Altered expression of basement-membrane components and collagenases in ascitic xenografts of OVCAR-3 ovarian cancer cells.

Ascitic ovarian cancer cells, which derive from solid tumors, complicate the treatment of ovarian cancer by spreading throughout the peritoneal cavity. Because basement-membrane components may influence tumor-cell proliferation and dissemination, the present studies examined the production of (a) basement-membrane attachment and migration factors (laminin, fibronectin and type IV collagen); (b) a laminin receptor, the 32/67-kDa laminin-binding protein, the presence of which correlates with malignancy; and (c) metalloproteinases (types I and IV collagenase and stromelysin), by ascitic and cultured OVCAR-3 cells and solid OVCAR-3 tumors. The cultured cells and solid tumors produced high levels of mRNA encoding attachment factors and metalloproteinases, and low levels of mRNA for the 32/67-kDa laminin receptor. In contrast, the ascitic ovarian cells had low or undetectable levels of mRNA encoding laminin, type IV collagen and metalloproteinases, but higher levels of transcripts for the laminin receptor. Our results suggest that the apparent inability of ascitic OVCAR-3 cells to attach to host-tissue surfaces may be a consequence, in part, of low levels of expression of laminin, type IV collagen and/or type IV collagenase.

CGS 19755: a novel competitive N-methyl-D-aspartate (NMDA) receptor antagonist with anticonvulsant, anxiolytic and anti-ischemic properties.

CGS 19755 is a potent and selective competitive antagonist at NMDA receptors in the brain. In preclinical animal tests, the compound produces anticonvulsant, anxiolytic and anti-ischemic effects. CGS 19755 is not very active when administered orally, and intravenous administration is the most practical for clinical application. The anti-ischemic potential of CGS 19755 provides the most attractive application for clinical investigation.

Hyperactivity induced by N-methyl-d-aspartate injections into nucleus accumbens: lack of evidence for mediation by dopaminergic neurons.

To test the hypothesis that the motor hyperactivity associated with intra-accumbens injections of N-methyl-d-aspartate (NMDA) results from stimulation (direct or indirect) of nucleus accumbens dopaminergic mechanisms, the behavioral effects of intra-accumbens and intraventricular NMDA were compared to those of the prototypic dopaminergic releasing agent, amphetamine, and the competitive NMDA receptor antagonist, 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP). Drugs were injected into the right lateral ventricle, or bilaterally into the nucleus accumbens of rats. Locomotor activity was monitored electronically and by direct observation for 40 min prior to, and 1 hour after, drug treatment. Intra-accumbens injections of NMDA (0.4, 1.2 and 2.0 micrograms/side) produced dose-related increases in distance traveled, but had no significant effect on movement time or vertical movements. The NMDA-induced increase in distance traveled was temporally correlated with convulsive wild running, but not with exploratory behavior, suggesting that this increase may have been secondary to seizure-like activity. Intra-accumbens injections of amphetamine (10, 20 and 40 micrograms) or CPP (0.1 microgram) produced dose-related increases in all three measures. By the intraventricular route, the effects of NMDA were similar to those of intra-accumbens administration, whereas intraventricularly administered d-amphetamine had no effect. The behavioral effects of intra-accumbens NMDA cannot be explained by an NMDA receptor-mediated facilitation of dopaminergic neurotransmission; rather, this type of facilitation may be associated with competitive NMDA receptor antagonism.

Behavioral pharmacological profile of CGS 19755, a competitive antagonist at N-methyl-D-aspartate receptors.

CGS 19755 (cis-4-phosphonomethyl-2-piperidine-carboxylic acid), a competitive antagonist at N-methyl-D-aspartate (NMDA)-preferring receptors, blocked both NMDA-induced convulsions in normal CF1 mice and sound-induced wild running in seizure-prone DBA/2 mice. The ED50 values for CGS 19755 to produce these effects (in the range of 2 mg/kg i.p.) were at least 3-fold lower than those which impaired the traction reflex, an index of motor coordination. When administered p.o. by gavage, CGS 19755 had little or no effect in these test procedures. In an experimental model of anxiety in rats, CGS 19755 significantly increased conflict responding within a relatively narrow dose range (minimum effective dose, 1.73 mg/kg i.p.). At higher doses of CGS 19755, this effect appeared to be obscured by drug-induced reductions in overall responding. Potential muscle relaxant effects were also suggested by the generalization of CGS 19755 to diazepam discriminative stimuli (ED50 = 9.0 mg/kg i.p.) and by impaired rotorod performance (ED50 = 6.2 mg/kg i.p.) in rats. Although some resemblances were apparent between the behavioral effects of CGS 19755 and those of phencyclidine-type drugs, the phencyclidine-like behaviors appeared only at considerably higher doses of CGS 19755 than those associated with anticonflict activity, and only partial generalization of CGS 19755 to dexoxadrol was observed at high doses. CGS 19755 promises to be an important new research tool for investigating the function of brain NMDA receptors.

