Abstract
Endocannabinoid system consists of two receptors (CB1, CB2), their endogeneous ligands and the enzymes responsible for their synthesis and degradation.
In our experiment we have exposed rats to cat odour to induce the ethologically relevant anxiety reaction in rats. The elevated zero-maze was also performed to test alterations of the emotional behaviour. The animals were killed and RNA was isolated from different brain regions. cDNA expression of genes involved in synthesis or degradation of endocananbinoids
(NAPE-PLD, FAAH, PLC and DAGLa, MGLL and receptor CB1) were analyzed in hippocampus, in amygdala and in mesolimbic structure using quantitative real-time PCR.
In control group the highest gene exspression level was in CB1 receptors. The FAAH ekspression was 2, 6 times higher in amygdala compared to mesolimbic structure. The MGLL expression in contrary was 6 times higher in mesolimbic structure compared to amygdala. DAGLa expression was 2 times higher than NAPE-PLD expression and there has been also shown that the level of 2-AG in brain is higher than the level of anandamide.
Unexpectedly, there were no significant gene expression changes in amygdala and in hipocampus in these animals exposed to cat-odour compared to the control group rats. Also, no differences of the gene expression were in rats preformed zero-maze compared to the control group. But, we found some gene expression changes in mesolimbic structure. There was higher (1, 4 times) CB1 gene expression level rats exposed to cat odour compared to the control group. Also, the expression of NAPE-PLD was 1, 6 times higher than the control group and the level of FAAH expression was 1, 8 times higher. Therefore, there is possible, that the endocannabionid system is more important in mesolimbic structure and anandamide, but not 2-AG synthesis mediates anxiety-related behaviour.