Clinical meaning of sarcopenia in patients undergoing endoscopic treatment

With increasing global life expectancy, the significance of geriatric assessment parameters has increased. Sarcopenia is a crucial assessment parameter and is defined as the age-related loss of muscle mass and strength. Sarcopenia is widely acknowledged as a risk factor for postoperative complications in diverse advanced malignancies and has a detrimental effect on the long-term prognosis. While most studies have primarily concentrated on the correlation between sarcopenia and advanced cancer, more recent investigations have focused on the relationship between sarcopenia and early-stage cancer. Endoscopic submucosal dissection (ESD), which is less invasive than surgical intervention, is extensively employed in the management of early-stage cancer, although it is associated with complications such as bleeding and perforation. In recent years, several reports have revealed the adverse consequences of sarcopenia in patients with early-stage cancer undergoing ESD. This literature review briefly summarizes the recent studies on the association between sarcopenia and ESD.

Confirmation of the anxiolytic-like effect of dihydrohonokiol following behavioural and biochemical assessments

Previous studies in this laboratory revealed that dihydrohonokiol-B (DHH-B; 3′-(2 propenyl)-5-propyl-(1,1′-biphenyl)-2,4′-diol), a partially reduced derivative of honokiol, was an effective anxiolytic-like agent in mice at an oral dose of 0.04 mg kg−1, and at higher doses, when evaluated by the elevated plus-maze test. The aim of this study was to further confirm the anxiolytic-like effect of DHH-B using an additional behavioural procedure (Vogel's conflict test in mice) and a biochemical assessment (in-vitro determination of muscimol-stimulated 36Cl− uptake into mouse cortical synaptoneurosomes). As in earlier experiments, DHH-B (0.04–1 mg kg−1, p.o.) was shown to prolong the time spent in the open-sided arms of the elevated plus-maze in a dose-dependent manner. Moreover, in the Vogel's conflict test, DHH-B (5 mg kg−1, p.o.) significantly increased punished water intake. In tests with mouse cerebral cortical synaptoneurosomes, 10 and 30 μm of DHH-B significantly increased 36Cl− influx in the absence of muscimol. In the presence of 25 μm muscimol, the addition of 1 μm DHH-B led to significant enhancement of 36Cl− uptake, while 30 μm DHH-B was required to further stimulate the 36Cl− uptake induced by 250 μm muscimol. The results of these studies confirm that DHH-B is a potent anxiolytic-like agent and that GABAA receptor-gated Cl−-channel complex is involved in the anxiolytic-like efficacy of DHH-B.

Detection of corn intrinsic and recombinant DNA fragments and Cry1Ab protein in the gastrointestinal contents of pigs fed genetically modified corn Bt11

Genetically modified corn has been approved as an animal feed in several countries, but information about the fate of genetically modified DNA and protein in vivo is insufficient. Genetically modified corn Bt11 is developed by inserting a recombinant DNA sequence encoding insecticidal Cry1Ab protein from Bacillus thuringiensis subsp. kurstaki. We examined the presence of corn intrinsic and recombinant cry1Ab gene by PCR, and the Cry1Ab protein by immunological tests in the gastrointestinal contents of five genetically modified corn Bt11-fed and five nongenetically modified corn-fed pigs. Fragments of corn zein (242 bp), invertase (226 bp) and of ribulose-1,5-bisphosphate carboxylase/ oxygenase genes (1,028 bp) were detected in the gastrointestinal contents of both Bt11 and nongenetically modified corn-fed pigs. Fragments of recombinant cry1Ab gene (110 bp and 437 bp) were detected in the gastrointestinal contents of the Bt11-fed pigs but not in the control pigs. Neither corn intrinsic nor cry1Ab gene fragments were detected in the peripheral blood by PCR. The gastrointestinal contents were positive for Cry1Ab protein by ELISA, immunochromatography, and immunoblot; however, these methods did not work for blood and precluded conclusions about any potential absorption of the protein. These results suggest that ingested corn DNA and Cry1Ab protein were not totally degraded in the gastrointestinal tract, as shown by their presence in a form detectable by PCR or immunological tests.

Detection of genetically modified maize DNA fragments in the intestinal contents of pigs fed StarLink CBH351

We tried to detect DNA fragments derived from maize in the intestinal contents of pigs fed genetically modified (GM) StarLink CBH351 maize (SL) or non-GM maize. Intestinal contents of 8 SL and 8 non-GM maize-fed pigs were collected at slaughter, and the genes of the recombinant cry9C and the maize intrinsic zein (Zel) were assayed by polymerase chain reaction (PCR) 3 times with a total of 4 primer pairs of different expected lengths. The cry9C gene (either 103 or 170 bp) was detected in the rectal contents (with a frequency of 25-37.5%) and in the cecal contents (25-50%) of the pigs fed SL. In a similar fashion, the zein (Zel) gene (either 242 or 329 bp) was detected in the rectal contents (with a frequency of 31.3%) and in the cecal contents (25-37.5%) of pigs fed on SL non-GM maize. These results suggested that ingested DNA was not totally degraded, but is present in a form detectable by PCR.

[A detection method for recombinant DNA from genetically modified maize CBH351]

A method using polymerase chain reaction (PCR) was designed for the detection of genetically modified maize CBH351, which has not authorized as safe for use in foods and feeds in Japan yet. We analyzed a recombinant DNA (r-DNA) sequence introduced into CBH351 maize and designed specific primer pairs to amplify a segment including part of the r-DNA. The PCR products obtained by using the designed primer pairs are specific for CBH351 and should prevent false positive results caused by other maizes and other main cereal crops. The r-DNA introduced into CBH351 could be detected from maize samples containing 0.05-0.1% CBH351 maize. This sensitivity is theoretically equivalent to a level of several genome copies and so this technique is a very efficient means to detect CBH351 maize.

The anxiolytic effect of Sho-ju-sen, a Japanese herbal medicine, assessed by an elevated plus-maze test in mice

Sho-ju-sen (SK), a Japanese herbal medicine with a nourishing tonic action, is composed of a water extract of Kumazasa leaves (Sasa kurinensis Makino et Sibata) (SS), and ethanol extracts of Japanese red pine needles (Pinus densiflora Sieb. et Zucc) (PN) and Ginseng roots (Panax ginseng C. A. Meyer) (PX) in the ratio 8:1:1. In this study, an elevated plus-maze test in mice was carried out to assess whether SK had an anxiolytic effect. No significant change was observed in either the plus-maze or activity test following a single administration of SK (10 and 20 mL/kg p.o.). However, mice allowed a free intake of SK (10% solution) for 5 days and longer showed a significant prolongation of the time spent in the open arms (an anxiolytic effect), as long as that caused by the benzodiazepine anxiolytic diazepam (1 mg/kg p.o.). SK (1%, 3% and 30% solutions for 7 days) tended to develop the anxiolytic effect. Of the constituents of SK, SS (8% solution), but not PN (1% solution) or PX (1% solution), resulted in the anxiolytic effect. Except for a slight acceleration in the motor activity by PN (1% solution), no significant change in the motor activity was produced by any treatment with SK, SS or PX. The combined treatment of SK (10% solution) or SS (8% solution) with 1 mg/kg diazepam enhanced the anxiolytic effect. Flumazenil (0.1 mg/kg s.c.), a benzodiazepine receptor antagonist, alone did not change the time spent in the open arms. However, it completely reversed the anxiolytic effect of SK, SS and diazepam. The present results suggest that: (1) long-term treatment with SK develops an anxiolytic effect, (2) SS is the main constituent for the anxiolytic effect of SK, and (3) benzodiazepine receptors are involved in the anxiolytic effect of SK and SS.

A multiplex PCR method of detecting recombinant DNAs from five lines of genetically modified maize

Seven lines of genetically modified (GM) maize have been authorized in Japan as foods and feeds imported from the USA. We improved a multiplex PCR method described in the previous report in order to distinguish the five lines of GM maize. Genomic DNA was extracted from GM maize with a silica spin column kit, which could reduce experimental time and improve safety in the laboratory and potentially in the environment. We sequenced recombinant DNA (r-DNA) introduced into GM maize, and re-designed new primer pairs to increase the specificity of PCR to distinguish five lines of GM maize by multiplex PCR. A primer pair for the maize intrinsic zein gene (Ze1) was also designed to confirm the presence of amplifiable maize DNA. The lengths of PCR products using these six primer pairs were different. The Ze1 and the r-DNAs from the five lines of GM maize were qualitatively detected in one tube. The specific PCR bands were distinguishable from each other on the basis of the expected length. The r-DNA could be detected from maize samples containing 0.5% of each of the five lines of GM maize. The sensitivity would be acceptable to secure the verification of non-GMO materials and to monitor the reliability of the labeling system.

