Advances in Reproductive Endocrinology and Neuroendocrine Research Using Catfish Models.

Sonika Kar,Balasubramanian Senthilkumaran

doi:10.3390/cells10112807

Abstract

Catfishes, belonging to the order siluriformes, represent one of the largest groups of freshwater fishes with more than 4000 species and almost 12% of teleostean population. Due to their worldwide distribution and diversity, catfishes are interesting models for ecologists and evolutionary biologists. Incidentally, catfish emerged as an excellent animal model for aquaculture research because of economic importance, availability, disease resistance, adaptability to artificial spawning, handling, culture, high fecundity, hatchability, hypoxia tolerance and their ability to acclimate to laboratory conditions. Reproductive system in catfish is orchestrated by complex network of nervous, endocrine system and environmental factors during gonadal growth as well as recrudescence. Lot of new information on the molecular mechanism of gonadal development have been obtained over several decades which are evident from significant number of scientific publications pertaining to reproductive biology and neuroendocrine research in catfish. This review aims to synthesize key findings and compile highly relevant aspects on how catfish can offer insight into fundamental mechanisms of all the areas of reproduction and its neuroendocrine regulation, from gametogenesis to spawning including seasonal reproductive cycle. In addition, the state-of-knowledge surrounding gonadal development and neuroendocrine control of gonadal sex differentiation in catfish are comprehensively summarized in comparison with other fish models.

Highlights

This review summarizes the present knowledge and key evidence on catfish being used as research models for studying fish endocrinology
Key evidence of neuroendocrine control of gonadal development and sex determination/differentiation are discussed followed by understanding of steroidogenic regulation in catfish
Since the discovery of gonadotropin-releasing hormone (GnRH) in vertebrates over three decades, considerable progress has been made towards understanding of the neuroendocrine control of gonadal development and reproduction in mammals and fish which has been reviewed extensively by Zohar et al [16]

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Catfish (order Siluriformes) are diverse groups of ray-finned fish that are mostly benthic or bottom dwellers [1] and are named so for their prominent barbells that resembles a cat’s whiskers. They represent one of the largest groups of freshwater fishes. This review summarizes the present knowledge and key evidence on catfish being used as research models for studying fish endocrinology. Key evidence of neuroendocrine control of gonadal development and sex determination/differentiation are discussed followed by understanding of steroidogenic regulation in catfish. Wherever necessary the research findings from catfish models were compared with other teleostean counterparts for comprehensive review of literature

Neuroendocrine Regulation-GnRHs

GTH Duality

Serotonin

Neuropeptide Y

Gonad genesis

Gonadal Recrudescence and Sex Reversal

Gamete Maturation

Final Oocyte Maturation

Findings

Sperm Maturation