Objective To investigate the protective effects and underlying mechanisms of sodium butyrate on rats exposed to hypoxia and cold conditions.Methods Fifty-eight male SD rats (aged 7～8 weeks,weighing 240～260 g ) were randomly divided into normoxia normothermia saline control (NNC ) group (n=10),normoxia normothermia sodium butyrate(NNB)group(n=10),hypoxia cold saline control (HCC) group (n=19),and hypoxia cold sodium butyrate (HCB)group (n=19).The intragastric dose of sodium butyrate was 200 mg/kg for the NNB and HCB groups,while the NNC and HCC groups were given normal saline of 5 mL/kg.①After continuous intragastric administration for 7 d,the rats in the HCC and HCB groups were placed in a low-pressure hypoxic chamber to simulate an altitude of 5000 m and exposed to a temperature of 8 ℃ for 7 d.Subsequently,blood samples were collected from the abdominal aorta for blood gas analysis,blood routine test,and detection for serum biochemical indicators.ELISA was used to determine serum inflammatory cytokines and endocrine hormones.The rats in the NNC and NNB groups(n=10)were fed outside the chamber and underwent the same tests in 7 d later to evaluate the protective effects of sodium butyrate on the body.②Core body temperature monitoring was conducted to assess the impact of sodium butyrate on the rmoregulation in rats exposed to hypoxia and cold(n=3).③Hypoxia exercise tolerance of the HCC group and HCB group in a hypoxic chamber (11％O2 )was evaluated for their hypoxia resistance (n=6).Results Compared to the NNC group,the rats in the HCC group exhibited significant decreases in arterial oxygen saturation (SaO2 )and arterial oxygen partial pressure (PaO2 ),serum levels of IL-4,estradiol (E2)and cortisol (F),core temperature,and exercise duration (P<0.05),and had notably increased levels of red blood cell (RBC)count,hemoglobin (HGB),hematocrit (HCT),cardiac troponin (CRDAC-T),uric acid (UA),alanine aminotransferase (ALT),total cholesterol (TC),low-density lipoprotein (LDL),IL-6 and granulocyte-macrophage colony-stimulating factor (GM-CSF)(P<0.05).Compared to the HCC group,the rats in the HCB group exhibited significant increases in SaO2,PaO2,IL-4,E2,F,corticotropin releasing hormone (CRH)and adrenocorticotropic hormone (ACTH)(P<0.05),remarkably longer exercise duration under hypoxic exposure (P<0.05 ),but decreases in RBC count,serum levels of HGB,HCT,CRDAC-T,UA,ALT,TC,LDL,IL-6,GM-CSF and free thyroxine (FT4 ),and core temperature (P<0.05).Conclusion Sodium butyrate exhibits protective effects on rats exposed to hypoxia and cold conditions,and it is helpful in their adaptation to these hypoxia and cold environments.