Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “SCOPOLAMINE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources
PubMed1990

A comparison of the effects of cholinergic and dopaminergic agents on scopolamine-induced hyperactivity in mice.

The effects of cholinesterase inhibitors, cholinergic agonists, dopaminergic agonists and dopaminergic antagonists on the hyperactivity produced by the muscarinic cholinergic antagonist scopolamine were evaluated in mice. Scopolamine (0.3-10 mg/kg) produced a dose-related increase in locomotor activity, with a peak effect at 3.0 mg/kg. The cholinesterase inhibitor physostigmine (0.03-0.175 mg/kg) was without effect on locomotor activity when administered alone, whereas the cholinesterase inhibitor tetrahydroaminoacridine hydrate (0.3-10 mg/kg) decreased locomotor activity. Both physostigmine and tetrahydroaminoacridine hydrate attenuated the effects of scopolamine. Administered alone, the cholinergic agonists oxotremorine (0.01-0.3 mg/kg) and RS86 (0.1-3.0 mg/kg) produced dose-related decreases in locomotor activity, whereas pilocarpine (0.3-10 mg/kg) had no effect on locomotor activity. None of these three muscarinic agonists significantly attenuated the hyperactivity produced by scopolamine. Administered alone, the dopaminergic agonists quinpirole (0.003-0.1 mg/kg), S-(-)-3-(3-hydroxyphenyl)-N-n-propylpiperidine (0.3-10 mg/kg) and SKF 38393 (8-64 mg/kg) had no significant effect on activity, whereas apomorphine (0.3-10 mg/kg) and d-amphetamine (0.1-3.0 mg/kg) increased activity. Quinpirole, apomorphine and S-(-)-3-(3-hydroxyphenyl)-N-n-propylpiperidine produced dose-related reversals of the increases in locomotor activity produced by scopolamine. The hyperactivity effects of d-amphetamine were approximately additive with scopolamine, whereas SKF 38393 did not significantly affect scopolamine. The mixed D1/D2 dopaminergic antagonist haloperidol (0.003-3.0 mg/kg) and the selective D1 antagonist SCH 23390 (0.01-0.3 mg/kg) produced dose-related decreases in locomotor activity when administered alone, and also produced dose-related reversals of the hyperactivity produced by scopolamine.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1987

[Transdermal scopolamine or droperidol in the prevention of postoperative nausea and vomiting in cholecystectomy patients].

Scopolamine, applicable without severe side effects as a transdermal therapeutic system (TTS), has a pronounced postoperative antiemetic effect. In one publication there was found even a 50% reduction of emetic symptoms compared with placebo. In this study TTS-Scopolamine was compared with a single dose of 7.5 mg Droperidol in a group of 40 Patients undergoing cholecystectomy under standardised balanced anesthesia. After cholecystectomy patients are very much inclined for postoperative nausea and vomiting since it is an abdominal operation and it is more often necessary in women than in men. In this randomized, one-side-blind study the antinausea and antiemetic effect of transdermal Scopolamine was insufficient and significantly less than with Droperidol. In the Droperidol-group there were 45% of patients without emetic symptoms, in the Scopolamine-group only 15%. Vomiting occurred in 25% of patients in the Droperidol-group and in 50% of patients in the Scopolamine-group. Unfavourable CNS-side-effects could not be found either with transdermal scopolamine or with Droperidol. As favourable side-effects there was found a more even postoperative blood-pressure-curve in the Droperidol-group and a better scoring of preoperative sleep in the Scopolamine-group. Overall there is need for an exact indication for transdermal Scopolamine as a postoperative antiemetic. In this study Droperidol turned out to be a much stronger antiemetic for patients undergoing cholecystectomy.

Administration, Cutaneous↗
PubMed1992

Oxiracetam antagonizes the disruptive effects of scopolamine on memory in the radial maze.

