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PubMed2006

Paradoxical facilitation of object recognition memory after infusion of scopolamine into perirhinal cortex: implications for cholinergic system function.

The cholinergic system has long been implicated in learning and memory, yet its specific function remains unclear. In the present study, we investigated the role of cortical acetylcholine in a rodent model of declarative memory by infusing the cholinergic muscarinic receptor antagonist scopolamine into the rat perirhinal cortex during different stages (encoding, storage/consolidation, and retrieval) of the spontaneous object recognition task. Presample infusions of scopolamine significantly impaired object recognition compared with performance of the same group of rats on saline trials; this result is consistent with previous reports supporting a role for perirhinal acetylcholine in object information acquisition. Scopolamine infusions directly before the retrieval stage had no discernible effect on object recognition. However, postsample infusions of scopolamine with sample-to-infusion delays of up to 20 h significantly facilitated performance relative to postsample saline infusion trials. Additional analysis suggested that the infusion episode could cause retroactive or proactive interference with the sample object trace and that scopolamine blocked the acquisition of this interfering information, thereby facilitating recognition memory. This is, to our knowledge, the first example of improved recognition memory after administration of scopolamine. The overall pattern of results is inconsistent with a direct role for cortical acetylcholine in declarative memory consolidation or retrieval. Rather, the cholinergic input to the perirhinal cortex may facilitate acquisition by enhancing the cortical processing of incoming stimulus information.

Acetylcholine↗
PubMed2005

Pharmacokinetics of scopolamine in serum and subcutaneous adipose tissue in healthy volunteers.

OBJECTIVE: The objective was to develop a microdialysis set-up to measure the concentration-time course of scopolamine in the interstitium of subcutaneous adipose tissue. MATERIALS AND METHODS: Six healthy male volunteers were eligible for data analysis. Subjects received 0.5 mg scopolamine as a 15-minute intravenous infusion. Microdialysis samples from interstitial space fluid of subcutaneous adipose tissue and blood samples were taken at predefined intervals over a period of 360 minutes. Scopolamine concentrations were measured by liquid chromatography-tandem mass spectrometry (LC-MS-MS). RESULTS: High inter-individual variability was observed in all pharmacokinetic parameters. The mean peak serum concentration (C(max)) of 6.5 +/- 3.9 ng/ml (data in mean +/- SD) was attained after 15 +/- 3 minutes (t(max)), whereas in dialysate, a mean peak concentration of 2.7 +/- 1.7 ng/ml was measured after 27 +/- 8 minutes. The ratio of the area under the concentration versus time curve from 0-360 min for interstitium (AUC(interstitium 0-360 min0) to the AUC for serum (AUC(serum 0-360 min)) was 0.96 +/- 0.7. The elimination half-life of scopolamine was 121 +/- 85 minutes in serum and 166 +/- 117 minutes in dialysate. Values for total clearance and volume of distribution in serum were 99.1 +/- 35.0 1/h and 188 +/- 76 1, respectively. CONCLUSIONS: In the present study, we were able to define a microdialysis set-up, which allows for the measurement of scopolamine concentrations in target tissues. In addition, we demonstrated that the concentrations of scopolamine in subcutaneous adipose tissue resemble closely the concentration-time course in serum of healthy volunteers.

Adipose Tissue↗
PubMed2001

Scopolamine: new preparations. Reference treatment for death rattle.

(1) The reference symptomatic drug treatment of death rattle is the use of atropinic agents such as scopolamine or atropine. (2) Marketing authorisation has now been granted in France for scopolamine in this indication, both for a subcutaneous preparation and a transdermal patch. (3) The clinical file on subcutaneous scopolamine delivery mainly comprises non comparative data on 200 patients studied prospectively and 196 patients studied retrospectively. (4) The assessment of transdermal scopolamine patches is limited to a few published cases. (5) Available data show the efficacy of scopolamine, when administered after aspiration of the back of the throat. (6) The main adverse effects are neuropsychological (excitation, hallucinations, delirium). (7) In practice, injectable scopolamine is the reference drug for symptomatic treatment of death rattle.

Administration, Cutaneous↗
PubMed2002

[mRNA expressions of voltage-dependent potassium channels in the brain of scopolamine-induced memory impaired rats].

