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Effect of Hachimi-jio-gan on scopolamine-induced memory impairment and on acetylcholine content in rat brain.

The effect of Hachimi-jio-gan (HJ) on scopolamine induced memory impairment was studied using a radial maze performance, the effect of HJ on the central cholinergic system as measured by acetylcholine (ACh) content, choline acetyltransferase (CAT) and acetylcholinesterase (AChE) activities was also examined. HJ (0.01-1.0 g/kg, p.o.) showed no influence on the radial maze performance. However, with the administration of scopolamine (0.5 mg/kg, i.p.), the number of the correct choices decreased and the number of the error choices increased. HJ (0.1 and 0.5 g/kg, p.o.) reduced this scopolamine-induced cognitive disturbance. The effect of HJ on ACh content and enzyme activities in the brain, frontal cortex, hippocampus and striatum was also investigated. In normal rats, HJ (0.1 and 0.5 g/kg, p.o. x 7 days) significantly increased ACh content in the frontal cortex, although it did not increased ACh content in the hippocampus. In scopolamine-treated rats, ACh content decreased in the brain regions examined. HJ (0.5 g/kg, p.o.) inhibited a decrease in ACh content in the frontal cortex, and with the same dosage of HJ increased CAT activity in the frontal cortex and AChE activity in the hippocampus. These results suggest that the behavioral effects of HJ may be related to its effect on the central cholinergic system.

Acetylcholine↗

Transdermal scopolamine use in the control of narcotic-induced nausea.

Nausea affects from 40% to 70% of cancer patients who received narcotics to manage their pain. This occurs more frequently when they are ambulatory than when they are recumbent and may be the result of narcotic-enhanced labyrinthine sensitivity to motion. Scopolamine has previously been found to be an effective antiemetic for motion sickness. In a prospective pilot study, 9 (69%) of 13 cancer patients experienced rapid relief of their narcotic-induced nausea when they used Scopolamine Transderm-V patches alone. Only two patients experienced side effects with the scopolamine, and in one patient, the side effects may have been dose related. Although tolerance to the increased vestibular sensitivity may occur, this was not universal. Further prospective trials are necessary to establish whether transdermal scopolamine is useful in controlling the narcotic-induced nausea experienced by cancer patients.

Administration, Cutaneous↗

Epidural scopolamine administration in preventing nausea after epidural morphine.

STUDY OBJECTIVE: To determine the effectiveness of epidural scopolamine in preventing nausea and vomiting in patients receiving epidural morphine. DESIGN: Randomized, double-blind study. SETTING: Inpatient surgery clinic at a regional general hospital. PATIENTS: 50 patients undergoing major abdominal and lower limb surgery. INTERVENTIONS: Morphine alone 2.5 to 4 mg was administered via epidural catheter to one group, while the other group received morphine plus scopolamine 0.25 mg via epidural catheter. MEASUREMENTS AND MAIN RESULTS: Occurrence of nausea and vomiting was recorded during the first postoperative day. Compared with the morphine alone group, the incidence of nausea and vomiting was significantly lower in the morphine plus scopolamine group without difference in the adequacy of analgesia. CONCLUSION: Epidural scopolamine can be used as an adjunct to epidural morphine in effectively reducing the incidence of postoperative nausea and vomiting.

Adolescent↗

Room novelty, sex, scopolamine and their interactions as determinants of general activity and rearing, and light-dark preferences in rats.

Male and female rats were assessed for effects of scopolamine on general activity, rearing and light-dark preferences when tested in either a familiar or a novel room. Males but not females reared more often when tested in the familiar rather than novel room, and the response was increased by scopolamine for all rats combined. Whereas scopolamine increased general activity for females (but not males) in the familiar room, it decreased the response for males (but not females) in the novel room. Females crossed more often between the dark and light sides of a light-dark box and, when treated with saline but not drug, spent more time in the light side than males. Scopolamine reduced the amount of time spent in the light side for females only. While the results were discussed mainly in terms of sex differences in fearfulness, their principal value was in demonstrating the effectiveness of room novelty and sex in determining levels of the behaviors recorded, and drug responsiveness.

