Intravenous Oxytocin Does Not Affect Glucose-Regulating Hormones or Markers of Bone Turnover During Graded Glucose Infusion in Healthy Men.

AIM: Oxytocin has been proposed to exert glucose-stabilising effects via modulation of pancreatic hormone secretion and to play a role in bone homeostasis. However, human data under controlled conditions are limited. We investigated the effects of intravenously infused oxytocin during a graded glucose infusion on glucose-regulating hormones and markers of bone turnover in healthy men. MATERIALS AND METHODS: In a randomised, placebo-controlled, double-blind, crossover study, healthy men received intravenous infusions of oxytocin (0.1 or 0.2 IU/min, or placebo [saline], respectively) on three separate days during a three-hour intravenous graded glucose infusion with increases every 30 min (2-12 mg/kg/min). The primary outcome was baseline-subtracted area under the curve for C-peptide concentrations. Secondary outcomes included concentrations of plasma glucose, glucagon, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide 1 (GLP-1), carboxy-terminal collagen crosslink (CTX), procollagen Type 1 amino-terminal propeptide (P1NP) and serum triglycerides. RESULTS: Twenty men (age: 24.9 ± 3.2 years; BMI: 23.8 ± 1.5 kg/m2) were included. Peak plasma oxytocin concentrations: 193 ± 29 and 401 ± 66 pg/mL. Circulating concentrations of plasma glucose, C-peptide, glucagon, GIP, GLP-1, CTX, P1NP and triglyceride were similar across study visits. Neither oxytocin dose affected C-peptide response or any secondary metabolic outcomes compared with placebo. CONCLUSION: Acute intravenous oxytocin infusion resulting in supraphysiological plasma concentrations did not modulate pancreatic or gut hormone secretion, or markers of bone turnover during a controlled, stepwise glucose challenge in healthy men, suggesting limited acute metabolic and skeletal effects of oxytocin under these conditions.