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Expression of 5HT-1A and 5HT-1B receptor genes in brains of Wistar-Zagreb 5HT rats

By selective breeding, two sublines of rats with extremely high or low values of platelet serotonin transporter (5HTt) activity have been developed (Wistar-Zagreb 5HT rats). Previous studies demonstrated significant differences between sublines in the expression of platelet 5HTt at the level of both mRNA and protein. Study on 5HTt gene expression in brains did not show significant differences between the sublines, although neuropharmacological studies indicated that changes in their brains might be expected. Here, we searched for possible adaptive/compensatory changes in expression of two 5HT receptors in physiological conditions and after chronic stress exposure. Studies were performed on females from the 15th breeding generation. A group of 9 animals from each subline was exposed to 9-day chronic stress consisting of: tail-suspension, isolation, forced swimming test, exposure to vibrations, immobilization, overcrowding and exposure to 24-hour light. On 10th day animals were sacrificed and RNA (from hippocampus and striatum) was isolated. Semi-quantitative RT-PCR was performed using three different housekeeping genes as reference (GAPDH,  -actin, cyclophylin B). Expression of 5HT-1A receptor gene was studied in hippocampus, and expression of 5HT-1B receptor gene in striatum. Sublines of Wistar-Zagreb 5HT rats showed no difference in expression of either 5HT-1A or 5HT-1B receptor gene, regardless of the housekeeping gene used. Similarly, chronic stress exposure did not result in any differences between the sublines. Alteration in serotonergic neurotransmission induced by up/downregulation of serotonin transporter did not result in change in expression of hippocampal 5HT-1A and striatal 5HT-1B receptors, either in physiological conditions or after chronic stress exposure.

serotonin receptor; gene expression; rat brain

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