The airway mucosa is known to be densely supplied with several types of peptidergic nerve fibers. The distribution of these fibers has been studied by conventional thin sections. In the present study, the distribution of substance
P-immunoreactive(SP-IR), vasoactive intestinal peptide-immunoreactive(VIP-IR), and neuropeptide Y-immunoreactive(NPY-IR) nerve fibers were demonstrated in the nasal mucosa and frontal sinus mucosa of cats, by using immunohistochemistry on whole
mount
preparations.
Thick posterior nasal nerve divided into many small bundles of axons containing immunoreactive fibers and non-immunoreactive ones. A large number of VIP-IR and moderate number of SP-IR nerve fibers, most of which had no varicosities, were found
in
nerve
bundles, whereas NPY-IR nerve fibers were hardlv found in nerve bundles. The immunoreactive nerve bundles divided again to make a single varicose axon. SP-IR nerve fibers were present in highest density in the epithelium and along the arterioles.
VIP-IR
nerve fibers were abundant around submucosal glands and arterioles. Venous vessels were also innervated by VIP-IR nerve fibers. NPY-IR nerve fibers were found exclusively around arterioles. SP-IR, VIP-IR, and NPY-IR nerve fibers were also found
in
frontal sinus mucosa.
Immunohistochemistry of whole mount preparations showed the detailed distribution of peptide-containing nerves, especially in the epithelium and different types of blood vessels. It may be useful to analyze changes of the neurons under various
stimuli
and in diseased conditions of airways.
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