Pharmacological studies of geissoschizine methyl ether, isolated from Uncaria sinensis Oliv., in the central nervous system.

The pharmacological properties of geissoschizine methyl ether, isolated from Uncaria sinensis Oliv., were analyzed in vitro and in vivo using mice central serotonin neurons. In the in vitro experiment, geissoschizine methyl ether inhibited [3H]8-hydroxy-2-(di-n-propylamino)tetralin) ([3H]8-OH-DPAT) (K(i)=0.8 microM), [3H]mesulergine (K(i)=0.9 microM) and [3H]ketanserin (K(i)=1.4 microM), but had less affinity toward [3H]prazosin (K(i) > 10 microM) and [3H]spiperone (K(i) >15 microM) binding to mouse brain membranes. The in vivo studies showed that geissoschizine methyl ether dose-dependently reduced 5-hydroxy-L-tryptophan (I-5-HTP) plus clorgyline-induced head twitch response without inhibiting the I-5-HTP plus clorgyline and 8-OH-DPAT-induced head weaving. On the other hand, geissoschizine methyl ether also decreased the rectal temperature of mice (hypothermic response) in a dose-dependent manner. These results suggest that geissoschizine methyl ether possesses mixed 5-HT(1A) receptor agonist/5-HT(2A/2C) receptor antagonist activities and inhibits the head twitch response by blocking the 5-HT(2A) receptors, and possibly, at least in part, by stimulating the 5-HT(1A) receptors in the central nervous system.

The effects of traditional tonics on fatigue in mice differ from those of the antidepressant imipramine: a pharmacological and behavioral study.

The present studies were undertaken to investigate the differences between the antidepressant drug, imipramine, and liquid nutritive and tonic drugs (NTDs) that consist of Ginseng radix, Epimedii herba, Holen and an additional eight to twelve crude drugs. After preloading forced swimming, the NTD (applied orally, 0.1 ml/10 g) significantly increased the duration time of swimming and decreased the duration time of immobility, while the administration of imipramine (5, 10 and 20 mg/kg, i.p.) under the same conditions and after the same treatment did not produce these positive effects. After pretreatment with 100 mg/kg tetrabenazine, the NTDs also elicited both the increased locomotor activity and the decreased duration time of immobility. The behavioral effect was similar to treatment with imipramine. The NTDs showed a long lasting effect on swimming behavior in the forced swimming test for 15 min, indicating a prolonged efficacy, not like the short effect of imipramine. The present results indicate that the effect of NTDs on fatigued subjects is different from that of imipramine, probably due to involvement of another factor in addition to the antidepressant effect.

Immunohistochemical estimation of brain choline acetyltransferase and somatostatin related to the impairment of avoidance learning induced by thiamine deficiency.

We have found that thiamine-deficient (TD) rats show significant impairment of avoidance learning on the 25th day after the start of TD diet, as measured by passive-avoidance task. Administration of physostigmine (0.1 mg/kg, i.p.) from the 14th day after the start of TD diet improved the impairment of avoidance learning to the pair-fed (PF) control level by the 25th day. However, the recovery effect of physostigmine did not occur on the 25th day when the treatment was begun on the 21st day. To ascertain the correlation between the cholinergic neuronal function in rat brain and the avoidance learning impairment induced by TD, the immunohistochemical distribution of brain choline acetyltransferase (ChAT) was determined by fluorescence intensity using two-dimensional microphotometry. The intensity of the ChAT fluorescence started to decrease in the cortex and hippocampus on the 14th day and showed a marked decrease in the cortex, hippocampus and thalamus on the 25th day of TD feeding in comparison with PF controls. The intensity of the somatostatin (SST) fluorescence was unchanged on the 14th day of TD feeding, but on the 25th day, SST was significantly decreased in comparison with PF controls. Furthermore, physostigmine treatment from 14th day after the start of TD diet reversed SST fluorescence intensity to the control level by the 25th day. These results suggest that the impairment of avoidance learning induced by TD may involve not only cholinergic but also somatostatinergic systems.

