Bicuculline activation of embryonic spontaneous motility

The activating effect of bicuculline on spontaneous central motor output activity was studied in chick embryos from the 11th to the 19th day of incubation by means of spontaneous motility. When applied onto the embryonic membranes, bicuculline [1 mg X kg-1 egg weight] significantly activated embryonic motility from the 15th day of incubation. In 15-day embryos it increased spontaneous motility 2.5-fold and in 17- and 19-day embryos 3.5-fold. The role of supraspinal factors in the activating effect of bicuculline increased with development. In 15-day embryos it accounted for 56.7% and in 17-day embryos for already 84.6% of the total effect of bicuculline. Antagonism was manifested between bicuculline and the inhibitory amino acids glycine and GABA; in the case of GABA it was quantitatively more pronounced. The results of this study of development of the activating effect of bicuculline and its antagonism with gamma-aminobutyric acid are evaluated from the aspect of the connecting-up and development of central GABA-ergic components in the regulation of embryonic motility.