Key result
Bilateral microinfusion of 6-OHDA in rats resulted in lower mean arterial pressure and heart rate compared to sham, alongside a decreased sympathetic component in spectral analysis.
In a rat model of Parkinson's disease, bilateral 6-OHDA infusion in the substantia nigra induces cardiovascular impairments, including lower blood pressure and heart rate, possibly due to decreased sympathetic activity.
Indicates sympathetic impairment may underlie hypotension in 6-OHDA rat models; leaves open applicability to clinical Parkinson's disease.
It is important to elucidate the mechanism of dysautonomias in patients with Parkinson's disease; therefore, this study aimed to investigate the cardiovascular and autonomic changes that occur in an animal model of Parkinsonism. Adult male Wistar rats were anesthetized before bilateral microinfusions of 6-hydroxydopamine (6-OHDA) into the substantia nigra. The sham group underwent the same surgical procedure but received vehicle. After 7 days, the mean arterial pressure (MAP) and heart rate (HR) were measured, and various drugs were injected into conscious rats through cannulas previously implanted in the femoral artery and vein. Spectral analyses of systolic arterial pressure (SAP) and pulse interval (PI) were conducted with the CardioSeries software as the spontaneous baroreflex gain and effectivity. The animals were subjected to α-, β-adrenergic, or muscarinic receptor antagonism. For confirmation of the lesion, the levels of dopamine in the striatum were quantified by high-performance liquid chromatography. Animals that underwent 6-OHDA microinfusion had lower MAP and HR compared with those in the sham group. Spectral analysis of SAP showed that 6-OHDA animals exhibited a decrease in the sympathetic component. The PI values did not differ between groups. After the administration of muscarinic and β-adrenergic antagonists, the cardiovascular measures did not differ between the groups. However, upon administration of the α-adrenergic antagonist, the 6-OHDA animals exhibited a lower decrease in the MAP. We report cardiovascular impairments in 6-OHDA animals, possibly due to decreased sympathetic activity. Determination of the origin of these changes (central or peripheral) requires further investigation.
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Ariza et al. (2014) studied Parkinson's disease model (dysautonomias). Bilateral microinfusions of 6-hydroxydopamine (6-OHDA) vs. Sham group (vehicle) was evaluated on Mean arterial pressure (MAP), heart rate (HR), and spectral analyses of systolic arterial pressure (SAP). Bilateral microinfusion of 6-OHDA in rats resulted in lower mean arterial pressure and heart rate compared to sham, alongside a decreased sympathetic component in spectral analysis.
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