University of Khartoum

Physiological Responses to Immobilization Stress in Relation to Gender, Heat Exposure and Supplementation of Antioxidants in the Domestic Rabbit (Oryctolagus cuniculus)

Physiological Responses to Immobilization Stress in Relation to Gender, Heat Exposure and Supplementation of Antioxidants in the Domestic Rabbit (Oryctolagus cuniculus)

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Title: Physiological Responses to Immobilization Stress in Relation to Gender, Heat Exposure and Supplementation of Antioxidants in the Domestic Rabbit (Oryctolagus cuniculus)
Author: Ahmed, Hadeel Sanhory Ibraheem
Abstract: The objective of the research was to evaluate the physiological responses of mature rabbits of both sexes to immobilization (IMO) stress and effects of gender on responses to IMO and administration of synthetic glucocorticoid dexamethasone phosphate (DXP). The effects of acute heat stress alone or in combination with immobilization, and alleviation by administration of Vitamin C or Vitamin E-Selenium were also investigated. The studies were carried out at the Department of Physiology, Faculty of Veterinary Medicine, University of Khartoum. A total number of 154 rabbits of both sexes (120 males and 34 females) were used. IMO was induced by fixing the rabbits in specially designed box. The parameters investigated were rectal temperature(Tr), heart rate(HR), haematological values including packed cell volume(PCV), total leukocyte count(TLC) and differential leukocyte count (DLC). Bloodc onstituents determined were plasma glucose, plasma total proteins, albumin, globulins, urea, creatinine, triglycerides, cholesterol, low density lipoprotein (LDL), high density lipoprotein (HDL), aspartate aminotrasferase (AST), alanine aminotransferase (ALT) and creatinine kinase (CK). The data were subjected to one-way and two-way ANOVA test using statistical analysis software (SAS, 2002).Experiment 1evaluated the effects of acute immobilization (AIMO) and chronic immobilization (CIMO) stress in rabbits, involving two trials using 20 male rabbits. AIMO was applied once (4hrs) and CIMO for 13 days(2 hrs daily). In trial 1, 10 male rabbits were assigned as control and AIMO groups. AIMO significantly (P<0.01) increaed TLC, neutrophils, glucose and cholesterol. In trial 2, 10 rabbits were used and arranged into control and CIMO groups. CIMO significantly (P<0.05) decreased TLC and increased serum ALT. In experiment 2, 68 rabbits of both sexes were used to evaluate the effects of gender on the responses to AIMO (trial1), CIMO (trial2) and DXP administration(trial 3). In trial 1, 20 rabbits were assigned into 4 groups (2 control and 2 AIMO). AIMO male rabbits had higher values of Tr, AST, ALT(P<0.01) and triglycerides (P<0.001) compared to the females. In trial 2, 20 rabbits were arranged into 4 gropups (2 control and 2 CIMO). CIMO male rabbits had significantly(P<0.01) higher values of glucose, triglycerides, LDL, AST and ALT compared to the females.In trial 3, 28 rabbits were used and divided into 4 groups(2 control,injected normal saline s/c and 2 DXP received single dose2mg/kg/BW DXP s/c). DXP treatment affected male rabbits more than females as evidenced by higher values of HR, globulins(P<0.01), urea(P<0.001), and lower values of PCV and basophils(P<0.001).In Experiment 3,66 male rabbits were used in three trials to investigate theeffects of acute heat stress(HS), immobilization and heat stress (IMO+HS) and administration of vitaminC (IMO+HS+Vit. C) or vitamin E-selenium(IMO+HS+Vit E-Se). HS was induced by exposing rabbits to direct solar radiation (≈370W/m2) for 1 hour (trial 1) and 2 hrs (trials 2 and 3). In trial 1, 18 rabbits were arranged in 3 groups (control, HS and IMO+HS). HS rabbits shows higher values of HR(P<0.01) compared to IMO+HS rabbits. For trial 2, 24 rabbits were used and assigned to 4 groups comprising control, HS, IMO+HS (received 2 doses normal saline)and IMO+HS+Vit.C (received 2 doses300 mg/kg/BW each Vit.C s/c).IMO+HS had higher effect compared to HS, as evidenced by significantly (P<0.01) higher values of Tr, HR, levels of glucose, albumin,urea and creatinine.Vit.C administration decreased Tr, and maintained HR and haematological parameters relatively constant and lowered the levels of glucose, urea, triglycerides, cholesterol, AST and ALT. In trial 3, 24 rabbits were used and assigned to 4 groups of control, HS, IMO+HS (received 2 doses normal saline s/c) and IMO+HS+Vit.E-Se (received 2 doses100 mg/kg/BW each Vit. E-Se s/c). IMO+HS had greater effects than HS alone. IMO+HS significantly (P<0.001) increased Tr, HR, ALT and CK. Administration of Vit.E-Se had limited effect as it decreased Tr,HR and maintained haematological parameters relatively constant. The study concluded that male rabbits were more susceptible to CIMO and DXP administration. Immobilization aggravated the negative effects of heat stress. Vit.C was more effective in alleviation effect of IMO+HS than Vit.E-Se.The study recommended that sex-specific differences should be considered when assessing the impact of stress in mammals. Modification of diet composition and supplementation of Vit. C and Vit.E-Se could be used to alleviate ofstress inmammals under tropical conditions. Future studies should explore the effects of breed and nutritional status of rabbits on the endocrine and immunological responses to immobilization and heat stress.
URI: http://khartoumspace.uofk.edu/123456789/26066


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