Boyle-Davis gags for tonsillectomy.
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Anesthesia, Inhalation↗
Biomedical subjects
G Vickers
Publications and source records attributed to G Vickers.
Lesions of central serotonin systems affect responding on a progressive ratio schedule reinforced either by intravenous cocaine or by food.
The effect of intraventricular infusions of the serotonergic neurotoxin, 5,7-dihydroxytryptamine (5,7-DHT), was examined in rats trained on a progressive ratio schedule for either IV cocaine or food reinforcement. Animals in the 5,7-DHT treatment group responded to significantly higher breaking points than vehicle-injected control animals, regardless of whether food or cocaine was used as the reinforcing stimulus. Analysis of the regional brain amines indicated that depletions of mesencephalic 5-HT correlated with postsurgical alterations in responding. These findings suggest that depletion of forebrain 5-HT produces a general effect on responding rather than a specific alteration in the reinforcing effects of psychomotor stimulant drugs.
5,7-Dihydroxytryptamine↗
Clozapine increases breaking points on a progressive-ratio schedule reinforced by intravenous cocaine.
The effect of the atypical neuroleptic clozapine on cocaine self-administration reinforced on a progressive-ratio schedule in rats was examined. The rat's first response on a lever each day produced an IV infusion of cocaine (0.6 mg/injection) after which the requirements of the schedule escalated with each infusion until the frequency of responding on the lever fell below a criterion level. The final ratio completed was defined as the breaking point. Doses of 5 and 20 mg/kg clozapine produced either no effect or a nonspecific disruption in responding. Rats pretreated with 10 mg/kg clozapine responded to significantly higher breaking points, indicating an increased motivation to self-administer cocaine.
Animals↗
Self-administration of cocaine on a progressive ratio schedule in rats: dose-response relationship and effect of haloperidol pretreatment.
Intravenous cocaine self-administration behavior in rats was investigated using a progressive ratio (PR) schedule of reinforcement. The first response on the lever each day produced a drug infusion, whereupon the requirements of the schedule escalated with each reinforcement until the behavior extinguished. The final ratio completed each day was found to be relatively stable, sensitive to changes in dose, and drastically reduced by pretreatment with haloperidol (0.05 mg/kg). We conclude that self-administration behavior of rats reinforced on a progressive ratio schedule can provide useful information about changes in the reinforcing efficacy of specific drugs.
Animals↗
The effect of haloperidol on cocaine self-administration is augmented with repeated administrations.
Administration of haloperidol (0.075 mg/kg) prior to a 4-h self-administration session increases cocaine intake by male rats. Animals pretreated daily with haloperidol showed a significant augmentation of this response, with cocaine intake climbing from 37% above baseline to 65% above baseline in 7 days. Control rats given two treatments of haloperidol 7 days apart showed no augmentation of the response. This increased drug effect is unusual, since most behavioral actions of haloperidol in laboratory animals show tolerance. In humans, the antipsychotic activity of neuroleptic drugs requires many days to develop. Cocaine self-administration behavior might therefore provide a model for antipsychotic drug action.
Animals↗
Disruption of cocaine and heroin self-administration following kainic acid lesions of the nucleus accumbens.
In previous experiments we have demonstrated that bilateral infusions of 6-hydroxydopamine (6-OHDA) into the nucleus accumbens result in a drastic reduction in the rate of cocaine self-administration. If this effect is due to the destruction of a presynaptic dopaminergic element in this nucleus, then selective removal of the postsynaptic neuron should also disrupt cocaine self-administration. This hypothesis was tested using the neurotoxin kainic acid. Bilateral kainic acid infusions into the nucleus accumbens resulted in a drastic destruction of cell bodies yet did not damage catecholamine innervation in areas anterior to the accumbens. The effects of these kainic acid infusions were evaluated in rats that had previously acquired cocaine self-administration behavior. These lesions were found to severely disrupt cocaine intake and the degree of damage produced in the accumbens was found to correlate (r = 0.88) with postlesion cocaine intake. These lesions were additionally found to disrupt apomorphine and heroin self-administration. The possibility that these results are due to destruction of systems necessary for stimulant and opiate reward is discussed.
Animals↗
Atypical neuroleptics increase self-administration of cocaine: an evaluation of a behavioural screen for antipsychotic activity.
Several drugs have been shown to exert antipsychotic effects, yet they display an atypical profile with respect to standard neuroleptic drug screens. Low doses of traditional neuroleptics are known to increase self-administration of psychomotor stimulants; we sought to determine whether these atypical drugs would cause a comparable effect. Sulpiride, metoclopramide and thioridazine produced a dose-dependent increase in cocaine intake similar to that found for chlorpromazine, haloperidol, pimozide and flupenthixol. This effect was found to correlate (r = 0.94) with daily clinical dose. Clozapine, however, produced a dose-dependent decrease in cocaine intake. The advantages and disadvantages of using this measure as a screening procedure for neuroleptic drugs are discussed.
