title: Ventrolateral periaqueductal grey matter neurotransmission modulates cardiac baroreflex activity.
abstract: Baroreflex activity is a neural mechanism responsible for short-term adjustments in blood pressure (BP). Several supramedullary areas, which send projections to the medulla, are able to control this reflex. In this context, the ventrolateral part of the periaqueductal grey matter (vlPAG), which is a mesencephalic structure, has been suggested to regulate the cardiovascular system. However, its involvement in baroreflex control has never been addressed. Therefore, our hypothesis is that the vlPAG neurotransmission is involved in baroreflex cardiac activity. Male Wistar rats had stainless steel guide cannulae unilaterally or bilaterally implanted in the vlPAG. Afterward, a catheter was inserted into the femoral artery for BP and HR recording. A second catheter was implanted into the femoral vein for baroreflex activation. When the nonselective synaptic blocker cobalt chloride (CoCl2) was unilaterally injected into the vlPAG, in either the left or the right hemisphere, it increased the tachycardic response to baroreflex activation. However, when CoCl2was bilaterally microinjected into the vlPAG it decreased the tachycardic response to baroreflex stimulation. This work shows that vlPAG neurotransmission is involved in modulation of the tachycardic response of the baroreflex. Moreover, we suggest that the interconnections between the vlPAG of both hemispheres are activated during baroreflex stimulation. In this way, our work helps to improve the understanding about brain-heart circuitry control, emphasizing the role of the autonomic nervous system in such modulation.
authors.affiliation: Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Bandeirantes Avenue 3900, Ribeirão Preto, SP, 14090-900, Brazil.
authors.forename: Davi C
authors.initials: DC
authors.lastname: Lagatta
authors.affiliation: Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Bandeirantes Avenue 3900, Ribeirão Preto, SP, 14090-900, Brazil.
authors.forename: Nilson C
authors.initials: NC
authors.lastname: Ferreira-Junior
authors.affiliation: Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Bandeirantes Avenue 3900, Ribeirão Preto, SP, 14090-900, Brazil.
authors.forename: Milena
authors.initials: M
authors.lastname: Deolindo
authors.affiliation: Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Bandeirantes Avenue 3900, Ribeirão Preto, SP, 14090-900, Brazil.
authors.forename: Fernando M A
authors.initials: FM
authors.lastname: Corrêa
authors.affiliation: Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Bandeirantes Avenue 3900, Ribeirão Preto, SP, 14090-900, Brazil.
authors.forename: Leonardo B M
authors.initials: LB
authors.lastname: Resstel
mesh_terms: D000818:Animals; D017704:Baroreflex; D001794:Blood Pressure; D006321:Heart / Q000294:innervation / Q000502:physiology*; D006339:Heart Rate; D008297:Male; D010487:Periaqueductal Gray / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D009435:Synaptic Transmission
keywords: brain-heart control; cardiovascular control; reflex tachycardia; sympathetic response