Interaction of xenobiotics with sex hormone binding globulin

National audienc

Binding and action of salmon growth-hormone (sGH) in the mature trout testis

International audienc

Evidence for binding and anction of growth hormone in trout testis

International audienceGrowth hormone (GH) binding to testis tissue and GH action on trout testicular cells were studied in vitro. Labeled salmon GH (sGH) was able to bind to a trout testis membrane preparation. Binding sites showed high affinity (Ka = 1-2 x 10(9) M-1) and low capacity (11 fmol/g fresh tissue) for 125I-sGH. Salmon GH and bovine GH, but not salmon gonadotropin, could compete with 125I-sGH for site occupancy. The binding characteristics were similar to those of trout liver GH receptors that we previously described. Salmon GH (0.1 and 1 microgram/ml) and bovine GH (10 micrograms/ml) could modulate steroidogenesis in cultured testicular cells: 17 alpha-hydroxy, 20 beta-dihydroprogesterone (17 alpha 20 beta OHP) accumulation in culture medium was stimulated by GH addition, and this effect increased with duration of culture and/or stimulation; 11-ketotestosterone accumulation tended to be inhibited in the presence of GH at the beginning of culture. These effects were dependent on GH concentration and were observed both in the absence and presence of gonadotropin. The amplitude of the sGH effect varied between experiments, probably according to the physiological state of the cells used. In vivo, GH and 17 alpha 20 beta OHP plasma levels increased at the beginning of spermiation (sperm production) and decreased at the end of spermiation. This relationship suggests that, at the end of the reproductive cycle, high GH levels are associated with the production of 17 alpha 20 beta OHP, a progestin necessary for efficient spawning in this species. We conclude that GH may play a role in testicular physiology, at least at certain stages of spermatogenesis

Insulin-like growth factor (IGF-I) mRNA and IGF-I receptor in trout testis and in isolated spermatogenic and sertoli cells

International audienc

Insulin-like growth factor (IGF-I) mRNA and IGF-I receptor in trout testis and in isolated spermatogenic and sertoli cells

International audienc

Growth hormone (GH) and gonadotropin subunit gene expression and pituitary and plasma changes during spermatogenesis and oogenesis in rainbow trout (Oncorhynchus mykiss).

International audienc

Sunlight nitrate-induced photodegradation of chlorotoluron: evidence of the process in aquatic mesocosms

absen

Tag retention and effects of PIT-tagging on survival and growth of Salmo trutta : preliminary results

Tag retention and effects of PIT-tagging on survival and growth of Salmo trutta : preliminary results. 1. International Workshop on PIT Telemetr