.4 to 230.1 mg/kg (P<0.05). In contrast, 2-PMPA at the lower dose of 100 mg/kg (i.p.) had no impact on the antiseizure activity of valproate in the maximal electroshock-induced seizure test. Likewise, 2-PMPA at 100 and 150 mg/kg did not affect the antiseizure action of carbamazepine, phenobarbital and phenytoin against maximal electroshock-induced seizures in mice. Additionally, none of the combinations investigated between 2-PMPA (150 mg/kg, i.p.) and carbamazepine, phenobarbital, phenytoin and valproate (at their ED50 values) produced motor coordination impairment in the chimney test. Pharmacokinetic evaluation of interaction between 2-PMPA and valproate revealed that 2-PMPA at 150 mg/kg selectively increased total brain concentrations of valproate, remaining simultaneously without any effect on free plasma concentrations of valproate, indicating a pharmacokinetic nature of observed interaction in the maximal electroshock-induced seizures in mice. Based on our preclinical data, it may be concluded that 2-PMPA possesses a seizure modulating property by increasing the electroconvulsive threshold. The reduction of glutamate neurotransmission in the brain, as a consequence of inhibition of GCP II activity by 2-PMPA, was however insufficient to enhance the anticonvulsant activity of conventional antiepileptic drugs, except for valproate, whose antiseizure action against maximal electroconvulsions was potentiated by 2-PMPA. Unfortunately, the favourable interaction between 2-PMPA and valproate was associated with a pharmacokinetic increase in total brain valproate concentrations.     

The effects of 4-imidazolyl-3-amino-2-butanone (McN-A-1293), a specific histidine decarboxylase inhibitor, on the expression of morphine tolerance and physical dependence in mice

McN-A-1293, a specific histidine decarboxylase inhibitor administered intracisternally in the 'withdrawal' phase, significantly suppressed the expression of morphine tolerance. Severity of withdrawal, assessed by percentage body weight loss, was significantly enhanced although incidence of jumping was unaltered. The opposite effects of this compound on morphine tolerance and withdrawal suggest that tolerance and physical dependence are based on different underlying mechanisms.     

L-type Ca(2+) channel blockers inhibit the development but not the expression of sensitization to morphine in mice

The relationship between opioid actions and L-type Ca(2+) channel blockers has been well documented. However, there is no report relevant to L-type Ca(2+) channel blockers and morphine sensitization, which is suggested to be an analog of behaviors that are characteristic of drug addiction. We now studied systematically the effects of three L-type Ca(2+) channel blockers, nimodipine, nifedipine and verapamil, on morphine-induced locomotor activity, the development and the expression of sensitization to morphine. The results showed that both nimodipine and verapamil attenuated, while nifedipine had only a tendency to decrease morphine-induced locomotor activity. All three drugs inhibited the development of sensitization to morphine. However, none of them showed any effects on the expression of morphine sensitization. These results indicate that blocking L-type Ca(2+) channel attenuates the locomotor-stimulating effects of morphine and inhibits the development but not the expression of morphine sensitization.     

Chemokine production and E-selectin expression in activated endothelial cells are inhibited by p38 MAPK (mitogen activated protein kinase) inhibitor RWJ 67657

Endothelial cells play an important role in inflammatory diseases like rheumatoid arthritis by recruitment of inflammatory cells. The cytokines TNF-alpha and IL-1beta are major inducers of endothelial cell activation and are stimulators of inflammatory signal transduction pathway involving p38 MAPK (mitogen-activated protein kinase). The present study investigated the effects of p38 MAPK inhibition on cell adhesion molecule (CAM) expression and chemokine production by endothelial cells both on mRNA and protein level. Pre-treatment of endothelial cells with the pharmacologically relevant concentration of 1 microM of the p38 MAPK inhibitor RWJ 67657 reduced TNF-alpha and IL-1beta induced mRNA and membrane expression of E-selectin. Moderate inhibitory effects on ICAM-1 and VCAM-1 expression were found. Significant reduction of mRNA expression and protein production of the inflammatory cytokine IL-6 and the chemokines IL-8 and MCP-1 was demonstrated. Treatment with RWJ 67657 could lead to reduced leukocyte infiltration by the reduction of E-selectin expression and chemokine production.     

Potentiation of 2-deoxy-D-glucose antinociception, but not hyperphagia by zolantidine, a histamine (H2) receptor antagonist.

