[Phosphoethanolamine in the brain of the eurythermal pond fish Perccottus glehni (Eleotridae, Perciformes, Dyb. 1877)...

Effects of a seasonal decrease of environmental temperature and cold shock on pools of free amino acids (FAA) was studied in brain of the eurythermal pond fish P. glehni. It is for the first time that in the brain of eurythermal animals the nonprotein amino acid phosphoethanolamine (PEA) was revealed. It was found there in a large amount only under conditions of near-zero temperatures. It was shown that in the P. glehni brain, as a result of the seasonal decrease of temperature, the PEA pool rose intensively from 0.3 % at the summer period to 33.6 % in winter. On the contrary, the brain taurine pool that in the summer was the highest as compared with other FAA (29.0% of the total pool) decreased to 8.9% by the beginning of the winter period. The same negative correlation of the taurine and PEA amounts was found under action of acute cold shock (+1 degree C): throughout 4 days the taurine level also decreased from 32.2 to 14.5% of the total pool, whereas the PEA level rose swiftly (from 2.1 to 15.3%). Both kinds of the low temperature action led, apart from PEA, to an intensive increase of the serine pool and accumulation of phosphoserine. Role of PEA in biochemical evolution and adaptation of brain to low temperatures is discussed. It is suggested that accumulation of PEA, phosphoserine, and serine is associated with a change of the status of phospholipids of membrane at low temperatures.