The effects of MPP on the dynamics of dopamine release in the corpus striatum of the rat brain /

Abstract

Parkinson's disease is a progressive disorder affecting mainly persons of middle age or older. The main disturbance of this disease is a loss of motor function caused by a pattern of cell loss in the zona compacta of the substantia nigra. As a result of substantia nigra degeneration, a depletion of a neurotransmitter, dopamine, occurs in the corpus striatum. By the depletion of the neurotransmitter, the symptoms associated with Parkinson's disease, such as tremor or rigidity often appear. Certain endogenous or exogenous hypotheses have emerged as to the cause of Parkinson's disease. MPP+, a potent neurotoxin, was fouod to cause symptoms equivalent to Parkinson's disease plus the degenerative effects in the nigrostriatal dopaminergic system of humans and rodents. MPP+ has given researchers an animal model for the specific investigation of Parkinson's disease. Researchers have proposed that the dopamine cell loss in the corpus striatum might lead to a "retrograde system" causing the loss in the substantia nigra. Presently, this study examined the effects MPP+ had on dopamine release in the rat brain. The technique of in vivo voltammetry was used to monitor the releases of dopamine directly in the major area of dopamine cell loss, the corpus striatum. Results of this study demonstrate that dopamine release is substantially decreased in the corpus striatum when induced by MPP+ compared to the potassium-stimulated (control) responses. Decay times, clearance rates, and overall secretion rates of the MPP+- induced releases suggest that this neurotoxin not only effects the release of dopamine but the reuptake mechanisms as well.