Regulation of Arctic char (Salvelinus alpinus) egg shell proteins and vitellogenin during reproduction and in response to 17beta-estradiol and cortisol

• Published in: General and comparative endocrinology Vol. 135; no. 3; pp. 276 - 285
• Main Authors: Berg, A H, Westerlund, L, Olsson, P E
• Format: Journal Article
• Language: English
• Published: United States 01.02.2004
• Subjects: Animals; Biologi; Biology; Blotting, Northern; Blotting, Western; Body Weight; Egg Proteins - blood; Egg Proteins - genetics; Egg Proteins - metabolism; Enzyme-Linked Immunosorbent Assay; Estradiol - blood; Estradiol - pharmacology; Estradiol - physiology; Female; Gene Expression Regulation, Developmental - drug effects; Gonads - anatomy & histology; Hydrocortisone - blood; Hydrocortisone - pharmacology; Hydrocortisone - physiology; Liver - anatomy & histology; Liver - chemistry; Membrane Glycoproteins - blood; Membrane Glycoproteins - genetics; Membrane Glycoproteins - metabolism; Molecular Sequence Data; Organ Size; Receptors, Cell Surface - blood; Receptors, Cell Surface - genetics; Receptors, Cell Surface - metabolism; Reproduction - physiology; Reverse Transcriptase Polymerase Chain Reaction; Salmonidae - genetics; Salmonidae - physiology; Seasons; Temperature; Vitellogenins - blood; Vitellogenins - genetics; Vitellogenins - metabolism; Zona Pellucida Glycoproteins
• ISSN: 0016-6480; 1095-6840
• DOI: 10.1016/j.ygcen.2003.10.004

Estrogens induce both vitellogenin (Vtg) and egg shell (zona pellucida; ZP) protein synthesis in salmonids. However, while Vtg is strictly under estrogenic control, recent reports suggest that additional mechanisms are involved in ZP protein synthesis. During sexual maturation both estrogen and glucocorticoid levels increase in the circulation of female fish. As glucocorticoids have been shown to interfere with Vtg induction in fish we investigated whether cortisol (F) had similar effects on ZP regulation. In the present study we determined both the natural variation in Vtg and ZP during an annual reproductive cycle in female Arctic char (Salvelinus alpinus), and the effect of co-treatment of juvenile Arctic char with 17beta-estradiol (E2) and F. During sexual maturation the expression of Vtg and ZP correlated to plasma levels of E2 and F. Determination of Vtg and ZP protein levels following co-treatment with E2 and F showed that F antagonized E2 induction of Vtg. However, F was observed to potentiate the expression of ZP protein in the same fish. These results indicate that in Arctic char Vtg and ZP proteins are not regulated by the same mechanisms and suggest that ZP protein expression does not necessarily imply exposure to estrogenic compounds alone, and may thus not be ideally suited as a biomarker of exposure to estrogenic compounds.