AIM: To study mRNA expression difference of voltage-dependent potassium channels in the brain of scopolamine-induced memory impaired rats. METHODS: Memory impairments induced in rats by scopolamine (1 mg.kg-1) were assessed in the Morris water maze test. After rats were injected intraperitoneally with scopolamine for 6 days, the mRNA expression level of five voltage-dependent potassium channels, Kv1.4, Kv1.5, Kv2.1, Kv4.2 and Kv4.3 were detected in the rat cortex and hippocampus by RT-PCR. RESULTS: Scopolamine (1 mg.kg-1) was shown to significantly induce memory impairment in rats. The mRNA levels of Kv4.2 were decreased by 28.8% and 33.9% in the cortex and hippocampus, respectively. The mRNA levels of Kv1.4 and Kv2.1 were increased in the hippocampus by 111.7% and 64.3%, respectively. There were no differences in the brain mRNA levels of other voltage-dependent potassium channels in scopolamine-induced memory impaired rat. CONCLUSION: The mRNA expression levels of voltage-dependent potassium channels changed significantly in the brain of scopolamine-induced memory impaired rats.

Adjuvants, Anesthesia↗
PubMed1991

Scopolamine blood levels following buccal versus ingested tablets.

Speed of absorption and elimination of an antimotion sickness drug sets limits on the protection afforded. The aim of this experiment was to determine whether a well proven antimotion sickness drug--scopolamine (hyoscine)--could be absorbed more rapidly from buccal tablets than from the standard issue ingested tablets. Plasma scopolamine levels were measured using a radioreceptor assay of repeated blood samples from 10 volunteers, each of whom took buccal and standard ingested tablets (both 0.6 mg scopolamine hydrobromide) on two different occasions, and from a further 8 volunteers following ingestion of a pharmacy-prepared scopolamine capsule (0.6 mg scopolamine hydrobromide). There was no statistically significant speed advantage for the buccal tablet (mean time to peak levels approx 50 min). Individual variation in the speed of scopolamine absorption and rate of elimination (mean half-life approx 170 min) was great. This may account for failure of motion sickness protection in some individuals.

Administration, Buccal↗
PubMed1989

[The history of scopolamine--with special reference to its use in anesthesia].

Potions from plants, now known to contain scopolamine, were used in antiquity and the middle ages. However, wide-spread application of drugs for induction of insensibility to pain did not occur, probably because of side-effects and unpredictable dose-effect relationships. The word "scopolamine" is derived from "Scopolia carniolica", a solanaceous plant so named by Carl von Linné in honour of supposed discoverer, J. A. Scopoli. However, description of the effects and picture of the same plant have been found in A. P. Matthioli's work. Scopolamine is still widely used in anaesthetic practice and has enjoyed applicability in other medical fields. Unethical misuse of scopolamine has been known for a considerable time. Nowadays, the unwanted effects of scopolamine can specifically be antagonized by physostigmine. Scopolamine has been used in folk-lore rituals and enjoys great interest among ethno-pharmacologists.

Anesthesiology↗
PubMed1988

Comparative studies on the effects of the nootropic drugs adafenoxate, meclofenoxate and piracetam, and of citicholine on scopolamine-impaired memory, exploratory behavior and physical capabilities (experiments on rats and mice).

The effects of adafenoxate (Adf), meclofenoxate (Mf), piracetam (Pc), and citicholine (CCh) on scopolamine (Scop)--impaired memory and exploratory behavior (experiments on rats) and on physical capabilities (experiments on mice) were studied. In the experiments with scopolamine (2 mg/kg i.p.) we used the step-through passive avoidance method to determine the memory changes. In the case of single treatment with the drugs tested scopolamine was injected immediately after training and Adf, Mf, and CCh at doses of 20 and 100 mg/kg and Pc at a dose of 100 mg/kg were administered immediately after scopolamine. In the case of multiple administration the drugs were applied at the same doses for 7 days before training. Scopolamine was injected immediately after training. Retention tests were given 3 and 24 hours later. All the four drugs tested prevented to a large extent or completely the scopolamine-induced retrograde amnesia. However, significant quantitative differences in the antiamnestic effects of the drugs tested were observed. The effects of the four drugs on exploratory behavior were tested in the Opto Varimex apparatus. After 7-day treatment with the drugs at the doses utilized, the behavior of experimental animals was observed for 10 min, checking out the changes in the frequency of rearing, ambulation, and rotation. Only Adf at a dose of 50 mg/kg significantly decreased rearing and ambulation frequencies; this effect was considered to be an expression of accelerated habituation. The physical capabilities of mice were studied, using the method of treadmill (revolving drum activity cage) training. Before the experiment the mice received orally Adf, Mf, and Pc at a dose of 100 mg/kg or were injected intraperitoneally with CCh at doses of 50 and 100 mg/kg once daily for 7 days. The number of revolutions of the drum cages was counted for 4 hours. Only Pc significantly increased the physical capabilities of mice and much delayed the occurrence of fatigue.

