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Updated: Mar 12, 2026
Implantation of Combined Telemetric ECG and Blood Pressure Transmitters to Determine Spontaneous Baroreflex Sensitivity in Conscious Mice
Published on: February 14, 2021
Hippocampal subareas arranged in the dorsoventral axis modulate cardiac baroreflex function in a site-dependent
Nilson Carlos Ferreira-Junior1, Davi Campos Lagatta1, Denise Resende Fabri1
1Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, 14049-900, Brazil.
Insights
The hippocampus modulates the cardiac baroreflex, with dorsal regions facilitating and ventral regions inhibiting this function. This finding highlights the topographical organization of the hippocampus in cardiovascular regulation.
Area of Science:
- Neuroscience
- Cardiovascular Physiology
Background:
- The cardiac baroreceptor reflex is traditionally linked to brainstem areas.
- Forebrain regions, including the hippocampus, may also influence baroreflex function.
- The hippocampus exhibits functional and anatomical distinctions along its dorsoventral axis.
Purpose of the Study:
- To investigate the specific involvement of hippocampal subregions in modulating cardiac baroreflex function.
- To determine if the dorsoventral topographical organization of the hippocampus impacts baroreflex sensitivity.
Main Methods:
- Utilized CoCl2, a blocker of calcium-dependent synaptic neurotransmission, to inhibit specific hippocampal subareas.
- Administered CoCl2 into the dorsal hippocampus (DH), ventral hippocampus (VH), and intermediate regions.
- Assessed the effects of these localized inhibitions on cardiac baroreflex sensitivity.
Main Results:
- Inhibition of the DH enhanced cardiac baroreflex function.
- Inhibition of the VH diminished cardiac baroreflex function.
- Inhibition of intermediate hippocampal regions showed no significant effect on baroreflex response.
Conclusions:
- The hippocampus differentially modulates cardiac baroreflex function based on its dorsoventral topographical organization.
- The dorsal and ventral hippocampus play distinct, opposing roles in regulating baroreflex sensitivity.
- These findings support a topographical model of hippocampal influence on cardiovascular control.
New Findings:
What is the central question of this study? Classically, areas of the brainstem are involved in the cardiac baroreceptor reflex. However, forebrain areas, such as the hippocampus, may also modulate the cardiac baroreflex function. What is the main finding and its importance? According to the hippocampal subarea recruited dorsoventrally, the baroreflex function can be either facilitated or inhibited. These results are according to the new topographical division proposed for the hippocampus, i.e. it can be divided into functionally and anatomically different regions along its dorsoventral axis. From a neuroanatomical point of view, we may split the hippocampal formation into the dorsal (DH) and ventral hippocampus (VH). Although the basic intrinsic circuitry of the hippocampus seems to be maintained throughout its longitudinal axis, dorsal and ventral portions connect differently with cortical and subcortical areas and express different gene patterns, being functionally distinct. Differential stimulation of the DH or VH can evoke either an increase or a decrease in blood pressure, heart rate and sympathetic activity. However, to the best of our knowledge, specific involvement of the hippocampus and its different subareas in the baroreflex function remains to be investigated. In the present work, therefore, we evaluated the involvement of hippocampal subareas arranged on the dorsoventral axis in cardiac baroreflex modulation. Our results suggest that inhibition of hippocampal subareas by CoCl2 , a calcium-dependent synaptic neurotransmission blocker, differentially affects baroreflex sensitivity; administration of CoCl2 into the DH increased cardiac baroreflex function, whereas it diminished cardiac baroreflex function when administered into the VH. In contrast, administration of CoCl2 into intermediate portions of the hippocampus did not affect the baroreflex response. Our findings suggest that the hippocampus influences baroreflex function according to the hippocampal subarea recruited dorsoventrally.
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