Effects of ginkgo biloba extract on impairment of learning induced by cerebral ischemia in mice.

The effect of Ginkgo biloba extract (GbE) on cerebral ischemia induced by 10-min bilateral occlusion of the carotid arteries in mice was studied. Severe impairment of memory was apparent when the passive avoidance test was carried out 48 hr after bilaterally induced ischemia. When GbE at doses of 50 and 100 mg/kg was given p.o. 1 hr before the 10-min occlusion, there was a significant improvement in memory. The i.p. injection of ifenprodil (30 mg/kg) also showed improvement on learning tasks. The p.o. administration of flavonoid, a fraction isolated from GbE, showed high step-through latency on scopolamine-induced amnesia. All these findings indicate that GbE is beneficial for clinical use in amnesia accompanied with cerebral vascular disease.

Spinally-mediated behavioural responses evoked by intrathecal high-dose morphine: possible involvement of substance P in the mouse spinal cord.

Intrathecal (i.t.) administration of morphine in the spinal subarachnoid space of mice produced a severe hindlimb scratching followed by biting and licking. The onset of the scratching behaviour was observed 60-70 s after i.t. injection of morphine (60 and 90 nmol), and had a duration of 3-4 min. The morphine-induced behaviour was increased additively by i.t. co-administration of substance P (SP). This characteristic behavioural response was inhibited dose-dependently by i.t. co-administration of the tachykinin NK-1 receptor antagonists, sendide and CP-96,345. Significant antagonistic effects of SP (1-7), a putative antagonist for NK-1 receptors and [D-Phe7, D-His9]SP (6-11), a selective antagonist for SP receptors, were observed against the morphine-induced behaviour. Pretreatment with i.t. SP antiserum and i.t. capsaicin resulted in reduction of the response to morphine. I.t. administration of somatostatin (SOM) antiserum, cysteamine, a relatively selective depletor of SOM and cyclo-SOM, a SOM receptor antagonist, produced no inhibitory effect on the morphine-induced behaviour. These results demonstrate that a spinal system of neurones containing SP may be involved in elicitation of the behavioural episode following i.t. injection of morphine in mice.

Pharmacological properties of beta-amyrin palmitate, a novel centrally acting compound, isolated from Lobelia inflata leaves.

Effects of beta-amyrin palmitate isolated from the leaves of Lobelia inflata were studied on the central nervous system of mice and were compared with those of antidepressant drugs, mianserin and imipramine. In the forced swimming test, beta-amyrin palmitate, like mianserin and imipramine, reduced the duration of immobility of mice significantly in a dose-dependent manner (5, 10 and 20 mg kg-1). beta-Amyrin palmitate (5, 10 and 20 mg kg-1) or mianserin (5, 10 and 20 mg kg-1) elicited a dose-related reduction in locomotor activity of mice and antagonized locomotor stimulation induced by methamphetamine. In contrast, imipramine (5, 10 and 20 mg kg-1) increased locomotor activity and potentiated methamphetamine-induced hyperactivity. beta-Amyrin palmitate showed no effect on reserpine-induced hypothermia, whilst mianserin (10 mg kg-1) and imipramine (10 and 20 mg kg-1) antagonized the reserpine-induced effect. Unlike imipramine, beta-amyrin palmitate and mianserin did not affect haloperidol-induced catalepsy, tetrabenazine-induced ptosis and apomorphine-induced stereotypy. beta-Amyrin palmitate and imipramine had no effects on the head-twitch response induced by 5-hydroxytryptophan, whereas mianserin (5, 10 and 20 mg kg-1) decreased it in a dose-dependent manner. A potentiating effect of beta-amyrin palmitate (5, 10 and 20 mg kg-1) on narcosis induced by sodium pentobarbitone was stronger than that of imipramine (10, 20 and 40 mg kg-1) but weaker than that of mianserin (2.5, 5 and 10 mg kg-1). These results suggest that beta-amyrin palmitate has similar properties in some respects to mianserin and might possess a sedative action.(ABSTRACT TRUNCATED AT 250 WORDS)

A possible mechanism of antidepressant activity of beta-amyrin palmitate isolated from Lobelia inflata leaves in the forced swimming test.