Comparative assessment of the anxiolytic-like activities of honokiol and derivatives

Honokiol has previously been shown to be an effective anxiolytic-like agent in mice when administered for 7 days at 0.2 mg/kg/day prior to evaluation in an elevated plus-maze, while 20 mg/kg is required for efficacy as a single oral dose. The aim of this study was to find analogs of honokiol that are more effective for acute administration. Among the eight analogs evaluated, one partially reduced derivative of honokiol [3'-(2-propenyl)-5-propyl-(1,1'-biphenyl)-2,4'-diol] exhibited significant anxiolytic-like activity at 0.04 mg/kg. Following oral administration of 1 mg/kg of this analog, anxiolytic-like activity was clearly evident at 1 h, peaked at 3 h, and remained significant for longer than 4 h after treatment. Combined administration of the derivative with diazepam led to enhanced anxiolytic-like efficacy. Moreover, as with diazepam, the anxiolytic-like effect of the analog was reduced by flumazenil. In contrast, bicuculline, a GABA(A) antagonist, had no effect on the activity of the derivative. Taken together, these results suggest that this analog of honokiol acts at the benzodiazepine recognition site of the GABA(A)-benzodiazepine receptor complex.

The anxiolytic effect of two oriental herbal drugs in Japan attributed to honokiol from magnolia bark

An improved elevated plus-maze test in mice revealed that seven daily treatments with two different traditional Chinese medicines, known as Kampo medicines in Japan, Hange-koboku-to (composed of extracts of 5 plants) and Saiboku-to (composed of extracts of 10 plants), produced an anxiolytic effect, and the effect was mainly due to the presence of honokiol derived from magnolia. This study was carried out to evaluate the anxiolytic potential of honokiol, Hange-koboku-to and Saiboku-to, which were prescribed with two different magnolia samples: Kara-koboku (Magnoliae officinalis) (KA) or Wa-koboku (Magnoliae obovata) (WA). The doses of test samples were adjusted to ensure a constant dose of honokiol at 0.2 mg kg(-1). Although the doses of magnolol (an isomer of honokiol), as well as those of undetermined chemicals, varied among samples, the seven daily treatments with 9 out of 10 test samples produced an anxiolytic effect almost equivalent to that produced by 0.2 mg kg(-1) honokiol. The only exception was the sample containing the lowest amount of honokiol. Magnolia-free preparations of Hange-koboku-to or Saiboku-to did not have any anxiolytic effect. These results confirm that honokiol derived from magnolia is the causal chemical of the anxiolytic effect of Hange-koboku-to and Saiboku-to.

Effects of drugs acting as histamine releasers or histamine receptor blockers on an experimental anxiety model in mice

Experimental anxiety in mice was evaluated using a light/dark test at 60 min after injection of various histaminergics. Thioperamide, a histamine H(3) receptor inhibitor (5-20 mg/kg, intraperitoneal [IP]), Compound 48/80, a mast cell degranulator (0.1-10 microg/2 microl, intracerebroventricularly [ICV]), mepyramine, a histamine H(1) receptor antagonist (0.1-10 microg/2 microl, ICV) or cimetidine, a histamine H(2) receptor antagonist (0.1-10 microg/2 microl, ICV) alone did not affect the locomotive activity, the time spent in the light zone, and number of shuttle crossings in the light/dark test. However, the time spent in the light zone and the number of shuttle crossings significantly decreased only when cimetidine (0.1-10 microg/2 microl, ICV) was co-treated with either thioperamide (10 mg/10 ml/kg, IP) or Compound 48/80 (1.0 microg/2 microl, ICV). The decrease in these behavioral parameters suggests induced experimental anxiety in mice. The experimental anxiety was antagonized by mepyramine (10 microg/2 microl, ICV). These results suggest that not only neuronal histamine release induced by thioperamide but also non-neuronal (mast cells) histamine release induced by Compound 48/80 play an important role in inducing experimental anxiety via post-synaptic H(1) and H(2) receptors. In addition, it is likely that the anxiety may be mediated by the stimulation of H(1) receptors, while H(2) receptors may inhibit the anxiety produced by the activation of H(1) receptors.

Does dihydrohonokiol, a potent anxiolytic compound, result in the development of benzodiazepine-like side effects?

The aims of this study were to assess whether dihydrohonokiol, 3'-(2-propenyl)-5-propyl-(1,1'-biphenyl)-2,4'-diol (DHH-B), a potent anxiolytic compound, developed benzodiazepine-like side effects. A 1 mg kg(-1) dose of diazepam, almost equivalent to the minimum dose for the anxiolytic effect, disrupted the traction performance, potentiated hexobarbital-induced sleeping and impaired learning and memory performance. DHH-B, even at a dose of 1 mg kg(-1) (i.e. five times higher than the minimum dose for significant anxiolytic effect) neither developed diazepam-like side effects nor enhanced the side effects of diazepam. Rather, the potentiation by diazepam of hexobarbital-induced sleeping was reduced by 1 mg kg(-1) DHH-B. Furthermore, mice treated with 10 daily administrations of 1 and 5 mg kg(-1) diazepam, but not 0.2-5 mg kg(-1) DHH-B, showed precipitated withdrawal symptoms characterized by hyper-reactivity, tremor and tail-flick reaction when they were challenged with flumazenil (10 mg kg(-1) i.p.). These results suggest that, unlike the benzodiazepine anxiolytic diazepam, DHH-B is less likely to induce motor dysfunction, central depression, amnesia or physical dependence at the effective dose required for the anxiolytic effect.

Learning and memory in mice treated with choline oxidase, a hydrolytic enzyme for choline

Learning and maintenance of memory in mice intraperitoneally (IP) injected with choline oxidase (ChO, 6 units/g), a hydrolytic enzyme for choline (Ch), were assessed by means of a step-through passive-avoidance task. The ChO treatment induced a hydrolysis of free Ch in plasma, which in turn, induced a decrease in cerebral acetylcholine (ACh) release. In the learning test, the ChO-treated mice showed significant inhibition to learn the avoidance from electric shock. In the retention test, the impairment of the memory once established was not produced by posttreated ChO. We concluded that the decreased cerebral cholinergic neurotransmission induced by ChO retarded acquisition of passive-avoidance learning more readily than the maintenance of memory.

Application of the elevated plus-maze test in mice for evaluation of the content of honokiol in water extracts of magnolia

In our previous study using an improved elevated plus-maze in mice, the oriental herbal medicine Saiboku-to prolonged the time spent in open arms, showing an anxiolytic effect, and the effect was mainly caused by honokiol derived from magnolia. This study was carried out to compare the anxiolytic potentials of honokiol and water extracts of three magnolia samples; two being Kara-koboku (Magnolia officinalis) (KA: from Zhejiang-sheng, China; honokiol 0.25% and magnolol 1.16%, and KB: from Sichuan-sheng, China; honokiol 1.72% and magnolol 1.71%), and one being Wa-koboku (Magnolia obovata) (WA: from Iwate-ken, Japan; honokiol 0.32% and magnolol 0.81%). Seven daily treatments with 0.1-1 mg/kg honokiol, but not 0.2 and 1 mg/kg magnolol, revealed an anxiolytic effect with the peak potential at 0. 2 mg/kg. The anxiolytic potentials of 40 and 80 mg/kg KA, which contained the highest amount of magnolol, were almost equivalent to those of 0.1 and 0.2 mg/kg honokiol, respectively. KB, at 11.6 mg/kg, and 62.5 mg/kg WA resulted in almost the same anxiolytic potential as that of 0.2 mg/kg honokiol. No significant change in the ambulatory activity was produced by any drug treatment. These results suggest that honokiol is the chemical responsible for the anxiolytic effect of the water extract of magnolia and that the other chemicals including magnolol in magnolia scarcely influence the effect of honokiol. It is also considered that the elevated plus-maze test is applicable for evaluation of the content of honokiol in magnolia.

Long-term clomipramine treatment upregulates forebrain acetylcholine muscarinic receptors, and reduces behavioural sensitivity to scopolamine in mice

We have investigated the effects of long-term treatment with clomipramine, a tricyclic antidepressant, on central muscarinic acetylcholine receptors (mAChR) in mice. Repeated clomipramine administration resulted in an increase in the forebrain receptor density value (Bmax) for [3H]quinuclidinyl benzilate, a muscarinic ligand (P < 0.05), that was dependent on dose per administration (saline or 5, 10, or 20 mg kg(-1) once a day for 7 days) and number of days treated (20 mg kg(-1) for 1, 3, 5, or 7 days). No change in apparent affinity (defined as the reciprocal of the dissociation constant) (KD) occurred. Seven daily treatments with clomipramine (saline or 5, 10, or 20 mg kg(-1)) reduced hyperlocomotion induced by scopolamine (0.5 mg kg(-1), s.c.) dose-dependently, and the effect of 20 mg kg(-1) clomipramine was significant (P < 0.05). These results suggest that an upregulation of mAChR is produced by repeated clomipramine administration, and such a change is responsible for the decreased sensitivity to the muscarinic antagonist scopolamine.