Animals↗
Infant rat hyperactivity elicited by home cage bedding is unaffected by neonatal telencephalic dopamine or norepinephrine depletion.
Newborn rats received either stereotaxically guided bilateral injections of 6-hydroxydopamine (6-OHDA) in the neostriatum so as to deplete dopamine (DA) there, or subcutaneous 6-OHDA to deplete forebrain norepinephrine (NE). Both the DA and NE depleted rats as well as their respective control rats were significantly more active at 15-16 days of age when tested in a novel environment containing soiled bedding from their home cages, than when tested in the presence of clean bedding material. Furthermore, under both the home cage and clean bedding conditions the DA depleted rats were more active at this age than their controls. Thus while transiently elevated locomotor activity is one consequence of neonatal, neostriatal DA depletion, inattention to olfactory stimuli (which occurs after adult neostriatal DA depletion) is not another. The NE depleted rats in both home cage and clean bedding test conditions showed activity levels equivalent to that of their control groups. Furthermore, the NE depletion did not affect hyperactivity elicited by artificially (peppermint) scented bedding like that in which the rats had been reared. Thus, contrary to expectations based on the reported reduction of preference for conspecific odor after neonatal and adult forebrain NE depletion, these data show that the locomotor activating effects of neither conspecific nor artificial odors associated with the nest odors are attenuated by neonatal NE depletion. The mortality rates among NE depleted rats raised in the peppermint scented shavings was unusually high and overall, these rats were less active than similarly raised controls.
Animals↗
Comparative studies in synaptosome formation: preparation of synaptosomes from the ventral nerve cord of the lobster (Homarus americanus).
A flotation method for preparing synaptosomes, previously developed for work with squid nervous tissue, has now been successfully applied to the ventral nerve cord of lobster. Perhaps due to the greater content of connective tissue, homogenization of the lobster nerve cord was more difficult than with squid optic lobes and the yield of synaptosomes was lower. The synaptosomes fraction showed a 3.8-fold enrichment of bound acetylcholine relative to the homogenate and was almost 10 times richer in acetylcholine than a guinea pig cerebral cortical synaptosome fraction. The lobster synaptosomes accumulated choline rapidly when incubated at room temperature in sea water, and showed a high degree of occlusion of lactate dehydrogenase, thus confirming that they are sealed structures. The lobster can thus be added to the wide range of species from whose nervous systems synaptosomes can be isolated, and merits further study as a possibly rich source of cholinergic synaptosomes.
Acetylcholine↗
Two streams of medicine?
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Family Practice↗
The promotion of psychiatric research.
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Psychiatry↗
Community medicine.
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Community Health Services↗
Public image of a psychiatrist.
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Nursing↗
What sets the goals of public health?
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Goals↗
Experimentally induced glucose intolerance increases oral ethanol intake in rats.
A number of studies have shown a relationship between glucose tolerance and ethanol intake. The present study uses a relatively simple procedure to induce glucose intolerance to test whether this condition is sufficient to produce an increase in chronic ethanol intake in male rats. Subjects were divided equally into four groups where they were given access to one of four solutions: peppermint-flavored sucrose (40%), peppermint-flavored saccharin (0.1%), peppermint in water (0.1%), or water alone presented three times a week, for a period of 11 weeks. After 12 weeks all animals were subjected to an oral glucose tolerance test which revealed that the chronically prepared sucrose animals had become glucose intolerant. At the start of week 13 all animals were given access to a 6% ethanol solution flavored with peppermint in place of the previous solutions for a period of 11 weeks. Sucrose animals displayed an immediate preference for ethanol and consumed approximately three times more ethanol than the remaining groups. The results of this study indicate that rats that are made glucose intolerant by long term access to a high concentration of sucrose, when given the opportunity, will subsequently choose to drink more ethanol than control animals.
Alcohol Drinking↗
A practical methodology for analysing and improving the measurement system.
Measurement systems are used widely in manufacturing organisations in order to make many important decisions. These decisions range from the acceptability of a given product against tolerance requirements to the level of statistical control of a process or its capability to consistently perform a given task. In most situations, however, little thought is given to the quality of the data generated by such measurement processes. By using potentially flawed data in making fundamental manufacturing decisions, organisations undermine the quality of the decision-making process itself. This paper reviews the approaches presently available from both a technical and a practical point of view, based on the priorities of process improvement practitioners. The conclusion of the paper is that the Evaluation of the Measurement Process proposed by Wheeler and Lyday offers the best balance of accuracy and utility.
Analysis of Variance↗