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Abstract:
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The amphetamine derivative , 3 ,4 -methylenedioxymethamphetamine (MDMA ) , is a popular drug often taken by young adults at dance clubs or rave parties . Laser light shows , fast -paced electronic music , and hot crowded dance floors are characteristic of these events , and Ecstasy users report that the acute effects of the drug are potentiated by these stimulatory conditions . However , it remains largely unknown how environmental stimuli impact the neurochemical and physiological effects of MDMA . The aim of the first study presented in this dissertation was to investigate how auditory stimuli (music , white noise , and no additional sound ) influence MDMA conditioned place preference (CPP ) , self -administration , and nucleus accumbens (NAcc ) dopamine (DA ) and serotonin (5 -HT ) responses . Findings revealed a significant CPP for animals exposed to white noise during MDMA conditioning trials . After self -administration of MDMA (1 .5 mg /kg ) , NAcc DA and 5 -HT were highest in rats exposed to music during the test session . The second study aimed to investigate the effects of ambient temperature (23°or 32°C ) on long -term MDMA self -administration and neurochemical responses . Results indicated no difference in self -administration or locomotor activity rates for the high versus room temperature groups across sessions . However , MDMA (3 .0 mg /kg ) administered in high ambient temperature resulted in significantly greater NAcc serotonin release compared to when taken at room temperature , but no differences in dopamine response was determined between the two conditions . Overall , these results indicate that auditory and thermal stimuli can effect MDMA -induced behavioral and neurochemical responses . The last aim tested a novel apparatus and method for use in animal models of drug reinforcement . By combining traditional CPP and self -administration procedures , this approach provided more informative data and circumvented some inherent drawbacks of each method alone . In addition to confirming the ability to produce drug conditioned place preferences after short - and long -term experiments , the long -term version of the procedure revealed a significant positive relationship between lever response rate and CPP magnitude . Therefore , this experimental design can be used to identify subgroups of rats that may vary in sensitivity to drug motivational effects . Further study of these populations may be useful in the development of behavioral and pharmacological therapies for drug addiction . |