Meclofenoxate therapy in tardive dyskinesia: a preliminary report.

Tardive dyskinesia seems to occur as a result of diminished cholinergic and enhanced dopaminergic activity in the striatum. Meclofenoxate has been shown to increase cerebral cholinergic activity. To ameliorate the tardive dyskinesia, meclofenoxate was given orally, 600-1200 mg/day, for 6-12 weeks. The effects of the drug were evaluated by scoring the degree of involuntary movement. Among 11 subjects with tardive dyskinesia or dystonia, 4 improved markedly, 1 moderately, 2 slightly, and there was no improvement in 4. One patient with subacute oral dyskinesia, induced by administration of neuroleptics for 1 month, improved markedly. The possibility that meclofenoxate may be effective in dealing with dyskinesias that are induced by neuroleptics warrants further attention.

Postural myoclonus associated with long-term administration of neuroleptics in schizophrenic patients.

Postural myoclonus associated with long-term administration of neuroleptics was demonstrated in schizophrenic patients. Sixty patients who had been taking neuroleptics for more than 3 months were investigated for myoclonus and the relationships between postural myoclonus and age, duration of illness, duration of medication, current daily dose, cumulative dose, occurrence of abnormal finger movement, parkinsonism, and tardive dyskinesia were evaluated. Twenty-three patients (38%) showed postural myoclonus when holding the hands forward with the elbow joints flexed at about 90%. Male patients showed a higher incidence of myoclonus than female patients. Patients with myoclonus had been given significantly higher doses of neuroleptics than those without myoclonus. There was a significant correlation between the occurrence of myoclonus and abnormal finger movement. Electromyographic recordings in 7 patients with prominent myoclonus revealed that arrhythmic jerks occurred in the extensor carpi radialis and posterior deltoid muscles and that the jerks on the left and right side were not synchronized. Clonazepam reduced the frequency of the myoclonic activity.

Inhibitory effect of taurine on wet-dog shakes produced by [D-Ala2,Met5] enkephalinamide with reference to effects on hippocampal epileptic discharges.

The effects of taurine on wet-dog shakes produced by [D-Ala2,Met5]enkephalinamide (DAME) were investigated in rats. Wet-dog shakes and epileptic discharges in the hippocampus were produced by intraventricular administration of 50 micrograms of DAME. Pretreatment with 10 microliter of taurine, given intraventricularly in a dose of 0.95 mumol, inhibited wet-dog shakes and epileptic discharges in the hippocampus. While the same dose of gamma-aminobutyric acid (GABA) also inhibited the wet-dog shakes, the same dose of L-leucine did not suppress them. These observations indicate that the inhibition of DAME-induced wet-dog shakes by taurine is associated with the suppression of seizure activities in the hippocampus. The possibility that taurine possesses an antagonistic action on opioid peptides is discussed.

Effects of morphine, naloxone, buprenorphine, butorphanol, haloperidol and imipramine on morphine withdrawal signs in cynomolgus monkeys.

This study was conducted to characterize the opiate dependence potential of a number of opiate and non-opiate psychoactive drugs in morphine-dependent cynomolgus monkeys (Macaca fascicularis). In addition, the agonist/antagonist profiles of buprenorphine and butorphanol were directly compared. Six male cynomolgus monkeys were maintained on morphine (3.0 mg/kg, q.i.d.) for 6 months. On evaluation days, monkeys were scored for opiate withdrawal signs 18 h after the last dose of morphine. Single dose suppression studies were conducted by giving subcutaneous injections of morphine (3 or 6 mg/kg), naloxone (0.01, 0.05 or 0.1 mg/kg), buprenorphine (1, 3, 10, 30 or 100 micrograms/kg), butorphanol (0.01, 0.1, 1.0 or 3.2 mg/kg), haloperidol (0.01, 0.05 or 0.1 mg/kg), imipramine (2, 5 or 10 mg/kg) or saline and measuring the number and frequency of withdrawal signs that appeared over a 2-h period. In a separate precipitation experiment either saline or 0.01 or 0.1 mg/kg butorphanol was administered 2 h after the last maintenance dose of morphine. In the single dose suppression test, morphine completely suppressed most withdrawal signs while naloxone increased the severity of withdrawal. All doses of buprenorphine increased many withdrawal signs such as backward gait, rearing, chafing face, chain biting, vomiting, masturbation, and vocalizations after intimidation. Only a few signs were reduced, but the overall withdrawal scores were not significantly increased. Low doses of butorphanol suppressed some signs while the highest dose almost completely eliminated all withdrawal signs. Butorphanol also failed to precipitate opiate withdrawal, and actually reversed the signs present in the saline-treated monkeys. Imipramine and haloperidol had little effect on the morphine withdrawal syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of methysergide and naloxone on analgesia induced by the peripheral electric stimulation in mice.