A mechanism of antidepressant activity of beta-amyrin palmitate was studied using the forced swimming method in mice. Beta-amyrin palmitate (10 mg/kg) reduced the increase in the duration of immobility induced by tetrabenazine (100 and 200 mg/kg), but showed no effect on that in mice treated with alpha-methyl-para-tyrosine (500 mg/kg). Beta-amyrin palmitate (5 and 10 mg/kg) decreased the duration of immobility in mice treated with desipramine plus 6-hydroxy-dopamine (50 micrograms/mouse), but did not affect that induced by nomifensine plus 6-hydroxydopamine. The decreased immobility produced by desipramine (15 mg/kg) was not affected by beta-amyrin palmitate. A study of norepinephrine release in mouse brain synaptosomes indicated that beta-amyrin palmitate caused a release of [3H]norepinephrine. The results of the present study suggest that beta-amyrin palmitate might release norepinephrine from newly synthesized pools, and thus, it might activate noradrenergic activity.

[Pharmacological studies of nutritive and tonic crude drugs on fatigue in mice].

The aim of the present study was to clarify acute anti-fatiguing effects of three crude liquid drug preparations (S1-S3), containing almost the same amounts of Ginseng Radix, Epimedii Herba and Agkistrodon Japonicae, with each differentially containing an additional 11, 13 or 15 crude drugs. After preloading forced swimming or tetrabenazine (TBZ: 50, 100 mg/kg, i.p.), each of the S1-S3 preparations applied orally (0.1 ml/10 g) significantly increased the duration times of swimming together with decreased total duration times of immobility during swimming. These effects peaked 60 min postinjection with the following decreasing order of effectiveness: S3 > S2 > S1. The same order of efficacy was also found for increased locomotor activity and decreased durations of swimming immobility after TBZ. After pretreatment with 200 mg/kg TBZ preparations S1-S3 also increased the numbers of jumping on a hot plate with greatly reduced latency. Without preloading the forced swimming, S1-S3 did not have any effect on jumping and its latency, but both S2 and S3 significantly, but more weakly, as compared to those after its preloading, decreased the immobility times. These results indicate that these crude preparations may cause tonic effects and so far tested, these effects seem to be more effective on subjects fatigued with physical and/or mental works than an normal subjects.

A selective and extremely potent antagonist of the neurokinin-1 receptor.

Sendide [Tyr6,D-Phe7,D-His9]-substance P(6-11) has been examined by measurements of ligand binding to crude membrane fractions and by functional tests on the spinally mediated behavioral response. Sendide potently displaced [3H]-labeled substance P (SP) binding to mouse spinal cord membranes in a competitive manner. In vivo, sendide, intrathecally co-injected with SP, competitively antagonized SP-induced scratching, biting and licking. The behaviors elicited by physalaemin, septide and [Sar9, Met(O2)11]-SP were also reduced by co-administration of sendide. Large doses of sendide were needed to reduce the action of neurokinin A, D-septide, neurokinin B and eledoisin. The in vitro and in vivo pharmacological profile of sendide demonstrated that it is a selective and extremely potent antagonist of the neurokinin-1 receptor.

Comparison of the antinociceptive effect between the cyclic dipeptide cyclo[Tyr(Et)-homoarginine] and the linear dipeptide Boc-Tyr(Et)-homoarginine-OMe in rats.

The antinociceptive effect of the cyclic dipeptide cyclo[Tyr(Et)- homoarginine] (C.TEHA) was examined utilizing the tail flick test and the digitus pinching test in rats in comparison with the linear dipeptide Boc-Tyr(Et)-homoarginine-OMe (B.TEHM). Though both dipeptides administered into the lateral, 3rd and 4th cerebroventricles produced antinociceptive effects equipotent to morphine, except for the 4th cerebroventricular administration of B.TEHM, the administration into the spinal subarachnoid space was without effect. The effect of B.TEHM was completely antagonized by the pretreatment of naloxone (i.p.) when administered into the 3rd cerebroventricle where its effect was demonstrated to be the most potent. However, naloxone had no significant effect on C.TEHA administered into the 3rd cerebroventricle in both tests. It was concluded that both dipeptides act on the upper brain stem, especially around the 3rd cerebroventricle. Moreover, it was also thought that the effect of B.TEHM may be involved in the brain opioid system, and that of C.TEHA can be produced via a naloxone-resistant opioid system or a non-opioid system.

