In vivo effects of 2-substituted [Mpa1Sar7Arg8]-oxytocin antagonists on postpartum rat

A set of oxytocin antagonists consisting of [Mpa1Sar7Arg8]-oxytocin substituted by various conformationally restricted or bulky D amino acids at position 2 were synthetized and biologically tested. In in vivo pharmacological investigations, the effects of these peptides were examined on the spontaneous motor activity of postpartum rat. Three of the newly prepared peptides proved at least as effective in inhibiting uterine contractions as clinically investigated atosiban.