The purpose of this study was to investigate the functional involvement of sympathetic nerve in the control of the microcirculation in the dental pulp with the aim of elucidation of the involvement of neuropeptides and sympathetic nerve in
neurogenic
inflammation.
Experiments were done on the 7 cats anesthetised with sodium pentobarbital, and sympathetic nerve to the dental pulp was stimulated electrically(10 Hz, 4V, 1.5ms, 3.5mins). Anα-adrenoceptor antagonist phentolamine and a neuropeptide Y antagonist
D-myo-inositol-1,2,6-trisphosphate (PP56) were injected close intra-arterially into the dental pulp without changing the systemic blood pressure. The probe of laser Doppler flowmeter was placed on the buccal surface of ipsilateral canine teeth to
the
stimulation, and pulpal blood flow was measured.
Stimulation of the sympathetic nerve decreased pulpal blood flow by 55.24±7.74%(mean±SEM, n=13).
Stimulation of the sympathetic nerve following the injection of the α-adrenoceptor antagonist phentolamine(0.1㎍/kg) caused decrease of pulpal blood flow by 14.35±3.43%(mean±SEM, n=5). Phentolamine attenuated the sympathetic nerve-induce
pulpal
blood
flow decrease by 74.02±9.32%(mean±SEM)
Stimulation of the sympathetic nerve following the injection of the neuropeptide Y antagonist PP56(2.3mg/kg) caused decrease of pulpal blood flow by 30.64±7.92%(mean±SEM, n=6). PP56 attenuated the sympathetic nerve-induced pulpal blood flow
decrease
by 44.37±11.01%(mean±SEM)
These data provide evidences of the co-contribution of nerepinephrine and neuropeptide Y on the sympathetic nerve-induced vasoconstriction in the feline dental pulp. In addition, they show functional evidences that sympathetic nerve plays an
active
role
in controlling the microcirculation of the dental pulp.
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