Current research and future perspectives of GH and IGFs family genes in somatic growth and reproduction of teleost fish

Abstract

The Growth hormone (GH)-insulin-like growth factors (IGFs) axis plays a central role as the endocrine regulator of physiological functions in teleost fish and other vertebrates. The basic mechanism of the GH-IGF system is well-known to be useful in a different manner, but it seems to operate differently between species. We have pointed out different aspects related to IGF family genes and their GH dependence that seems to vary according to species. We discussed the effects of nutritional status, and physiological functions of IGFs in teleost gonads to facilitate somatic growth as well as embryonic development and oocyte maturation regulation. We found that nutrients and diet composition are environmental factors that influence somatic growth. The effects of fasting and re-feeding serving as key factors in the expression of IGF genes in different tissues were briefly described, whereby we have found that prolonged fasting causes ceasing of growth but significant elevation of GH concentration. Also, the IGFs have been reported to play significant roles in regulating both male and female gonad development. In addition, IGF3 is constantly expressed throughout all stages of embryogenesis. Therefore, improving our knowledge and understanding of these interactions will impact the design of better feeding intake and reproduction approaches to maximize growth performance, fish well-being, and maximum production of teleosts. This study is intended as a summary to provide the reader with a modern, and unique perspective on the past, present, and future of IGF research in teleosts. Therefore, we expect that gaps of knowledge will be exposed and stimulate future research areas related to IGFs in teleost fish with respect to growth and reproduction as well as other physiological functions.