Animals↗

Heat-shock pretreatment prevents suppression of long-term potentiation induced by scopolamine in rat hippocampal CA1 synapses.

We examined the effect of heat-shock pretreatment on long-term potentiation (LTP) in the CA1 hippocampal slices of the rat using the muscarinic blocker scopolamine as the LTP (memory) suppressor. Time course study using immunohistochemical techniques indicated peak expression of HSP70 16 h after heat-shock treatment. Focusing on that time point we found tetanic stimulation (at 100 Hz) induced LTP of 191.1+/-12.2% in control slices (n=7), which was suppressed by scopolamine to 114.5+/-2.8 %. Heat-shock pretreatment successfully prevented such suppression (216.6+/-38.2% and 190.2+/-10.6% with and without scopolamine, respectively, n=7). Both HSP expression and LTP responses were relatively small taken either 2 or 48 h after heat-shock or sham pretreatment. These results suggest that the induction of HSPs is time-dependent and can prevent scopolamine-mediated LTP suppression.

Animals↗

Hebb-Williams performance and scopolamine challenge in rats with partial immunotoxic hippocampal cholinergic deafferentation.

Recent studies suggested that the cholinergic innervation of the hippocampus is not crucial for spatial learning, but it might be important for other forms of learning. This study assessed the effects of partial immunotoxic cholinergic lesions in the medial septum and concurrent scopolamine challenge in a complex learning task, the Hebb-Williams maze. Long-Evans rats were given intraseptal injections of 192 IgG-saporin (SAPO). Rats injected with phosphate-buffered saline (PBS) served as controls. Starting 25 days after surgery, behavioural performance was assessed in the Hebb-Williams maze test without prior or after injection of scopolamine (0.17 or 0.5 mg/kg, i.p.). In SAPO rats, histochemical analysis showed a 40-45% decrease in the density of hippocampal AChE staining. The number of ChAT-positive cell bodies in the medial septum was also significantly decreased (-56%) and there was a non-significant reduction of the number of parvalbumine-positive neurons. The behavioural results demonstrated that the lesions induced small but significant learning deficits. At 0.17 mg/kg, scopolamine produced more impairments in SAPO rats than in PBS-injected rats, suggesting an additive effect between the partial lesion and the drug. These observations indicate that the Hebb-Williams test may be more sensitive to alterations of septohippocampal cholinergic function, than radial- or water-maze tasks. They also show that subtle learning deficits can be detected after partial lesions of the cholinergic septohippocampal pathways. Finally, the data from the scopolamine challenge are in keeping with clinical results showing higher sensitivity to muscarinic blockade in aged subjects in whom weaker cholinergic functions can be presumed.

Acetylcholine↗

Biotransformation of hyoscyamine into scopolamine in transgenic tobacco cell cultures.

Hyoscyamine-6beta-hydroxylase (H6H) catalyses the conversion of hyoscyamine into its epoxide scopolamine, a compound with a higher added value in the pharmaceutical market than hyoscyamine. We report the establishment of tobacco cell cultures carrying the Hyoscyamus muticus h6h gene under the control of the promoter CAMV 35S. The cell cultures were derived from hairy roots obtained via genetically modified Agrobacterium rhizogenes carrying the pRi and pLAL21 plasmids. The cultures were fed with hyoscyamine, and 4 weeks later the amount of scopolamine produced was quantified by HPLC. The transgenic cell suspension cultures showed a considerable capacity for the bioconversion of hyoscyamine into scopolamine, and released it to the culture medium. Although the scale-up from shake-flask to bioreactor culture usually results in reduced productivities, our transgenic cells grown in a 5-L turbine stirred tank reactor in a batch mode significantly increased the scopolamine accumulation.

