The influence of trait anxiety on the elevation of arterial pressure induced by l-NAME in rats

Abstract

Due to the high prevalence of anxiety disorders and hypertension comorbidity in the general population, the establishment of anxiety as a risk factor for elevated blood pressure, or the reverse, is of great relevance. In this context, animal models can be of great scientific value, as they permit the control of several variables. Bearing this in mind, the influence of anxiety, not as a state, but as a personality trait (trait anxiety), on blood pressure elevation and vice versa were investigated for the first time in rats, using the free-exploratory paradigm (FEP). Sixty adult male Wistar rats were evaluated on FEP and categorized according to their levels of anxiety. From this sample, 24 animals with high (n=12) and low (n=12) trait anxiety were allocated to two treatment groups: (1) l-NAME (NG-nitro-l-arginine methyl ester, 20mg/kg, p.o., for 7 days to increase blood pressure; n=6/anxiety category); (2) CTRL (tap water, p.o., for 7 days; n=6/anxiety category). During treatment, measurements of systolic blood pressure (SBP) were taken daily. After treatment, the animals were again tested on FEP. SBP and trait anxiety levels were compared pre- and post-treatment. Additionally, correlations between trait anxiety levels and SBP increases (l-NAME group) were analyzed. The results showed that l-NAME was able to induce significant SBP elevation, but only for the high-anxious animals, while SBP elevation did not significantly interfere with anxiety levels. A significant correlation between anxiety levels and SBP peaks in response to l-NAME was also shown. No differences were observed between the levels of anxiety before and after treatment. These findings suggest that individuals with high trait anxiety are more susceptible to increases in blood pressure, but that high blood pressure does not affect the levels of trait anxiety.