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.     

Ethological analysis of cholecystokinin (CCKA and CCKB) receptor ligands in the elevated plus-maze test of anxiety in mice

Membranes for determination of maltose, lactose and sucrose with the use of an oxygen electrode are described. They were obtained by immobilization of glucose oxidase with suitable disaccharide hydrolase in gelatin or albumin. For the sucrose determination mutarotase was also used. The membranes contained one, two or three enzymes working in sequence. The enzyme composition of the membranes influenced the linear range slightly and the value of electrode response considerably. The electrode response of the maltose membranes was also affected by the immobilization material. The measurements with the use of enzymatic membranes were very sensitive to temperature and, to some degree, the pH of the sample. Stability of the membranes was differentiated. The albumin membranes for sucrose determination generated almost the same signal after 1 month of frequent use, whereas the gelatin membranes for lactose determination lost about 85% of the initial activity after 1 week of operation. The electrode response of both the gelatin and albumin maltose membranes decreased in the same time by about 50%.     

Propylene glycol elicits anxiolytic-like responses to the elevated plus-maze in male mice

Propylene glycol is a common solvent often contained in injectable solutions of anxiolytics of low water-solubility, such as diazepam (Valium) and pentobarbital (Nembutal). Several studies have shown that propylene glycol can have an inhibitory effect on the central nervous system. This study, using ethanol for comparison, further examined whether propylene glycol has anti-anxiety properties. Use of the elevated plus-maze test with male mice revealed that propylene glycol at doses (27 or 41 mmol kg-1, i.p.) which did not affect general activity, increased the number of entries into open arms and of head dips over open arm edges, indicative of an anxiolytic effect. In parallel, ethanol (14 and 27 mmol kg-1, i.p.) caused an increase in the amount of time spent on open arms and number of entries into open arms, accompanied by reduction of returns into closed arms. These doses of ethanol had no significant effect on motor ability. The results suggest that propylene glycol can act as an anxiolytic agent and that its anxiolytic potency is weaker than that of ethanol. In addition to previous warnings about the pharmacological effects of propylene glycol, the findings of this study alert investigators to the anxiolytic properties of the compound when it is employed as a solvent in anxiety or anxiety-related studies.     

Anxiogenic-like effects of spontaneous and naloxone-precipitated opiate withdrawal in the elevated plus-maze

PURPOSE: Endopyelotomy has become the initial treatment of choice for ureteropelvic junction obstruction. Debate persists regarding the preferred approach (percutaneous or ureteroscopic) and the need for preoperative stenting. We review our experience with ureteroscopic endopyelotomy without preoperative stenting. MATERIALS AND METHODS: We treated 21 patients a mean of 37 years old who had ureteropelvic junction obstruction with ureteroscopy and without preoperative stenting. Endoluminal ultrasound was performed in all cases for imaging the periureteral anatomy. A minimum of 1 year of followup is available in all cases. Success was defined as pain-free status with resolution of obstruction on diuretic renal scintigraphy. RESULTS: Success was achieved in 17 of 21 patients (81%). Complications included stent irritation, postoperative urinary tract infection and stent displacement requiring repositioning in 1 case each. Crossing vessels in 57% of the patients affected success (67 versus 100% in those with and without crossing vessels, respectively). No patient had significant hemorrhage. CONCLUSIONS: Ureteroscopic endopyelotomy without preoperative stenting is effective and safe for ureteropelvic junction obstruction.     

