Changes of ammonia and glutamine content in rat brain by electric shock of various duration

Abstract

A relationship between the excitation of the central nervous system by electric shock and the ammonia content in rat brain was studied.
It is convenient to use the apparatus as shown in Fig. 1 for giving electric shock to animals and immersing them into liquid air immediately. Ammonia and glutamine contents in rat brain which was frozen in liquid air under various conditions were measured by the microdiffusion method of Conway.
The ammonia content in brain was increased by the continuous electric shock for five seconds. And also an increase of ammonia was caused by the conditioning stimulus (light). When the continuous electric shock of longer than fifteen minutes was given, the ammonia content was not increased at all. Only on the case of continuous electric shock for thirty minutes, the increase of glutamine content was significantly recognized.
The facts above might be explained as follows : By the electric shock ammonia is formed rapidly in brain. At the same time the ammonia binding system also becomes active, and then glutamine synthesis which is formed from glutamic acid and ammonia is continued for one hundred and thirty minutes.
The second electric shock had no effect on an increase of ammonia content for one hundred and twenty minutes after the first electric shock. But when the discrimination conditioning was given to rats, the second electric shock became effective after sixty minutes.