Effects of 5-HT1A agonists and 5-HT2 antagonists on haloperidol-induced dyskinesias in squirrel monkeys: no evidence for reciprocal 5-HT-dopamine interaction.

Dyskinetic movements and dystonic postures may be induced by neuroleptics in monkeys that have undergone previous neuroleptic treatment, and these motor abnormalities constitute a primate model of drug-induced extrapyramidal symptomatology. In view of previous suggestions that brain serotonergic systems may tonically inhibit dopamine neurons, the effects of several new and selective 5-HT2 receptor antagonists and 5-HT1A receptor agonists were investigated in this model. Setoperone, a dopamine D2 receptor antagonist with extremely potent 5-HT2 antagonism, caused dyskinetic movements. Although ritanserin is a potent 5-HT2 antagonist with very weak dopamine antagonist properties, this drug did not antagonize dyskinesias but induced them when administered at a high dose (30 mg/kg). Buspirone induced dyskinesias and blocked apomorphine-induced climbing, supporting prior reports that it has dopamine antagonist effects. Gepirone, a 5-HT1A agonist with less marked dopamine antagonist properties, induced dyskinesias in only one of six monkeys at 30 mg/kg and did not block haloperidol-induced dyskinesias. 8-OH-DPAT partly attenuated haloperidol-induced dyskinesias, an effect possibly attributable to its weak dopamine agonist properties. Tonic inhibition of brain extrapyramidal dopamine systems by serotonin systems does not appear to characterize neuroleptic-related dyskinesias in squirrel monkeys.

Unsulfated CCK-8 not blocked by proglumide or CR 1409 in the mouse abdominal irritant-induced stretching assay: possible central site of action.

Previous studies have shown that unsulfated cholecystokinin octapeptide (CCK-8-U) shares with the sulfated octapeptide (CCK-8-S) and the carboxyl-terminal tetrapeptide (CCK-4) the ability to block abdominal irritant-induced stretching when administered intracerebroventricularly. The effects of CCK-8-U, however, are not naloxone-reversible and do not appear upon systemic administration. To assess the hypothesis that the antistretching effects of CCK-8-U are mediated by central-type (CCK-B), rather than peripheral-type (CCK-A) receptors, the present experiments examined the reversal of these effects by CR 1409, a CCK receptor antagonist with in vitro selectivity for CCK-A receptors, and by proglumide. Both antagonists, when administered ICV, blocked the antistretching effects of CCK-8-S and CCK-4 (ICV), but not those of CCK-8-U. CR 1409 was approximately 40 times more potent against CCK-8-S by the ICV route than subcutaneously, indicating a likely action on CCK-A receptors in the brain. The effects of morphine, bombesin and neurotensin (ICV) were not blocked by CR 1409, indicating specificity for CCK receptor-mediated effects. The antistretching effects of CCK-8-U do not appear to be mediated by CCK-A receptors, and the possibility of a CCK-B receptor site of action must be considered.

Antagonism of morphine analgesia by CCK-8-S does not extend to all assays nor all opiate analgesics.

The conditions under which CCK-8-S may block opiate-induced analgesia were examined in detail. A U-shaped dose-response relationship was observed for the ability of CCK-8-S to attenuate (by approximately 50%, at most) morphine-induced tail flick analgesia. The analgesic effects of morphine in the hot plate or acetic acid-induced stretching tests were not altered by CCK-8-S at doses that antagonized morphine in the tail flick test. Tail flick latency elevations induced by meptazinol, a putative mu-1 receptor agonist, were also attenuated by CCK-8-S according to a U-shaped dose-response relationship, but those induced by U-50,488, a kappa agonist, were not antagonized by CCK-8-S doses that attenuated morphine analgesia. Thus, the ability of CCK-8-S to antagonize opiate analgesia does not follow a conventional dose-response relationship, does not extend to all tests of analgesia and may not extend to all opioid drugs. Analgesia mediated by the mu-1 opioid receptor subtype may be more amenable to antagonism by CCK-8-S than that mediated by the kappa receptor subtype.