Antagonism of the histamine (H2) receptor reduces antinociception induced by naloxone-resistant foot-shock, naloxone-sensitive foot-shock, and morphine with a rank-order potency similar to their H2 antagonism. The antimetabolic glucose analog 2-deoxy-D-glucose (2DG) produces antinociceptive and hyperphagic responses that dissociate from each other and are in part mediated by opioid systems. The present study determined the effects of the brain-penetrating H2 receptor antagonist zolantidine (ZOL) on 2DG antinociception on the tail-flick and jump tests, as well as on 2DG hyperphagia, in rats. ZOL (0.01-1 mg/kg) potentiated the antinociceptive responses induced by a moderate (450 mg/kg) dose of 2DG, but had lesser effects upon antinociception induced by a lower (100 mg/kg) 2DG dose. ZOL itself slightly increased jump thresholds, but not tail-flick latencies. Combinations of ZOL and 2DG produced supraadditive antinociception, even though ZOL failed to significantly shift the 2DG dose-response curve to the left. In contrast, ZOL failed to alter basal intake or 2DG hyperphagia, supporting previous evidence implicating the H1 but not the H2 receptor in these effects. These results further dissociate the antinociceptive and hyperphagic effects of 2DG, and also support previous results indicating both pro- and antinociceptive roles for H2 receptors.     

Irreversible inhibition of thromboxane (TX) A2 synthesis by Y-20811, a selective TX synthetase inhibitor.

As Y-20811, sodium (+-)-4-[alpha-hydroxy-5-(1-imidazolyl)-2-methylbenzyl]-3,5-dimethylb+ ++ enzoic acid, has been reported to inhibit serum thromboxane (TX) A2 production with a long duration of action, its mechanism of action was investigated. When [3H]Y-20811 (3 mg/kg) was administered orally to rats, the peak platelet concentration of Y-20811 was obtained 1 hr after the administration, and the T1/2 was 43 hr. The peak plasma concentration of Y-20811 was also obtained 1 hr after administration, but the elimination of Y-20811 from plasma was faster (T1/2 alpha = 1.5 hr, T1/2 beta = 15 hr) than that observed in platelets. Serum TXA2 (estimated as TXB2) production was inhibited significantly from 1 to 72 hr after the oral administration of unlabeled Y-20811 (3 mg/kg), which temporally resembled the change of the platelet Y-20811 concentration. In platelet-rich plasma, [3H]Y-20811 completely inhibited TXA2 production at about 1500 pg/10(9) platelets, and the IC50 level was about 600 pg/10(9) platelets, which was similar to values obtained in ex vivo studies. In addition, inhibition of TXA2 production by Y-20811 still remained after washing the drug-pretreated microsomes, whereas that of dazoxiben completely disappeared. A similar irreversible inhibition of TXA2 production was observed with aspirin. These results suggest that Y-20811 may firmly combine with platelet TX synthetase and may irreversibly inhibit TXA2 production.     

(2,2':6',2"-Terpyridine)platinum(II) complexes are irreversible inhibitors of Trypanosoma cruzi trypanothione reductase but not of human glutathione reductase

(2,2':6',2"-terpyridine)platinum(II) complexes possess pronounced cytostatic activities against trypanosomes and leishmania. As shown here, the complexes are irreversible inhibitors of trypanothione reductase (TR) from Trypanosoma cruzi, the causative agent of Chagas' disease. The most effective derivatives are the (4'-chloro-2, 2':6',2"-terpyridine)platinum(II) ammine and the (4-picoline)(4'-p-bromophenyl-2,2':6',2" -terpyridine)platinum(II) complexes which in the presence of NADPH inhibit TR with second-order rate constants of about 1.3 x 10(4) M(-1) s(-1). The modified enzyme species possess increased oxidase activities. The inhibition is not reversed upon dialysis or treatment with low-molecular-mass thiols. Kinetic and spectroscopic data suggest that Cys52 in the active site has been specifically altered. Inhibition of this key enzyme of parasite thiol metabolism probably contributes to the antitrypanosomal activity of the compounds. In contrast to the parasite enzyme, most (terpyridine)platinum complexes interact only reversibly with human glutathione reductase and an initial inhibition is completely abolished during the course of the assay.     

Changes in GABA(A) receptor gene expression induced by withdrawal of, but not by long-term exposure to, zaleplon or zolpidem.

The effects of long-term treatment with and subsequent withdrawal of the two hypnotic drugs zaleplon and zolpidem on the abundance of gamma-aminobutyric acid type A (GABA(A)) receptor subunit mRNAs in cultured rat cerebellar granule cells were investigated. Incubation of neurons with either drug at a concentration of 10 microM for 5 days did not significantly affect the amounts of mRNAs encoding the alpha(1), alpha(4), beta(1), beta(2), beta(3), gamma(2)L, or gamma(2)S subunits. As expected, similar treatment with the nonselective benzodiazepine diazepam resulted in a decrease in the abundance of alpha(1), beta(2), gamma(2)L, and gamma(2)S subunit mRNAs as well as an increase in that of the beta(1) subunit mRNA. Withdrawal of zaleplon or zolpidem, like that of diazepam, induced a marked increase in the amount of the alpha(4) subunit mRNA. In addition, discontinuation of treatment with either hypnotic drug resulted in a decrease in the amounts of alpha(1), beta(2), gamma(2)L, and gamma(2)S subunit mRNAs as well as an increase in that of the beta(1) subunit mRNA. These effects of zaleplon and zolpidem on GABA(A) receptor gene expression are consistent with the reduced tolerance liability of these drugs, compared with that of diazepam, as well as with their ability to induce both physical dependence and withdrawal syndrome.     