Potentiating effects of prostaglandin E2 on bradykinin and capsaicin responses in medial thalamic nociceptive neurons.

Potentiating effects of prostaglandin E2 (PGE2) on bradykinin and capsaicin responses were studied in 34 gallamine triethiodide immobilized cats. Single neurons were recorded from the medial thalamus by using stainless steel microelectrodes. The animals were given agents into the femoral artery through a retrogradely inserted cannula. Of the 22 neurons responding to bradykinin, 13 were potentiated by the injection of PGE2, and the remaining 9 neurons were ineffective. Nine of the 17 neurons responding to capsaicin were also potentiated by PGE2. PGE2 significantly shortened the mean latency of bradykinin to fire the neuronal activity without changing the duration, but with the injection of capsaicin, there was no change in latency and duration in the presence of PGE2. Aspirin suppressed the increased activity of the medial thalamic neurons produced by bradykinin, and this suppression was antagonized by arterial infusion of PGE2. However, the activity of medial thalamic neurons with capsaicin was scarecely affected by aspirin. These results suggest that the bradykinin-induced activity of medial thalamic neurons may be mediated by PGE2 and that the mechanism of activation of nociceptive neurons produced by capsaicin is different from that of bradykinin.

Changes in ingestive behavior, serum glucose and free fatty acids concentrations in rats following intracerebroventricular injection of spermine.

We examined the changes in ingestive behavior, serum glucose (Glc) and free fatty acids (FFA) concentrations in male rats following intracerebroventricular (i.c.v.) injection of spermine (SPM). In satiated rats, over a 53.3 nmol of SPM suppressed feeding and drinking behavior in a dose-dependent manner. The median suppressive dose was 90.8 nmol for feeding behavior and 68.3 nmol for drinking behavior. Spermidine also suppressed ingestive behavior but the potency was appreciable weak compared to that of SPM, and the occurrence of the maximal suppression was observed 2-3 days later than that of SPM. The most significant anorexia and adipsia induced by SPM appeared between 16 and 36 hr after i.c.v. administration. SPM (180 nmol) produced a biphasic increase in serum Glc concentration. The 1st peak was at 1 hr and the other peak was 24 hr after the dosing. The same dose of SPM elevated serum FFA concentrations gradually, and the maximal increase appeared 24 hr after the injection. As less than a 120 nmol dose of SPM did not alter serum Glc and FFA concentrations, there seems to be no causal relation between SPM-induced anorexia, and changes in serum Glc and FFA concentrations. Nevertheless, the findings that a very small dose of SPM produced anorexia and adipsia support the possibility that SPM may play some functional role in the brain.

Effects of intracerebroventricular administration of aliphatic diamines on ingestive behavior in the rat.

We examined the pharmacological effects of intracerebroventricularly administered aliphatic diamines on ingestive behavior in male rats adapted to a 4 hr per day feeding and drinking schedule. 1,2-Ethanediamine (ETD), 1,3-propanediamine (PRD), 1,4-butanediamine (putrescine, PUT), 1,5-pentanediamine (cadaverine, CAD) and 1,6-hexanediamine (HED) suppressed feeding and drinking behavior in a dose-dependent manner, but not unless a relatively high dose (over 80 micrograms) was given. The approximate anorectic potency was HED greater than CAD divided by PUT greater than ETD greater than PRD. A sedation was also produced in fairly good parallel to these alterations in feeding and drinking behavior. Thus, there appears to be a relationship between the length of the carbon chain and the potency of the pharmacological action, and these inhibitory effects on feeding and drinking behavior are probably not due to a specific action on the regulatory system for ingestive behavior, but rather to a nonspecific action.

