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Title: The striato-nigral pathway : its role in the regulation of dopamine metabolism
Author: Garcia-Munoz, M.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1979
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In rats, unilateral lesions in the ventro-medial area of the crus cerebri, where the atriato-nigral pathway runs, produced a significant decrease in the concentration of substance-P, Gamma-amino-butyric-acid and glutamic-acid-decarborylase activity in the substantia nigra ipsilateral to the lesioned side. The striato-nigral pathway has been proposed to mediate the effects produced by the systemic administration of dopamiaergic agonists, (e.g. apomorphine or amphetamine) and antagonists (e.g. haloperidol) on dopamine metabolism in nigral cells. However, the lesions reported here do not alter the concentration of dopamine or its metabolites homovalinic-acid and dihydroxyphenylacetic acid in the striatum, in comparison with control animals, even after the administration of haloperidol and apomorphine. Recordings of dopaminergic nigral cells in rats with chronic and acute electrolytic lesions in the crus cerebri or with kainic acid lesions in the striatum, did not differ from recordings done in control animals. An intravenous administration of amphetamine, significantly reduced the firing rate of dopamine nigral cells in both control and lesioned animals. Similarly, haloperidol blocked the effect of a subsequent administration of amphetamine in both groups. The only lesions which effectively abolished the inhibition of nigral cell activity after amphetamine injections were those which destroyed some of the dopamine cells. These results are discussed as evidence for an alternative mechanism responsible for the observed inhibition which could also be involved in the regulation of dopamine metabolism. A behavioural study shows that lesions in the striato-nigral pathway induced after apomorphine a dose-dependent turning towards the lesioned side and significantly decreased the number of turns induced in a 6-hydroxydopamine lesioned animal after apomorphine. Rats also changed their paw preference during lever pressing after a true cerebri lesion contralateral to the preferred paw. A possible function for the striatonigral pathway in the expression of motor behaviour is discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available