Hippocampal subareas arranged in the dorsoventral axis modulate cardiac baroreflex function in a site‐dependent manner in rats

From a neuroanatomical point of view, we may split the hippocampal formation into the dorsal (DH) and ventral (VH) hippocampus. 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 (BP), heart rate (HR) 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. Therefore, in the present work, we evaluated the involvement of hippocampal subareas arranged on the dorsal-ventral axis in cardiac baroreflex modulation. Our results suggest that inhibition of hippocampal subareas by cobalt chloride (CoCl2), a calcium-dependent synaptic neurotransmission blocker, differentially affects baroreflex sensitivity: administration of CoCl2 into the DH increased cardiac baroreflex function, while it diminished cardiac baroreflex function when administered into the VH. On the other hand, administration of CoCl2 into intermediate portions of the hippocampus (IH) did not affect the baroreflex response. Therefore, our findings suggest that the hippocampus influences baroreflex function according to the hippocampal subarea recruited dorsoventrally. This article is protected by copyright. All rights reserved