Application of the elevated plus-maze test in mice for evaluation of the content of honokiol in water extracts of magnolia

In our previous study using an improved elevated plus-maze in mice, the oriental herbal medicine Saiboku-to prolonged the time spent in open arms, showing an anxiolytic effect, and the effect was mainly caused by honokiol derived from magnolia. This study was carried out to compare the anxiolytic potentials of honokiol and water extracts of three magnolia samples; two being Kara-koboku (Magnolia officinalis) (KA: from Zhejiang-sheng, China; honokiol 0.25% and magnolol 1.16%, and KB: from Sichuan-sheng, China; honokiol 1.72% and magnolol 1.71%), and one being Wa-koboku (Magnolia obovata) (WA: from Iwate-ken, Japan; honokiol 0.32% and magnolol 0.81%). Seven daily treatments with 0.1-1 mg/kg honokiol, but not 0.2 and 1 mg/kg magnolol, revealed an anxiolytic effect with the peak potential at 0. 2 mg/kg. The anxiolytic potentials of 40 and 80 mg/kg KA, which contained the highest amount of magnolol, were almost equivalent to those of 0.1 and 0.2 mg/kg honokiol, respectively. KB, at 11.6 mg/kg, and 62.5 mg/kg WA resulted in almost the same anxiolytic potential as that of 0.2 mg/kg honokiol. No significant change in the ambulatory activity was produced by any drug treatment. These results suggest that honokiol is the chemical responsible for the anxiolytic effect of the water extract of magnolia and that the other chemicals including magnolol in magnolia scarcely influence the effect of honokiol. It is also considered that the elevated plus-maze test is applicable for evaluation of the content of honokiol in magnolia.

Does nicotine modify the psychotoxic effect of methamphetamine? Assessment in terms of locomotor sensitization in mice

In this study, effects of nicotine on locomotor sensitization to methamphetamine in mice were investigated to assess whether nicotine modified induction and expression of psychotoxic action of methamphetamine. Although nicotine (0.03-1 mg/kg s.c.) had no effect at first administration, 5-time nicotine administrations at 3-day intervals progressively developed a significant locomotor stimulant effect, and caused an enhanced sensitivity (cross-sensitization) to methamphetamine (2 mg/kg s.c.). Five-time administrations of methamphetamine (2 mg/kg) at 3-day intervals produced not only a locomotor sensitization to methamphetamine itself, but also a cross-sensitization to nicotine (0.1-1 mg/kg). Nicotine (0.03-1 mg/kg) did not affect the locomotor stimulant effect of methamphetamine (2 mg/kg) in the drug-naive mice. However, nicotine acted dose-dependently to reduce the progressive enhancement of the locomotor stimulant effect of methamphetamine during 5-time repeated administrations. Mice treated with coadministration of methamphetamine with nicotine (1 mg/kg) showed less sensitization to methamphetamine than mice treated with methamphetamine alone. In addition, nicotine (1 mg/kg) inhibited the locomotor stimulant effect of methamphetamine in mice sensitized to methamphetamine. These results suggest that methamphetamine and nicotine produce a symmetrical cross-sensitization, although nicotine may act to inhibit the induction and expression of locomotor sensitization to methamphetamine in mice.

Honokiol, a putative anxiolytic agent extracted from magnolia bark, has no diazepam-like side-effects in mice

Use of the elevated plus-maze experiment and activity and traction tests in mice have revealed that seven daily treatments with 0.2 mg kg(-1) and higher doses of honokiol, a neolignane derivative extracted from Magnolia bark, had an anxiolytic effect without change in motor activity or muscle tone. Diazepam, 1 mg kg(-1), had the same anxiolytic potential as 0.2 mg kg(-1) honokiol but induced muscle relaxation. The aim of this study was to determine whether honokiol had diazepam-like side-effects. Mice treated with 1-10 mg kg(-1) diazepam, but not those treated with 0.1-2 mg kg(-1) honokiol, for 12 days showed withdrawal symptoms characterized by hyperactivity and running-fit when they were challenge-administered intraperitoneal flumazenil (10 mg kg(-1)) 24 h after the last treatment with diazepam. Oral diazepam (0.5-2 mg kg(-1), 10 min before) dose-dependently prolonged hexobarbital (100 mg kg(-1), i.p.)-induced sleeping, disrupted learning and memory, and inhibited (+)-bicuculline (40 mg kg(-1), i.p.)-induced death. Honokiol (0.2-20 mg kg(-1), p.o., 3 h before) had no such effects. The prolongation by diazepam (1 mg kg(-1)) of hexobarbital-induced sleeping was not modified by honokiol (0.2-20 mg kg(-1)). These results suggest that honokiol is less likely than diazepam to induce physical dependence, central depression and amnesia at doses eliciting the anxiolytic effect. It is also considered that honokiol might have no therapeutic effect in the treatment of convulsion.

[Evaluation of transition zone biopsy in systematic prostate biopsy]

We evaluated the systematic biopsies performed on 83 patients suspected of having prostate cancer. In the systematic biopsy, 6 cores were from the peripheral zone and 2 cores from the transition zone. Cancer was detected in 25 patients (30.1%). The percentage of patients who had abnormal digital rectal examination and transrectal echo findings, average PSA and PSA density, and the number of examinations which suggested cancer were higher in the cancer group than in the non-cancer group, although the mean prostate volume was smaller. Cancer was more frequently detected in the peripheral zone than in the transition zone. Cancer was detected only in the transition zone in only 1 of the 25 cancer patients. We conclude that biopsy of the transition zone to all the patients is not always needed in systematic biopsy.

[Prostate specific antigen doubling time in prostate cancer before treatment and in refractory status]

Prostate-specific antigen(PSA) increases exponentially in prostate cancer patients before treatment and in refractory status. PSA increases in 68-86% of prostate cancer patients before treatment, and that of the remaining 14-32% of the patients is stable. Those patients with a higher pre-treatment PSA level are more likely to have a shorter PSA-doubling time(PSA-DT). The relationship between pre-treatment stage, grade and PSA-DT is controversial. PSA-DT in biochemical failure patients predicts the risk of clinical recurrence. PSA-DT was correlated well with time to clinical recurrence after biochemical failure. Distant recurrence was associated with short PSA-DT. Higher clinical stage and lower differentiation before treatment correlated with shorter PSA-DT in recurrent cancer patients. PSA-DT is an important parameter for judging malignant potential of each cancer.

Behavioural pharmacological characteristics of honokiol, an anxiolytic agent present in extracts of Magnolia bark, evaluated by an elevated plus-maze test in mice

Honokiol, a neolignane derivative of Magnolia bark, has central depressant action and, at much lower doses, anxiolytic activity. We have investigated the characteristics of the behavioural effects of honokiol by means of an elevated plus-maze test. In the plus-maze test a single oral dose of 20 mg kg(-1) honokiol significantly prolonged the time spent in the open arms of the maze, suggesting anxiolytic effect. Moreover, when honokiol was administered daily for seven days and the plus-maze test was conducted 3 or 24 h after the last administration, significant prolongation of the time in the open arms was manifested even for doses of 0.2 mg kg(-1). The maximum effect was observed for doses of 0.5 mg kg(-1). Honokiol at any dose in both single and repeated administration schedules caused neither change in motor activity nor disruption of traction performance. Orally administered diazepam, 0.5-2 mg kg(-1), caused dose-dependent prolongation of the time spent in the open arms of the maze with a significant increase in motor activity at 1 mg kg(-1), and dose-dependent disruption of traction performance. The changes in the plus-maze performance after treatment for seven days with 0.2 mg kg(-1) honokiol and after a single treatment with 1 mg kg(-1) diazepam were almost equivalent. The effect of honokiol (0.2 mg kg(-1), treatment for seven days) was inhibited by subcutaneous flumazenil (0.3 mg kg(-1)) and (+)-bicuculline (0.1 mg kg(-1)) and by intraperitoneal CCK-4 (50 microg kg(-1)) and caffeine (30 mg kg(-1)). The anxiolytic effect of diazepam (1 mg kg(-1)) was also inhibited by flumazenil and bicuculline. However, the combined administration of diazepam with caffeine enhanced the effect, and diazepam completely reversed the effect of CCK-4. These results suggest that, in contrast with diazepam, honokiol selectively induces an anxiolytic effect with less liability of eliciting motor dysfunction and sedation or disinhibition. The combined effects of the drug also revealed that the mechanism of anxiolytic effect of honokiol is partially different from that of diazepam.