The effects exerted by oxiracetam on the disruption of performance induced by scopolamine in the radial arm maze were investigated in overtrained rats. Scopolamine induced a dose-related decrease in the efficiency of responding and an increase of running time. The effect of the SC injection of 0.2 mg/kg scopolamine on the efficiency of responding was antagonized by the IP administration of 30 mg/kg oxiracetam, while the effect on running time induced by the same dose of scopolamine was not. Physostigmine (0.3 mg/kg SC) antagonized both effects of 0.2 mg/kg scopolamine. Methylscopolamine, at the dose of 0.2 mg/kg SC, was devoid of any effect on both parameters. Increasing the dose of methylscopolamine to 0.63 mg/kg did cause serious peripheral effects which eventually prevented some animals from completing the task. Similar peripheral effects were observed after administration of 0.63 mg/kg scopolamine. The effects of this dose of scopolamine on efficiency and running time were not antagonized by pretreatment with 100 mg/kg oxiracetam. Oxiracetam alone (30 or 100 mg/kg IP) did not modify the performance of previously trained rats. The present results suggest that oxiracetam selectively restores cholinergic mechanisms which are involved in learning and memory.

Animals↗
PubMed1989

The effects of scopolamine and methylscopolamine on visual and auditory discriminations in male and female Wistar rats.

The present experiment was designed to investigate whether or not the administration of scopolamine hydrobromide would differentially disrupt auditory or visual discrimination performance in male and female Wistar rats. Two groups of male and female Wistar rats were trained to discriminate between a continuous and intermittent visual stimulus, while two other groups were trained to discriminate between a continuous or intermittent auditory stimulus in a discrete-trial discrimination procedure. Once discrimination performance had stabilized, subjects were treated with different doses (0.125, 0.25, 0.50 or 1.0) of scopolamine hydrobromide or scopolamine methylbromide. Treatment effects were assessed with respect to discrimination performance, as well as with respect to the number of trials which were not completed. Scopolamine hydrobromide, but not scopolamine methylbromide, disrupted visual and auditory discrimination performance. The auditory discrimination was more seriously disrupted. However, both the administration of scopolamine hydrobromide and of scopolamine methylbromide increased the number of trials which were not completed suggesting that the accuracy of visual and auditory discriminations after drug treatment may have been influenced by other variables than drug effects on memory processes. Sex differences were not observed, neither with respect to discrimination performance, nor with respect to the number of trials which were not completed.

Acoustic Stimulation↗
PubMedDate not supplied

The effects of scopolamine on memory for time in rats and pigeons.

In Experiment 1, pigeons were trained to match short (2 s) and long (8 s) sample durations to red and green comparison stimuli and red and green samples to vertical and horizontal line comparisons. They received injections of scopolamine hydrobromide (0.02 mg/kg), scopolamine methylbromide (0.02 mg/kg), or saline, and the delay interval was manipulated (0, 1, 3, and 9 s). In Experiment 2, rats were trained to discriminate short (2 s) or long (12 s) durations of house-light illumination using a choice procedure. During the test phase of each trial, the left and right levers were presented with the cue light on above one of them (cued lever) while the other was off (uncued lever). For half of the rats, the correct response following the short sample was to press the cued lever, whereas following the long sample, it was to press the uncued lever. This was reversed for the remaining rats. The rats received injections of scopolamine hydrobromide (0.15 mg/kg), scopolamine methylbromide (0.15 mg/kg), or saline, and the delay interval was manipulated (0, 1, 3, and 9 s). In pigeons, scopolamine equivalently disrupted both temporal and nontemporal memory. Memory for time, in both rats and pigeons, was significantly poorer following scopolamine injections than following methylscopolamine or saline injections. No choose-short effect was observed in either rats or pigeons during saline test sessions. The data indicate that central cholinergic blockade in both pigeons and rats disrupts the accuracy of delayed temporal discriminations. However, scopolamine does not appear to accelerate the rate at which memory for temporal events is foreshortened.

Animals↗
PubMed1988

Characterization of the scopolamine stimulus in rats.

