other پژوهشي Orginal research papers To investigate the effects of carvacrol supplementation in rainbow trout induced by lipopolysaccharide (LPS), relative gene expressions levels of some pro-inflammatory cytokines and apoptosis markers in kidney and liver were measured. Fish with a mean weight of 44.71&plusmn;1.33 g were studied using four different treatments with three replicates each. Inflammation and apoptosis were performed using LPS of <em>Escherichia coli</em> (25 &micro;g ml^-1) except in the control group and only carvacrol (100 &micro;g ml^-1 diet) containing diets were fed to this group (CAR). The last group was the infected fish fed carvacrol supplemented diet (+CAR). Kidney and liver tissues were removed 3 days after to determine the levels of interleukin-1&beta; (IL-1&beta;), interferon gamma (INF-&gamma;), caspase 3 (Cas 3), caspase 8 (Cas 8) using Real-Time PCR analyses. IL-1&beta; expressions of both kidney and liver was significantly decreased (12.9 and 2.14 fold, respectively) in LPS treated cells (<em>p</em><0.05). While IFN-&gamma; expression was up regulated in kidney, it had down regulation in liver. LPS decreased both Cas 3 and 8 expressions in kidney but increased in liver. +CAR increased expressions of IL-1&beta; and IFN-&gamma; compared with the control (up to 2-3 fold) in all tissues except caspase gene expressions that were similar in the control. In all tissues, IL-1&beta; and IFN-&gamma; expressions increased in +CAR group, expect IFN-&gamma; in the kidney. However, Cas 3 and 8 expressions including apoptosis was induced by up-down regulations in all tissues compared to LPS-injected fish. The results showed that carvacrol had pro-inflammatory and apoptotic effects especially on liver tissue of LPS-induced inflammation model of <em>Oncorhynchus mykiss</em>.<br> &nbsp; Carvacrol, Caspases, Inflammatory cytokines, LPS, Rainbow trout 205 214 http://jifro.ir/browse.php?a_code=A-10-558-4&slc_lang=other&sid=1 A. Kucukgul azimekucukgul@hotmail.com 100319475328460029807 100319475328460029807 Yes Tunceli University, Fisheries Faculty, TR62000, Tunceli, Turkey Tunceli University, Fisheries Faculty, TR62000, Tunceli, Turkey A. Kucukgul 100319475328460029808 100319475328460029808 No Mustafa Kemal University, Veterinary Faculty, TR31000, Hatay, Turkey Mustafa Kemal University, Veterinary Faculty, TR31000, Hatay, Turkey İ. Gulsafak 100319475328460029809 100319475328460029809 No Tunceli University, Fisheries Faculty, TR62000, Tunceli, Turkey Tunceli University, Fisheries Faculty, TR62000, Tunceli, Turkey