Importance of initial environments in the development of ambulatory sensitization to methamphetamine and cocaine in mice

Repeated administration of CNS stimulants such as amphetamines and cocaine induces behavioural sensitization which can be influenced by the animal's environment. This study has evaluated the effect of restraint on the development and maintenance of ambulatory sensitization to methamphetamine and cocaine in mice. Subcutaneous administration of the CNS stimulants methamphetamine (2 mg kg(-1)) and cocaine (20 mg kg(-1)) seven times at three-day intervals resulted in ambulatory sensitization when the mice were placed in 20-cm diameter activity cages after each dose of the drug. However, if methamphetamine or cocaine was administered when the mice were in small jars (6-cm diameter) in which expression of ambulation, but not of circling and rearing, was completely restricted, the development of ambulatory sensitization was retarded or inhibited, with circling behaviour concurrently increased, when subsequent repeated doses of the drug were administered in the activity cage. Subsequent repeated treatment of ambulatory-sensitized mice with the drug or saline when the mice were in the jars did not change the levels of the ambulatory sensitization or the circling behaviour. These results suggest that the mice are sensitized to the behavioural effect of CNS stimulants which can be expressed in the environment in which the drug is administered. It is also considered that the established sensitization is strongly retained and is responsible for retardation or suppression of the development of sensitization to other behavioural stimulant effects.

Identification of magnolol and honokiol as anxiolytic agents in extracts of saiboku-to, an oriental herbal medicine

The principal active anxiolytic components in Saiboku-to, an Oriental herbal medicine, have been isolated and identified as magnolol (5,5'-di-2-propenyl-1,1'-biphenyl-2,2'-diol) and honokiol (3',5-di-2-propenyl-1,1'-biphenyl-2,4'-diol). Evaluation by means of an elevated plus-maze test showed that honokiol was at least 5000 times more potent than Saiboku-to when mice were treated orally for 7 days.

Induction of sensitization to hyperactivity caused by morphine in mice: effects of post-drug environments

Mice given five repeated administrations of morphine (10 mg/kg sc) at 3 day intervals in a round tilting-type activity cage (20 cm in diameter) or round spaces 15-30 cm in diameter with fixed floor showed almost the same level of ambulatory sensitization to morphine. Whereas, mice given morphine in the same schedule in spaces 4 and 12 cm, but not 6 and 9 cm, in diameter demonstrated a partial increase in the sensitivity to morphine. Furthermore, mice given morphine five times in a transparent cage (20W x 25L x 15H cm) with woodchip bedding, that was the same as the home cage, showed a weak and strong ambulatory sensitization when they were placed in group of ten and singly, respectively, for 3 h after each morphine administration. Repeated administrations of saline to mice in the space 4 cm in diameter resulted in increased sensitivity to morphine. However, the pretreatment with saline in the other environments (activity cage, spaces 6-30 cm in diameter with fixed floor, and home cage-like cage in which mice were placed singly or in group of ten) did not change the sensitivity to morphine. These results suggest that repeated experience of pharmacological effect of morphine and the resultant ambulation is one of the most important factors for induction of strong ambulatory sensitization to morphine in mice. It is estimated that a space 15 cm in diameter, which corresponds to 2-2.5 times as long as the body length without tail is a minimum requirement for induction of strong ambulatory sensitization to morphine. In contrast, even though mice are placed in a sufficient space for ambulation, an interference of ambulation by the other mice acts to inhibit the induction of ambulatory sensitization. It is also suggested that a strong stress caused by restraint is responsible for significant increase in sensitivity to morphine.

Behavioral effects of N-cyanomethylmethamphetamine, a product derived from smoking methamphetamine with tobacco, in mice and rats

The stimulant effects of N-cyanomethylmethamphetamine (CMMA), a product derived from smoking methamphetamine (MA) mixed in tobacco, were studied by observing stereotyped behavior and measuring spontaneous motor activity in mice and rats over 180 min CMMA. 1.3 and 10 mg/kg IP, elicited strong stimulant-like effects which were almost equivalent to those produced by MA. Drug monitoring for 180 min in mouse and rat plasma revealed that the principal substances responsible for the stimulant effect of CMMA were MA and amphetamine (AP) which were metabolized from CMMA by the animal. There was a species difference in metabolism of CMMA between mice and rats. The major metabolites were MA and AP in mouse plasma, followed by N-formylmethamphetamine (FMA), whereas the major metabolite was FMA in rat plasma, followed by MA and AP. The differences in the stimulant effects of CMMA between mice and rats were discussed in relation to its metabolic fate in mice and rats.

Memory disturbance and hippocampal degeneration induced by continuous intraventricular infusion of a protease inhibitor, leupeptin

Effects of a protease inhibitor, leupeptin, on the memory function and the morphological changes in the hippocampus were examined in rats. The leupeptin was infused by an implanted-osmotic minipump into the lateral ventricle of the rats for 14 days. The acquisition and the maintenance of memory were evaluated by a step-down passive avoidance task. The control rats, infused with an artificial cerebral spinal fluid, showed good retention for the passive avoidance training for 21 days after training. The leupeptin-treated rats showed good retention for 7 days following training; however, pronounced impaired retention was observed on day 10 and thereafter. These rats were accompanied by a degeneration of the dentate gyrus in the histological examinations on Days 14 and 21. The granule cells in the dentate gyrus of the hippocampus appeared much more eosinophilic pyknotic. Numerous eosinophilic spherical structures of the cell processes were seen in the neuropil beneath the granule cell layer. Electron microscopic examination disclosed a marked accumulation of lipofuscin-like granules in the perikaryon of the cells and in the dendrites and the axons. These findings suggest that the memory impairment is closely related to the degeneration of the dentate gyrus in the hippocampus in the leupeptin-treated rats.

Assessment of the anxiolytic and amnesic effects of three benzodiazepines, diazepam, alprazolam and triazolam, by conflict and non-matching to sample tests in mice

The anti-conflict and amnesic effects of three benzodiazepines (diazepam, alprazolam and triazolam) po-administered in mice were assessed by a modified Geller Seifter conflict test and a non-matching to sample test using a 4-arm maze with 3 selectable arms, respectively. Diazepam (10 mg/kg), alprazolam (1-10 mg/kg) and triazolam (1 and 3 mg/kg) significantly increased the lever-press in the alarm period (punished responding) under the conflict test. Under the non-matching to sample test, the correct response (CR), but not non-reward response (NR), decreased depending on the delay time. Diazepam (3 mg/kg) significantly decreased the CR under 0-sec delay condition, but not that under 30-sec delay condition. Comparatively higher doses of the benzodiazepines, diazepam (10 mg/kg), alprazolam (1 and 3 mg/kg) and triazolam (0.3 and 1 mg/kg), significantly decreased the CR under both 0- and 30-sec delay conditions. However, no significant change in the NR was produced by any dose of the three benzodiazepines. These results suggest that the decrease in CR during the non-matching to sample test is caused by the impairment of cognitive function rather than working and reference memories, and that such effects appear at doses equal to and/or less than the effective doses for anti-conflict effect. However, the assumption that triazolam has the highest risk of induction of amnesia, as compared to the advantage of sleep induction or relief of anxiety in the benzodiazepine group, was not supported by the present results.

Effects of postmethamphetamine treatment with restraint on ambulatory sensitization to methamphetamine in mice

The administration of methamphetamine (2 mg/kg SC) to mice was followed by acceleration of ambulation (locomotion) for 3 h, with the peak effect at 1/2-1 h. When mice were allowed free ambulation for 3 h in an activity cage of 20 cm in diameter after methamphetamine administration, repeated administrations of methamphetamine, four times at 3-day intervals, caused ambulatory sensitization; the count at the fourth administration being approximately 2.3 times as high as that at the first administration. Furthermore, the mice that were allowed ambulation in the activity cage during postmethamphetamine period of either 0-1/2, 0-1, 0-2, or 1/2-1 h (during the other periods, the mice were put in jars of 6 cm in diameter to restrict ambulation) demonstrated ambulatory sensitization to methamphetamine, and these levels were as same as that in the mice given methamphetamine with free ambulation for 3 h. However, the free ambulation during postmethamphetamine periods of 0-1/4 h and 1-3 h failed to produce strong sensitization to methamphetamine. These results suggest that a free ambulation for at least 1/2 h during the postmethamphetamine period of 0-1 h is important for induction of ambulatory sensitization to methamphetamine in mice.

