Temporal expression of Laminin-111 in the developing rat larynx

Area of Science:

• Developmental Neuroscience
• Molecular Biology
• Anatomy

Background:

• Laminin-111 (basement membrane protein) is crucial for motor neuron guidance.
• Netrin-1 (NTN1) interacts with laminin-111, modulating growth cone attraction/repulsion.
• Previous studies show increased laminin-111 and NTN1 after recurrent laryngeal nerve (RLN) injury, but developmental expression is unknown.

Purpose of the Study:

• To investigate the developmental expression of laminin-111 and NTN1 in rat laryngeal muscles during primary innervation.
• To compare developmental expression patterns with known post-injury expression.

Main Methods:

• Immunohistochemistry for βIII-Tubulin, laminin subunit α-1 (LAMA1), NTN1, and α-bungarotoxin on embryonic and adult rat larynges.
• Single-molecule RNA fluorescence in situ hybridization for LAMA1 mRNA.

Main Results:

• LAMA1 expression increased in most intrinsic laryngeal muscles at embryonic day 20.5 (E20.5), except the medial thyroarytenoid (MTA).
• At E20.5, LAMA1 expression was higher in the lateral thyroarytenoid (LTA) and posterior cricoarytenoid (PCA) than MTA.
• NTN1 upregulation at E16.5 was restricted to LTA and lateral cricoarytenoid (LCA), with no increase in MTA or PCA.

Conclusions:

• Developmental expression of LAMA1 and NTN1 in laryngeal muscles does not strictly follow innervation timing.
• These developmental patterns differ from those observed after RLN injury.
• Discrepancies highlight potential therapeutic targets for nerve injury by understanding developmental roles.