Behavioral tolerance and sensitization to CGS 19755, a competitive N-methyl-D-aspartate receptor antagonist.

Competitive N-methyl-D-aspartate (NMDA) receptor antagonists, including CGS 19755, have the ability to antagonize NMDA-induced convulsions, to cause ataxia and, at high doses, to increase spontaneous locomotor activity. It was of interest to determine whether or not repeated treatment with CGS 19755 would induce tolerance to some or all of these effects. CGS 19755 was administered to mice twice daily for 14 days at 54 mg/kg i.p. per injection. One day after the last repeated injection, mice were challenged with vehicle or one of several doses of CGS 19755 (10, 30, 54 and 100 mg/kg) and were tested for evidence of motor impairment (using righting reflex and traction tests), for spontaneous locomotor activity and for the threshold dose of NMDA required to induce convulsions. When challenged with CGS 19755, mice that had previously received only vehicle showed reduced motor activity in response to doses of 54 and 100 mg/kg. In contrast, mice that had received the repeated treatment regimen of CGS 19755 increased motor activity in response to challenge doses of 30 and 54 mg/kg. These effects resembled those reported previously by some investigators for phencyclidine. However, repeated treatment with CGS 19755 induced only slight tolerance to the ability of this drug to cause ataxia. In mice treated repeatedly with CGS 19755, the threshold dose of NMDA to induce convulsions did not differ significantly from that in mice treated repeatedly with vehicle, indicating no demonstrable tolerance to the apparent anticonvulsant effects of CGS 19755 over this time period.(ABSTRACT TRUNCATED AT 250 WORDS)

Dopamine neurochemical profile of atypical antipsychotics resembles that of D-1 antagonists.

The release and metabolism of dopamine in the mouse caudate-putamen were determined after the oral administration of antipsychotic drugs at doses equal to or sixfold greater than the ED50 dose for their inhibition of apomorphine-induced climbing. Dopamine release was equated with concentrations of 3-methoxytyramine (3-MT) and metabolism was equated with concentrations of dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) levels. Like the D-1 antagonists SCH 23390 and SKF 83566, most antipsychotic agents with an atypical preclinical profile suggestive of low extrapyramidal symptomatology (CGS 10746B, flumezapine, CL 77328, rimcazole, clozapine, RMI 81582, and fluperlapine) never increased dopamine release and produced variable increases in dopamine metabolism. Other atypical antipsychotics (thioridazine, mesoridazine, melperone) increased dopamine release at only one dose tested but increased dopamine metabolism at most doses. Antipsychotic agents associated with extrapyramidal side effects (setoperone, perlapine, haloperidol, chlorpromazine, and metoclopramide) increased dopamine release and metabolism at almost every dose tested. Thus, atypical antipsychotics increase the metabolism but not release of dopamine at behaviorally effective doses. The resemblance of these minimal effects on dopamine release to those obtained with D-1 antagonists that also have an atypical preclinical profile suggests that a mechanism related to D-1 receptor antagonism may contribute to the action of atypical antipsychotics.

The N-methyl-D-aspartate antagonists CGS 19755 and CPP reduce ischemic brain damage in gerbils.

N-Methyl-D-aspartate (NMDA) antagonists reduce ischemic brain damage and associated hypermotility. Two potent, selective and competitive NMDA antagonists, cis-4-(phosphonomethyl)-2-piperidine-carboxylic acid (CGS 19755) and 4-(3-phosphonopropyl)-2-piperazine-carboxylic acid (CPP), were characterized in the gerbil ischemia model with respect to dose-response and time course effects. Both drugs were effective in reducing ischemia-induced hippocampal brain damage as well as hypermotility. In this model, CGS 19755 was more potent than CPP, and had protective effects when given after longer delays between ischemia and drug administration.

Heterogeneous rotational responsiveness in 6-hydroxydopamine-denervated rats: pharmacological and neurochemical characterization.