Effects of tetrabenazine on methamphetamine-induced hyperactivity in mice are dependent on order and time-course of administration

The ambulation-increasing effect of methamphetamine (MAP: 2 mg/kg s.c.) in mice persisted for about 3 h. Tetrabenazine (TBZ: 4 mg/kg s.c.), a depleter of monoamines from the cytoplasmic pool did not increase ambulation on its own. Pretreatment with TBZ at 1.5 h before administration of MAP inhibited the stimulant effect of MAP. In contrast, combined administration of two drugs resulted in a transient but considerable enhancement of MAPs stimulant effect. Post-MAP treatment with TBZ at 0.5-2 h hardly modified MAPs behavioral effects. In contrast, 3-6 h post-MAP treatment with TBZ induced a transient increase in activity, although the stimulant effect of MAP had already disappeared. The maximum increase in ambulatory stimulation was produced by 4-h post-MAP treatment with TBZ. The inhibitory effect of TBZ pretreatment on MAP-induced hyperactivity, as well as the transient hyperactivity elicited by TBZ when administered along with MAP, or 4 h after MAP, was dose-dependent. Preliminary studies revealed that transient hyperactivity was never produced by combination of GBR-12909 (a selective dopamine reuptake inhibitor) with TBZ or MAP with oxypertine (a selective norepinephrine releaser/depleter), but produced by combination of nialamide (a monoamine oxidase inhibitor) with TBZ. Inhibition of MAPs effects by TBZ pretreatment suggests that enhancement of dopamine release from cytoplasmic pool, and inhibition of dopamine reuptake by MAP, are involved in MAPs acute behavioral effects. Further, the fact that neither TBZ administration following GBR-12909 pretreatment, nor oxypertine treatment following MAP pretreatment, elicited transient hyperactivity suggests that dopamine is involved in hyperactivity elicited by post-MAP treatment with TBZ. It is also suggested that inhibition of monoamine oxidase (MAO) by MAP and dopamine displacement by TBZ may be responsible for the transient stimulation produced by 3-6 h post-MAP treatment with TBZ. It is hypothesized that the MAO inhibitory action of MAP persists after cessation of its acute stimulant effect, possibly up to 6 h after administration.

Effects of interdose interval on ambulatory sensitization to methamphetamine, cocaine and morphine in mice

To determine the minimum interdose interval for induction of ambulatory sensitization to methamphetamine, cocaine and morphine, 3 sets of 5 groups of mice were treated with either methamphetamine (2 mg/kg s.c.), cocaine (10 mg/kg s.c.) or morphine (10 mg/kg s.c.) 3 times at intervals of 3, 6, 12, 24 or 48 h, and then 2 times at intervals of 3 days in all groups. During the first 3 administrations of both methamphetamine and cocaine, interdose intervals of 3-12 h did not produce a significant change in the ambulatory stimulation. However, 3 repeated administrations of morphine with interdose intervals of 3 and 6 h, but not 12 h, caused tolerance to the ambulatory stimulant effect. The administration of all drugs with interdose intervals of 24 and 48 h produced ambulatory sensitization. Furthermore, following the fourth and fifth administrations of each drug, all groups of mice demonstrated sensitization. These results indicate that an interdose interval of 24 h or longer is required for induction of ambulatory sensitization to methamphetamine, cocaine and morphine.

Age-dependent induction and maintenance of sensitization to methamphetamine-induced hyperactivity in mice

Repeated administrations of methamphetamine (2 mg/kg, s.c.), 10 times at 3-day intervals, induced ambulatory sensitization in all groups of mice that were 13-, 15-, 19-, 23- and 36-week-old at the start of methamphetamine administration. The most prominent sensitization was observed in the 19-week-old mice. Among five groups of mice, even though the mice of 36 weeks old showed the highest sensitivity to methamphetamine at the first administration, they exhibited the lowest sensitization during the latter stage of repeated methamphetamine administration. Methamphetamine sensitization once established was well reproduced by the post-sensitization period of 8 weeks. Furthermore, the group of mice given methamphetamine with post-sensitization interval of 8 weeks (19-week-old mice) exhibited further enhancement of the sensitization. In contrast, the groups of mice given methamphetamine with post-sensitization intervals of 12 and 25 weeks (the 23- and 36-week-old, respectively) showed a significant reduced sensitization, and the latter group failed to reach the level of sensitization previously established. These results suggest that the induction of and maintenance of methamphetamine sensitization are dependent on the age of the mice, and that methamphetamine sensitization once established completely persists for up to 8 weeks.

Regulation of phospholipase D by low molecular weight GTP-binding proteins

Phospholipase D (PLD) is believed to play an important role in cell signal transduction: PLD catalyzes the hydrolysis primarily of phosphatidylcholine (PC) to produce phosphatidic acid that may serve as a lipid second messenger. Although the mechanism of PLD activation has not yet been fully understood, a member of the low molecular weight GTP-binding protein (small G protein) superfamily, ADP-ribosylation factor (ARF), has been identified as a PLD-activating factor. In addition to ARF, we found that RhoA, another member of the small G proteins, activated rat brain PLD, and that ARF and RhoA synergistically stimulated the enzyme activity. When proteins of bovine brain cytosol were subjected to anion exchange column chromatography and then reconstituted with rat brain PLD partially purified from the membranes, fractions eluted at 60 mM NaCl, where ARF was not detected, activated the enzyme in a guanosine 5'-O-(3-thiotriphosphate)-dependent manner. This PLD-stimulating activity seemed to be attributed to a small G protein RhoA. Evidence provided includes the findings that: (1) the partially purified preparation of the PLD-activating factor by subsequent column chromatographies contained a 22 kDa substrate for botulinum C3 exoenzyme ADP-ribosyltransferase; (2) the 22 kDa protein strongly reacted with anti-RhoA antibody; (3) the treatment of the partially purified PLD-activating factor with C3 exoenzyme and NAD together, but not individually, significantly inhibited the PLD-stimulating activity; and (4) recombinant isoprenylated RhoA activated the PLD. On the contrary, recombinant nonisoprenylated RhoA failed to activate the PLD. Interestingly, the partially purified PLD-activating factor and ARF synergistically activated rat brain PLD, and recombinant isoprenylated RhoA could substitute for the partially purified preparation. These results conclude that rat brain PLD is regulated by RhoA in concert with ARF, and that the post-translational modification of RhoA is essential for its function as the PLD activator.

Importance of post-drug environmental factors for induction of sensitization to the ambulation-increasing effects of methamphetamine and cocaine in mice

Mice given five repeated administrations of methamphetamine (MAP: 2 mg/kg SC) or cocaine (COC: 20 mg/kg SC) at 3-day intervals in a round tilting-type activity cage (20 cm in diameter) showed sensitization to the ambulation-increasing effect of each drug. The mean 3- or 2-h overall activity count at the fifth administration of MAP or COC, respectively, was 2.3-2.5 times higher than that at the first administration. Mice given MAP or COC 4 times in round spaces (15-30 cm in diameter), where the floor did not tilt, exhibited sensitization as strong as that demonstrated by mice given each drug in the activity cages, when the mice were given the fifth administration in the activity cages. In contrast, mice repeatedly given the drugs in spaces 4-9 cm in diameter never, and those in space 12 cm in diameter only partially, exhibited sensitization to MAP and COC. Furthermore, mice given MAP or COC 4 times in their home cages (25D x 20W x 15H cm, with ten mice in each cage) showed partial sensitization. Repeated administration of saline to mice in activity cages, in the spaces 4-30 cm in diameter, or in the home cages did not cause significant change in the sensitivity to either MAP or COC. These results suggest that repeated experience of the stimulant effect of drug and the resultant ambulation is required for induction of sensitization to MAP and COC in terms of ambulation in mice. It is also suggested that spaces larger than 12 cm in diameter, which correspond to 2-2.5 times as long as the body length without tail, and no interference from other mice are required for induction of strong sensitization to both MAP and COC.

Effect of haloperidol on the behavioral stimulation by N-cyanomethylmethamphetamine, a main product of smoking methamphetamine mixed with tobacco

N-Cyanomethylmethamphetamine is a main product of smoking methamphetamine mixed with tobacco. The aim of this experiment was to evaluate the effects of haloperidol on behavioral stimulation by N-cyanomethylmethamphetamine (3 mg/kg s.c.) in terms of ambulation in mice. Repeated administration of N-cyanomethylmethamphetamine, carried out 5 x at 3-day intervals, induced a sensitization to its ambulation-increasing effect. Haloperidol (0.01, 0.03, 0.1 and 0.3 mg/kg s.c.) significantly inhibited not only the acute stimulant effect of N-cyanomethylmethamphetamine but also the induction of sensitization. The dose-effect curves for the inhibitory effects of haloperidol on the N-cyanomethylmethamphetamine-induced ambulatory stimulation were almost the same between the drug-native and N-cyanomethylmethamphetamine-sensitized mice. Moreover, such behavioral characteristics of N-cyanomethylmethamphetamine; the behavioral stimulant effect, the induction of sensitization following repeated administration, and the inhibition of its effects by haloperidol, were qualitatively the same as those of methamphetamine (2 mg/kg s.c.). These results suggest that N-cyanomethylmethamphetamine possesses methamphetamine-like central stimulant effect and that D2 dopaminergic mechanisms are involved in the effect of N-cyanomethylmethamphetamine.

