K. Nario et al., THE ACTION OF SUBSTANCE-P METHYL-ESTER ON COCHLEAR POTENTIALS IN THE GUINEA-PIG, European archives of oto-rhino-laryngology, 252(1), 1995, pp. 42-47
The action of the substance P agonist, substance P methyl ester (SPME)
on cochlear potentials was examined in the guinea pig. Previous studi
es have shown that SPME is a selective agonist for neurokinin 1(NK1) r
eceptor. Perfusion with SPME at a concentration of more than 10(-6)M p
roduced an increase in the amplitudes of the compound action potential
and negative summating potential in a dose-dependent manner. N1 laten
cy showed a tendency to be shortened, but this change was not signific
ant. Amplitudes of the cochlear microphonics and endocochlear potentia
l remained unchanged. Substance P fragment 7-11, an inactive analogue,
produced no changes in the cochlear potentials. In contrast, the subs
tance P antagonist [D-Pro2,D-Trp7,9]-SP blocked the action of SPME on
the cochlear potentials. These results suggest that substance P may mo
dulate neurotransmission through NK1 receptors in the cochlea.