Projects
10: Are organisational effects of estrogens on sexual differentiation, development and growth of fish mediated via the Insulin-like growth factor I (IGF-I) system?
Developmental interference of estrogens in fish.
Insulin-like growth factors (IGF), especially IGF-I, play a central role in the complex system that regulates growth, differentiation and reproduction. This project intends to clarify the role of IGF-I in mediating the influence of natural estrogens and xeno-estrogens on growth processes and gonadal differentiation of fish.
Reinecke Manfred, University of Zurich
e-mail: reinecke@anatom.unizh.ch
Background
Growth and reproduction are regulated by environmental factors, such as nutrition, temperature, season and endogenous hormonal signals. The insulin-like growth factor system, especially IGF-I, plays a central role in the complex system that regulates growth, differentiation, metabolism and reproduction in mammals. The major source of circulating IGF-I is the liver, but it occurs also in other organs like gonads and cartilage. The main trophic factor for IGF-I is growth hormone (GH). Most recently, studies in mammals have indicated that (xeno)estrogens may interfere via IGF-I with growth, differentiation and reproductive function. There is increasing evidence that similar mechanisms may exist in bony fish.
Aim
This project intends to clarify the role of IGF-I in mediating the influence of natural estrogens and xeno-estrogens on growth processes and gonadal differentiation of fish.
Significance
The hypothesis of our proposal that the endocrine-disrupting effects of natural estrogens and xeno-estrogens on growth processes and gonadal differentiation in fish are mediated via the IGF-I system is innovative. To date, only a few studies, mainly concentrating on mammals, have dealt with isolated parameters of the IGF-I system and xenobiotics. If we are able to verify our hypothesis, estrogens and estrogenic compounds must be considered to have a greater effect as endocrine disruptors than expected. They would interfere with an endocrine system that is a key part of numerous processes such as metabolism, reproduction, differentiation, growth, development and ageing. Our studies may provide an important basis for the risk assessment of endocrine disruptors.