VIP like immunoreactive nerves in human respiratory tract. Light and electron microscopic study

Area of Science:

• Respiratory System Biology
• Neuroanatomy
• Immunohistochemistry

Background:

• The innervation of the human lower respiratory tract plays a crucial role in regulating airway function.
• Vasoactive Intestinal Peptide (VIP) is a neuropeptide known to influence smooth muscle relaxation and glandular secretion.

Purpose of the Study:

• To investigate the presence and distribution of Vasoactive Intestinal Peptide (VIP)-like immunoreactive nerves in the human lower respiratory tract using light and electron microscopy.
• To provide anatomical evidence for the functional regulation of the lower airways.

Main Methods:

• Utilized the peroxidase antiperoxidase (PAP) technique for light and electron microscopical localization of VIP-like immunoreactivity.
• Examined tissue samples from the human lower respiratory tract, including bronchi, bronchioli, bronchial glands, and microganglia.

Main Results:

• VIP-like immunoreactive nerves were found in the smooth muscle layer of secondary bronchi to small bronchioli and within bronchial glands.
• A positive VIP nerve network was observed around nerve cell bodies in small microganglia.
• Bronchial epithelium did not show VIP-positive nerve fibers.
• Ultrastructurally, VIP-like immunoreaction was localized in large granular vesicles (90-210 nm) within nerve profiles.

Conclusions:

• This study provides novel light and electron microscopical evidence of VIP-like immunoreactive nerves in the human lower airway tract.
• The findings contribute to a broader understanding of the anatomical basis for the functional regulation of the human lower respiratory system.