Effects of Starvation on Hematological Parameters and Hematogenesis in Myxocyprinus asiaticus

Hematological parameters are closely related to the response of the animal to the environment, an indication that the environment where fishes live could exert some influence on the hematological characteristics. Starvation is one of the stress factors that fish often undergo in their life history. There is a direct relationship between the resistance to some diseases and good nutritional state since fish immune systems are affected by nutritional state. Myxocyprinus asiaticus (Bleeker), Chinese suker, is a national protected species and an important resource for culture industry in China. Under this background, we observed the effects of starvation (0 to 60 days) on hematological parameters and hematopoiesis in Chinese suker. The specimens were (94.824.52) g in weight, 141-178 mm in length and maintained in tanks (10 individuals /m3) supplied with a continuous flow of normoxic water, at average temperature of 26.5(26-27.5℃). After the acclimation period (7 days), fish were separated into six groups of 10 individuals each. The control group was sampled just after the acclimation period. The other five groups were distributed over five individual tanks. Each group was then subjected to a different period of food deprivation (5, 10, 20, 30 and 60 days). The result showed that starvation had significant effect on physiological parameters, such as RBC, Hb, MCV, MCH and MCHC, but the influence on WBC and HCT was not significant in Myxocyprinus asiaticus. When Chinese sucker were deprived of food from 5 to 30 days, circulatory erythroid cells included large numbers of immature erythrocytes and young erythrocytes. The decreased number of erythroblasts suggests that food deprivation impaired erythrocyte production in Chinese suker. The ability of generating new erythrocytes almost lost after 60 days of food deprivation. Blood cells had achieved their maximum age concomitant with the low nutrient/energy availability to cell replacement. Bilobed erythrocytes were observed in the blood of healthy fish at a low frequency, but stressed fish at a high frequency. The presence of a high number of erythrocytes with segmented nuclei in Chinese suker starved for 30 days may indicate cell pathology resulting from malnutrition. Changes of hemoglobin content and hematocrit were consistent with the changes in number of erythrocytes. hematological parameters were all effected by starvation except cholesterol and aspartate aminotransferase.blood glucose is a sensitivity index to food deprivation. Continuous starvation caused significant changes of hematopoietic organs such as kidney, head kidney, spleen and liver. These included decreasing of cell volume, loosening of their cell arrangement, cellular atrophy and hematopoietic tissue disintegration. With the prolonging of starvation, the number of mature and degenerative blood cells increased significantly, and hematogonium and immature blood cells decreased in hematopoietic organs. Moreover, the function of hematopoiesis decreased, even lost finally. These changes coincided with the exhaustion of the main endogenous energy reserves. The period of 60 days of starvation seems critical to this species survival. The hematopoiesis and the senescence of existing erythrocyte were slowed down corresponding to starvation to slow down energy metabolism. It is possible that the preservation of existing erythrocytes and cessation of erythropoiesis is a strategy commonly employed by fish to tolerate starvation as an energy-saving mechanism. The biochemical parameters excepting cholesterol and aspartate aminotransferase were affected significantly by starvation.