Fig. 4

Retrograde labeling of rostral ventrolateral medulla-projecting pPVN oxytocin neurons. Representative photomicrographs of coronal sections through the brain at the level of the PVN showing: a, b fluorescently stained retrogradely labeled cells and c, d fluorescently stained oxytocin-positive cells, e, f Bright-field c-Fos-positive cells and g, h the co-localization of retrograde label, oxytocin, and c-Fos-protein (yellow arrow) for MI rats (n = 8) and sham rats (n = 8). Inset: high-power magnification showing a close-up of neurons co-labeled for c-Fos + OT + retrograde tracer. Bar graphs (mean ± SEM) present the number of I retrogradely labeled cells, j retrogradely labeled + c-Fos-positive cells, k oxytocin-positive cells, l retrogradely labeled + oxytocin-positive cells, m retrogradely labeled + c-Fos-positive + oxytocin-positive cells, as well as the proportion (%) of n retrogradely labeled cells expressing c-Fos protein, o retrogradely labeled cells expressing oxytocin, and p retrogradely labeled cells expressing c-Fos and oxytocin, per section in the left parvocellular division of the PVN. ***P < 0.001 significant difference between MI rats (n = 8) and sham rats (n = 8; unpaired t-test). Scale bars = 25 μm. pPVN parvocellular paraventricular nucleus