The discriminative stimulus properties of scopolamine, a potent antagonist at muscarinic receptors, were used for testing the discriminative effects of drugs known to act on cholinergic transmission. Rats were trained in a standard two-bar operant conditioning procedure with food as the reinforcer, according to a FR10 schedule. The training dose of scopolamine was progressively reduced from 0.25 mg/kg SC to the low dose of 0.062 mg/kg SC. Scopolamine yielded an accurate discrimination in all the six rats tested. The generalization gradient resulted in an ED50 of 0.027 mg/kg. The scopolamine cue lasted for 1 h and was of central origin, since it was not mimicked by scopolamine methylbromide. The scopolamine stimulus generalized to atropine and trihexyphenidyl (respective ED50 values 2.20 and 0.21 mg/kg SC). Atropine depressed rate of responding, while trihexyphenidyl did not. Antagonism experiments with both direct agonists at the muscarinic receptor (arecoline and oxotremorine) and indirect agonists, i.e., inhibitors of the acetylcholine esterase [physostigmine and tetrahydroaminoacridine (THA)], led to inconsistent results. Increasing the doses of the agonists in order to block the scopolamine cue may be limited by their rate suppressant effect on responding. Based upon previously published results, it is suggested that the muscarinic agonist cue is more useful than the antagonist cue for investigating muscarinic transmission.

Animals↗
PubMed1985

Effects of oral scopolamine on human stimulus evaluation.

In a previous study of the effect of age on information processing, both age and stimulus complexity slowed reaction time (RT) and the latency of the P300 component of the brain event-related potential (ERP). The aim of the present study was to compare the effects of scopolamine (an anticholinergic) with the previously noted effects of age. The choice of scopolamine was prompted by current hypotheses concerning decline in cholinergic function with age. Twelve adult women were studied on a battery of tasks before and after scopolamine in oral doses of 0.0 (placebo), 0.6 and 1.2 mg. Reaction times (RT) and event-related potentials (ERP) were measured. The principal task was one that combined two levels of stimulus complexity and two levels of response difficulty to provide four subtasks. Scopolamine slowed RT and P300 as had age, but scopolamine slowed responses to simple stimuli more than responses to complex stimuli. Scopolamine effects on other tasks in the battery were small but consistent with an action of scopolamine on an early stimulus preprocessing stage that is independent of a stimulus evaluation stage that is also affected by age.

Adult↗
PubMed1985

Effects of transdermal scopolamine upon psychological test performance at sea.

The effects of transdermal scopolamine upon objective psychological performance assessments and self reports of feeling states, were investigated with volunteer subjects at sea. Scopolamine and placebo patches were administered on consecutive days in a counterbalanced order. Psychological performance was assessed 24 h following each transdermal patch. Choice reaction time and code substitution performance levels were not significantly changed, but letter cancellation errors were significantly more frequent following transdermal scopolamine. Transdermal scopolamine caused significantly more reports of dry mouth. More subjects were also unable to undertake the performance tests following scopolamine than placebo, due to difficulties in focusing on the test materials. However despite deleterious side effects with some personnel, others responded positively to the scopolamine patch. As noted by other workers, responses to the transdermal scopolamine patch seem to be quite variable.

Adolescent↗
PubMed1990

Effect of imipramine in the "learned helplessness" model of depression in rats is not mimicked by combinations of specific reuptake inhibitors and scopolamine.

Administration of imipramine, which blocks noradrenergic, serotonergic and cholinergic reuptake, to rats for 4 days counteracts the shuttlebox escape failures otherwise seen in rats which have been exposed to inescapable shock (the "learned helplessness" model of depression). The effects of the more selective reuptake inhibitors talsupram (noradrenergic), citalopram (serotonergic) and the anticholinergic compound scopolamine were assessed alone and in combination after acute or 4 days' administration on escape behavior. Their possible synergistic effects when combined with imipramine were also assessed. Talsupram and citalopram were ineffective, whereas scopolamine counteracted the escape failures. Combinations of talsupram, citalopram and a subeffective dose of scopolamine were ineffective. A synergistic effect was only seen when scopolamine was combined with a suboptimal dose of imipramine. Thus, the effect of imipramine on "learned helplessness" might rely partly on its anticholinergic component. However, as an acute high dose of imipramine (25 mg/kg) was ineffective [unlike the acute administration of scopolamine (0.12 mg/kg)], this drug retains a pharmacological effect which is not mimicked by scopolamine alone or by combining the specific reuptake inhibitors with scopolamine.

Animals↗
PubMed1991

Reversal effect of DM-9384 on scopolamine-induced acetylcholine depletion in certain regions of the mouse brain.