Characteristics of behavioural stimulant effect of N-cyanomethylmethamphetamine, a main product of smoking methamphetamine mixed with tobacco: evaluation by ambulatory activity in mice

N-cyanomethylmethamphetamine is main product of smoking methamphetamine HCl (CAS code value: 537-46-2, molar mass: 185.70 g/mol) mixed with tobacco, and has a central stimulant action. The aims of this study were to assess in terms of ambulation in mice whether repeated administration of N-cyanomethylmethamphetamine HCl (molar mass: 211.70 g/mol) induced sensitization to its central stimulant effect, and whether there were cross-sensitization from N-cyanomethylmethamphetamine HCl to methamphetamine HCl, and from methamphetamine HCl to N-cyanomethylmethamphetamine HCl. N-cyanomethylmethamphetamine HCl 14.2 and 47.2 mumol/kg subcutaneously dose-dependently accelerated ambulation of mice. Five administrations at 3 day intervals caused sensitization, the activity counts in the fifth administration being approximately 2.6 and 1.6 times, higher respectively, than those in the first administration. Furthermore, the mice repeatedly given 14.2 and 47.2 mumol/kg N-cyanomethylmethamphetamine HCl exhibited cross-sensitization to methamphetamine HCl (10.8 mumol/kg subcutaneously). Whereas 1.4 and 4.7 mumol/kg N-cyanomethylmethamphetamine HCl did not induce significant acceleration of the ambulation throughout the 5 repeated administrations, nor cross-sensitization to methamphetamine HCl. On the other hand, the 5 repeated administrations of methamphetamine HCl (10.8 mumol/kg) also caused sensitization to its ambulation-increasing effect, and the activity count in the fifth administration attained approximately 2.0 times higher than that in the first administration. The mice given methamphetamine HCl demonstrated cross-sensitization to 1.42-14.2 mumol/kg N-cyanomethylmethamphetamine HCl. Haloperidol (CAS code value: 52-86-8, molar mass: 375.88 g/mol; 0.027-0.80 mumol/kg subcutaneously) dose-dependently reduced the ambulation-increasing effects of N-cyanomethylmethamphetamine HCl and methamphetamine HCl in the drug-naive, and N-cyanomethylmethamphetamine HCl- and methamphetamine HCl-sensitized mice. These dose-effect relationships were similar between groups. The present results suggest that N-cyanomethylmethamphetamine HCl has a behavioural stimulant effect almost similar to that of methamphetamine HCl.

Inhibitory effect of restraint on induction of behavioral sensitization to methamphetamine and cocaine in mice

Repeated intermittent (generally 3-day intervals) administrations of methamphetamine (MAP: 2 mg/kg, SC) or cocaine (COC: 20 mg/kg, SC) induced sensitization to the ambulation-increasing effect of individual drug in mice. The induction of MAP and COC sensitization was inhibited when restraint of the mouse (putting the mouse in a jar of 6 cm in diameter for 3 and 2 h after administration of MAP and COC, respectively) was started immediately after each drug administration. Furthermore, the induction of sensitizations to MAP and COC was significantly reduced when the restraint was started within 1/4 h and 1/6 h after the administration of MAP and COC, respectively, whereas the restraint starting thereafter did not affect the induction of sensitization. The three times repeated administrations of saline with or without restraint did not significantly change the sensitivities to MAP and COC. The ambulation-increasing effects of MAP and COC reached the peak at approximately 2/3 and 1/2 h, respectively, and persisted for 3 and 2 h after the administration. The present results suggest that, to completely induce sensitization to MAP and COC in terms of ambulation, the mice must freely move for at least half of the latency to their peak effects.

Differential effects of morphine-6-glucuronide, an active metabolite of morphine, and morphine on locomotor activity in mice: involvement of the opioid receptor

Subcutaneous administration of morphine (2.5 to 20 mg/kg) or an active metabolite of morphine, morphine-6-glucuronide (2.5 to 20 mg/kg), increased the locomotor activity of mice in a dose-dependent manner. Fifteen mg/kg of morphine and 20 mg/kg of morphine-6-glucuronide were almost equipotent. Subcutaneous administration of the universal opioid antagonist, naloxone, but not the delta-selective antagonist, naltrindole, significantly suppressed the hyperlocomotion induced by morphine (15 mg kg). On the other hand the subcutaneous administration of relatively higher doses of naloxone or naltrindole significantly reduced the hyperlocomotion induced by morphine-6-glucuronide (20 mg/kg). These findings suggest that agonistic actions at the opioid receptors, especially at the delta- and mu-receptors, contribute to the morphine-6-glucuronide-induced hyperlocomotion.

Interval-dependent inhibition of morphine sensitization of ambulation in mice by post-morphine treatment with naloxone or restraint

The ambulation-increasing effect of morphine (10 mg/kg SC) persisted for approximately 3 h with a peak effect at around 1 h after the administration. This was examined on four occasions at 3-day intervals. Thus, treatment regimen-induced sensitization and the 3-h overall activity in the fourth administration was about 1.7 times higher than that in the first administration. Post-morphine treatments with naloxone (1 mg/kg SC) at 0 (i.e., simultaneously with) to 30 min after each morphine administration almost completely inhibited the induction of morphine sensitization. However, post-morphine treatments with naloxone at 1 h and later had no such inhibitory effect. Similarly, physical restriction of the ambulation of mice for 3 h (restraint), by putting them in a jar (6 cm in diameter, and 15 cm in height) inhibited the induction of morphine sensitization when restrain was started 0-30 min after each administration of morphine. Restraint starting 1 h and later did not alter the morphine sensitization. Post-morphine treatment with saline at any times did not change morphine sensitization. Furthermore, repeated administration of saline alone, naloxone alone, and saline with naloxone post-treatment or restraint did not change the sensitivity to morphine. These results clearly indicate that free ambulation for at least 1 h after the administration of morphine, i.e., the latency to reach the peak effect, is required completely to induce sensitization to morphine in terms of ambulation in mice.

Effects of sulpiride and nemonapride, benzamide derivatives having distinct potencies of antagonistic action on dopamine D2 receptors, on sensitization to methamphetamine in mice

The acute ambulatory stimulation by methamphetamine (2 mg kg-1 S.C.) was dose-dependently reduced by 3-h pretreatment or combined treatment with sulpiride (1-100 mg kg-1 S.C.), and combined treatment with nemonapride (0.003-0.03 mg kg-1 S.C.), benzamide derivatives having selective antagonistic action on dopamine D2 receptors. The repeated (5 times) administrations of methamphetamine at 3-day intervals induced a sensitization to its ambulation-increasing effect, and the sensitization was significantly inhibited by 3-h pretreatment with either sulpiride (10-100 mg kg-1), or combined treatment with either sulpiride (3 or 10 mg kg-1) or nemonapride (0.01 or 0.03 mg kg-1) at each methamphetamine administration. Although the ambulation-increasing effect of methamphetamine disappeared by 3 h after the administration, the 3-h post-treatment with sulpiride (3 mg kg-1) or nemonapride (0.03 mg kg-1) after each methamphetamine administration was effective for a significant inhibition of the induction of methamphetamine sensitization, whereas, the comparatively higher doses of sulpiride (30 and 100 mg kg-1 in the combined treatment, and 10-100 mg kg-1 in the post-treatment) did not inhibit the methamphetamine sensitization. On the other hand, the repeated administrations of sulpiride (30 and 100 mg kg-1) alone, but not any doses of nemonapride, at 3-day intervals elicited a significant increase in the sensitivity to methamphetamine. These results suggest that, although the potencies of the anti-methamphetamine effects of sulpiride and nemonapride differ by a factor of 3000, they inhibit the induction of sensitization to methamphetamine in the pretreatment, combined treatment and early post-treatment schedules. However, it is also suggested that the repeated treatment with comparatively higher doses of sulpiride may produce a denervation supersensitivity of dopamine D2 receptors, and resultant increase in the sensitivity to methamphetamine.