Improvement by FUB 181, a novel histamine H3-receptor antagonist, of learning and memory in the elevated plus-maze test in mice

PURPOSE: Initial experimental results of contrast-enhanced pulmonary MR angiography using the new superparamagnetic iron oxide blood pool agent FeO-BPA. METHOD: Pulmonary MRA was performed in 7 domestic pigs using a cardiac-triggered coronal T1-weighted FFE-Sequence before and up to 90 minutes after contrast injection obtained on a 1.5 T magnet with a standard gradient equipment. A dose of 4 mg Fe/kg bodyweight was used for MRA. The images were qualitatively assessed and compared with X-ray i.v.-DSA. RESULTS: The injection of FeO-BPA allows the acquisition of unsaturated in-plane images of the pulmonary vascular tree down to the first order subsegmental branches including vessel diameters of approximately 1.5 mm. In the normal non-occluded vasculature, no signal void is seen in the TE range of 2.8-5.5 ms secondary to exceeding susceptibility effects which are caused by the iron oxide accumulation. Even 90 minutes after injection of FeO-BPA, assessment of the pulmonary vasculature is still satisfactory. CONCLUSIONS: In the animal experiment, the use of the blood pool agent FeO-BPA provides detailed pulmonary angiograms even on a magnet with a conventional gradient system. The major advantage is the comfortable diagnostic window of > 1.5 hours which also portends its utility for future MR-guided pulmonary interventions.     

Anxiogenic effect of phenylethylamine and amphetamine in the elevated plus-maze in mice and its attenuation by ethanol

In previous experiments beta-phenylethylamine (PEA), like the standard anxiogens caffeine, pentylenetetrazole, and yohimbine, has exhibited an anxiogenic effect in the two animal models of anxiety: the social interaction test and the conflict situation test. In the present study, PEA acts as an anxiogen in an elevated plus-maze, diminishing (compared to controls) the ratio of entries into open arms over the total number of entries and shortening the time spent in the open arms. DL-Amphetamine sulfate (AMPH) also had a similar action. These data support the previous suggestion that PEA may belong to the group of endogenous anxiety-inducing compounds. Pretreatment with ethanol prevented the effects of both PEA and AMPH.     

D-cycloserine blocks the effects of ethanol and HA-966 in rats tested in the elevated plus-maze

Previous studies from our laboratory have shown gender-related behavior in rats tested in the elevated plus-maze under the influence of ethanol and other drugs. The present study investigated the effects of pretreatment with the NMDA-receptor partial agonist at the glycine site D-cycloserine (DCS; doses 3 to 9 mg/kg for females; 3 to 12 mg/kg for males, intraperitoneally) on the effects of ethanol (1.2 g/kg, i.p.; 14% w/v) and (+/-)-3-amino-1-hydroxy-2-pyrrolidone (HA-966; 2 or 4 mg/kg, i.p.), an antagonist at the glycine site of the NMDA receptor complex in rats submitted to the elevated plus-maze test. The results showed that DCS, at doses that did not affect the behavior of control animals, significantly (p < 0.05) prevented the increase in the percentage of open-arm entries and the time spent in the open arms of elevated plus-maze test induced by ethanol, exhibiting a U-shaped dose-response curve. Similarly, DCS blocked the anxiolytic effects of HA-966 in animals of both gender. Data confirm our previous results, suggesting that the NMDA-receptor system contributes significantly to the anxiolytic effect of ethanol. Furthermore, the similarity between the blockade by DCS of anxiolysis induced either by ethanol or by HA-966 strengthens the suggestion that ethanol acts on the glycine site of the NMDA receptor complex.     

