OXYTOCIN INCREASES THE SURVIVAL OF MUSCULOCUTANEOUS FLAPS

The aim of the present study was to evaluate the effect of oxytocin on survival of musculocutaneous flaps in male Sprague-Dawley rats. For t his purpose oxytocin (0.1 or 1.0 mg/kg), an oxytocin nist(1-deamino-2- D-Tyr-(OEt)-4-Thr-8-Orn-oxytocin) (1,0 mg/kg) alone or in combination with oxytocin (1.0 mg/kg) or saline was given subcutaneously (s.c.), 2 4 hours and 1 hour before and 24 hours after flap surgery. In addition , oxytocin (1 mu g/kg) or saline was given intracerebroventricularly ( i.c.v.) according to the same schedule. Six days after surgery the amo unt of viable tissue was measured. Oxytocin 1.0 (but not 0.1) mg/kg s. c. and 1.0 mu g/kg i.c.v. increased survival of the flaps (s.c.: 13.8/-14.6% versus 6.10+/-5.45%; p<0.05 and i.c.v.: 25.5+/-14.0% versus 10 .3+/-5.79%; p<0.01). This effect was abolished by the oxytocin antagon ist. Furthermore, the oxytocin-treated rats had significantly higher p lasma levels of insulin-like growth factor-1 (IGF-1) (p<0.05). These d ata indicate that oxytocin increases the survival of musculocutaneous flaps. The effect seems to be exerted within the central nervous syste m since a 1000 fold lower dose of oxytocin given i.c.v. increased flap survival to the same extent as the s.c. given dose. IGF-1 might be on e of the mediators of this effect.