We investigated the antinociceptive effects produced by peripheral electric stimulation (PES) in mice and the influence of administration of L-5-hydroxytryptophan (5-HTP), methysergide and naloxone on the antinociceptive effect of the PES. Administration of 5-HTP enhanced antinociceptive effects induced by PES, while methysergide and naloxone abolished this antinociception. The mechanisms of analgesia produced by PES involve both endogenous opiate systems and central serotonergic mechanisms.

Anti-tremor activity of talipexole produced by selective dopamine D2 receptor stimulation in cynomolgus monkeys with unilateral lesions in the ventromedial tegmentum.

The anti-tremor activity of talipexole (6-allyl-2-amino-5,6,7,8-tetrahydro-4H-thiazolo[4,5-d]azepine dihydrochloride, B-HT 920 CL2, Domin), a non-ergot dopamine D2 receptor agonist which possesses alpha 2-adrenoceptor agonistic and 5-HT3 receptor antagonistic properties, was examined in monkeys with a unilateral lesion in the ventromedial tegmentum. Talipexole dose dependently suppressed the tremor and had ED50 values of 34 micrograms/kg s.c. and 84 micrograms/kg p.o. The anti-tremor effect of talipexole occurred at much lower doses than that of an ergot dopamine receptor agonist, bromocriptine (2-bromo-alpha-ergocryptine mesilate, ED50; 2.5 mg/kg s.c.), and talipexole acted synergistically in combination with L-DOPA (3,4-dihydroxyphenylalanine). In ventromedial tegmentum-lesioned monkeys, anti-tremor doses of talipexole did not cause emetic behavior, but had sedative effects. Conversely, monkeys given bromocriptine exhibited oral movement, salivation and vomiting when anti-tremor effects were observed, but not marked sedative behavior at any of the doses investigated. During repeated administration of talipexole (a daily dose of 50 micrograms/kg s.c. for 21 days), the extent and duration of the anti-tremor effect did not change, but those of the sedative effect decreased gradually. The anti-tremor effect of talipexole was significantly suppressed by sulpiride, but not by SCH 23390 (7-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine-7-ol) or yohimbine, while the sedative effect was inhibited by sulpiride and yohimbine. The main metabolites of talipexole had no anti-tremor or sedative effects. These results indicate that talipexole exerts its anti-tremor activity via selective dopamine D2 receptor stimulation.

Modification of the antiepileptic actions of phenobarbital and phenytoin by the taurine transport inhibitor, guanidinoethane sulfonate.

We investigated whether chronic administration of guanidinoethane sulfonate, an inhibitor of taurine uptake, could modify the antiepileptic actions of phenobarbital and phenytoin on maximal electroshock seizures in mice. Treatment with 1% guanidinoethane sulfonate decreased the taurine concentration in the brain to 76% of the control value. Under these conditions, neither the severity of tonic convulsions of maximal electroshock seizures nor the threshold for tonic extension caused by electroshock was altered. However, treatment with guanidinoethane sulfonate lessened the antiepileptic actions of phenobarbital and phenytoin on electroshock seizures. The brain concentrations of phenobarbital and phenytoin were unaltered by administration of guanidinoethane sulfonate. The brain concentrations of guanidinoethane sulfonate and total guanidino compounds were unchanged by the injection of either phenobarbital or phenytoin. It is suggested that the observed loss of anticonvulsive potency of phenobarbital and phenytoin may have been related to the decrease in taurine concentration produced by guanidinoethane sulfonate.

Corneal lesions induced by the systemic administration of capsaicin in neonatal mice and rats.

