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Biomedical subjects

D A Booth

Publications and source records attributed to D A Booth.

At least 73 records · Page 4Linked to original sources
PubMed1986

Intrahypothalamic noradrenaline injection in the rat enhances operant licking but not lever pressing for milk reward.

Injection of noradrenaline into the hypothalamus of the rat produces poor performance of lever pressing for liquid food reinforcement at moderate ratio values, even though such injection facilitates intake of liquid food available without an operant requirement. The present work shows that a tube-licking operant response was more facilitated and less suppressed by noradrenaline than a lever-pressing response. Noradrenaline produced rear-limb ataxia which might have affected lever pressing more than licking, but results of manipulating the height of the tube suggested that this was unlikely. It is concluded that the operant performance deficit is more evident with lever pressing than with a response naturally involved in ingestion.

Animals↗
PubMed1986

Gastromotor mechanism of fenfluramine anorexia.

A gastric slowing effect of fenfluramine accounts for most of the drug's suppressant effect on food intake in freely feeding rats. It is conceivable on the evidence to date that this gastromotor action of fenfluramine explains all its effects on appetite and metabolism, but additional peripheral and central effects--such as motor inhibition--are likely. Rate of gastric emptying is quantitatively the dominant physiological control of appetite: it determines the duration for which absorption of a meal sustains metabolic satiety; it also influences gastric distension, which can be a source of innate satiation and of learned carbohydrate-specific satiation. Since most of the neurotransmitter serotonin (5HT) resides in the gastrointestinal wall, not the brain, gastromotor suppression of appetite should be the first working hypothesis for a serotoninergic drug such as fenfluramine. The largest effect on food intake that arises from gastric slowing by fenfluramine and active metabolites is a lengthening of the period of satiety after a meal of a given size. The residue of this extended satiety could reduce appetite at a subsequent fixed mealtime and hence the size of such a meal. Fenfluramine appears not to intensify satiation processes generated by a meal. Rather, it affects eating processes from the start. Also, fenfluramine disrupts learned carbohydrate-specific satiation operative within a meal. This negates the claim that fenfluramine reduces carbohydrate-specific appetite--which in any case (like other claims that drugs modulate nutrient selection) is not based on adequately designed dietary selection tests.

Animals↗
PubMed1985

Norepinephrine-facilitated eating: reduction in saccharin preference and conditioned flavor preferences with increase in quinine aversion.

Paraventricular (PVN) hypothalamic norepinephrine (NE) injections which facilitated feeding were nonetheless found to reduce both the unconditioned preference for saccharin and starch-conditioned preferences for almond odor and lemon taste, as well as enhancing aversion to quinine. These results add to the evidence that PVN NE elicits eating by attenuating a satiety signal.

Animals↗
PubMed1985

Central and peripheral contributions to the enhancement of amphetamine anorexia by desmethylimipramine (DMI).

Intrahypothalamic administration of amphetamine to rats increased food intake, but pre-treatment with the alpha-receptor antagonist phentolamine unmasked an anorexic effect commensurate with that seen after peripheral amphetamine administration. Pretreatment with systemic DMI increased anorexia after peripheral or central amphetamine administration, but the enhancement of centrally-induced anorexia was small. It is concluded that enhancement of the anorexic effect of peripherally administered amphetamine by DMI is primarily a peripheral phenomenon, with interactions within the central nervous system making a relatively minor contribution.

Amphetamine↗
PubMed1983

A robust, brief measure of an individual's most preferred level of salt in an ordinary foodstuff.

A single-session procedure to assess an individual's most preferred level of a factor in a product is justified theoretically and illustrated by the results for salt concentration in samples of bread and tomato soup tested on 30 young men who had had no previous experience of the task. Each man rated the saltiness of each sample as a distance below or above his ideal for that food type. Without the rater knowing, his stimulus set was coordinated to his rating responses in order to minimise biases in what other have shown can be a linear response mode. The Weber fraction is constant for the medium range of NaCl solutions when concentration units are used, and so Fechner's principle of direct scaling was applied: mean linear regressions between ideal-relative intensity responses and the logarithm of salt concentrations in each individual were nearly always statistically reliable with only six to 20 ratings of three to six salt levels in bread or soup. Values of the regression intercepts for bread at the initial session and five months later correlated significantly, as also did the regression slopes. Thus, a robust value for each individual's ideal salt level for each food could be interpolated from the regression equation. There was no effect of sequence of bread and soup sessions. Bread and soup salt-ideals were correlated, as were their slopes. A regression slope appears to represent an individual's tolerance of deviations from ideal. The relation of the slope to choice behaviour, and its relative dependence on intensity sensitivity and a preference motivation characteristic of the individual and test situation, remain to be elucidated. This procedure should have wide application in consumer preference measurement.

Adult↗
PubMed1978

Factors influencing feeding elicited by intracranial noradrenaline in rats.

An improved design of microcannula was used to inject noradrenaline into discrete areas of the rat hypothalamus. The area of the paraventricular nucleus was shown to be a more effective site than the midlateral anterior hypothalamus for eliciting feeding with noradrenaline (4.8 microgram). The magnitude but not the direction of the effect of noradrenaline on feeding was influenced by the day-night cycle. The facilitating effect of the drug reached significance in the light period but not in the dark period, possibly because the baseline food intake was higher by night than by day. The facilitation of feeding occurred whether the rats were maintained and tested on a diet of solid or liquid food.

Animals↗
PubMed1977

Factors influencing flavour aversions conditioned with amphetamine in rats.

Rats would not drink distinctively flavoured solutions after their previous ingestion had been followed by injection of amphetamine (1 mg/kg). In the same rats, intake of flavoured solutions followed by saline injections was not suppressed. Providing the rats with cues as to the location of flavoured solutions paired with amphetamine did not alter either the speed of development or the final severity of the aversion. Neither increasing the interval between presentation of the flavour and injection of amphetamine, nor decreasing baseline drinking levels, altered the final degree of aversion. The aversion became progressively weaker as the dose of amphetamine was reduced, but it was detectable at doses as low as 0.1 mg/kg. Further decreases in dose did not enhance intake of flavours paired with amphetamine, even when combined with reductions in baseline drinking brought about by reduced fluid deprivation and flavour palatability. The results are discussed in relation to the conditions in which amphetamine has been shown to exhibit either rewarding or aversive properties.

Animals↗
PubMed1977

Comparative potencies of amphetamine, fenfluramine and related compounds in taste aversion experiments in rats.

1 Rats failed to drink a flavoured solution when its consumption had been followed by injection of amphetamine (conditioned taste aversion).2 There was very little difference between the potencies of (+)- and (-)-amphetamine.3p-Chloromethamphetamine was a more potent aversive agent than methamphetamine.4 Strong taste aversions were also conditioned with other congeners of amphetamine. The rank order of potency was: fenfluramine > chlorphentermine >p-hydroxyamphetamine.5 Cocaine induced only moderate taste aversions, even at high doses.6 Aversive potency did not appear to be correlated with known neurochemical actions of the drugs or with behavioural stimulation, but appeared to be a central action which may have been linked to anorexigenic potency or time course of action.

Amphetamines↗