Date of Award


Degree Type


Degree Name

Doctor of Philosophy


In Experiment 1 the effect of food-deprivation on the development of tolerance to amphetamine-anorexia was examined. It was demonstrated that both food-deprivation and access to food contingent on amphetamine administration were necessary for tolerance to develop.;It has been suggested that stimulant-induced anorexia is partially caused by concurrent drug-induced motor behaviour which is incompatible with eating or drinking. This implies that tolerance to amphetamine-anorexia should be accompanied by some tolerance to amphetamine-induced motor activity. The results of Experiment 2 demonstrated that tolerance to amphetamine-induced stereotypy develops at the same time as tolerance to amphetamine-induced anorexia. Furthermore, it was found that animals that have developed tolerance to amphetamine-induced anorexia are less affected by haloperidol-induced catalepsy than animals with the same chronic history of amphetamine-administration but which have not developed tolerance.;Not all rats are acutely sensitive to amphetamine-anorexia. The results of Experiment 3 suggest that the development of tolerance to amphetamine-anorexia produces an effect on central dopamine pathways which is not produced by chronic amphetamine administration in either the contingent or noncontingent paradigm per se. Animals that were acutely insensitive to amphetamine-anorexia, and thus had not developed tolerance to it, were not similarly insensitive to haloperidol-catalepsy.;In Experiment 4, the effects on the maintenance of tolerance to amphetamine-anorexia of deprivation level, the presence of milk, continued injection regimen with or without amphetamine or no treatment, were investigated. The effects of tolerance maintenance on haloperidol-catalepsy were also studied. No significant loss of tolerance to amphetamine-anorexia was found in groups that were maintained at 85% ad lib weight, even after 3 months of training. Contrastingly, every group maintained at 100% ad lib weight lost tolerance after only 1 month. Furthermore, animals that retained tolerance to amphetamine-anorexia were significantly less cataleptic than the animals that lost tolerance.;The importance of food-deprivation in the development and maintenance of tolerance to amphetamine-anorexia is considered in relation to current theoretical accounts of the development of tolerance. Also, the behavioural and neurochemical implications of the finding that the development of tolerance to amphetamine-anorexia affects both the response to amphetamine-induced motor effects and the response to haloperidol-catalepsy are discussed.



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