Following a single subcutaneous injection of capsaicin to neonatal mice, a high incidence of corneal lesions with opacity developed after a long latency. The intensity of the lesions progressed for about 1 month in animals which had received a high dose (50 or 100 mg/kg) of capsaicin. Although the intensity gradually decreased thereafter, 50% of animals still exhibited a visible opacity 6 months after treatment. Similar corneal lesions were also produced in neonatal rats which had been injected with capsaicin. It is suggested that the corneal lesions induced by capsaicin may be due to destruction of the trigeminal nerve.

Effects of new neuroleptics, isofloxythepin and zotepine, on post-decapitation convulsions and prolactin secretion in rats.

Oral administration of isofloxythepin (0.5-8.0 mg/kg) inhibited decapitation convulsions in a dose-dependent manner as shown by decreasing the incidence and shortening the convulsion's duration, the effects continuing until 24 hr after administration. Zotepine (8, 16 mg/kg, SC) also decreased the duration but not the incidence of the convulsion. However, the other neuroleptics such as haloperidol, spiperone, perphenazine, trifluoperazine, pimozide and sulpiride failed to affect decapitation convulsions. Reserpine (8 mg/kg, SC) inhibited decapitation convulsions, accompanied by decreasing levels of norepinephrine, dopamine and serotonin in the spinal cord. Isofloxythepin at doses of 4 and 8 mg/kg, PO which completely abolished decapitation convulsions, failed to change norepinephrine and dopamine levels but increased serotonin levels in the spinal cord. Isofloxythepin (0.5-8.0 mg/kg) increased serum prolactin levels in a dose-dependent manner and zotepine (16 mg/kg), haloperidol (1 mg/kg) and reserpine (8 mg/kg) also elevated the levels. The results imply that both isofloxythepin and zotepine, but not the other neuroleptics, inhibit convulsions without decreasing spinal levels of norepinephrine which appears to be the amine most directly involved in the occurrence of decapitation convulsions, although these neuroleptics enhance prolactin secretion by blocking dopamine receptors in the pituitary.

Phenytoin potentiates methamphetamine-induced behavior in mice.

We demonstrated that stereotyped behavior and tremor induced by methamphetamine (MA) were potentiated by pretreatment with phenytoin (PNT) in mice. Similar enhancing effects were obtained by pretreatment with carbamazepine. Gas chromatographic study demonstrated that pretreatment with PNT increased MA concentrations in the brain to approximately 2.5 times of control level. The increased MA concentrations were thought to be a major factor for the observed potentiation of MA-induced behavior by PNT. However, all MA-induced behavior were not equally potentiated; tremor was enhanced more than stereotypy. These results suggest that central neuronal mechanisms may also be involved in PNT-potentiated MA-induced behavior in mice.

[The effect of inhalation of sevoflurane for an hour on the liver of beagles].

The effect of sevoflurane in comparison with that of enflurane and halothane, each at 1.8 MAC, on the liver was examined after inhalation exposure to beagles under controlled respiration for 1 hr. No abnormalities were observed in general conditions in the animals exposed to any of these anesthetics. Recovery time to spontaneous respiration after the end of anesthesia was similar for each group, but the awakening was quickest in sevoflurane exposed group. Blood pressure dropped immediately after the initiation of exposure in each group, but it recovered quickly to preexposure levels after the end of the exposure. Minor and reversible elevations in the values of GOT, GPT, LDH and bilirubin were noted without the organic change of the liver in beagles after the inhalation exposure to 1.8 MAC of each anesthetic. Since similar changes were observed in beagles exposed to enflurane or halothane, we conclude that no change in the liver specifically associated with sevoflurane was found under these experimental conditions.

[Power spectral analysis of tremor induced by TRH and oxotremorine in mice].

