Aim: 

Flow mediated vascular dilation (FMD, "endothelial function") is reduced only in subjects with low hypnotizability (Lows) during mental stress and significantly more in Lows than in highly hypnotizable individuals (Highs) during nociceptive stimulation. The aim was to study the association between single nucleotide polimorphysms (SNP) of the gene coding endothelial NO synthase (eNOS3) with hypnotizability. In fact, the activity of local vasoactive factor, i.e nitric oxide, can be responsible for the FMD differences previously observed.

Methods: 

DNA was obtained from 24 Highs, 22 Lows and 90 newborns. Nine SNPs of the NOS3 gene were analyzed by direct sequencing using published primers (http://genecanvas.idf.inserm.fr/).

Results: 

Two SNPs located in the promoter region were significantly associated with differences in hypnotizability (rs1800783 allele T frequency: 0.40 in Highs, 0.66 in Lows, P=0.013; rs2070744 allele T frequency: 0.48 in Highs, 0.73 in Lows, P=0.020). The allele frequencies of both SNPs in the newborn sample were intermediate between Highs and Lows. Haplotype analysis showed that the newborns were in linkage equilibrium for these SNPs, whereas both Highs and Lows showed linkage disequilibrium. The A-C haplotype (associated with lower NO availability in the general population) was more frequent in Highs and the T-T haplotype was more frequent in Lows.

Conclusions: 

The lower FMD reduction observed in Highs during nociceptive stimulation, which is indicative of higher NO availability, should be due to greater efficacy of shear stress-related transcriptional factors and /or to lower effects of NOS inhibitory controls.