A short-term in vitro gill culture system to study the effects of toxic (copper) and non-toxic (cortisol) stressors on the rainbow trout, Oncorhynchus mykiss (Walbaum)

A short-term (24 h) method of gill filament culture system was developed to predict the effects of environmental contamination and stress in fish. Gill culture system containing two or three rainbow trout gill filaments in sterile glutamine supplemented Leibovitz 15 (L-15) media was submitted for 24 h to six different treatments: (i) CONT (control, medium only); (ii) CORT (cortisol, 0.28 μM cortisol); (iii) BLOCK (glucocorticoid receptor blocker, 14 μM RU 486); (iv) CORT + BLOCK (cortisol and blocker, 0.28 μM cortisol + 14 μM RU 486); (v) CORT + CU (cortisol and copper, 100 μM CuSO 4 + 0.28 μM cortisol); (vi) CU (copper, 100 μM CuSO 4). After 24 h, the overall gill structure and cellular components resembled those of salmonids in vivo. Lactate dehydrogenase (LDH) activity in the culture media increased in the CORT + CU and CU groups but was significantly lower in the CORT + CU compared to CU group. Apoptotic cells increased in the CORT and CORT + BLOCK. The numbers of glucocorticoid (GR) receptor-positive cells were lower in the CU group. This short-term culture system seems to be suitable for studying the effects of both external and internal stress effectors (toxicants and hormones respectively), as it contains all cell types found in the gills and the cells give similar biological response as in vivo.