Effects of kainate during glutamine synthetase induction in chick embryo retina.

This report concerns the effect of kainate on induction of glutamine synthetase in chick embryo retina. This enzyme can be prematurely induced in such retinas at 12 days of development by cortisol. Induction is 50-70% inhibited if 2.4 mM L-glutamate is added to the medium with cortisol for the 24-h induction period. Addition of kainate, an analogue of glutamate, enhances cortisol induction of glutamine synthetase by a factor of 2 under similar conditions. Kainate or L-glutamate treatment for 5 min (followed by incubation with cortisol for 24 h) also sometimes enhances retinal glutamine synthetase compared with untreated controls.