Abstract
In emotional processing, dopamine (DA) plays an essential role, and its deterioration involves important consequences. Under physiological conditions, dopamine exhibits brain asymmetry and coexists with various neuropeptides that can coordinate the processing of brain functions. Brain asymmetry can extend into a broader concept of asymmetric neurovisceral integration, including behavior. The study of the activity of neuropeptide regulatory enzymes (neuropeptidases, NPs) is illustrative. We have observed that the left and right brain areas interact intra- and inter-hemispherically, as well as with peripheral tissues or with physiological parameters such as blood pressure or with behaviors such as turning preference. To obtain data that reflect this integrative behavior, we simultaneously analyzed the impact of left or right brain DA depletion on the activity of various NPs in corticolimbic regions of the left and right hemispheres, such as the medial prefrontal cortex, amygdala and hippocampus, as well as on the plasma activity of the same aminopeptidase activities (APs) and on systolic blood pressure (SBP). Intra- and inter-hemispheric interactions as well as the interactions of NPs from the left or right hemispheres were analyzed with the same plasma APs and the SBP obtained from sham and from left or right lesioned rats. The results demonstrate a complex profile depending on the hemisphere considered. They definitively confirm an asymmetric neurovisceral integration and reveal a higher level of inter-hemispheric corticolimbic interactions including with SBP after left dopamine depletion.
Highlights
Dopamine coexists and interacts with other neurotransmitters, including various neuropeptides such as enkephalins, oxytocin, cholecystokinin or angiotensins, that may participate in the pathogenesis of the above-mentioned disorders that implicate DA
Noteworthy is the asymmetry observed in the significant correlations between oxytocinase activity (CysAP) in the left or right hemispheres of animals with left lesion and systolic blood pressure (Figure 6)
While CysAP in the right amygdala correlates positively with systolic blood pressure (SBP) (r = +0.882, p = 0.0007), CysAP in the left hippocampus correlates negatively with SBP (r = −0.723, p = 0.01). These results demonstrate an inverse behavior in the neurovisceral brain–cardiac interaction in animals with left DA depletion, but not in those with right DA depletion
Summary
The analysis of neuropeptidases and some biochemical factors in the brain as a whole or considering left and right brain hemispheres, in peripheral tissues and fluids together with cardiovascular or renal physiological functions, demonstrated asymmetrical effects and interactions between them under different experimental conditions. Captopril treatment changed the left predominance of correlations between neuropeptidases of the frontal cortex and aminopeptidases of ventricular tissue observed in untreated animals, and to the right in the treated ones. The present work essentially analyzes a possible pattern of asymmetrical neurovisceral interaction that involves intraand inter-hemispheric interactions between some corticolimbic structures and between such structures and systolic blood pressure (SBP), as a peripheral functional parameter, and plasma aminopeptidase activities in controls and left or right DA-depleted animals
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