Animals↗
PubMed1979

Effect of transdermally administered scopolamine in preventing motion sickness.

The efficacy of transdermally administered scopolamine was compared with the efficacy of oral dimenhydrinate and placebo therapy in the prevention of motion-induced mausea in a vertical oscillator; medications were administered on a double-blind cross-over basis, with the order of treatments counterbalanced. Thirty-five subjects known to be susceptible to the stimulus were utilized. A placebo effect reduced the motion sickness incidence (MSI) from 100% to 59%. Administration of dimenhydrinate reduced the MSI to 32%, and use of the transdermal therapeutic system scopolamine (TTS-scopolamine) further reduced the MSI TO 16%. TTS-scopolamine afforded 73% protection against motion-induced nausea, compared to 46% protection with dimenhydrinate. The TTS-scopolamine is designed to remain in the body for 72 hours, providing advantages over intramuscular or oral administration of scopolamine, which include reduced daily dosage, and an effective alternate to the gastrointestinal tract for administrating medication at times of gastrointestinal distress.

Administration, Topical↗
PubMed1983

Transdermal scopolamine in the prevention of motion sickness: evaluation of the time course of efficacy.

This study evaluated the time course of efficacy of transdermal scopolamine in the prevention of motion sickness induced by exposure to coriolis stimulation in a rotating chair. We measured levels of efficacy, quantified side effects and symptoms, and determined inter- and intra-subject variability following use of transdermal scopolamine. The response to transdermal scopolamine was highly variable, although overall we recorded a 40% improvement (p less than 0.05) in test scores 16-72 h after application of the transdermal system. This variability could not be explained solely by the levels of scopolamine present in the blood. The improvement was not due to the artifactual repression by scopolamine of selected symptoms of motion sickness. An unexpectedly high incidence of side effects was reported. It was concluded that the therapeutic use of transdermal scopolamine be evaluated individually and that individuals be cautioned that subsequent usage may not always be effective.

Administration, Topical↗
PubMed1984

Muscimol-scopolamine interactions in the rat brain: a study with 2-deoxy-D-[1-14C]glucose.

The 2-deoxy-D[1-14C]glucose method of Sokoloff was used to measure local cerebral glucose utilization (LCGU) in rats after injections of the GABA receptor agonist, muscimol (1.6 mg/kg and 4.0 mg/kg, i.v.); the muscarinic receptor antagonist, scopolamine (0.4 mg/kg and 2.0 mg/kg, i.v.); or combinations of both drugs. The aim was to identify brain regions where functional effects of GABAergic-cholinergic interactions could be seen. As noted previously, muscimol reduced LCGU in many brain regions. In contrast, scopolamine alone had no effect on LCGU in most brain regions; however, decreases were seen in the medial geniculate body, medial thalamic nucleus, and auditory and frontal cortical areas. Scopolamine increased LCGU in the cerebellar vermis and mesencephalic reticular formation. Although muscimol alone did not significantly affect LCGU in the external plexiform layer of the olfactory bulb or the anterior, periventricular, and parafascicular thalamic nuclei, rats treated with 0.4 mg/kg of scopolamine before 4.0 mg/kg of muscimol had LCGU decrements in those brain regions. Furthermore, the muscimol-induced decrease in LCGU in the medial cortex was enhanced by prior treatment with 0.4 mg/kg of scopolamine. In contrast, in certain brain regions where muscimol alone reduced LCGU (locus ceruleus; central gray matter; striatum; ventral, medial, reunients , and rhomboid thalamic nuclei; and the auditory cortex), scopolamine pretreatment antagonized these decrements. These findings suggest that endogenous cholinergic and GABAergic systems act antagonistically in some brain regions. However, in other brain regions, cholinergic transmission is required for full expression of GABAmimetic effects on LCGU.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

Scopolamine-induced hypermotility in rats is mediated via a dopaminergic system.

