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.