engleski

Wistar-Zagreb 5HT rats: study of serotonergic activity in brain regions

By selective breeding for the extreme values of platelet serotonin level and platelet serotonin uptake, two sublines of Wistar-derived rats: "low 5HT " and "high 5HT" subline, were developed in our laboratory (Wistar-Zagreb 5HT rat). In search for possible differences in brain serotonin homeostasis between the mentioned sublines, which were indicated in previous neurochemical and behavioral studies, levels of serotonin (5-hydroxytryptamine, 5HT) and its metabolite (5-hydroxyindoleacetic acid, 5HIAA) were measured in different brain regions of the animals from the selected sublines. Animals were decapitated and brain was frozen on dry ice for two minutes before isolation of particular brain region (prefrontal cortex, somatosensory cortex, entorhinal cortex, raphe nuclei, striatum, amygdala, hippocampus, thalamus, hypothalamus). Samples were homogenized, deproteinated with perchloric acid and centrifuged. Levels of serotonin and 5-hydroxyindoleacetic acid were determined in supernatant by high-perfomance liquid chromatography with electrochemical detection (HPLC-EC). N-methylserotonin was used as internal standard. 5HT and 5HIAA contents were expressed per milligram of wet brain tissue. Results. Serotonin content, as well as content of its metabolite (5HIAA) did not show significant differences between the sublines. However, the ratio between acid and amine, i.e 5HIAA/5HT, indicating serotonin turnover rate, demonstrated significant differences in several brain regions, higher values being related to brains of animals from the "high 5HT" subline. These results suggest that, in addition to the peripheral 5HT compartments, differences in central serotonin homeostasis between "low 5HT" and "high 5HT" subline also exist. It seems that animals from the "high 5HT" subline demonstrate higher serotonergic activity in their brains. However, this conclusion should be supported by additional neurochemical measurements on synaptic 5HT elements: 5HT transporter, 5HT receptors and 5HT-related enzyme activity.

serotonin; 5HIAA; rat brain; HPLC

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