To clarify the relation between cholinergic and dopaminergic transmission systems involved in locomotor effects the influence of dopaminergic drugs on scopolamine hypermotility was investigated. Scopolamine and apomorphine in locomotor stimulant doses showed additive effects. Apomorphine in a dose acting on presynaptic dopaminergic receptors decreased the scopolamine hypermotility markedly. Haloperidol antagonized both scopolamine and apomorphine hypermotility in an apparently competitive way. Sulpiride potentiated scopolamine locomotor effect. Additionally, it was shown that LSD potentiated scopolamine hypermotility as well as apomorphine hypermotility. The results suggest in connection with literature data that locomotor effects of drugs affecting cholinergic transmission may by mediated by a dopaminergic system.

Animals↗
PubMed1996

[Clinical study of scopolamine detoxification for the treatment of heroin addicts].

OBJECTIVE: To evaluate the efficacy of treatment of heroin addicts (n = 100) by scopolamine detoxification (10 days program). METHODS: Methadone detoxification (10 days program) group (n = 50) and clonidine treated group (n = 50) served as controls. RESULTS: The scores of abstinence syndrome in scopolamine detoxification group were lower that those in clonidine treated group in the first three days of protocol, but this difference disappeared in the late stage of treatment. While scopolamine detoxification was effective as methadone detoxification in the control of abstinence syndrome during the first five days of treatment but the difference in the scores of abstinence syndrome between scopolamine and methadone group was observed during the late five days of protocol. The side-effects produced by scopolamine in general were dry mouth, somnolence, tachycardia, blurred vision and so on, which relieved gradually or disappeared with decreasing of its doses. CONCLUSION: Scopolamine does not result in potential dependence and has definite curative effect in the treatment of heroin addiction.

Adult↗
PubMedDate not supplied

Pramiracetam effects on scopolamine-induced amnesia in healthy volunteers.

Pramiracetam has been evaluated for its potential antiamnesic properties in scopolamine-induced amnesia in healthy volunteers. Two groups of twelve males, 18-42 and 55-65 years old, respectively, were randomly assigned to oral treatment with pramiracetam (600 mg twice a day) or with placebo for 10 consecutive days. On day 11 each subject was injected intramuscularly with scopolamine hydrobromide (0.5 mg). Before scopolamine injection and then 1, 3 and 6 h after it, subjects were administered the following psychometric tests: simple and choice visual reaction times, digit symbol substitution test, Rey's 15 words test for short and long term verbal memory. Scopolamine significantly impaired episodic memory and selective attention tests in both scopolamine and placebo groups. Instead visuo-motor and incidental learning measures were unaffected. Pramiracetam, when compared to placebo, was able to partially reduce the amnesic effects induced by scopolamine both in young and old subjects.

Clinical Trial↗
PubMed2000

Role of the laterodorsal tegmental nucleus in scopolamine- and amphetamine-induced locomotion and stereotypy.

Scopolamine (1.5 mg/kg; i.p.) or amphetamine (3 mg/kg; i.p.) increases locomotion and stereotyped behavior patterns in rats. Previous studies suggest that scopolamine acts via muscarinic receptors near the midbrain-pons border. In this study, unilateral microinjections in N-methyl-scopolamine (2.5-10 microg) into the laterodorsal tegmental nucleus (LDT) increased locomotion. Bilateral ibotenate lesions of the LDT attenuated scopolamine-induced locomotion by 68% 7 days postlesion, and by 35% 28 days postlesion. LDT lesions reduced scopolamine-induced stereotypy less than locomotion. The sensitization to amphetamine observed on repeated tests was attenuated by LDT lesions for stereotypy, but not for locomotion. These findings suggest that scopolamine induces locomotion largely, but not exclusively, by blocking muscarinic receptors in LDT.

Amphetamine↗
PubMed2000

A peripheral mechanism of fever: differential sensitivity to the antipyretic action of methyl scopolamine.

