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Effects of kainate during glutamine synthetase induction in chick embryo retina
Insights
Kainate enhances cortisol-induced glutamine synthetase in chick embryo retinas, unlike glutamate which inhibits it. This finding offers new insights into enzyme induction mechanisms in neural development.
Area of Science:
- Neuroscience
- Developmental Biology
- Biochemistry
Background:
- Cortisol prematurely induces glutamine synthetase in 12-day chick embryo retinas.
- Glutamate, a neurotransmitter, partially inhibits this cortisol-induced enzyme production.
Purpose of the Study:
- To investigate the effect of kainate, a glutamate analogue, on cortisol-induced glutamine synthetase in chick embryo retina.
- To compare the effects of kainate and glutamate on enzyme induction.
Main Methods:
- Chick embryo retinas at 12 days of development were used.
- Cortisol was applied to induce glutamine synthetase.
- Kainate or L-glutamate was added to the culture medium with cortisol.
Main Results:
- Kainate significantly enhanced cortisol induction of glutamine synthetase by a factor of 2.
- L-glutamate inhibited cortisol induction by 50-70%.
- Short-term kainate or L-glutamate treatment also sometimes enhanced enzyme levels.
Conclusions:
- Kainate acts as an enhancer, while glutamate acts as an inhibitor, in cortisol-mediated glutamine synthetase induction.
- These findings suggest distinct roles for glutamate and its analogue in regulating enzyme synthesis in the developing retina.
Abstract:
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.