Since the caudate nucleus and putamen, there is a path to the black substance secreted by the inhibitory neurotransmitter GABA (gamma aminobutyric acid). In turn, a series of fibers originating in the substantia nigra send axons to the caudate and putamen, secreting an inhibitory neurotransmitter from their terminals, dopamine. This pathway maintains a degree of mutual inhibition of the two areas and the injury causes a series of neurological syndromes, among which is Parkinson’s disease.
The fibers from the cerebral cortex secrete acetylcholine, an excitatory neurotransmitter, in the neostriatum. The causes of abnormal motor activities that make up Parkinson’s disease are related to the loss of the secretion of dopamine by nerve endings in the substantia nigra on the neostriatum (nigrostriatal tract) to the left of suppression.
Thus, neurons that secrete predominantly acetylcholine, excitatory signals broadcast to all basal ganglia, responsible in whole, motor planning and some cognitive functions. It requires a loss of approximately 80% of striatal dopamine to the symptoms.
Histologically, the disease is characterized by the presence of Lewy bodies in the substantia nigra and locus coeruleus, but can also appear in other locations of the extrapyramidal system. These intracytoplasmic inclusions composed of protein, free fatty acids, sphingomyelin, and polysaccharides.
The incidence of Parkinson’s disease, assessment difficult, is variable ranging from 4.5 to 21 cases per 100,000 population per year. It is the most accurate estimate of the disease and the extent of new cases in a period of time. Prevalence is the total number of cases in a population and at the same time.
