Blood Pressure Correlates Asymmetrically with Neuropeptidase Activities of the Left and Right Frontal Cortices

It was suggested that the brain-heart connection is asymmetrically organized. However, evidence connecting neurochemical factors from each brain hemisphere with changes in cardio-vascular functions have not yet been reported. In order to analyze potential asymmetrical connections between brain neurochemical factors with cardio-vascular functions, we studied the level of correlations between the left and right frontal cortex (FC) soluble (Sol) and membrane-bound (MB) neuropeptide-degrading enzymes alanyl (AlaAP), cystinyl (CysAP), and glutamyl (GluAP) aminopeptidase activities, involved among others in the metabolism of angiotensins, with heart rate (HR), systolic (SBP), and diastolic (DBP) blood pressure, in rats treated or not with hypotensive or hypertensive drugs such as captopril, propranolol or L-NAME. The present study suggests the existence of a bidirectional asymmetrical connection between these brain neuropeptidases and cardio-vascular functions. Specifically, depending on treatment, in control group, Sol AlaAP from the left FC correlates negatively with SBP and DBP. In captopril-treated animals, MB CysAP and MB GluAP from the right FC correlate negatively with HR. In L-NAME treated rats, Sol CysAP from the right FC correlates negatively with DBP. No significant correlations were observed in the propranolol group. Considering together all the values obtained from the left or the right cortex of the four groups regardless of drug treatment, the results demonstrated significant negative correlations between these neuropeptidase activities, mainly from the left frontal cortex, with the levels of systolic and diastolic blood pressure. Remarkably, these findings contrast drastically with previously reported results indicating significant positive correlations between the left frontal cortex with other peripheral functions such as water intake and diuresis. Both results represent noteworthy information that strongly supports the concept of a bidirectional asymmetric organization of neurovisceral integration involving left and right brain neurochemical processes with peripheral physiological functions, most probably mediated by the autonomic nervous system. Overall, the present results suggest that cognitive functions involving the frontal cortex may be asymmetrically connected with peripheral physiological processes, and vice versa.