Biochemical and Physiological Stress Responses to Heat Shock and Their Recovery in Labeo rohita Fingerlings

Abstract

Primary and secondary stress responses due to thermal stress and their recovery were tested in Labeo rohita. The fingerlings of L. rohita were exposed to 38 °C for 2 h and were allowed to recover afterwards. Samples (liver, muscle, gill and blood) were taken from control, after heat shock as well as after 2, 4, 8, 12, 24 and 48 h of recovery. Cortisol, tryptophan, blood glucose, glycogen, ascorbate and enzyme activities such as aspartate aminotranferase, alanine aminotransferase, lactate dehydrogenase, malate dehydrogenase, catalase and superoxide dismutase were tested in all the experimental groups. Significantly (p < 0.05) higher level of cortisol and glucose were observed after heat shock and a concomitant increase in the activity of transaminases, lactate dehydrogenase, malate dehydrogenase, catalase and superoxide dismutase were observed. However, reverse trend was observed in case of glycogen, l-tryptophan and ascorbate level. During acclimation aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase and malate dehydrogenase attained normal value in 24 h of acclimation whereas blood glucose, glycogen, cortisol and oxidative enzyme took 48 h. Serum tryptophan recovered to normal level only after 12 h of acclimation and ascorbate does not return to its normal value. Overall results indicate that L. rohita fingerlings exposed to heat shock of 38 °C for 2 h recovered to normal conditions after 48 h of acclimation.