Qualitative differences in pharmacological responsiveness to various types of dopamine agonists have been reported in rats that have undergone unilateral 6-hydroxydopamine (6-OHDA)-induced denervation of the nigro-striatal pathway. The present experiments further characterize these differences, pharmacologically and neurochemically. Rats were classified as having high rotational sensitivity (0.03 mg/kg SC apomorphine sufficient to induce more than 100 rotations/20 min) or low sensitivity (0.3 mg/kg SC apomorphine required to meet this criterion). High sensitivity rats showed marked contralateral rotational behavior (approximately 150 rotations/20 min) in response to apomorphine (ED50 = 0.08 mg/kg IP), CGS 15855A (ED50 = 0.07 mg/kg), CGS 15873A (ED50 = 0.43 mg/kg), (+)-3-PPP (ED50 = 2.3 mg/kg), (-)-3-PPP (ED50 = 0.87 mg/kg) and quinpirole (peak effective dose, 0.03 mg/kg). In low sensitivity rats, 3- to 10-fold higher doses of apomorphine induced a maximal rate of rotational behavior, but only partial effects were produced by quinpirole, CGS 15855A, CGS 15873A, (+)-3-PPP, and (-)-3-PPP (40-80 rotations/20 min). Because apomorphine is a nonselective D1 and D2 agonist, it is proposed that activation of either D1 or D2 receptors suffices to induce high rates of rotation in high sensitivity rats, whereas in low sensitivity rats, D1 or D2 agonism alone induces submaximal rotation rates. The ipsilateral rotational behavior induced by d-amphetamine was more pronounced and occurred at lower doses in the high-sensitivity rats. Striatal dopamine depletion on the lesioned side did not differ between the groups, but low sensitivity rats showed two-fold higher DOPAC/DA ratios on the lesioned side than did high-sensitivity rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Rotational behavior induced by 8-hydroxy-DPAT, a putative 5HT-1A agonist, in 6-hydroxydopamine-lesioned rats.

Rats with unilateral 6-hydroxydopamine (6-OHDA)-induced lesions of the ascending nigro-striatal pathway have been shown to rotate in response to dopamine (DA) agonists that are not considered to have postsynaptic DA stimulant properties in intact animals, suggesting a relative loss of DA receptor selectivity in the denervated striatum. The present experiments assessed the possibility that this loss of selectivity may extend to serotonin (5HT) agonist drugs. The 5HT-1a agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), at doses of 0.3-3 mg/kg SC, induced robust contralateral rotational behavior (RB) in 6-OHDA-lesioned rats that had been preselected on the basis of high responsiveness to the atypical DA agonists 3-PPP and SKF 38393. Rats with unilateral dorsal raphe lesions induced by 5,7-dihydroxytryptamine (5,7-DHT) showed contralateral RB in response to similar doses of 8-OH-DPAT but with a different behavioral pattern. The putative 5HT-1b agonist RU 24969 produced contralateral RB in 5,7-DHT-lesioned rats while showing a much weaker effect in 6-OHDA-lesioned rats. Striatal DA levels were depleted by 99% in representative 6-OHDA-lesioned rats but striatal 5HT levels were unaffected. The effects of 8-OH-DPAT in 6-OHDA-lesioned rats were therefore not attributable to destruction of ascending 5HT-containing neurons. These effects may result from indirect actions, mediated by 5-HT neurons or neuronal receptors, that result from asymmetry of brain DA systems.(ABSTRACT TRUNCATED AT 250 WORDS)

Unique behavioral effects of the NMDA antagonist, CPP, upon injection into the medial pre-frontal cortex of rats.

Injection of the specific N-methyl-D-aspartate (NMDA) antagonist, 3(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), into the frontal cortex of rats, induced hyperactivity characterized by unique episodic darting behavior. This behavioral profile contrasts sharply with the ataxia and hyperactivity seen after intracerebroventricular CPP and other NMDA antagonists.

Antinociceptive profile of sulfated CCK-8. Comparison with CCK-4, unsulfated CCK-8 and other neuropeptides.

