Cancer risks among the users of ergot-derived dopamine agonists for Parkinson's disease, a nationwide population-based survey.

BACKGROUND: Factors of cancer occurrence among Parkinson disease patients are still not well known, although genetic predilection has been investigated. The aim of this study is to evaluate the medication effect of dopamine agonists of Parkinson disease on incidence of cancers from the Taiwan National Health Insurance Research Database. METHODS: We conducted a population-based nested case-control study by using the resources of the Taiwanese National Health Insurance from 1996 to 2000 and analyzed the prevalence of cancer among patients with Parkinson disease. A nested analysis was then implemented among those patients with both Parkinson disease and cancer, focusing separately on the use of ergot- and nonergot-derived-dopamine agonists. RESULTS: We reviewed 6211 patients with Parkinson's disease and found 329 patients with cancer. The ergot-derived dopamine agonists users were associated with an increased odds ratio for cancer, compared with nonergot-derived dopamine agonist users, with an adjusted odds ratio of 2.16 (95% confidence interval, 1.55-2.99). Among all the cancer types, we observed the higher occurrence of liver cancer among the ergot-derived dopamine agonist users. CONCLUSION: The association of ergot-derived-dopamine agonist use and cancers, especially the liver cancers, has provided us the information to further understand the drug-cancer interaction. We hope this result would prompt further investigations on the risk and benefit of the dopamine agonists use among the Parkinson's disease patients.

Repeated BOLD-fMRI imaging of deep brain stimulation responses in rats.

Functional magnetic resonance imaging (fMRI) provides a picture of the global spatial activation pattern of the brain. Interest is growing regarding the application of fMRI to rodent models to investigate adult brain plasticity. To date, most rodent studies used an electrical forepaw stimulation model to acquire fMRI data, with α-chloralose as the anesthetic. However, α-chloralose is harmful to animals, and not suitable for longitudinal studies. Moreover, peripheral stimulation models enable only a limited number of brain regions to be studied. Processing between peripheral regions and the brain is multisynaptic, and renders interpretation difficult and uncertain. In the present study, we combined the medetomidine-based fMRI protocol (a noninvasive rodent fMRI protocol) with chronic implantation of an MRI-compatible stimulation electrode in the ventroposterior (VP) thalamus to repetitively sample thalamocortical responses in the rat brain. Using this model, we scanned the forebrain responses evoked by the VP stimulation repeatedly of individual rats over 1 week. Cortical BOLD responses were compared between the 2 profiles obtained at day1 and day8. We discovered reproducible frequency- and amplitude-dependent BOLD responses in the ipsilateral somatosensory cortex (S1). The S1 BOLD responses during the 2 sessions were conserved in maximal response amplitude, area size (size ratio from 0.88 to 0.91), and location (overlap ratio from 0.61 to 0.67). The present study provides a long-term chronic brain stimulation protocol for studying the plasticity of specific neural circuits in the rodent brain by BOLD-fMRI.