RESUMEN
The effects of two pyrethroid insecticides, cypermethrin and permethrin, on juvenile Senegalese sole, Solea senegalensis, were assessed. For this purpose, LC50 at 24 h and 72 h were determined as 500 μg L-1 and 900 μg L-1, respectively. The specimens were divided into 5 experimental groups exposed to: i) ethanol vehicle in sea water (control), ii) 1/25 of cypermethrin LC50 (20 μg L-1), iii) 1/10 of cypermethrin LC50 (50 μg L-1), iv) 1/25 of permethrin LC50 (36 μg L-1) and v) 1/10 of permethrin LC50 (90 μg L-1) during 10 days. At the end of the experiment, gill and hepatic samples were obtained for studying the expression patterns of different enzyme genes related to toxicity and osmoregulation, namely glyceraldehyde-3-phosphate dehydrogenases1 and 2 (GAPDH-1 and 2), and Na+, K+-ATPase subunits α and β (NKA α and β). Both pyrethroid insecticides enhanced gill GAPDH-1, NKA-α and NKA-β expressions. However, hepatic responses were less prominent. The low dose of cypermethrin decreased GAPDH-2 expressions. Also, the lowest permethrin dose decreased GAPDH-2 expression. These results indicate that pyrethroids induce some degree of oxidative stress in Solea senegalensis specimens led to an osmotic imbalance, activating -mainly at branchial level- different antioxidant and osmoregulatory enzyme genes.