Excitatory effects of dihydrocapsaicin on nociceptive neurons in the medial thalamus.

Effects of capsaicin and dihydrocapsaicin, which are pungent substances contained in Capsicum annuum L., were studied in 32 gallamine triethiodide immobilized cats. Single units were recorded from the medial thalamus using stainless steel microelectrodes. Of the 56 neurons recorded, 28 were responsive to both noxious (pinching) and non-noxious (hair and/or tapping) stimuli, while 16 were activated only by non-noxious stimuli. The remaining 12 neurons did not respond to any natural stimulus. Somatic receptive fields of nociceptive and non-nociceptive neurons were found to be widely distributed over the whole body. Twenty-six of 28 nociceptive neurons were activated by an intra-arterial administration of bradykinin, capsaicin and dihydrocapsaicin. Fourteen of 16 non-nociceptive neurons were not activated by these substances. The mean latency and duration of bradykinin were 8.7 and 12.5 sec, those of capsaicin were 1.2 and 6.1 sec and those of dihydrocapsaicin were 1.3 and 5.0 sec, respectively. The increase of firing frequency produced by capsaicin and dihydrocapsaicin was inhibited by morphine and this inhibition was antagonized by naloxone. However, the activity of medial thalamic neurons with non-noxious stimuli was not affected by these drugs. These results suggest that the pain-conducting fibers were selectively activated by capsaicinoids as well as by bradykinin.

[The effect of thiamine deficiency on the actions of drugs affecting the central nervous system in rats (author's transl)].

Male Wistar rats, 35-days-old, maintained on a thiamine deficient diet for 30 days showed marked growth inhibition and a heart rate less than 70% of that of control rats. We examined the effect of thiamine deficiency on the action of drugs effecting the central nervous system at this period. In thiamine deficient rats treated with chloral hydrate 200 mg/kg, ketamine 100 mg/kg sodium pentobarbital 50 mg/kg, and hexobarbital 100 mg/kg, the sleeping time increased. Pretreatment with 15 mg/kg of the metabolic enzymes inhibitor, SKF-525A, 30 min prior to the hexobarbital administration resulted in prolongation of sleeping time in all groups. The thiamine deficient rats slept almost 3.5 times longer than did the control group. Pretreatment with 100 mg/kg of the metabolic enzyme inducer, sodium phenobarbital, 48 hours prior to hexobarbital treatment resulted in decreased sleeping time in all groups, as compared with only hexobarbital treatment. In the thiamine deficient rats the catalepsy and ptosis induced by the i.p. administration of tetrabenazine 50 mg/kg was reduced even when the control and pair-fed groups responded to this drug at the drug peak time. The spontaneous neuronal activity of lateral hypothalamus was most sensitive to the administration of 5-hydroxytryptophan in thiamine deficient rats.

Changes of ejaculation due to suppression of noradrenaline biosynthesis by diethyldithiocarbamate in dogs: a supplemental report with reference to changes of posterior urethral pressure.

In the preceding paper (Kimura et al.-1979) it was reported that diethyldithiocarbamate suppresses ejaculation, although penile erection is maintained, and that the suppression is not mediated by the central nervous system but by the decrease of catecholamine contents in the organs relating to sperm transport. In this paper, changes of ejaculation following administration of diethyldithiocarbamate was studied with the posterior urethrogram; measurement of the posterior urethral pressure during hypogastric nerve stimulation. From the results obtained in this study the above results were confirmed. It was also confirmed that both seminal emission and ejaculation are under the influence of an alpha-adrenergic receptor mechanism. Also, a dopamine receptor mechanism was suspected to be present in the male accessory sexual glands.

[Effects of diazepam on rage reaction elicited by the lateral hypothalamus (LH) and on single unit activities in the LH and the basal medial amygdaloid nucleus (Abm) in cats (author's transl)].

