The Journal of Neuroscience, September 15, 2000, 20(18):6968-6973
Stellate Neurons Mediate Functional Hyperemia in the Cerebellar
Molecular Layer
Guang
Yang1,
Josee M. T.
Huard1,
Alvin
J.
Beitz2,
M. Elizabeth
Ross1, and
Costantino
Iadecola1
1 Center for Clinical and Molecular Neurobiology,
Department of Neurology, School of Medicine, and
2 Department of Veterinary Pathobiology, School of
Veterinary Medicine, University of Minnesota, Minneapolis, Minnesota
55455
Mice lacking cyclin D2 have a profound reduction in the number of
stellate neurons in the cerebellar molecular layer. We used cyclin
D2-null mice to study the contribution of stellate neurons in the
increase of cerebellar blood flow (BFcrb) produced by neural activation. Crus II, a region of the cerebellar cortex that receives trigeminal sensory afferents, was activated by stimulation of the upper
lip (5-30 V; 10 Hz), and BFcrb was recorded at the activated site by
the use of a laser-Doppler flow probe. In wild-type mice, upper lip
stimulation increased BFcrb in crus II by 32 ± 2%. The rise in
BFcrb was attenuated by 19% in heterozygous mice and by 69% in
homozygous mice. In contrast to the cerebellum, the increases in
somatosensory cortex blood flow produced by upper lip stimulation was
not attenuated in D2-null mice. The field potentials evoked in crus II
by upper lip stimulation did not differ between wild-type and D2-null
mice. Stellate neurons are a major source of nitric oxide (NO) in the
cerebellar molecular layer. The neuronal NO synthase inhibitor
7-nitroindazole attenuated the vascular response to crus II
activation in wild-type mice but not in D2-null mice, suggesting that
stellate neurons are the major source of NO mediating the vascular
response. The data provide evidence that stellate neurons are a
critical link between neural activity and blood flow in the activated
cerebellum and that NO is the principal effector of their vascular actions.
Key words:
cerebral circulation; cerebellum; laser-Doppler
flowmetry; vasodilation; glutamate; nitric oxide
Copyright © 2000 Society for Neuroscience 0270-6474/00/20186968-06$05.00/0
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