Atropine↗

Scopolamine-induced convulsions in fasted mice after food intake: effects of glucose intake, antimuscarinic activity and anticonvulsant drugs.

The present study was performed to further evaluate the contribution of antimuscarinic activity and hypoglycaemia to the development of scopolamine-induced convulsions in fasted mice after food intake. The effects of anticonvulsant drugs on convulsions were also evaluated. Antimuscarinic drugs atropine (3 mg/kg) and biperiden (10 mg/kg) were given intraperitoneally (i.p) to animals fasted for 48 h. Like scopolamine, both drugs induced convulsions after animals were allowed to eat ad libitum. Another group of animals was given glucose (5%) in drinking water during fasting. These animals, although they had normoglycaemic blood levels after fasting, also developed convulsions after treated with scopolamine i.p. (3 mg/kg), atropine (3 mg/kg) or biperiden (10 mg/kg) and allowed to eat ad libitum. Among the drugs studied, only valproate (340 mg/kg), gabapentin (50 mg/kg) and diazepam (2.5 and 5 mg/kg) markedly reduced the incidence of scopolamine-induced convulsions. The present results indicate that antimuscarinic activity, but not hypoglycaemia, underlies these convulsions which do not respond to most of the conventional anticonvulsant drugs.

Animals↗

Ethological analysis of scopolamine treatment or pretreatment in morphine dependent rats.

Although scopolamine is currently used to treat morphine addiction in humans, its extensive actions on behaviors have not been systematically analyzed yet, and the underlying mechanisms of its effects still remain ambiguous. The present study was carried out to clarify the possible mechanisms by evaluating the effects of scopolamine pretreatment and treatment on naloxone-precipitated withdrawal signs and some of other general behaviors in morphine dependent rats. Our results showed that scopolamine pretreatment and treatment attenuated naloxone-precipitated withdrawal signs including jumping, writhing posture, weight loss, genital grooming, teeth-chattering, ptosis, diarrhea and irritability, except for wet dog shakes, while general behaviors such as water intake, urine volume and morphine excretion in urine were increased. Our findings suggest that scopolamine has significant actions in the treatment of opiate addiction, which might result from increasing morphine excretion from urine.

Analysis of Variance↗

Electroencephalographic characterization of scopolamine-induced convulsions in fasted mice after food intake.

The present study was conducted to evaluate scopolamine-induced convulsions in fasted mice after food intake effects on the cortical electroencephalogram (EEG). Continuous EEG recordings were taken with Neuroscan for 10 min in freely moving mice with six chronic cortical electrode implants. Animals were weighed and deprived of food for 48 h. EEG recordings were taken at the 24th and 48th hour after their food deprivations. Later, all animals were treated with saline or scopolamine of 3mg/kg i.p. and EEG recordings were repeated for 10 min. Twenty minutes later, they were given food pellets and were allowed to eat ad libitum. All animals were observed for 60 min to determine the incidence and onset of convulsions and EEG recordings were taken simultaneously. The present results demonstrate that food deprivation causes differences in EEG in the elapsed time. The changes in EEG induced after food deprivation become different with scopolamine administration. In scopolamine treatment group, eating caused a series of high-voltage polyspikes and synchronized spikes with a predominant frequency in the 1-3 Hz range and fast activity that represents a typical epileptiform manifestation. It was concluded that the EEG properties and the behavioral patterns of these convulsions are in accordance with each other.

Animals↗

Differential response of rapid eye movement sleep to cholinergic blockade by scopolamine in currently depressed, remitted, and normal control subjects.

