Thesis (M.Sc.)--Chulalongkorn University, 1997

In this study platelets obtained from 10 patients, each with aminergic disorder such as migraine, migraine with depression and Parkinson's disease were ultrastructurally examined with particular reference to the number of dense granules, alpha granules, mitochondria and dilated canaliculi in both resting and activated states. In migraine group, platelets showed a significant increase in the number of dense granules in both resting and activated conditions (p<0.01). After activation by glass surface, a significant increase in the number of dilated canaliculi was demonstrated in patients with migraine (p<0.01). Platelets obtained from migraine patients with depression showed no difference in the number of dense granules when compared to the controls. However, there was a significant decrease in the number of dense granules when compared to the migraine patients (p<0.01). Moreover, the increased number of dilated canaliculi was demonstrated in resting and activated conditions in patients suffered from migraine with depression. In patients with Parkinson's disease, the number of dense granules and dilated canaliculi in the resting platelets was increased but only the number of the latter was still high in activated state. Increased number of dense granules in these aminergic disorders could be related to the up-regulation mechanism while dilatation of canalicular system perhaps reflects the hypersecretion of the platelets. The result obtained from this study are useful in explaining the physiological responses found in these aminergic disorders such as hypersecretion and hyperaggregation of platelets. This study also provides clues as to the pathophysiology of the respective disease.