The effects of NMDA on spontaneous motility and its development in chick embryos.
The effects of acute and chronic systemic application of N-methyl-D-aspartate (NMDA) on the spontaneous motor activity, its development and sensitivity to some drugs connected with the function of the NMDA-receptor were studied in chick embryos aged from 4 to 19 days of incubation. 1. The acute application of NMDA in doses from 20 to 50 mg/kg e.w. evoked in 15- and 17-day-old embryos the paroxysmal activation of spontaneous motility in chick embryos both normal and chronically decapitated (i.e. in spinal preparations). After chronic pre-treatment by ketamine (7.17 mg/kg e.w./24 h, from day 4 to day 12 or 16 of incubation) the activatory effects of acute NMDA application decreased and amounted two thirds of the value in control embryos. 2. As a result of damaged development of central motor generator the chronic application of NMDA (the average dosis of 2.55 +/- 0.25 mg/kg e.w./24 h) from day 4 of incubation to day 12 or 16 resulted in 17-day-old embryos in reduction of resting spontaneous motility on one hand, and in changed reactivity to acute application of NMDA (20 mg/kg e.w.) and ketamine (12.5 mg/kg e.w.) on the other hand: the activatory effect of NMDA was augmented, whereas the inhibitory effect of ketamine was diminished. On the contrary the response of spontaneous motility to acute application of glycine (100 mg/kg e.w.) and glutamate (15 mg/kg e.w.) remained unchanged. 3. Presented results are evaluated as the proof of possible participation of the NMDA-ergic mechanism in the genesis of embryonic spontaneous motility.
Sedlácek
J
J
Institute of Physiology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
D000818:Animals; D002642:Chick Embryo / Q000187:drug effects / Q000502:physiology*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D007649:Ketamine / Q000494:pharmacology; D009068:Movement / Q000187:drug effects / Q000502:physiology; D016202:N-Methylaspartate / Q000494:pharmacology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D016202:N-Methylaspartate; D007649:Ketamine