The effect of a new cognition enhancer, DM-9384, N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl) acetamide, on regional acetylcholine (ACh) levels and against scopolamine-induced ACh depletion was examined in mouse brain. In addition, the effects of DM-9384 were compared with those of oxiracetam, physostigmine and tacrine. Independent administration of DM-9384 (1, 3, 10 or 30 mg/kg, PO) or oxiracetam (10 or 50 mg/kg, PO) to mice had no effect on the ACh level in the hippocampus, frontal cortex, amygdala and striatum. Nevertheless, in all brain regions, pretreatment with DM-9384 significantly reduced the depletion of ACh induced by scopolamine (0.5 mg/kg, IP) in a nondose-related bell-shaped manner. By contrast, oxiracetam attenuated the effect of scopolamine in the hippocampus, frontal cortex and striatum but not in the amygdala. Physostigmine (0.2 mg/kg, SC) significantly increased ACh levels and reversed the scopolamine-induced ACh depletion in all brain regions. Unlike physostigmine, tacrine (10 mg/kg, PO) increased ACh levels in the striatum but not in the other regions. Tacrine reversed the effect of scopolamine in the hippocampus, amygdala and striatum, but not in the frontal cortex. In the present study, DM-9384 more effectively inhibited scopolamine-induced depletion of ACh levels than the other agents tested. The results obtained indicate that the protective action of DM-9384 against scopolamine-induced amnesia is due to its ability to reverse the ACh depletion.

Acetylcholine↗
PubMed1996

Effects of scopolamine on learning and memory in monkeys.

The effects of scopolamine were evaluated in monkeys responding under operant procedures designed to evaluate drug effects on learning and memory. In one procedure, responding was maintained by food presentation under a multiple schedule. One component of the multiple schedule was a repeated-acquisition task in which the discriminative stimuli for left- and right-key responses changed each session (learning). In the other component, the discriminative stimuli for responses were the same each session (performance). In both components of the multiple schedule, scopolamine produced dose-related decreases in responding; there was little evidence of differential rate-decreasing effects between components. Percent errors in learning were increased in a dose-related manner, whereas percent errors in performance were generally unaffected except at high doses, which also produced substantial decreases in response rate. These results suggest that acquisition is more sensitive to the disruptive effects of scopolamine than is performance. The second procedure utilized repeated acquisition and delayed performance as a technique to study the effects of scopolamine on memory. In this procedure, each session was divided into three phases: acquisition, delay and performance. After a 24-h delay, scopolamine had little or no effect on retention, accuracy or rate of responding. In contrast, after a 60-min delay, scopolamine decreased retention in a dose-related manner. These data suggest that scopolamine produces a greater disruptive effect on short (60-min) versus long (24-h) delays.

Animals↗
PubMed1996

The neurosteroid pregnenolone sulfate reduces learning deficits induced by scopolamine and has promnestic effects in mice performing an appetitive learning task.

The effects of the neurosteroid pregnenolone sulfate (PS) on learning as well as on scopolamine-induced learning deficits were studied in Swiss mice using an appetitively reinforced Go-No Go visual discrimination task. Subcutaneous (SC) administration of scopolamine (0.3-3 mg/kg) after the first session of training dose-dependently impairs learning during the following sessions in this task. Moreover, intracerebroventricular (ICV) administration of PS (0.01-10 nmol) dose-dependently blocks learning deficits induced by scopolamine (3 mg/kg), with the most potent effects at the dose of 0.5 nmol PS. In addition to antagonizing the amnestic effects of scopolamine, PS (0.5 nmol ICV) has a memory-enhancing effect, when administered alone after the first training session. Scopolamine (3 mg/kg SC) also produced substantial deficits on retrieval performance in the Go-No Go visual discrimination task, and caused motor disturbances, when administered 15 min before testing. PS (0.5 nmol ICV) also reduced scopolamine-induced deficits on retrieval but had no effect on scopolamine-induced motor impairments in the traction reflex test. Such a rapid effect of PS on memory processes may be mediated via NMDA and/or GABAA receptors.

Animals↗
PubMed1988

Potential interactions between GABAb and cholinergic systems: baclofen augments scopolamine-induced performance deficits in the eight-arm radial maze.