GABAergic influences on plus-maze behaviour in mice

Manipulations of GABA function have been found to produce highly variable effects in animal models of anxiety. In the present series, an ethological version of the murine elevated plus-maze was used to examine in detail the behavioural profiles of diazepam (1.5 mg/kg; positive control) and a range of GABA-related compounds: valproic acid (100-400 mg/kg), No-711 (1.25-10.0 mg/kg), muscimol (0.5-3.0 mg/kg), (+)bicuculline (4.0-8.0 mg/kg), picrotoxin (0.25-2.0 mg/kg), R(+)baclofen (0.375-3.0 mg/kg) and CGP 35348 (25-200 mg/kg). On both conventional and ethological indices, results confirmed the anxiolytic profile of diazepam under present test conditions, and revealed substantially similar effects for the GABA-T inhibitor, valproic acid (100-400 mg/kg), and the GABAA receptor agonist, muscimol (2 mg/kg). The GABA reuptake inhibitor, No-711, produced weak anxiolytic-like effects at low doses (1.25-2.5 mg/kg) but disrupted behaviour at the highest dose tested (10 mg/ kg). Although the GABAA receptor antagonists, (+)bicuculline and picrotoxin, produced changes indicative of anxiety enhancement, concomitant behavioural suppression was evident at high doses (8 mg/kg and 1-2 mg/kg, respectively). Further studies suggested that the effects observed with bicuculline may be mediated by an active metabolite, such as bicucine. In contrast to the effects of valproic acid and direct GABAA receptor manipulations, the GABAB receptor agonist, R(+) baclofen, non-specifically disrupted behaviour at the highest dose tested (3 mg/kg) while the GABAB receptor antagonist, CGP 35348, was inactive over the dose range studied. Although present data confirm the sensitivity of the plus-maze to agents which modify GABAA receptor function, further studies will be required in order more fully to characterize this relationship.     

Risk assessment behaviour: evaluation of utility in the study of 5-HT-related drugs in the rat elevated plus-maze test

The present study compared the effects of a wide range of 5-hydroxytryptamine (5-HT)-modulating and potential anxiolytic agents in the rat elevated plus-maze using spatiotemporal (i.e., open arm time and entries) and ethologically derived measures (i.e., risk assessment activities and directed exploration). The drugs used were 5-HT1A receptor partial (buspirone and ipsapirone) and full (8-OH-DPAT and flesinoxan) agonists, mixed 5-HT2A/2C receptor antagonists (ritanserin, ketanserin, mianserin, and pirenperone), selective 5-HT3 receptor antagonists (ICS 205-930, MDL 72222, ondansetron, and (RS)-zacopride), and selective (fluoxetine, fluvoxamine, and zimelidine) and nonselective (imipramine) 5-HT reuptake inhibitors. Only buspirone and mianserin produced effects indicative of an anxiolytic-like action on the spatiotemporal measures. However, all 5-HT1A receptor ligands, as well as mianserin, ketanserin, ondansetron, and zacopride, decreased the number of aborted attempts at entry into open arms (risk assessment). In addition, buspirone, mianserin, and zacopride increased head-dipping (directed exploration). Among the 5-HT reuptake inhibitors, zimelidine reduced head-dipping and total entries. The present findings demonstrate that risk assessment responses are sensitive to the action of 5-HT1A receptor ligands, but their modulation by drugs targetting 5-HT2A, 5-HT2C, and 5-HT3 receptors was not convincingly established.     

The pharmacology of local anesthetics

As practitioners of dentistry we are truly fortunate to have these wonder agents which we tend to use like water everyday. It is estimated that over 11,000,000 cartridges of local anesthetics are administered every year in Ontario. The incredible safety record speaks for itself. However, we must caution ourselves that a local anesthetic is a drug and as such demands our ongoing skill, care and judgment for each individual case.     

Illumination has no effect on rats' behavior in the elevated plus-maze

Male Wistar rats Shoe:Wist(Shoe) were tested in the elevated plus-maze under three different illumination levels (30, 300, and 900 lx). It was found that illumination did not change percentage of time spent in closed arms, number of closed arm entries, or time spent on open arms, or total arm entry. This confirms earlier findings that rat's behavior in the elevated plus-maze is independent of light levels.     