The antinociceptive activity of sulfated cholecystokinin octapeptide (CCK-8-S) was characterized by comparison with two other endogenous forms, unsulfated CCK-8 (CCK-8-U) and the carboxyl tetrapeptide fragment (CCK-4) and two other peptides present in the gut and brain: bombesin and neurotensin. By the intracerebroventricular (i.c.v.) route, CCK-8-S was antinociceptive in the hot plate and phenylquinone-induced writhing assays, but CCK-8-U and CCK-4 were active only in the latter test. By systemic administration, CCK-8-S retained anti-writhing activity but CCK-8-U and CCK-4 did not. Therefore, CCK receptors in brain may be involved in the apparent antinociception produced by CCK-8-U and CCK-4. Bombesin produced potent antinociceptive activity, along with a distinct, head-scratching syndrome, in both the writhing and hot plate tests. Naloxone reversed bombesin-induced elevation of latencies of mouse jump but not the head-scratching syndrome, indicating that the analgesic effect in the hot plate test was independent of the scratching behaviour. Neurotensin, unlike CCK-8-S, elevated tail-flick latencies, and was more potent in the writhing than in the hot plate test. Several differences between CCK-8-S and opioid substances included the need for relatively large doses of naloxone to block the effects of CCK-8-S in the phenylquinone-induced writhing test and the lack of effect of CCK-8-S in the tail-flick test. Global sedation can account for some, but not all, of the effects of CCK-8-S.(ABSTRACT TRUNCATED AT 250 WORDS)

CGS 8216, a benzodiazepine antagonist, reduces food intake in food-deprived rats.

CGS 8216, a benzodiazepine receptor antagonist with weak inverse agonist properties, reduced food intake in food-deprived rats when administered orally or intraperitoneally at doses that antagonize diazepam. This effect was sustained when CGS 8216 was administered daily for five days, indicating no rapid tolerance to the anorectic effect. Ro 15-1788 did not reduce feeding when administered orally, and was active only at high intraperitoneal doses (54 and 100 mg/kg). CGS 9896, a close analog of CGS 8216 but a benzodiazepine partial agonist with anxiolytic properties, did not reduce food intake at doses as high as 100 mg/kg IP or PO. These results support prior suggestions that benzodiazepine receptors may modulate feeding behavior, and suggest that CGS 8216 may have appetite suppressant properties.

SCH 23390 dissociated from conventional neuroleptics in apomorphine climbing and primate acute dyskinesia models.

SCH 23390 induced only a negligible incidence of the acute dyskinetic syndrome, a predictor of neuroleptic-induced extrapyramidal liability, in squirrel monkeys. However, haloperidol-induced dyskinesias were potentiated by SCH 23390 and were blocked by the D-1 agonist, SKF 38393. When administered orally or intraperitoneally to mice, SCH 23390 showed a considerably wider dose separation than did conventional neuroleptics between antagonism of apomorphine climbing and antagonism of stereotyped sniffing. Clinically relevant distinctions may exist between D-1 and D-2 antagonists, with D-1 antagonists (exemplified by SCH 23390) showing lower, although possibly not negligible, potential to cause extrapyramidal side effects.

CGS 9896: agonist-antagonist benzodiazepine receptor activity revealed by anxiolytic, anticonvulsant and muscle relaxation assessment in rodents.

CGS 9896, a pyrazoloquinoline that potently binds to benzodiazepine receptors, has been reported to have anticonflict activity in conventional footshock paradigms and to antagonize pentylenetetrazol-induced seizures. In the present experiments, the pentylenetetrazol discriminative cue was blocked by CGS 9896 with a potency comparable to that of diazepam. CGS 9896 also selectively lengthened the latency to terminate self-initiated brain stimulation reward. These procedures extend the anxiolytic activity of CGS 9896 to models that do not rely upon footshock-induced conflict. CGS 9896 did not impair the traction reflex in mice, did not impair rotorod performance in rats, did not reduce unpunished operant responding and decreased motor activity only slightly, indicating no distinguishable sedation or muscle relaxation in rodent models. In fact, diazepam-induced rotorod impairment was blocked by CGS 9896. The anticonvulsant effects of CGS 9896, as indicated by audiogenic seizure and pentylenetetrazol-induced seizure studies, were substantial but were weaker than those of diazepam, possibly because of the muscle relaxant component of diazepam. Ethanol-induced motor impairment was potentiated more markedly by diazepam than by CGS 9896. Mixed agonist-antagonist properties of CGS 9896 therefore emerge when a comprehensive battery of behavioral assessments is utilized. CGS 9896 may have clinical anxiolytic activity without sedation or muscle relaxation.