Pharmacological modification of the serotonergic transmitter system and beta-N-acetylhexosaminidase activity in rats

The enzyme activity and activation energy of plasma beta-N-acetylhexosamini dase (Hex) was determined in rats whose serotonergic system had been pharma cologically altered. In the group of animals treated with 5-hydroxytryptoph an, in the different dissected brain regions (brain stem, cortex and hippoc ampus) significantly higher levels of serotonin and 5-hydroxyindolacetic ac id were found, and significantly lower in the group treated with p-chloroph enylalanine. than in the control group. In the total number of animals stud ied (n = 21), a statistically significant correlation was found between the plasma concentration of 5-hydroxyindolacetic acid and the levels of this m etabolite in the different brain regions (p < 0.001). No significant differ ences were found for the activity of Hex in the plasma, or for its activati on energy, which is a marker of its isoenzyme composition, among the three groups of animals. The results obtained using our experimental model in rat s do not confirm the hypothesis of other authors who suggest that the Hex r esponds secondary to increases or decreases of serotonin turnover, and coul d be a biological test to monitor the serotonin status in psychiatric patie nts. (C) 2000 Elsevier Science Inc. All rights reserved.