The degree of cholinergic dysregulation of sleep in adult depression was evaluated using scopolamine. On separate sessions, placebo and scopolamine (4.5 micrograms/kg, IM) were administered to 14 patients with unipolar major depression, 16 recovered/remitted patients, and 18 normal controls. Scopolamine increased rapid eye movement (REM) latency (RL), reduced REM activity (RA), REM density (RD), and REM duration, and increased the percentage of stage 4 sleep in all groups. There was a differential effect of scopolamine on RL, RA, and REM duration for the first REM period, and on percentage of stage 4 sleep. Whereas a primary cholinergic hyperactivity could account for the RA and RD responses, the response profile for RL was more compatible with reduced aminergic tone as the proximal cause of the cholinergic hyperactivity. Whether the sleep abnormalities observed in remitted patients reflect an underlying vulnerability for development or recurrence of depression, and/or a scar, remains to be determined.

Adult↗

Differential effects on delayed non-matching-to-position in rats of microinjections of muscarinic receptor antagonist scopolamine or NMDA receptor antagonist MK-801 into the dorsal or ventral extent of the hippocampus.

Glutamatergic NMDA and cholinergic muscarinic receptors are thought to contribute to cognitive processes mediated by the hippocampus. Evidence from lesion studies suggests that, despite cytoarchitectural uniformity within the hippocampus, information processing may not be uniform along the septo-temporal axis. The present study examined whether blockade of NMDA or muscarinic receptors in hippocampal subregions produced regional dissociations in the disruption of performance on an operant, spatial delayed non-matching-to-position (DNMTP) paradigm that also assessed vigilance. Rats were extensively pretrained on DNMTP, then bilaterally cannulated into either the dorsal or ventral hippocampus. Following retraining, scopolamine or MK-801 were administered prior to sessions. MK-801 administered into dorsal hippocampus produced delay-independent deficits in DNMTP delayed choice. Neither scopolamine administered into the dorsal or ventral hippocampus, nor MK-801 administered into the ventral hippocampus, produced significant disruption of DNMTP delayed choice. However, some dissociations were evident in other measures of vigilance. Scopolamine into the dorsal and ventral hippocampus increased errors of omission, scopolamine into the ventral hippocampus decreased sample response accuracy, and MK-801 into the dorsal hippocampus decreased sample response accuracy and increased response bias. These results are consistent with the suggestion that subregions of the hippocampus may be involved in different aspects of information processing and also suggest that the cholinergic inputs to the hippocampus may be functionally independent of NMDA receptor-mediated neurotransmission.

Animals↗

Effects of molsidomine on scopolamine-induced amnesia and hypermotility in the rat.

Nitric oxide (NO) is hypothesized to be a novel intracellular messenger in the central nervous system. Recently, NO involvement in learning and memory processes has been proposed. Compounds that inhibit nitric oxide synthase, the key synthesizing enzyme, may block cognition, while NO donors may facilitate it. The aim of this study was to assess in the rat the effects of the NO donor molsidomine (2 and 4 mg/kg, i.p.) on memory deficits caused by scopolamine. For this purpose, the object recognition task and the step-through passive avoidance procedure were chosen. In addition, the effects of molsidomine in antagonizing the scopolamine-induced hypermotility were also examined. Scopolamine at 0.2 mg/kg (object recognition) and 0.75 mg/kg (passive avoidance) disrupted acquisition in both the tasks and induced locomotor hyperactivity at the dose of 0.2 mg/kg. Molsidomine at either dose reversed the scopolamine-induced deficits in the object recognition paradigm but did not counteract the hypermotility and the deficits occurred in the passive avoidance test. These results suggest that to some extent, the NO donor molsidomine is involved in memory processing.

Amnesia↗

Ameliorative effect of vasopressin-(4-9) through vasopressin V(1A) receptor on scopolamine-induced impairments of rat spatial memory in the eight-arm radial maze.