Sixteen male Fischer-344N rats were trained on a eight-arm radial maze task for food reinforcement. The effects of various doses of baclofen (1.25 or 2.50 mg/kg) and scopolamine (0.188, 0.375, and 0.750 mg/kg) were determined alone and in combination. Relative to vehicle controls, baclofen alone did not affect performance in the radial arm maze (number correct in the first eight responses, total errors) or the time required to complete the maze. Scopolamine alone decreased the number of correct responses in the first eight arm choices, while increasing both the number of errors and the time necessary to complete the maze. When the two drugs were co-administered, baclofen had no effect on the number of errors or time required to complete the maze in the presence of scopolamine; however, in combination with the high dose of scopolamine, it significantly increased the number of errors made during the first eight choices. Baclofen thus can exacerbate some radial arm maze dificits produced by an anticholinergic drug. In a subsequent experiment to test the interaction between scopolamine and baclofen using a nonlearned behavior, baclofen (1.25 and 2.5 mg/kg) did not affect motor activity, whereas all doses of scopolamine (0.188-0.75 mg/kg) increased activity. The higher dose of baclofen attenuated scopolamine-induced hypermotility by 50%, but the lower dose of baclofen was not effective. These data demonstrate pharmacological interactions between baclofen, a drug used clinically for spaticity, and a drug having anticholinergic properties.

Animals↗
PubMed2006

Scopolamine induces impairments in the recognition of human facial expressions of anger and disgust.

RATIONALE: Recent psychopharmacological studies lend support to the notion of partially dissociable neuronal systems dedicated to processing specific emotions. For example, GABA-ergic enhancement after an acute dose of the benzodiazepine, diazepam, produces specific impairments in anger and fear recognition. However, it is unclear if these impairments are a general property of benzodiazepines and other drugs that produce a similar profile of neurocognitive impairment to benzodiazepines, such as the anticholinergic, scopolamine. OBJECTIVE: We investigated the effects of scopolamine and the benzodiazepine, lorazepam, on emotion-recognition accuracy. METHODS: A double-blind independent group design was used with 48 healthy volunteers to compare the effects of scopolamine and lorazepam with an inactive placebo on a commonly used emotion-recognition task. Control measures included an episodic memory task and subjective mood ratings. RESULTS: Anger and disgust recognition accuracy was impaired after scopolamine. In contrast, lorazepam produced no impairment in emotion-recognition despite producing similar levels of sedation and anterograde amnesia to scopolamine. CONCLUSIONS: Scopolamine-induced cholinergic hypofunction selectively impaired the recognition accuracy of disgust and anger facial expressions. The effects of scopolamine on emotion-recognition are similar to those found in Huntington's disease patients. Furthermore, the impairments in anger and fear recognition previously observed with diazepam do not appear to be a general property of benzodiazepines. This suggests that alterations in emotional processing involving changes in the ability to recognize threat-related emotions (particularly, fear and anger) may not be a principal mechanism underlying anxiolysis or paradoxical aggression seen with benzodiazepines.

Adolescent↗
PubMed1987

Selectivity of pirenzepine in the central nervous system. III. Differential effects of multiple pirenzepine and scopolamine administrations on muscarinic receptors as measured autoradiographically.

The effects of intrahippocampal injections of scopolamine and pirenzepine on muscarinic receptor binding were examined by quantitative autoradiographic techniques. Brain slices from animals which had received 7 injections of either scopolamine (n = 5) or pirenzepine (n = 5) over a 22-day injection schedule were compared with slices from 5 saline-injected controls for receptor binding to the whole slice and within selected regions of the brain as measured autoradiographically. The total number of receptors was determined from direct binding assays with 1-[3H]quinuclidinyl-benzilate ([3H]-1-QNB), while the binding of the selective ligands pirenzepine, carbamylcholine, and scopolamine was examined through inhibition studies. The data from the whole slices indicated that pirenzepine-treated animals contained more receptors for [3H]-1-QNB than either saline- or scopolamine-injected controls. Slices from the same animals also displayed a lower affinity for pirenzepine. Slices from scopolamine-injected animals revealed neither an increase in receptor number nor a decrease in antagonist affinity, although the binding of the agonist carbamylcholine was increased. Quantitative analysis of the autoradiograms generated from the slices indicated that the increase in receptor number for pirenzepine-injected animals was predominantly within the cerebral and cingulate cortices. The inhibition by pirenzepine was also lower in these areas in the same group of animals. Agonist inhibition was altered in the central layers of the cerebral cortex and in the pretectal area in scopolamine-treated animals. The results suggest separate mechanisms of drug action and adaptation for pirenzepine and scopolamine.

