Neural calcitropic peptides: immunoreactive characterization in fish and invertebrates

Area of Science:

• Comparative Endocrinology
• Neurobiology
• Evolutionary Biology

Background:

• Parathyroid hormone (PTH) and stanniocalcin (STC) are traditionally recognized as endocrine hormones produced by specialized glands in vertebrates.
• Recent findings indicate extraglandular synthesis of these calcitropic peptides.
• The presence and function of PTH and STC in neural tissues across a wide range of species remain largely unexplored.

Purpose of the Study:

• To investigate the presence and characteristics of parathyroid hormone (PTH) and stanniocalcin (STC) in neural tissues of various vertebrates and invertebrates.
• To explore the potential evolutionary origins of PTH and STC as neuropeptides.

Main Methods:

• Western blot analysis was utilized to detect and characterize immunoreactive PTH-like and STC-like peptides.
• Neural tissues from a diverse array of species were examined, including mammals (rats), fish (hagfish, dogfish, rockfish, trout, skate), and invertebrates (starfish, squid, cuttlefish, snails, prawns).

Main Results:

• Immunoreactive PTH-like peptides, similar in size to PTH 1-84, were detected in the brains of rats and fish, as well as in snail ganglia.
• Immunoreactive STC-like peptides of varying molecular weights were identified in the brains of rats and fish, and in the ganglia of snails and prawns.
• These findings demonstrate the presence of PTH and STC in neural tissues across a broad phylogenetic spectrum.

Conclusions:

• Parathyroid hormone (PTH) and stanniocalcin (STC) are present in the neural tissues of diverse vertebrates and invertebrates.
• The detection of PTH and STC in neural tissues suggests they may function as neuropeptides.
• PTH and STC potentially represent ancestral neuropeptides, with their roles extending beyond traditional endocrine functions.