In order to clarify the mechanism by which pGlu-Asn-Cys(Cys)-Pro-Arg-Gly-NH(2) (vasopressin-(4-9)), a major metabolite C-terminal fragment of [Arg(8)]-vasopressin (vasopressin-(1-9)), improves learning and memory, we used several different drugs such as an acetylcholine receptor antagonist, a Ca(2+)/calmodulin-dependent protein kinase II inhibitor, vasopressin receptor antagonists and L-type Ca(2+) channel blocker to disrupt spatial memory in rats. Moreover, we examined the effect of vasopressin-(4-9) on acetylcholine release in the ventral hippocampus using microdialysis. Vasopressin-(4-9) (10 fg/brain, i.c.v.) improved the impairment of spatial memory in the eight-arm radial maze induced by scopolamine, pirenzepine and Ca(2+)/calmodulin -dependent protein kinase II inhibitor. Pirenzepine, a vasopressin V(1A) receptor antagonist, and L-type Ca(2+) channel blocker, but not a vasopressin V(2) receptor antagonist, suppressed the effects of vasopressin-(4-9) on scopolamine-induced impairment of spatial memory. Moreover, vasopressin-(4-9) did not affect acetylcholine release in the ventral hippocampus of intact rats or of scopolamine-treated rats as assessed by microdialysis. These results suggest that vasopressin-(4-9) activates vasopressin V(1A) receptors on the postsynaptic membrane of cholinergic neurons, and induces a transient influx of intracellular Ca(2+) through L-type Ca(2+) channels to interact with muscarinic M(1) receptors. The activation of these processes by vasopressin-(4-9) is critically involved in the positive effect of vasopressin-(4-9) on scopolamine-induced impairment of spatial memory.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

Differential gene expression of scopolamine-treated rat hippocampus-application of cDNA microarray technology.

The molecular study of learning and memory has been concentrated at muscarinic acetylcholine receptors and their associating signaling molecules. To explore alternative pathways we applied human cDNA microarray and searched for differentially expressed genes in the hippocampus of scopolamine-treated rat. Interspecies hybridization using human cDNA microarray to analyze scopolamine-treated rat hippocampus exhibited a minor difference for the expression profile compared to normal control with standard deviation of 0.08-fold in ratio. Based on differential expression, forty-two genes were selected for further analysis from 9,600 candidate genes on the array. Twenty-eight genes were validated by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) using primer pairs against rat orthologs. The broad spectrum of the differentially expressed genes indicated an overall cellular response upon scopolamine treatment. In addition to genes associated with muscarinic receptor signaling pathways, we have disclosed genes associated with novel pathways such as apoptosis, cytoskeleton reconstruction, protein trafficking, cell differentiation, and genes without a clear role. Our result should provide an insight into the molecular study of scopolamine-induced memory impairment.

Alzheimer Disease↗

Intraseptal injection of scopolamine increases the effect of systemic diazepam on passive avoidance learning and emotionality in rats.

This experiment was designed to assess the role of the septo-hippocampal cholinergic (ACh) system in the deleterious effects produced by systemic benzodiazepine injection on learning processes in rats. Retention of a step through passive avoidance task was analysed after systemic injection of increasing doses of either scopolamine or diazepam applied alone 30 min before the acquisition phase. Results indicated a dose related impairment of retention by each drug: in addition, sub-threshold doses of scopolamine and diazepam applied in combination (diazepam: 2mg/kg plus scopolamine: 0.3mg/kg) produced a decrease of retention latencies, thus showing an additive effect of the combined treatment. Secondly, a sub-threshold dose of scopolamine (15microg/0.5microl) was also administered into the medial septal area, together with an i.p. injection of 2mg/kg of diazepam. This combined treatment produced a severe impairment of retention, in parallel with a large reduction in emotionality (number of faeces). The data are consistent with the hypothesis that peripheral administration of behaviorally effective doses of diazepam on passive avoidance learning might act partially via a septal ACh-GABA/benzodiazepine mechanism. It is also suggested that this mechanism subserves both anxiety and the memorisation of contextual stimuli associated with passive avoidance acquisition, through the modification of the septo-hippocampal activity.

