Physiological and haematological response of Oreochromis niloticus (Osteichthyes: Cichlidae) exposed to single and consecutive stress of capture

Abstract

ABSTRACT. This work is a sequence of studies on tropical fish of economic importance that evaluated the effects of two different stress of handling on the physiology and haematology of Oreochromis niloticus L. acclimated for 10 days before the essay. The stress consisted in net capture of all fish from each aquarium for 30s emersion. Fish exposed to single stress (SS) the samples were collected in the times 0, 10, 20, 30, 40, 50, 60, 120, 180, 240 and 300min. after stress. In the consecutive stress (CS) the samples were collected in the times 0; 15min. after the first stress; 15min. after the second stress; 15min. after the third stress and 15, 30, 45, 60, 120, 180 e 240min. after the fourth stress totalizing four stimuli every 60min. Fish exposed to SS showed increased cortisol and glucose concentrations at 60min. as well as in the leucocytes number and hematocrit at 50min. after stress. Cortisol did not alter in fish exposed to CS, but glucose increased 15min. after the third stress. On the other hand, CS provoked reduction in the leucocytes number and later hematocrit increasing. Neutrophilia and lymphopenia were related to SS and CS.Key words: Oreochromis niloticus, consecutive stress, cortisol, glucose, haematology. RESUMO. Resposta fisiológica e hematológica de Oreochromis niloticus (Osteichthyes:Cichlidae) exposto ao estresse único e consecutivo de captura. Este trabalho é seqüência de estudos com peixes tropicais de importância econômica avaliando os efeitos de dois tipos de estresse sobre a fisiologia e hematologia de O. niloticus L, aclimatados durante 10 dias antes do experimento. O estresse consistiu na captura de todos os peixes do aquário com rede e emersão por 30 s. Nos animais submetidos ao estímulo único de captura (EU) as amostras foram coletadas nos tempos 0, 10, 20, 30, 40, 50, 60, 120, 180, 240 e 300min. após o estresse. No estímulo consecutivo (EC) as amostras foram coletadas nos tempos 0; 15min. após o primeiro estresse; 15min. após o segundo estresse; 15min. após o terceiro estresse e 15, 30, 45, 60, 120, 180 e 240min. após o quarto estresse totalizando quatro estímulos a cada 60min. Os peixes expostos ao EU apresentaram aumento nas concentrações de cortisol e glicose 60min., bem como no número de leucócitos e hematócrito 50min. após o estresse. Não houve alteração do cortisol nos peixes do EC, mas a glicose aumentou 15min. após o terceiro estresse. Por outro lado, o EC provocou redução no número de leucócitos e aumento tardio do hematócrito. Observou-se neutrofilia e linfopenia após o EU e EC.

Hematology of juvenile pacu, Piaractus mesopotamicus (Holmberg, 1887) fed graded levels of mannan

“…Handling and sampling stress can ruled out as a causative agent of the variation in leukocyte numbers in the present study. Reduced lymphocyte numbers were described in stressed fishes (Pulsford et al, 1994;Martins et al, 2004) however, as opposed to our results, these authors observed an increase in neutrophils and leukocyte numbers. In fact, the contradictory results regarding neutrophil and leukocyte numbers occurs because the response depends on fish species, stress intensity, duration (Pickering et al, 1982;TavaresDias et al, 2001), nutritional condition (Pickering et al, 1982) and stressor (Davis & Schreck, 1997).…”

“…Elevated plasmatic glucose was also observed after stress capture in pacu (Abreu et al, 2009), rainbow-trout (Wells & Pankhurst, 1999), Nile tilapia (Martins et al, 2004), goldfish C. auratus (Dror et al, 2006), sablefish Anoploma fimbria (Lupes et al, 2006). Fish (L. rohita) fed glucan supplemented diets and submitted to consecutive blood sampling, as well as the same in the present experiment did not show any differences in blood glucose concentration during trial (Misra et al, 2006a(Misra et al, , 2006b) and this results are attributed to adequate managing during sampling and biometrics and not to prebiotic supplementation.…”

Protective effect of dietary vitamin E against fungicide copperoxychloride stress on Nile tilapia, Oreochromis niloticus (L.), fingerlings

“…The first portion was collected with anticoagulant 10 % EDTA (ethylenediaminetetraacetate) to measure hematocrit (Ht), hemoglobin (Hb) and white blood cells (WBCs). Ht was determined as described by Reitman and Frankel (1957), hemoglobin (Hb) was determined by the hemoglobin kits which is a standardized procedure of the cyanomet hemoglobin method as well as the total count of white blood cells (WBCs) was carried out by the indirect method (Martins et al 2004). The second portion of the blood sample was allowed to clot overnight at 4°C, centrifuged at 3,000 rpm for 10 min.…”

Acute inflammation and hematological response in Nile tilapia fed supplemented diet with natural extracts of propolis and Aloe barbadensis

“…Blood smears in duplicate were stained with a lood combination of Giemsa/May-Grünwald (Rosenfeld, 1947). The smears were used for differential leukocyte count and the total count of thrombocytes and leukocytes (Martins et al, 2004).…”

“…In fish, carrageenin, thioglycolate and inactivated Aeromonas hydrophila were tested in the swim bladder of Piaractus mesopotamicus (Martins et al, 2000;Moraes et al, 2003;Bozzo et al, 2007) and Oreochromis niloticus (Martins et al, 2004;Dotta et al, 2011). According to Bozzo et al (2007), thioglycolate and inactivated Aeromonas hydrophila induced vascular congestion, accumulation of thrombocytes followed by macrophages, granulocytes and oedema.…”