Glutamate receptors in the dorsal hippocampus mediate the acquisition,but not the expression,of conditioned place aversion induced by acute morphine withdrawal in rats

Aim： To evaluate the role of glutamate receptors in the dorsal hippocampus （DH） in the motivational component of morphine withdrawal. Methods： NMDA receptor antagonist D-AP5 （5 pg/0.5 pL per side） or AMPA receptor antagonist NBQX （2 pg/0.5 pL per side） was micro- injected into DH of rats. Conditioned place aversion （CPA） induced by naloxone-precipitated morphine withdrawal were assessed. Results： Preconditioning microinjection of D-AP5 or NBQX into the DH impaired the acquisition of CPA in acute morphine-dependent rats. However, intra-DH microinjection of D-AP5 or NBQX after conditioning but before the testing session had no effect on the expres- sion of CPA. Conclusion： Our results suggest that NMDA and AMPA receptors in the dorsal hippocampus are involved in the acquisition, but not in the expression, of the negative motivational components of acute morphine withdrawal in rats.     

Glutamate receptors in the dorsal hippocampus mediate the acquisition,but not the expression,of conditioned place aversion induced by acute morphine withdrawal in rats

Aim:

To evaluate the role of glutamate receptors in the dorsal hippocampus (DH) in the motivational component of morphine withdrawal.

Methods:

NMDA receptor antagonist D-AP5 (5 μg/0.5 μL per side) or AMPA receptor antagonist NBQX (2 μg/0.5 μL per side) was microinjected into DH of rats. Conditioned place aversion (CPA) induced by naloxone-precipitated morphine withdrawal were assessed.

Results:

Preconditioning microinjection of D-AP5 or NBQX into the DH impaired the acquisition of CPA in acute morphine-dependent rats. However, intra-DH microinjection of D-AP5 or NBQX after conditioning but before the testing session had no effect on the expression of CPA.

Conclusion:

Our results suggest that NMDA and AMPA receptors in the dorsal hippocampus are involved in the acquisition, but not in the expression, of the negative motivational components of acute morphine withdrawal in rats.     

Cocaine-like subjective effects of nicotine are not blocked by the D1 selective antagonist ecopipam (SCH 39166)

The effects of ecopipam (a D(1) selective antagonist) or triazolam pretreatment on the subjective and physiological effects of intravenously administered nicotine were examined in 10 cigarette-smoking cocaine abusers. Under double-blind, randomized conditions, subjects received oral capsule pretreatment (0, 30 or 100 mg ecopipam, or 0.25 mg/70 kg triazolam), followed 120 min later by an intravenous injection of 2 mg/70 kg nicotine or saline. Subjective ratings, heart rate and blood pressure were assessed before and repeatedly after each intravenous injection. Compared to oral placebo pretreatment, both ecopipam and triazolam pretreatment produced significant elevations in subject-reported capsule effect and observer ratings of sleepiness/sedation. Nicotine increased ratings of 'drug effect', 'rush', 'high', 'stimulated', 'liking', 'good effects' and 'bad effects', and produced modest increases in heart rate and blood pressure. Following both intra-venous saline and nicotine injection, ecopipam tended to reduce heart rate and blood pressure. Although both ecopipam and triazolam lowered several subjective ratings following intravenous saline injection, neither ecopipam nor triazolam affected nicotine subjective effects. In contrast to Romach et al. (Arch Gen Psychiatry 56: 1101-1106, 1999), who showed that pretreatment with ecopipam blocked cocaine subjective effects, the current study found no attenuation of the subjective effects of nicotine, and thus, provides no support for the hypothesis that D(1) receptors mediate the cocaine-like subjective effects of nicotine.     

Benadrostin, new inhibitor of poly(ADP-ribose) synthetase, produced by actinomycetes. II. Structure determination

Benadrostin, a new inhibitor of poly(ADP-ribose) synthetase, has been isolated from the culture broth of Streptomyces flavovirens MH499-O'F1. The structure of benadrostin was defined as 8-hydroxy-2H-1,3-benzoxazine-2,4-dione by an analysis of spectral properties and chemical studies of benadrostin and its derivatives.