Age- and sex-based hematological assays in rhesus monkeys

Abstract Objective: Currently, increasing use of rhesus monkeys has been observed in biomedical research, with their blood parameter assays acting as critical indicators. Since age and sex can influence blood parameters, establishing reference intervals for such parameters based on age and sex becomes vital along with identifying the effect of age and sex on those parameters. Methods: A total of 1385 rhesus monkeys were randomly chosen from the Kunming Institute of Zoology, Chinese Academy of Sciences. The rhesus monkeys were aged 0-32 years, which included all age ranges. Ketamine was used to anesthetize rhesus monkeys, followed by the collection of their blood samples by trained veterinarians. Blood aliquots were stored in EDTA anticoagulant and anticoagulant-free tubes. Subsequently, the serum was separated using centrifugation at 1600 g for 15 min, followed by blood biochemical analysis. It included routine blood examination (white blood cells, red blood cells, platelets, etc.), liver and kidney function test (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, etc.), creatine kinase (CK), glucose lipids, inflammatory factors (Interleukin 6, homocysteine, C-reactive protein), anemia indicators, bone metabolism, anti-Mullerian hormone (AMH), etc. along with the analysis of the effect of age and sex on these indicators. Comparisons between groups were performed using ANOVA while comparisons within groups were performed by the t-test. Correlations between 1 #These authors contributed equally to this work and were co-first authors. 2 *These authors are co-corresponding authors. two variables were tested and p<0.05 was considered statistically significant. Results: We established baseline indices for hematological and biochemical parameters based on age and sex, separately, and found significant impacts of age, sex, and age-sex interactions on blood parameters. Among different age groups, significant differences were found in white blood cell (WBC), neutrophil percentage (NEUT%), lymphocyte percentage (LYMPH%), eosinophil percentage (EO%), lymphocyte (LYMPH#), eosinophil (EO#), mean corpuscular volume (MCV), red blood cell volume distribution width-CV (RDW-CV), platelets (PLT), mean platelet volume (MPV), plate volume distribution width (PDW), plateletcrit (PCT), total protein (TP), albumin (ALB), globulin (GLB), albumin:globulin ratio (A/G), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin (T-BIL), gamma-glutamyl transferase (r-GGT), blood urea nitrogen ( UREA), creatinine (CREA), glucose (GLU), creatine kinase (CK), triglycerides (TG), low-density lipoprotein (LDL-C), homocysteine (XHCY), interleukin 6 (IL-6), folic acid (FOL), vitamin B12 (VB12), 25 hydroxyvitamin D (VITD-T), parathyroid hormone (PTH) and anti-Müllerian tubular hormone (AMH). Additionally, significant differences were observed in red blood cell (RBC), hemoglobin (HGB), hematocrit (HCT), mean platelet volume (MPV), albumin (ALB), blood urea nitrogen (UREA), creatinine (CREA), glucose (GLU), total cholesterol (TC), triglycerides (TG), high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C), homocysteine (XHCY), and 25 hydroxyvitamin D (VITD-T) between the two sexes. An age-sex interaction exerted a significant effect on white blood cell (WBC), neutrophil (NEUT#), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), plate volume distribution width (PDW), globulin (GLB), alkaline phosphatase (ALP), creatinine (CREA), total cholesterol (TC), triglycerides (TG), high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C), homocysteine (XHCY), interleukin 6 (IL-6), vitamin B12 (VB12), 25 hydroxyvitamin D (VITD-T). However, neither age, sex, and age-sex interactions exerted significant effects on monocyte percentage (MONO%), mean corpuscular hemoglobin (MCH), red blood cell volume distribution width-SD (RDW- SD), C-reactive protein (CRP), and calcitonin (CT). Conclusion: Our study investigated the blood parameters of rhesus monkeys to provide a reference basis for rhesus monkey-related scientific experimental research.