Animals↗

Ameliorative effect of NC-1900, a new AVP4-9 analog, through vasopressin V1A receptor on scopolamine-induced impairments of spatial memory in the eight-arm radial maze.

The mechanism by which NC-1900, a new pGlu-Asn-Cys(Cys)-Pro-Arg-Gly-NH(2) (AVP(4-9)) analog, improves spatial memory in rats using an eight-arm radial maze was examined. Even at very low doses (0.2 ng/kg for s.c., 1 microg/kg for p.o., 1 fg for i.c.v.) NC-1900 improved scopolamine-induced impairment of spatial memory. NC-1900 (1 ng/kg, s.c.) also improved impairment of spatial memory induced by pirenzepine, a muscarinic(1) (M(1)) receptor antagonist, and by KN-62, a Ca2+/calmodulin (CaM)-dependent protein kinase II inhibitor. [Pmp(1), Tyr(Me)(2)]-Arg(8)-vasopressin, a vasopressin(1A) (V(1A)) receptor antagonist, and nicardipine, L-type Ca2+ blocker, but not OPC-31260, a V(2) antagonist, suppressed the effect of NC-1900 on scopolamine-induced impairment of spatial memory. A microdialysis study showed that NC-1900 did not affect acetylcholine release in the ventral hippocampus (VH) of intact rats or of scopolamine-treated rats. NC-1900 (1 microM) increased [Ca2+](i) in the VH than in the dorsal hippocampus (DH). Pretreatment with nicardipine (1 microM) and Ca2+ -free conditions inhibited the NC-1900-induced [Ca2+](i) response in the VH. Whereas co-administration of NC-1900 (1 microM) and carbachol (500 microM) increased [Ca2+](i) in the VH. Moreover, nicardipine concentration-dependently inhibited the increase in [Ca2+](i) induced by the co-administration of NC-1900 and carbachol in the VH. These results suggest that NC-1900 activates the V(1A) receptor at the postsynaptic cholinergic nerve, and causes a transient influx of intracellular Ca2+ through L-type Ca2+ channels, to interact with the M(1) receptor. The activation of these Ca2+ -dependent processes induced by NC-1900 may be involved in the positive effect of NC-1900 on scopolamine-induced impairment of spatial memory.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

Reduction of the scopolamine-induced impairment of passive-avoidance performance by sigma receptor agonist in mice.

We examined the ameliorating effects of several sigma receptor agonists on scopolamine-induced memory impairment in mice. Scopolamine was administered IP 30 min before the training session. Each sigma receptor agonist was administered 60 min before or immediately after the training session, or 60 min before the retention test in the passive-avoidance performance experiments. (+)-N-Allylnormetazocine ((+)-SKF-10,047), a prototype sigma 1 receptor agonist, showed an ameliorating effect on the scopolamine-induced memory impairment in these 3 administration schedules, and (-)-SKF-10,047, a stereoisomer with low affinity for the sigma 1 receptor subtype, failed to reduce this memory impairment in mice. In addition, 1,3-di(2-toly1)guanidine (DTG) and (+)-3-(3-hydroxyphenyl)-N-(1-propyl)piperizine ((+)-3-PPP), nonselective sigma receptor agonists, did not affect this memory impairment. Physostigmine, an acetylcholinesterase (AChE) inhibitor, alleviated the scopolamine-induced memory impairment in all these drug administration schedules. In addition, (+)-SKF-10,047-induced antiamnesic effect was antagonized by the concurrent administration of haloperidol, a sigma receptor antagonist, or N,N-dipropyl-2-(4-methoxy-3-(2-phenylethoxy) phenyl)ethylamine monohydrochloride (NE-100), a selective sigma 1 receptor antagonist. These findings indicate that the sigma 1 receptor agonist has ameliorating effects on all phases of learning and memory processes. This profile of sigma 1 receptor agonist is similar to that of an AChE inhibitor.

Acetylcholinesterase↗