The organophosphate pesticide (OP) chlorpyrifos leads to an acute period of hypothermia followed by a delayed fever in the rat. Methyl scopolamine, a peripheral muscarinic antagonist, is thought to have little effect on body temperature of the rat because it does not cross the blood brain barrier. However, administration of methyl scopolamine (1 mg/kg, i.p.) during the period of chlorpyrifos-induced fever results in a rapid recovery of core temperature. This indicates a peripheral cholinergic pathway is operative in the febrile response to chlorpyrifos and possibly other modes of fever. In this study, we evaluated the possible antipyretic role of methyl scopolamine (i.p.) to a variety of stimuli that lead to fever-like responses in the rat: stress-induced (handling and cage switch), chlorpyrifos-induced (15 mg/kg, p.o.), nocturnal-induced, and lipopolysaccharide (LPS)-induced fever (50 microg/kg, i.p.). Methyl scopolamine led to marked reversal in the elevated core temperature caused by handling, cage switch, and during the nocturnal phase. It is of interest to note that all these elevations of core body temperature are prostaglandin mediated and are blocked with the antipyretic drug, sodium salicylate. However, LPS-induced fever, also a prostaglandin dependent fever, was unaffected by methyl scopolamine. Methyl scopolamine also lowered baseline core temperature when administered during the afternoon, but not during the morning in unstressed animals. It is proposed that a peripheral cholinergic pathway, possibly mediated through afferent vagal pathways, is operative in controlling core temperature during fevers associated with stress, nocturnal phase, and a pesticide. During recovery from exposure to a LPS, the fever appears to be mediated independently of peripheral cholinergic activation.

Animals↗
PubMed1987

Epoxidation in vivo of hyoscyamine to scopolamine does not involve a dehydration step.

Hyoscyamine is epoxidized to scopolamine via 6beta-hydroxyhyoscyamine in several solanaceous plants. 6,7-Dehydrohyoscyamine has been proposed to be an intermediate in the conversion of 6beta-hydroxyhyoscyamine to scopolamine on the basis of the observation that this unsaturated alkaloid is converted to scopolamine when fed to a Datura scion. To determine whether a dehydration step is involved in scopolamine biosynthesis, [6-(18)O]6beta-hydroxyhyoscyamine was prepared from l-hyoscyamine and (18)O(2) using hyoscyamine 6beta-hydroxylase obtained from root cultures of Hyoscyamus niger L. When [6-(18)O]6beta-hydroxyhyoscyamine was fed to shoot cultures of Duboisia myoporoides R. B(R)., the labeled alkaloid was converted to scopolamine which retained (18)O in the epoxide oxygen. It is concluded that 6beta-hydroxyhyoscyamine is converted in vivo to scopolamine without a dehydration step.

Journal Article↗
PubMed1990

Modelling working and reference memory in rats: effects of scopolamine on delayed matching-to-position(1,2).

A model of working and reference memory in rats is described, based on a discrete-trial operant procedure with concurrent components of spatial matching (for working memory) and nonspatial discrimination (for reference memory). On each trial in the matching component, rats received food for pressing one of two retractable levers after a delay if that lever had been presented in the prior sample phase of the trial. On each trial in the discrimination component, food was delivered if the rat pressed a lever illuminated by a cue light after the delay interval. The model was tested with scopolamine (0.10 to 0.56 mg/kg, ip), which reduced matching accuracy in a dose-related manner. Linear slope and intercept estimates of retention gradients showed that intercepts declined and slopes remained unchanged with increasing scopolamine dose. In contrast, scopolamine had no significant effect on nonspatial discrimination accuracy, indicating a relative insensitivity of reference memory to cholinergic blockade. Because the matching component involved spatial cues and the discrimination component did not, a second group of rats was trained to discriminate between the spatial locations of two levers, to compare the effects of scopolamine on spatial and nonspatial discriminations. Scopolamine at the same doses caused a small, consistent decrease in spatial discrimination accuracy, suggesting that spatial discrimination was more sensitive to disruption by scopolamine than was nonspatial discrimination. The combined delayed matching-to-position/nonspatial discrimination procedure appears to provide a useful technique for characterizing mnemonic effects of drugs and toxicants in rats.

Journal Article↗
PubMed1994

[Comparison of pharmacological effects of L- and DL-n-butyl-scopolamine in rat uterus].

The affinities of L-n-butyl-scopolamine, DL-n-butyl-scopolamine and atropine for the M-cholinergic receptors of rat uterus were compared using radioligand binding assay. Results showed that the affinity of L-n-butyl-scopolamine for the M-receptors was similar to that of DL-n-butyl-scopolamine, but lower than that of atropine. In isolated rat uterus, L- and DL-n-butyl-scopolamine were found not to influence the automatic contraction but antagonize the contraction induced by acetylcholine with nearly the same PA2, although the PA2 of both compounds were still lower than that of atropine. Therefore, no difference between L- and DL-n-butyl-scopolamine in either biological activity or receptor affinity was observed.

Acetylcholine↗