Temporal oscillations of serum electrolytes in N-phthaloyl GABA-treated rats

N-Phthaloyl gamma-aminobutyric acid (P-GABA) has been known to cross the blood-brain barrier and ultimately to increase brain GABA level. In the present study, P-GABA was administered to Wistar rats for 21 days and circadian rhythms of sodium, potassium, and calcium levels in serum were studied under seminatural light-dark conditions. P-GABA administration caused desynchronization of the rhythms and advanced the peak times of serum electrolytes. Exogenously administered P-GABA could alter the photic information received by the clock. The results could be explained by slightly less or more than 1-h daily delays, which would bring the peak times to the points 21 days after the start of administration. The changes in amount of electrolytes after P-GABA administration are discussed.