Hippocampal subareas arranged in the dorsoventral axis modulate cardiac baroreflex function in a site-dependent manner in rats.
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 CoCl2into the DH increased cardiac baroreflex function, whereas it diminished cardiac baroreflex function when administered into the VH. In contrast, administration of CoCl2into 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.
Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, 14049-900, Brazil.
Nilson Carlos
0000-0003-1220-3465
NC
Ferreira-Junior
Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, 14049-900, Brazil.
Davi Campos
DC
Lagatta
Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, 14049-900, Brazil.
Denise Resende
DR
Fabri
Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, 14049-900, Brazil.
Fernando Henrique Ferrari
FH
Alves
Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, 14049-900, Brazil.
Fernando Morgan Aguiar
FM
Corrêa
Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, 14049-900, Brazil.
Leonardo Barbosa Moraes
LB
Resstel
D000818:Animals; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D003035:Cobalt / Q000494:pharmacology; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
D003035:Cobalt; C018021:cobaltous chloride
arterial baroreflex; autonomic nervous system; blood pressure; cobalt chloride; limbic system