Tremor induced by TRH and oxotremorine was recorded by a capacitance transducer, and its intensity and frequency were evaluated using power arrays. In mice treated with TRH (20 mg/kg, i.p.), the latency of tremor was 17.1 +/- 1.7 min (mean +/- S.E.) and the duration was 20.4 +/- 2.2 min, while the frequency was 13.7 +/- 0.3 Hz. In animals with oxotremorine (0.5 mg/kg, i.p.), the latency was 4.3 +/- 0.4 min and the duration was 18 +/- 2.2 min, while the frequency was 12.7 +/- 0.3 Hz. The latter frequency, however, was significantly shifted to a lower frequency as a function of time. In TRH-induced tremor, vertical movements appeared in the same degree as horizontal movements. In oxotremorine-induced tremor, the vertical movements were few, whereas the horizontal movements were observed in a degree similar to those of TRH. The TRH tremor was suppressed by haloperidol and propranolol, but not by atropine. On the contrary, the oxotremorine tremor was inhibited by atropine, but not by haloperidol or propranolol. These results suggest that mechanisms of tremor induced by TRH differ qualitatively from those by oxotremorine; dopaminergic and beta-adrenergic receptor mediated functions may be linked to the developments of tremor caused by TRH, while cholinergic systems have a little effect in mice. The apparatus used in this study and power spectral analysis with power arrays may provide a useful method for simultaneous evaluation of the latency, duration, intensity and frequency of tremors.

Capsaicin-induced corneal lesions in mice and the effects of chemical sympathectomy.

Effects of chemical sympathectomy on corneal changes induced in mice by a s.c. injection of capsaicin were investigated. Pretreatment with a s.c. injection of 6-hydroxydopamine (6-OHDA) on the 1st and 2nd postnatal day or on the 14th and 15th postnatal day led to a marked suppression of the capsaicin-induced corneal lesions. This suppressive effect also was evident in case of administration after capsaicin treatment. Intraventricular injection of 6-OHDA had a slight, transient effect. DSP4 [N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine], another potent substance used for sympathetic denervation, had a suppressive effect similar to that of 6-OHDA. The concentration of capsaicin in tissues of the head was unaltered with 6-OHDA. The content of substance P (SP) in the ocular anterior segments was decreased, dose-dependently, with capsaicin administration. Neonatal administration of 6-OHDA decreased the rate of capsaicin-induced reduction of SP. However, this effect of 6-OHDA was too slight to explain the suppression of the corneal lesions, as the intensity score of lesions with a large dose of capsaicin after 6-OHDA was lower than that with a small dose of capsaicin without 6-OHDA, whereas SP content in the former was still much lower than that in the latter. On the other hand, the content of norepinephrine in the ocular tissues was decreased in the presence of 6-OHDA but not capsaicin. These results suggest that the corneal changes induced by capsaicin are largely inhibited by a decreased activity in the peripheral sympathetic system.

Taurine and tolerance to opioid peptides.

The finding that taurine may possess an ability to inhibit development of tolerance to opioid peptides was demonstrated in the present study. Tolerance was produced in rats by five IVT administrations of DAME during 3 consecutive days. Pretreatment with taurine that had been injected IVT 10 min prior to every administration of DAME suppressed the development of tolerance to both the akinetic and analgetic effects of the peptide. In addition, taurine pretreatment inhibited the induction of hyperlocomotor activity which was observed in tolerant animals as the number of the DAME injections was increased. Tolerance to WDS effects also resulted from the repeated administration of the peptide. However, it could not be concluded from the present experimental condition that taurine affects development of tolerance to WDS, since the amino acid suppressed the induction of WDS from the first injection of DAME.

Reduced taurine contents and modification of anticonvulsive effects of phenobarbital and phenytoin by guanidinoethane sulfonate in mice.

In the present study, we investigated whether administration of guanidinoethane sulfonate, and inhibitor of taurine uptake, worsens electroshock-induced convulsions or modifies the antiepileptic actions of phenobarbital or phenytoin against maximal electroshock seizures in mice. Treatment with 1% guanidinoethane sulfonate in drinking water for 9 days decreased taurine concentration in the brain to 76% of control value. Under these conditions, neither the severity of tonic convulsions of maximal electroshock seizures nor the threshold for tonic extension caused by electroshock was altered. On the other hand, the antiepileptic potency of phenobarbital and phenytoin against tonic convulsions of maximal electroshock seizures in mice was significantly lessened by chronic administration of guanidinoethane sulfonate. This decrease in potency was not due to an alteration in pharmacokinetics, as the brain levels of these drugs were unchanged. Furthermore, administration of the anticonvulsive drugs did not change brain concentrations of guanidinoethane sulfonate and total guanidino compounds. It is suggested that the observed loss of anticonvulsive potency of phenobarbital and phenytoin may be related to the decreased concentration of taurine produced by administration of guanidinoethane sulfonate.