Partially purified RhoA-stimulated phospholipase D activity specifically binds to phosphatidylinositol 4,5-bisphosphate

Phosphatidylinositol 4,5-bisphosphate (PIP2) is absolutely required for the ADP-ribosylation factor-stimulated phospholipase D (PLD) activity. In the present study, partially purified rat brain PLD was found to be activated by another PLD activator, RhoA, when PIP2, but not other acidic phospholipids, was included in vesicles comprising phosphatidylethanolamine (PE) and the PLD substrate phosphatidyicholine (PC) (PE/PC vesicles), demonstrating the absolute requirement of PIP2 for the RhoA-stimulated PLD activation, too. It is interesting that the RhoA-dependent PLD activity in the partially purified preparation was drastically decreased after the preparation was incubated with and separated from PE/PC vesicles containing PIP2. The PLD activity was extracted by higher concentrations of NaCl from the vesicles containing PIP2 that were incubated with and then separated from the partially purified PLD preparation. These results demonstrate that RhoA-dependent PLD binds to PE/PC vesicles with PIP2. The degree of binding of the RhoA-dependent PLD activity to the vesicles was totally dependent on the amount of PIP2 in the vesicles and correlated well with the extent of the enzyme activation. Further-more, it was found that a recombinant peptide of the pleckstrin homology domain of beta-adrenergic receptor kinase fused to glutathione S-transferase, which specifically binds to PIP2, inhibited the PIP2-stimulated, RhoA-dependent PLD activity in a concentration-dependent manner. From these results, it is concluded that in vitro rat brain PLD translocates to the vesicles containing PIP2, owing to its specific interaction with PIP2, to access its substrate PC, thereby catalyzing the hydrolysis of PC. PLD appears to localize exclusively on plasma membranes of cells and tissues. An aminoglycoside, neomycin, that has high affinity for PIP2 effectively extracted the RhoA-dependent PLD activity from rat brain membranes. This indicates that PIP2 serves as an anchor to localize PLD on plasma membranes in vivo.

Modification by MK-801 (dizocilpine), a noncompetitive NMDA receptor antagonist, of morphine sensitization: evaluation by ambulation in mice

The effects of five administrations (3- to 4-day intervals) of morphine (MOR: 10 and 20 mg/kg, s.c.) alone, MK-801 (dizocilpine: 0.03, 0.1, 0.3 and 1 mg/kg, i.p.) alone, and combinations of MOR with MK-801 on the ambulation in mice were investigated. MK-801 at 0.3 and 1 mg/kg, but not at 0.03 and 0.1 mg/kg, significantly increased the ambulation of mice. Although the mice given repeated administrations of MK-801 (0.3 and 1 mg/kg) exhibited enhancement and reduction, respectively, in the ambulation-increasing effect of the individual doses, they showed significantly higher sensitivity than the saline-treated mice to the challenge with MOR (10 mg/kg). The repeated administrations of MOR (10 and 20 mg/kg) induced a progressive enhancement of the ambulation-increasing effect. The mice repeatedly given MOR (10 mg/kg) exhibited significant increase in the sensitivity to MK-801 (0.03-0.3 mg/kg). The coadministrations of MOR with MK-801 intensified the ambulation-increasing effect, and repeated coadministrations induced progressive enhancement of the effect, except for the combinations of MOR (10 or 20 mg/kg) with MK-801 (1 mg/kg). However, the induction of MOR sensitization was not modified by any doses of MK-801, except for the case of combination of MOR (20 mg/kg) with MK-801 (1 mg/kg) which was highly toxic (i.e., eliciting death or a moribund condition). On the other hand, simultaneous treatment with SCH 23390 (0.05 mg/kg, s.c.) or nemonapride (0.05 mg/kg, s.c.), or 4-hr pretreatment with reserpine (1 mg/kg, s.c.) strongly, and 4-hr pretreatment with alpha-methyl-p-tyrosine (200 mg/kg, i.p.) partially reduced the ambulation-increasing effect of both MOR (10 mg/kg) and MK-801 (0.3 mg/kg). Simultaneous treatment with naloxone (1 mg/kg, sc) selectively reduced the effect of MOR. However, simultaneous treatment with apomorphine (0.1 mg/kg, s.c.) did not modify the effects of either drug. These results suggest that the characteristics of the ambulation-increasing effects of MOR and MK-801 are similar to each other, and that the repeated treatments with MK-801 induce a cross-sensitization to MOR and vice versa.

Dopamine D1 receptor antagonist SCH 23390 retards methamphetamine sensitization in both combined administration and early posttreatment schedules in mice

SCH 23390 [0.003-0.03 mg/kg, subcutaneously (SC)], a dopamine D1 receptor antagonist, dose-dependently inhibited the ambulation-stimulant effect of methamphetamine (MAP) (2 mg/kg, SC) in mice when two drugs were combined in repeated administrations at 3- to 4-day intervals, repeated five times. SCH 23390 (0.03 mg/kg), which was sufficient to abolish the acute effect of MAP completely throughout the repeated administrations, significantly inhibited the induction of MAP sensitization. Moreover, when the mice were posttreated with SCH 23390 (0.01 and 0.03 mg/kg) 3 h after each MAP administration, at which the ambulation-stimulant effect of MAP had almost disappeared, they showed a significant and dose-dependent retardation of the induction of MAP sensitization. However, the 24-h posttreatment with SCH 23390 had no such effect. The administration of SCH 23390 (0.003-0.03 mg/kg) alone in either the activity cage or the home cage, or saline in the activity cage with 3- or 24-h posttreatment with SCH 23390 (0.01 or 0.03 mg/kg) five times at 3- to 4-day intervals did not elicit any significant changes in MAP sensitivity. The present results indicate that an intense blockade of dopamine D1 receptors in the acute or subacute period after MAP administration causes retardation of MAP sensitization by means of ambulation in mice.

Delayed effects of ethanol, caffeine and nicotine assessed by wheel-running and drinking in mice

Effects of ethanol, caffeine and nicotine, pleasurable substances, on wheel-running and drinking in mice that were housed under a 12 : 12-hr light-dark schedule (lighting period ; 6 : 00-18 : 00) were investigated. All drug administrations were carried out at 11: 00, a mid-light period. Although ethanol (0.8-2.4 g/kg p.o.) scarcely changed both the wheel-running and drinking during the light period, it was followed by a strong suppression of both behaviors during the coming dark period (18 : 00-6 : 00). The same treatment with caffeine (1-10 mg/kg s.c.) produced significant increase in the drinking during the light period, but suppression of the wheel-running during the dark period. Nicotine (0.1-1 mg/kg s.c.) significantly suppressed the wheel-running, but not drinking, during the dark period. The coadministration of nicotine (0.1-1 mg/kg) with ethanol (2.4 g/kg) reduced the behavioral suppression during the dark period. Whereas nicotine (0.1-1 mg/kg) reduced the increased drinking during light period by caffeine (10 mg/kg), but enhanced the caffeine-induced behavioral suppression during the dark period. These results indicate that the administration of pleasurable substances in the mid-light period results in a delayed effect which is characterized by a suppression of either and/or both wheel-running and drinking during the coming dark period starting 7 hr after the administration, and that nicotine acts to antagonize the effect of ethanol, but contrally to enhance the effect of caffeine.

Synergistic activation of rat brain phospholipase D by ADP-ribosylation factor and rhoA p21, and its inhibition by Clostridium botulinum C3 exoenzyme

An activator of rat brain phospholipase D (PLD) that is distinct from the already identified PLD activator, ADP-ribosylation factor (ARF), was partially purified from bovine brain cytosol by a series of chromatographic steps. The partially purified preparation contained a 22-kDa substrate for Clostridium botulinum C3 exoenzyme ADP-ribosyltransferase, which strongly reacted with anti-rhoA p21 antibody, but not with anti-rac1 p21 or anti-cdc42Hs p21 antibody. Treatment of the partially purified PLD-activating factor with both C3 exoenzyme and NAD significantly inhibited the PLD-stimulating activity. These results suggest that rhoA p21 is, at least in part, responsible for the PLD-stimulating activity in the preparation. Recombinant isoprenylated rhoA p21 expressed in and purified from Sf9 cells activated rat brain PLD in a concentration- and GTP gamma S (guanosine 5'-O-(3-thiotriphosphate))-dependent manner. In contrast, recombinant non-isoprenylated rhoA p21 (fused to glutathione S-transferase) expressed in Escherichia coli failed to activate the PLD. This difference cannot be explained by a lower affinity of non-isoprenylated rhoA p21 for GTP gamma S, as the rates of [35S]GTP gamma S binding were very similar for both recombinant preparations and the GTP gamma S-bound form of non-isoprenylated rhoA p21 did not induce PLD activation. Interestingly, recombinant isoprenylated rhoA p21 and ARF synergistically activated rat brain PLD; a similar pattern was seen with the partially purified PLD-activating factor. The synergistic activation was inhibited by C3 exoenzyme-catalyzed ADP-ribosylation of recombinant isoprenylated rhoA p21 in a NAD-dependent manner. Inhibition correlated with the extent of ADP-ribosylation. These findings suggest that rhoA p21 regulates rat brain PLD in concert with ARF, and that isoprenylation of rhoA p21 is essential for PLD regulation in vitro.

