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Neuropeptide Y and the cerebral circulation
U I Tuor1, P A Kelly, L Edvinsson
1Biomedical Research Division, Hospital for Sick Children, Toronto, Ontario, Canada.
Summary
Neuropeptide Y (NPY) constricts rat cerebral arteries and reduces blood flow in the caudate nucleus, independent of glucose metabolism. This suggests NPY plays a key role in regulating blood flow in the brain.
Area of Science:
- Neuroscience
- Cerebrovascular Physiology
Background:
- Neuropeptide Y (NPY) is a peptide found in the nervous system.
- Its role in regulating blood flow within the brain (cerebral circulation) is not fully understood.
Purpose of the Study:
- To investigate the function of NPY in the rat's cerebral circulation.
- To determine if NPY affects local cerebral blood flow (CBF) and glucose utilization.
Main Methods:
- Used immunocytochemistry to locate NPY nerve fibers.
- Studied isolated rat cerebral arteries to observe NPY's contractile effects.
- Employed quantitative autoradiography to measure local CBF and glucose use after NPY injection.
Main Results:
- NPY nerve fibers were abundant around rat cerebral arteries, including those supplying the caudate nucleus.
- NPY caused concentration-dependent contraction of middle cerebral artery segments.
- Microinjections of NPY into the striatum significantly decreased blood flow in the caudate nucleus by 36% without altering glucose utilization.
Conclusions:
- NPY is present in perivascular nerves of the rat cerebral vasculature.
- NPY can directly contract cerebral arteries and reduce local blood flow.
- NPY may be a significant factor in regulating cerebral blood flow, potentially independent of metabolic demand.