Catfish somatostatin is unique to piscine tissues

Area of Science:

• Comparative Endocrinology
• Molecular Biology
• Neuroscience

Background:

• Catfish islets possess two somatostatin forms: somatostatin-14 and catfish somatostatin (a 22-residue peptide).
• Catfish somatostatin is structurally related to somatostatin-14 but is the predominant form in catfish islets.

Purpose of the Study:

• To investigate the distribution of catfish somatostatin and somatostatin-14 in various catfish tissues.
• To examine the presence of these somatostatin forms in pancreatic tissues of non-piscine species.
• To explore potential differential gene expression of somatostatin in different tissues and species.

Main Methods:

• Utilized antisera specific to catfish somatostatin and somatostatin-14.
• Analyzed tissue extracts from catfish (islets, intestine, brain) and pancreatic tissues from anglerfish, frog, chicken, and rat.

Main Results:

• Catfish intestine showed high levels of catfish somatostatin, while catfish brain predominantly contained somatostatin-14.
• Catfish somatostatin was detected in anglerfish islet but absent in frog, chicken, and rat pancreatic tissues.
• Somatostatin-14 was abundant in the pancreatic tissues of frog, chicken, and rat.

Conclusions:

• Catfish somatostatin appears to be exclusively present in piscine (fish) tissues.
• The findings indicate a tissue-specific and potentially species-specific differential expression of somatostatin genes.
• This suggests distinct evolutionary and functional roles for the two somatostatin forms across vertebrates.