Current local anesthetics in segmental nerve blocks

The evolution of central segmental blockades was studied in 133 patients by using epidural and spinal anesthesias. The efficiencies of 2% Ultracaine (Hoechst) and 2% Lidocaine (Egis) solutions used for epidural anesthesia and 5% Ultracaine (Hoechst) and 0.75% Bupivacaine (Astra) hyperbaric solutions were evaluated. Central segmental blockade induced by Ultracaine was found to be similar to Lidocaine and Bupivacaine in clinical parameters. At epidural blockade, the latent period was identical for the two agents and the duration of analgesia caused by Ultracaine was 20 minutes longer than that with Lidocaine, the consumption of the former being 20% less. At spinal anesthesia, there were no great differences in the depth and duration of conduction block, but with 5% Ultracaine, the analgesic zone was large (13.2 +/- 1.0 and 15.1 +/- 0.6 segments, p < 0.05). No differences were found in the magnitude of hemodynamic changes both with various anesthetics and different types of segmental blockades. The findings make it possible to regard Ultracaine as an drug that has some advantage over Lidocaine for prolonged epidural anesthesia and similar to the latter in pharmacological characteristics. Ultracaine may be regarded as alternative to Bupivacaine for spinal anesthesia.     

Induction of Fos immunoreactivity in the brain by exposure to the elevated plus-maze

The log-rank test is commonly used to assess therapeutic effect in prospective, randomised clinical trials. This test is sensitive to differences in survival between treatment groups at a specific endpoint, but cannot determine whether such a difference is due to an enhanced cure rate or an enhanced survival time among uncured patients. To investigate the clinical impact of such limitations, an algorithm was constructed to simulate clinical, randomised, adjuvant therapy trials in patients with a cured fraction of 0.27 and a median survival time for uncured patients of 3.4 years. Hypothetical therapies were introduced to increase rate of cure, increase median survival time, or achieve a combination of these effects. For 500 simulated patients recruited over a 5 year period and then followed for three additional years, a 50% enhancement of median survival time (to 5.1 years) led to a survival increase detectable at the P = 0.05 level in 780 of 1000 trials, whereas a 50% enhancement of cured fraction (to 40.5%) led to a detectable increase at the same level in only 449 of 1000 trials. These findings suggest that, in clinical trials of adjuvant therapy for stage 2 breast cancer, the log rank test may be more sensitive to increases in tumour-related survival time than to increases in cured fraction.     

Ethopharmacological analysis of behaviour of rats using variations of the elevated plus-maze

Besides allowing better observation and recording of the behaviour of rodents, we have shown that the elevated plus-maze with transparent walls is as sensitive to anxiolytic and anxiogenic drug effects as a traditional apparatus with opaque walls. In this study we extend these observations with an ethopharmacological analysis of the behaviour of rats in the elevated plus-maze with transparent walls. A factor analysis of the behaviour of control (saline-treated) rats on the modified maze and on a standard maze revealed a characteristic distribution of the behavioural categories in six factors. For the modified maze, the first three factors, representing standard indices of anxiety, locomotion and risk assessment, were similar to the factor distribution reported by this and other studies using the standard elevated plus-maze test. Distinct features appeared on Factor 4, with the loading of rears in the modified maze together with the occurrence of the percentage of centre time and flat-back approach common to both mazes. Scanning and grooming, which are generally grouped on Factor 5 in the standard maze, appeared as isolated behavioural elements loading on Factors 5 and 6, respectively, in the modified maze. An ethopharmacological analysis of behaviour in the modified maze showed that midazolam (1 and 2 mg/kg) produced an anxioselective profile, whereas pentylenetetrazol (5 and 10 mg/kg) produced an anxiogenic-like profile. These results point to the distinct features of the elevated plus-maze with transparent walls, which may be beneficial in the study of the different facets of anxiety and the mode of action of anxiolytic drugs in rats.     

