A role of insular cortex in cardiovascular function

Abstract

We sought to determine whether the insular cortex contributes to the regulation of arterial blood pressure (AP). Responses to electrical and chemical stimulation of the cortex were studied in the anesthetized, paralyzed, and artificially ventilated Sprague-Dawley rat. The insular cortex was initially defined, anatomically, by the distributions of retrogradely labeled perikarya following injections of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) into the nucleus tractus solitarii (NTS). Injections of WGA-HRP into the insular cortex anterogradely labeled terminals in cardiopulmonary and other divisions of the NTS and confirmed projections revealed by retrograde tracing experiments. Electrical stimulation of the insular cortex elicited elevations of AP (less than or equal to 50 mm Hg) and cardioacceleration (less than or equal to 40 bpm). The locations of the most active pressor sites corresponded closely to the locations of retrogradely labeled cells in layer V of granular and posterior agranular areas of the insular cortex (areas 14 and 13) and the extreme capsule. Maximal pressor responses were obtained at a stimulus intensity of three to five times threshold current of 20-30 microA. Responses elicited mostly with higher-threshold currents were also mapped in areas 2a and 5lb and the claustrum and within the corpus callosum. Unilateral injections into the insular pressor area of the excitatory amino acid monosodium glutamate (L-Glu; 0.05 nmol to 10 nmol) or the rigid structural analogue of L-Glu, kainic acid (KA) (0.4 nmol) (which specifically excite perikarya), caused topographically specific elevations in AP and tachycardia. During the course of the anatomical transport studies, new findings were obtained on the organization and characteristics of the cortical innervation of the NTS and the nucleus reticularis parvocellularis. Topographic relationships between the cortex and the NTS were organized in a more complex manner than previously thought. Cells projecting to caudal cardiopulmonary segments of the NTS were fewer and generally located ventrally and caudally and in a more restricted area than cells projecting rostrally or to the parvicellular reticular formation. Anterograde transport data revealed new presumptive terminal fields in dorsolateral, ventral, periventricular, and commissural regions of the NTS, including an area overlapping the terminal field of the aortic baroreceptor nerve. We conclude that neurons within an area of the insular cortex projecting to multiple brainstem autonomic nuclei, including a region of the NTS innervated by baroreceptor afferents, increase arterial blood pressure and heart rate.(ABSTRACT TRUNCATED AT 400 WORDS)

Forebrain neural patterns associated with sex differences in autonomic and cardiovascular function during baroreceptor unloading

“…Among the forebrain structures responsible for the modulation of baroreceptor reflex action, the insular cortex has received the most focus (5,33,43). The role of the insular cortex in autonomic regulation appears to be lateralized, with the left side predominantly mediating depressor responses and the right insula regulating pressor actions (29,30).…”

Differential Columnar Processing in Local Circuits of Barrel and Insular Cortices

“…Tasteresponsive neurons together with low-threshold mechanoreceptive and wide-dynamic range neurons were mainly identified in layer V, whereas nociceptive-specific neurons were in layer II/III (Wang and Ogawa, 2002). The insular cortex is also involved in autonomic responses, because electrical stimulation of the insular cortex caused salivary secretion (Penfield and Boldrey, 1937;Cechetto and Saper, 1990), swallowing, throat sensation (Penfield and Boldrey, 1937), and changes in arterial blood pressure, heart rate (Ruggiero et al, 1987;Yasui et al, 1991), and gastric motility (Yasui et al, 1991). The neurons involved in these autonomic responses were found to be located in layer V (Ruggiero et al, 1987;Yasui et al, 1991).…”

Coronary artery disease affects cortical circuitry associated with brain-heart integration during volitional exercise

“…Importantly, the combined results indicate close homology between cortical sites identified experimentally in lower animals and those observed in humans (Cechetto 2014). These experimental studies indicate that the IC, MPFC, and HC are of particular relevance to HR control (Burns and Wyss 1985;Cechetto and Saper 1990;Fisk and Wyss 1997;Oppenheimer et al 1992;Owens and Verberne 2001;Ruggiero et al 1987;Verberne 1996;Yasui et al 1991). Anatomically, the MPFC and HC have a large number of direct connections with subcortical structures (Verberne and Owens 1998) and have been linked in connectivity analyses of functional magnetic resonance imaging data in humans (Norton et al 2013).…”