| Different doses of cyclophosphamide(0,5,10,20mg/kg weight) andhydrocortisone(0,50,100,200mg/kg weight) were respectively injected into bodycavity of Chinese mitten crabs (Eriocheir sinensis) in test groups every5days for threetimes, to explore the conditions and methods of establishing experimentalimmunosuppression model of E. sinensis. A series of immune-related indicators wereexamined at1,4,7days after the third injection. Crabs were challenged with a virulentstrain of Aeromonas hydrophila (CL99920) at1.2×107colony forming units (cfu)/kgweight at the second sampling time (4d), and cumulative mortalities were recordedafter7days. The results showed that:(1) Most of the immunology parameters in the testgroups were significantly lower than the control group, and the hepatopancreas weredamaged. The10mg/kg body weight of cyclophosphamide and the100mg/kg bodyweight of hydrocortisone were more effective, by contrast.(2) Compared with thecontrol group, the injection of cyclophosphamide at10mg/kg body weight couldsignificantly reduce the total hemocyte counts (THC), phagocytic percentage (PP) andrespiratory burst of hemocytes, the activity of the phenoloxidase (PO), peroxidase(POD), lysozyme (LSZ), superoxide dismutase (SOD), acid phosphatase (ACP),alkaline phosphatase (ALP) in serum, and the activity of SOD, ACP, ALP inhepatopancreas (P<0.05). And it could improve the malondialdehyde (MDA) contentin hepatopancreas dramatically as well (P<0.05). Its effect on the phagocytic index (PP)of hemocytes was not evident (P>0.05). The group of10mg/kg and20mg/kg had thehighest cumulative mortality after the injection of A. hydrophila.(3) Compared with thecontrol group, the THC, PP, PP and respiratory burst of hemocytes, the activity of PO,POD, LSZ, ACP, ALP in serum, the activity of SOD, ACP, ALP in hepatopancreas of E.sinensis were decreased significantly in100mg/kg group (P<0.05). Meanwhile theMDA content in hepatopancreas were increased evidently (P<0.05). However, obvious differences were not observed in the SOD activity of serum. After the infectionof A. hydrophila, the cumulative mortality of100mg/kg group was the most. The resutssuggested that the injection of10mg/kg body weight of cyclophosphamide and100mg/kg body weight of hydrocortisone that implemented every5days for three timescan successfully establish the experimental immunosuppression model of E. sinensis.To study the immune regulation of bamboo shoots polysaccharides onimmunosuppressive E. sinensis that treated with cyclophosphamide, the crabs wereassigned to three groups, the control group, the natural recovery group, and thepolysaccharide recovery group. The crabs in the control group were injected with sterilesaline every5days for three times, while the crabs in test groups were injected with10mg/kg body weight of cyclophosphamide with the same method. All the crabs werefed with basic feed during the modeling, and the basic feed was replaced by the feedwith bamboo shoots polysaccharides (2g/kg basic feed) from the12d of the test in thepolysaccharide recovery group. A series of immunology parameters were examined at0,3,6and12days when the crabs in the polysaccharide recovery group was fed with thepolysaccharide feed. The results showed that:(1) The THC, respiratory burst ofhaemocyte, the activity of nitrie oxide synthase (NOS), PO, POD, LSZ, SOD, ACP,ALP in serum, and the SOD, ALP activity, the total antioxidant capacity (T-AOC) inhepatopancreas of the natural recovery group and the polysaccharide recovery groupwere evidently lower than the control group on day0(P<0.05). And their MDA contentin hepatopancreas were significantly higher than the control group (P<0.05). TheT-AOC in serum and ACP activity in hepatopancreas were also evidently lower than thecontrol group in the third day (P<0.05). These results suggested that the experimentalimmunosuppression model of E. sinensis was established successfully.(2) Thehaemocyte respiratory burst of E. sinensis could naturally recover to the same as thecontrol group in the third day. The activity of NOS could naturally recover to the levelof control group in the6th day. The THC, POD, ALP activity in serum could naturallyrecover to control levels in the12th day. The PO, LSZ, SOD, ACP activity, T-AOC inserum, and the SOD, ACP, ALP activity, T-AOC, MDA content in hepatopancreas werestill obviously lower than the control group in the12th day (P<0.05).(3) After fed withthe polysaccharides feed for the12days, the THC, respiratory burst of haemocytes,NOS, PO, POD, SOD, ACP, ALP activity and T-AOC in serum, the ACP activity,T-AOC, and MDA content in hepatopancreas of immunosuppressive E. sinensis were fully restored. And the THC, NOS, POD, ACP, ALP activity in serum and T-AOC inhepatopancreas were significantly higher than the control group (P<0.05), and the MDAcontent was significantly lower than the control group (P<0.05). The LSZ activity inserum and the SOD, ALP activity in hepatopancreas were not fully recovered, thatmeans the activity of the above3indicators were notably higher than the naturalrecovery group (P<0.05), but still notably lower than the control group (P<0.05). It isthought that the feed that with2g bamboo shoots polysaccharides per kg can effectivelyregulate the immune function of immunosuppressive E. sinensis that induced bycyclophosphamide. |