Inhibition of cocaine sensitization by MK-801, a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist: evaluation by ambulatory activity in mice

Alterations of cocaine effects, which were induced by prior repeated 5-time administration of MK-801 ((+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine) (i.p.) alone or in combination with cocaine (s.c.) at 3- to 4-day intervals, were investigated by means of ambulatory activity in mice. The repeated administration of either cocaine (10 and 20 mg/kg) alone or MK-801 (0.3 mg/kg) alone progressively enhanced each drug's effect. The enhanced effects of cocaine and MK-801 were estimated to be 1.8-2.2 times and about 1.4 times, respectively, as great as those at the 1st administration. Although the coadministration of MK-801 with cocaine produced a significant enhancement in the ambulation-increasing effect, the comparatively higher doses of MK-801 (0.3 and 1 mg/kg) acted not only to reduce cocaine sensitivity but also to inhibit the development of cocaine sensitization. Thus, the mice that had been given MK-801 (0.3 and 1 mg/kg) alone 5 times showed lower sensitivities to cocaine (20 mg/kg) than the mice given saline alone. The mice coadministered MK-801 (0.3 and 1 mg/kg) with cocaine (10 and 20 mg/kg) also exhibited lower sensitivities to cocaine (10 and 20 mg/kg) than those given cocaine alone. However, MK-801 could not ameliorate the established sensitization to cocaine. Similar interactions have been demonstrated between MK-801 at 1 mg/kg, but not 0.3 mg/kg, and methamphetamine. The present results indicate that MK-801 can inhibit the development of sensitization to cocaine at a lower dose than that required to inhibit methamphetamine sensitization.

Modification of cocaine sensitization by dopamine D1 and D2 receptor antagonists in terms of ambulation in mice

The progressive enhancement in the ambulation increase caused by the repeated five-time dosings of cocaine (10 mg/kg SC) at 3- to 4-day intervals was dose dependently reduced by simultaneous administration with the selective dopamine D1 and D2 receptor antagonists, SCH 23390; R(+)-7-chloro-8-hydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine (0.01, 0.03, and 0.1 mg/kg SC) and YM-09151-2 (nemonapride); cis-N-(1-benzyl-2-methylpyrrolidin-3-yl)-5-chloro-2-methoxy-4- methylaminobenzamide (0.01, 0.03, and 0.1 mg/kg SC), respectively. However, the mice given cocaine with SCH 23390 (0.03 mg/kg) or YM-09151-2 (0.03 and 0.1 mg/kg) demonstrated significantly higher sensitivity than the mice given cocaine alone to challenge cocaine. Both 2-h and 24-h posttreatments with SCH 23390 (0.01-0.1 mg/kg) after each cocaine administration, at which the acute stimulant effect of cocaine had disappeared, significantly and dose dependently enhanced the cocaine sensitization. In contrast, 2-h, but not 24-h, posttreatment with YM-09151-2 (0.01-0.1 mg/kg), slightly retarded the induction of cocaine sensitization. The present results suggest that the blockade of dopamine D1 receptors is responsible for a significant enhancement in the cocaine sensitization, independent of the timings of its administration, whereas the blockade of dopamine D2 receptors elicits time-dependent alterations in the cocaine sensitization, a strong enhancement in the simultaneous administration schedule, but a slight retardation in the early posttreatment schedule.

Evaluation of acute and sub-acute effects of cocaine by means of circadian variation in wheel-running and drinking in mice

The effects of cocaine on wheel-running and drinking activities in mice, housed under a 12-h light-dark schedule (lighted period; 6:00-18:00 h), were investigated through long continuous observation. Cocaine (20 and 40 mg/kg, sc), administered at 11:00 h, acutely increased wheel-running and drinking, but it was followed by a sub-acute suppression of the spontaneous increment in both of these behaviors during the coming dark period (18:00-6:00 h). Such behavioral accelerating and suppressing effects of cocaine did not change throughout the whole course of administration, which was repeated five times at 3- to 5-day intervals. In addition to these findings, wheel-running and drinking spontaneously increased during the light period and decreased during the dark period on the day after the drug administration. On the other hand, the repeated administration of cocaine at 18:00 h never increased, but rather acutely suppressed both behaviors during the dark period, and no trends in the behavioral changes on the next day were clearly shown. These results suggest that the effects of cocaine on wheel-running and drinking differ depending on the time of day of the administration.

Contrasting effects on methamphetamine sensitization of ceruletide, a cholecystokinin-like decapeptide, and haloperidol

Ceruletide, a cholecystokinin-like decapeptide, and haloperidol show neuroleptic actions through inhibition of dopamine release and blockade of dopamine receptors, respectively. In this study, the effects of both drugs on methamphetamine sensitization were assessed by means of ambulation in mice. The enhancement in ambulation increase caused by five repeated administrations of methamphetamine (2 mg/kg, SC) at 3- to 4-day intervals was dose-dependently reduced when it was administered simultaneously with ceruletide (0.01-0.1 mg/kg, SC) or haloperidol (0.03-0.3 mg/kg, SC). However, only haloperidol could inhibit the induction of methamphetamine sensitization as assessed by challenge with methamphetamine alone. Post-treatment with ceruletide (0.03 mg/kg) 3 h after each methamphetamine accelerated, whereas such post-treatment with ceruletide (0.1 mg/kg) or haloperidol (0.03-0.3 mg/kg) delayed, the induction of methamphetamine sensitization. On the other hand, mice given five pretreatments with ceruletide (0.01-0.1 mg/kg) or haloperidol (0.03-0.3 mg/kg) at 3- to 4-day intervals did not exhibit any significant change in the sensitivity to methamphetamine. The present results suggest that, in contrast to the dose-dependent inhibition of methamphetamine sensitization in the simultaneous administration and post-treatment schedules, although both drugs can antagonize the acute stimulant effect of methamphetamine.

Haloperidol and restraint differently inhibit the induction of sensitization to the ambulation-increasing effect of methamphetamine in mice

Haloperidol (HPD: 0.4 mg/kg, sc) completely abolished not only the ambulatory stimulation by methamphetamine (MAP: 2 mg/kg, sc) but also the induction and expression of MAP sensitization in the combined administration schedule. HPD also significantly reduced the induction of MAP sensitization when the mice were treated with HPD at 1/12, 1/4, 1, 2, 3, 4 or 5 hr but not at 1/2 hr or later than 6 hr, after each administration of MAP. The inhibition by the 3-hr post-treatment with HPD was as strong as that by the combined administration. On the other hand, a restraint of abulation for 3 hr (putting the mouse in a small jar) significantly inhibited the induction of MAP sensitization when it was started at 0/4 hr, but not at 1/2-6 hr, after each MAP administration. The inhibitory effects of restraint, starting at 0-1/4 hr, were almost equivalent to those of the post-treatments with HPD at the same times. The post treatments with HPD + restraint showed similar inhibitory effects on MAP sensitization to those of HPD alone. The repeated administration of saline together with post-treatment with either HPD, restraint or HPD + restraint did not change MAP sensitivity. These results suggest that a couple of free movement in the activity cage and stimulation of dopamine receptors for longer than 1/2 hr immediately after administration of MAP, and an agonistic effect on dopamine receptors during 1-5 hr after MAP are responsible for perfect induction of the MAP sensitization in terms of ambulation in mice.

Inhibition of methamphetamine sensitization by post-methamphetamine treatment with SCH 23390 or haloperidol

Methamphetamine (2 mg/kg SC) increased ambulation in mice for about 3 h, with a peak effect at around 40 min after the administration, and its repeated administration induced sensitization. Both SCH 23390 (0.03 mg/kg SC) and haloperidol (0.4 mg/kg SC), dopamine D1 and D2 receptor antagonists, respectively, completely inhibited not only the acute stimulant effect of methamphetamine but also its sensitization when repeated methamphetamine was repeatedly combined with either of these drugs. Moreover, treatment with SCH 23390 2-5 h or haloperidol 1-5 h after each methamphetamine administration significantly antagonized methamphetamine sensitization. The maximal inhibitory effect was observed in the schedules of 3-h post-methamphetamine treatment for both drugs. However, treatments with SCH 23390 or haloperidol at 0.5 h, 6 h and 24 h after methamphetamine had no such inhibitory effect. The mice treated with SCH 23390 or haloperidol after each saline administration (the control administration for methamphetamine) did not show significant change in the sensitivity to methamphetamine. These results suggest that methamphetamine has an effect on both dopamine D1 and D2 receptors for several hours even after cessation of its acute stimulant effect, and that such an effect is involved in the induction of sensitization to the stimulant effect of methamphetamine on ambulation in mice.

[Assessment of anxiolytics (1)--Geller-type conflict tests]

The Geller-type conflict test and its modified tests, which are based on operant conditioning, have been applied for preclinical evaluation of the anxiolytic effect of drugs in parallel with the clinical use of benzodiazepines. Here, the author describes the experimental procedures of the Geller-type conflict test, including its modified tests, using mice and rats in detail. The effects of drugs, particularly benzodiazepines and 5-HT1A receptor agonists, on the established conflict behaviors in rats and mice are also presented.