[Effects of opioids on the development of preimplantation mouse embryos].

Opioid peptide DAGO, agonist of opiate mu-receptors and naloxone antagonist of mu-, delta- and kappa-receptors in concentration 3 x 10 M inhibit embryonic development of CBA mice. Inhibition was stage-specific with maximal effect after addition of opioids to zygotes: in the presence of Naloxone no more than 6.7% of embryos reached morula and blastula stages and in the presence of DAGO--36.8%. The other embryos were arrested at two-, four- or, sometimes even, at eight-cell stages without any signs of fragmentation. Four and eight-cell embryos were less sensitive to drug action. Inhibitory effects of these opioids were reduced when they were added simultaneously to zygotes. Agonist of opiate delta-receptors, opioid peptide DADLe, failed to affect embryonic development.