Fig. 2: Mechanical and chemical activation of corneal mechano- and polymodal nociceptors induce a functional hyperaemia in the ipsilateral trigeminal ganglion. | Communications Biology

Fig. 2: Mechanical and chemical activation of corneal mechano- and polymodal nociceptors induce a functional hyperaemia in the ipsilateral trigeminal ganglion.

From: Ultrasound localization microscopy and functional ultrasound imaging reveal atypical features of the trigeminal ganglion vasculature

Fig. 2

a Schematic presenting the corneal afferents (C and A delta fibers) and fUS imaging of the TG. b, c Double staining CGRP (red)/vascular in toto staining (DiI, Green) showing that the TG is richly vascularized, especially in the ‘Cell Body Rich Area’ (CBRA), delineated by a dashed white line (b, c). The vascularization is on the contrary sparse in the ‘Nerve Fibers Rich Area’ (NFRA). Red arrowheads point at CGRP-positive sensory neurons located in the near proximity of stained blood vessels (white arrowheads). Panel c displays a high-power magnification taken in another animal. d–h Hemodynamic responses in the TG induced by mechanical stimulations of the cornea. d Example of Doppler image of the brain and trigeminal ganglion, imaged through an acute craniotomy, e map of Z-score and f: delta blood volume (BV) change in a representative example, illustrating the response in the medio-lateral part of the TG. Panel g shows the spatially averaged temporal changes in TG’s blood volume in the ipsilateral (red) and contralateral (blue) region of interest delineated by the Z-score. h Quantification of the changes in TG blood volume in 18 trains of stimulations, (obtained from 8 animals) reveals a significant hyperhaemia in the ipsilateral, but not contralateral TG. i–l Phasic hemodynamic response in the TG induced by activation of the TRPV1 polymodal corneal nociceptors by topical administration of capsaicin (10 μM). i–k Example of Z-score map (i), delta BV (j), and temporal changes of the TG’s blood volume (k) in the ipsilateral region of interest delineated by the Z-score in a representative animal. l Quantification of the changes in TG delta BV (N = 7 animals). For all panels, the region of interest (ROI) drawn in the contralateral side was the symmetrical ROI of the ipsilateral site. In h and l: results are presented an overlay of both boxplots (median, first and third quartiles) and individual values. The red crosses are outliers. *p < 0.05, **p < 0.01, ***p < 0.001. Scale bars = b: 200 μm, c: 100 μm, d, e, f, i, j: 2 mm. Panel b: A-P and M-L indicate the antero-posterior and the medio-lateral directions, respectively. They also apply to the panel c. The panel a was created with Biorender.com.

Back to article page