Rogulatory mechanism of Cerebral microcirculation

1997 Fiscal Year Final Research Report Summary

• Project/Area Number: 08670724
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Neurology
• Research Institution: KEIO University
• Principal Investigator: TANAHASHI Norio KIEO University Dept.of Internal Medicine Assistant Professor, 医学部, 講師 (10124950)
• Project Period (FY): 1996 – 1997
• Keywords: cerebral circulation / Neuropeptide Y / Photoelectric method / nitric oxide

Research Abstract

The effects of intracarotidly injected neuropeptide Y (NPY ; 0.1 mug/kg) on the local cerebral blood volume (CBV) and blood flow (CBF) in the parietotemporal cortex were examined by the photoelectric method in 17 anesthetized cats. CBV reflects the cumulative crosssectional area of the cerebral microvascular beds. NPY immediately caused transient but significant increase in CBV and CBF,which lasted for less than 5 min. Thereafter, CBV returned to and remained at the control level, although CBF was decreased by 30-40% for 60 min during the monitoring period. The CBV increases after NPY were prevented by a 15-min preinjection of 0.35 mg/kg/min of N^G-monomethyl-L-arginine (L-NMMA), which is a competitive blocker of nitric oxide synthesis. The CBV increases after NPY reappeared following a 15-min administration of 0.25 mg/kg/min of L-arginine, which is a precursor of nitric oxide. We conclude that NPY administered in vivo exerts a previously unreported effect of transient vasodilatation on the cerebral microvessels. This action appears to be mediated by mitric oxide, which is a major candidate as an endothelium-derived relaxing factor (EDRF).