Animals↗
PubMed1993

Dopaminergic involvement in the improving effects of dynorphin A-(1-13) on scopolamine-induced impairment of alternation performance.

The present study was designed to clarify whether dopamine systems are involved in the effect of dynorphin A-(1-13), an endogenous kappa-opioid receptor agonist, on the scopolamine-induced impairment of spontaneous alternation performance related to working memory in mice. Sulpiride (10 and/or 30 mg/kg), a dopamine D2-selective antagonist, markedly improved the impairment of alternation performance and significantly reduced the increase in total arm entries (i.e. locomotor activity) induced by scopolamine (1 mg/kg). In contrast, SCH 23390 (0.01, 0.03 and 0.1 mg/kg), a dopamine D1-selective antagonist, did not influence the impairment of alternation performance, whereas it dose dependently reduced total arm entries in scopolamine-treated mice RU 24213 (1 mg/kg), a dopamine D2-selective agonist, almost completely reversed the improving effect of dynorphin A-(1-13) (3 micrograms) on the scopolamine-induced impairment of alternation performance and reduced total arm entries, although it was without effects on behavioral responses in normal mice. However, SKF 38393 (3 and 10 mg/kg), a dopamine D1-selective agonist, failed to change alternation performance or total arm entries in normal or scopolamine-treated mice. These findings suggest that the impairment of spontaneous alternation performance induced by scopolamine is improved by the blockade of dopamine D2 receptors. Furthermore, the improving effect of dynorphin A-(1-13) on the scopolamine-induced impairment of spontaneous alternation performance may be based upon the inhibition of dopaminergic activity through the mediation of kappa-opioid receptors.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1995

Methamphetamine plus scopolamine potentiates behavioral sensitization and conditioning.

The effects of repeated methamphetamine (4.0 mg/kg) plus scopolamine (0.5 mg/kg) treatment on behavioral sensitization and drug conditioning in rats were compared with the effects of repeated methamphetamine treatment. Behavioral sensitization induced by repeated methamphetamine plus scopolamine treatment was more vigorous than that induced by repeated methamphetamine treatment. Repeated methamphetamine plus scopolamine treatment produced sensitized responses, not only to methamphetamine plus scopolamine and methamphetamine but also, to a lesser extent, to scopolamine. Methamphetamine plus scopolamine-sensitized rats but not methamphetamine-sensitized rats exhibited conditioned responses to a low-frequency tone (300 Hz, 100 dB) associated with the drug state, suggesting that robust methamphetamine plus scopolamine-induced behavioral sensitization may lead to enhanced conditioning. It is plausible that robust behavioral sensitization might operate via a reciprocal balance between the dopaminergic and cholinergic systems in favor of dopaminergic dominance. Conditioning to the drug-associated tone may be mediated via a reciprocal balance between the two transmitter systems.

Acoustic Stimulation↗
PubMed1983

Scopolamine blocks play fighting behavior in juvenile rats.

Play fighting, social investigation, and locomotor activity of prepubescent male laboratory rats were observed 20 min following administration of scopolamine hydrobromide. Play fighting was inhibited by an intraperitoneal dosage of 0.3 mg/kg and was effectively blocked at all dosages greater than 0.5 mg/kg; activity and social investigatory behavior were increased by scopolamine. Play fighting inhibition following a threshold dosage of 0.3 mg/kg scopolamine was effective at 30 min; after 120 min, drug- and saline-treated groups failed to differ reliably. Behavioral tolerance to scopolamine was observed after five days of daily treatment with 0.5 mg/kg scopolamine; play fighting, following a 0.5 mg/kg dosage of scopolamine, did not differ from that of saline-treated controls. The results are discussed in terms of central and peripheral effects of scopolamine and the competing response hypothesis.

Aggression↗