Neurohypophysial Hormones Regulate Amphibious Behaviour in the Mudskipper Goby.

Area of Science:

• Neuroendocrinology
• Fish Biology
• Amphibious Vertebrate Behavior

Background:

• Neurohypophysial hormones like arginine vasotocin (AVT) and isotocin (IT) regulate hydromineral balance and social behaviors in fish.
• In the amphibious mudskipper (Periophthalmus modestus), AVT specifically regulates aggressive behavior and water-seeking actions.

Purpose of the Study:

• To investigate the in vivo effects of AVT and IT administration on the amphibious behavior of mudskippers.
• To understand the role of these hormones in adaptation to dehydration and habitat preference.

Main Methods:

• Intracerebroventricular (ICV) injections of AVT or IT in mudskippers.
• Administration of an isotocin receptor antagonist alongside AVT or IT.
• Measurement of time spent in water and frequency of migration.
• Analysis of mRNA expression of AVT and IT precursors in brain tissue.

Main Results:

• ICV injection of AVT or IT increased the time mudskippers spent in water.
• Hormone administration decreased the frequency of migration, indicating a tendency to stay in water.
• Isotocin receptor antagonist blocked the effects of AVT and IT.
• Terrestrial conditions led to increased mRNA expression of AVT and IT precursors in the brain.

Conclusions:

• AVT and IT administration promote aquatic behavior in mudskippers.
• These hormones, particularly AVT, play a significant role in regulating amphibious behavior and dehydration adaptation.
• The induction of AVT and IT under terrestrial conditions suggests their involvement in aquatic habitat preference, potentially via brain isotocin receptors.