Effects of diazepam were examined on the whine reaction elicited by LH stimulation and on unit activities in the LH and Abm in cats. The spontaneous firing frequency of Abm neurons was 5 to 30 spikes/sec and in all 6 neurons isolated the firing frequency increased by non-nociceptive and/or clap-stimulation. Diazepam decreased the spontaneous firing frequency of all Abm neurons isolated and the increased firing frequency elicited by non-nociceptive and/or clap-stimulation was also depressed by diazepam. The spontaneous firing frequency of neurons in the LH was 4 to 5 spikes/sec and all 6 neurons isolated firing frequency increased by non-nociceptive stimulation. Only one of 6 neurons, however, was activated by clap-stimulation. Diazepam decreased the spontaneous firing frequency of all LH neurons. Out of 6 neurons responsive to non-nociceptive stimulation, 3 were also depressed by diazepam. The other neurons were not affected by diazepam. These results suggest that depressed action of diazepam on the whine reaction elicited by the LH stimulation may be related to the decrease of firing in the Abm and/or the LH by diazepam.

[Interaction of d-pseudoephedrine with water soluble extracts of Platycodi Radix on acute toxicity (author's transl)].

Effect of various combinations of Platycodi Radix water soluble extracts (Pla), 1-ephedrine (1-eph), d-pseudoephedrine (d-pseudo) and Ipecacuanhae Radix water soluble extracts (Ipe) on acute toxicity were examined in mice. Oral LD50 of Ipe, d-pseudo and 1-eph was 490 (415--578) mg/kg, 1550 (1360--1767) mg/kg and 1400 (1102--1778) mg/kg, respectively, while that of Pla was over 10 g. LD50 of Pla Ipe, d-pseudo and 1-eph given intraperitoneally was 1400 (1228--1596) mg/kg 235 (210--263) mg/kg, 245 (229--262) mg/kg and 300 (259--348) mg/kg, respectively. The ratio of the predicted LD50 value, which was calculated on the assumption that each component drug would be additively toxic when combined, to the observed LD50 value was used for comparison. The combination of d-pseudo with Pla gave a significantly greater LD50 value than the predicted LD50 value, while the combination of 1-eph with Pla showed a LD50 value which was not significantly different from Finney's additive model. A combination of d-pseudo with 1-eph and Ipe, and of 1-eph with Ipe showed a LD50 value which was not significantly different from that of the additive model.

[Effects of diazepam on evoked potential recorded from basal medial amygdaloid nucleus, lateral hypothalamus and midbrain reticular formation (author's transl)].

The evoked potential in the lateral hypothalamus (LH) recorded by stimulation of basal medial amygdaloid nucleus (Abm) showed a triphasic pattern and diazepam (2 mg/kg, i. p.) decreased the late component. The evoked potential in the midbrain reticular formation (MRF) recorded by stimulation of Abm showed a fast component with a relatively short latency followed by a biphasic late component and diazepam decreased the late component. Though the evoked potential in the Abm recorded by stimulation of LH showed a triphasic pattern, diazepam had no influence on the amplitude. Diazepam increased markedly the amplitude of evoked potential in the MRF recorded by stimulation of LH. Diazepam was ineffective on the evoked potential in the Abm recorded by stimulation of MRF. Diazepam decreased markedly the late component of evoked potential in the LH recorded by stimulation of MRF. These results suggest that the depression of emotional behavior by diazepam may be particularly related to the fact that the evoked potential in the LH recorded by stimulation of Abm was decreased by diazepam.

[Analgesic effect of pentazocine and its action on nociceptive afferent pathway].

Nociceptive stimulus was applied to the skin of adult cats by pinching with a serrated forceps or by radiant heat with Pain meter. This stimulation caused motor or emotional responses such as movements of the head and trunk, vocalization, escape and attack. After the administration of pentazocine, these responses disappeared and the animals behaved normally. Analgesic action appeared approximately 15 min after the administration and lasted more than 90 min. Effects of pentazocine on pain-afferent pathways were studied and the evoked potential was recorded by tibial nerve stimulation. Though pentazocine did not influence the evoked potential recorded from somatic sensory area I and mesencephalic central gray, the evoked potential in pre-central association area, nucleus centralis lateralis, nucleus suprageniculatus-limitans and reticularis pontis caudalis was reduced by pentazocine.