Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.595414
Title: Neural and psychological mechanisms underlying heroin self-administration
Author: Alderson, H. L.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1999
Availability of Full Text:
Full text unavailable from EThOS. Please contact the current institution’s library for further details.
Abstract:
The aim of this thesis was initially to establish i.v. heroin self-administration in rats, and to examine the neural mechanisms underlying this behaviour, using both continuous reinforcement and second-order schedules of reinforcement. The effects of variations in dose and of opiate-receptor antagonist pre-treatment on responding under both continuous reinforcement and second-order schedules of heroin self-administration were examined. Behavioural manipulations were used to investigate the role of discrete heroin-associated cues in maintaining drug-seeking behaviour under a second-order schedule of reinforcement, and the effects of excitotoxic lesions of the basolateral amygdala on responding under such a schedule were studied. The role of the nucleus accumbens core and shell subregions in mediating heroin reward was also investigated. Responding under continuous and second-order schedules of reinforcement was found to be altered in different ways by changes in dose and opiate-receptor antagonist pre-treatment. Under a continuous reinforcement schedule, responding showed an inverse-U shaped dose response function, and was increased by pre-treatment with an opiate-receptor antagonist. Responding under a second-order schedule, however, showed no alteration in response to changes in dose, but was reduced over three days of opiate-receptor antagonist pre-treatment. Behavioural evidence was provided for a limited role for discrete heroin-associated cues in maintaining drug-seeking behaviour under a second-order schedule of reinforcement. Excitotoxic lesions of the basolateral amygdala did not affect acquisition of heroin self-administration under either continuous or second-order schedules of reinforcement. These results suggest that the basolateral amygdala does not mediate either heroin reward, or conditioning to discrete heroin-associated cues as suggested by the lack of effect on acquisition of heroin self-administration under either continuous or second-order schedules of reinforcement, respectively. The rate of responding under a second-order schedule of responding was increased following basolateral amygdala lesions. Nucleus accumbens core lesions were found to impair the acquisition of heroin self-administration under a continuous reinforcement schedule and to attenuate the response to changes in dose. By contrast, excitotoxic lesions of the nucleus accumbens shell had no effect on responding under a continuous reinforcement schedule of heroin self-administration.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.595414  DOI: Not available
Share: