Effect of inferior laryngeal nerve section on thyroid function in rats

Area of Science:

• Neuroendocrinology
• Physiology
• Thyroid Research

Background:

• The thyroid gland's function is influenced by neural regulation.
• The roles of sympathetic and parasympathetic innervation in thyroid physiology are not fully understood.

Purpose of the Study:

• To investigate the role of thyroid parasympathetic innervation, specifically the inferior laryngeal nerve (ILN), in thyroid function.
• To elucidate the interplay between sympathetic and parasympathetic nervous systems in regulating thyroid growth and secretion.

Main Methods:

• Inferior laryngeal nerve (ILN) section in rats to assess parasympathetic denervation.
• Administration of methylmercaptoimidazole to induce goitrogenic response.
• Thyroidectomy (hemi Tx) and superior cervical ganglionectomy (SCGx) in combination with ILN section.
• Measurement of thyroid [3H]choline uptake, serum T4 and TSH levels, and thyroid mitotic index.

Main Results:

• ILN section reduced thyroid [3H]choline uptake and impaired the goitrogenic response.
• Nerve sectioning led to decreased serum T4 and increased serum TSH levels.
• Sympathetic denervation (SCGx) enhanced thyroid growth and secretion, an effect partially blocked by ILN section.

Conclusions:

• Thyroid parasympathetic innervation plays a significant role in regulating thyroid growth and secretory activity.
• Both sympathetic and parasympathetic nerves are crucial for maintaining normal thyroid function and response to stimuli.