Combination of open field and elevated plus-maze: a suitable test battery to assess strain as well as treatment differences in rat behavior

1. A test battery consisting of a standard open field, an enriched open field and an elevated plus maze was used to study behavior in rats. 2. Male rats of the strains PVG/OlaHsd (PVG) and Sprague-Dawley-Hsd (SPRD) (150-200 g body wt) were used to assess interstrain differences as well as handling effects. In a subsequent experiment an other set of male PVG rats (150-200 g body wt) treated either with diazepam or zolpidem was used to evaluate the test battery for pharmacological purposes. 3. SPRD rats displayed higher motor activity levels and also higher levels of exploratory behavior than the PVG rats. In contrast plus-maze activity indicated more anxiety of SPRD than PVG rats. One week pre-test handling increased the activity of both strains but it increased explorative behavior in the enriched open field only in SPRD rats. Diazepam had a substantial anxiolytic effect. Zolpidem enhanced the explorative activity in a differently to diazepam and exerted only minor anxiolytic properties. 4. We concluded that the test battery used here enables to reveal differentially strain, and treatment effects in rats.     

Response of human uterine arteries to local anesthetics

The in vitro effects of local anesthetics and norepinephrine upon strips of early gestation and term pregnancy uterine arteries were studied in eight cases. In another case, the effect upon uterine veins was studied with a standard organ bath used to record isometric contractions. Histologic preparations were made to verify the type of vessel studied. An artery obtained from an eight-week gestation did not respond to either lidocaine or mepivacaine. All other arterial specimens (radial and helicoidal strips) responded with slow, rising, strong contractions to diluted concentrations of both of these substances. Likewise they responded with rapid contractions when exposed to norepinephrine. Alpha blockers were unable to prevent the contractions triggered by the local anesthetics. The vein specimens did not respond to local anesthetics but contracted when stimulated by norepinephrine. Based on these observations and after brief review of some hypotheses advanced to explain post-paracervical anesthesia fetal bradycardia, it is postulated that this bradycardia is probably due to uterine artery spasm, causing decreased intervillous space blood flow and fetal hypoxia.     

5-HT1A and benzodiazepine receptors in the basolateral amygdala modulate anxiety in the social interaction test, but not in the elevated plus-maze

In order to investigate the role of the 5-HT1A receptors of the amygdala in modulating anxiety, rats were implanted with bilateral cannulae aimed at the basolateral nucleus of the amygdala complex and infused with either artificial cerebrospinal fluid (aCSF) or the selective 5-HT1A receptor agonist 8-OH-DPAT (50-200 ng) and tested in two animal models of anxiety. In the elevated plus-maze test, no significant effects were detected in this dose range. In contrast, 8-OH-DPAT caused an overall reduction in levels of social investigation, thus indicating anxiogenic actions in the social interaction test. At 50 ng, 8-OH-DPAT had a selective action on anxiety, while at 200 ng there was a concomitant reduction in locomotor activity and, in some animals, signs of the 5-HT1A syndrome. Evidence that the anxiogenic effect of 8-OH-DPAT (50 ng) was due to activation of 5-HT1A receptors came from the finding that (-)-tertatolol, a 5-HT1A receptor antagonist, reversed this effect at a dose (1.5 micrograms) which was silent when given alone. The benzodiazepine receptor agonist, midazolam (1 and 2 micrograms) was bilaterally administered into the basolateral nucleus of the amygdala and evoked clear-cut anxiolytic effects in the social interaction test. These data indicate that the agonist activation of post-synaptic 5-HT1A receptors in the basolateral nucleus of the amygdala may produce anxiogenic effects, while agonist activation of BDZ receptors in the same areas evokes anxiolytic effects. Our results from the social interaction test are similar to those previously reported from tests of anxiety using punished paradigms, but contrast with those found in the elevated plus-maze. Thus, it is concluded that either the two tests have different sensitivities to midazolam and 8-OH-DPAT or more intriguingly, the tests are evoking fundamentally different states of anxiety, with that evoked by the plus-maze being mediated via brain areas or receptors different from those studied here.     

Biological dyes may improve the safety of local anesthetics

One of our patients was a 66-year-old woman with a T2 renal cell carcinoma weighing 3900 g. Two years after radical nephrectomy the woman was alive and well. A survey of Japanese medical literature revealed that patients with renal cell carcinomas weighing more than 2000 g have an unexpectedly favorable prognosis with a 5-year survival rate of 76.9%.