Melatonin localization in human salivary glands

Area of Science:

• Endocrinology
• Cell Biology
• Histology

Background:

• Circulating melatonin is thought to enter body fluids via passive cell membrane crossing.
• Alternative, active transport mechanisms for melatonin remain hypothesized.
• Understanding melatonin's route to saliva is crucial for its physiological role.

Purpose of the Study:

• To provide ultrastructural evidence for melatonin transport by salivary gland cells.
• To identify potential pathways for circulating melatonin to reach saliva.
• To investigate the role of salivary glands in melatonin regulation.

Main Methods:

• Bioptic samples from parotid, submandibular, and labial salivary glands were obtained.
• Samples were processed for electron microscopy.
• Immunogold staining was used to detect melatonin reactivity.

Main Results:

• Melatonin reactivity was primarily observed in the granules and vesicles of serous cells.
• Acinar cells demonstrated the capacity to store melatonin.
• The parotid gland showed the highest involvement in melatonin release into saliva.

Conclusions:

• Salivary gland acinar cells actively store and release melatonin.
• Melatonin enters saliva through the exocytosis of granules and vesicles.
• The parotid gland plays a significant role in salivary melatonin secretion.