Figure 1.
TRPV1 receptor immunoreactivity in trigeminal ganglia in vehicle- and RTX- treated rats.
(A) TRPV1 receptor immunoreactivity is present throughout the ganglia in vehicle-treated but not in RTX-treated rats. One week following RTX treatment, TRPV1 receptor immunoreactivity is nearly abolished. After two and three-week survivals, TRPV1 receptor immunoreactivity is more evident but remains greatly diminished compared with vehicle-treated rats. Scale bar, 200 µm. (B) TRPV1 immunoreactive cell counts per section in the trigeminal ganglia in vehicle and RTX-treated rats. TRPV1 receptor cellular profiles are significantly decreased following RTX-treatment compared to vehicle treated at all survival times. Cell counts represented as mean ± S.E.M. Number of animals per group is indicated.
Figure 2.
CGRP immunoreactivity in trigeminal ganglia in vehicle- and RTX- treated rats.
(A) In vehicle-injected rats, CGRP immunoreactivity was evident in scattered small to medium sized neurons within the TG. RTX-treatment diminished CGRP immunoreactivity by 1 week of survival and further reduced positive profiles at two and three-week post RTX-treatment. Scale bar, 200 µm. (B) CGRP immunoreactive cell counts per section in the trigeminal ganglia in vehicle and RTX-treated rats. At all survival times (one, two and three weeks) following RTX treatment, CGRP positive cell counts are significantly reduced compared with vehicle-treated rats. Cell counts represented as mean ± S.E.M. Number of animals per group is indicated.
Figure 3.
Relative expression levels of TRPV1 and TRPA1 mRNA in trigeminal ganglia following RTX treatment.
RTX treatment induced a significant and similar reduction in both TRPV1 and TRPA1 mRNA expression levels at all survival times compared with vehicle injected controls. N = 4–9 animals per group.
Figure 4.
Blood flow changes in the middle meningeal artery following nasal administration of acrolein (A, B) or capsaicin (C, D) in RTX and vehicle injected animals.
(A, C) Representative traces of middle meningeal blood flow changes in response to nasally administered acrolein or capsaicin. Laser Doppler flowmetry measurements were collected at 1 Hz and filtered at 0.1 Hz for graphical representation. Nasal application of acrolein or capsaicin in vehicle injected animals induced a rapid and robust increase in meningeal blood which returned toward baseline values within minutes while similar application of acrolein or capsaicin in RTX treated animals induced a reduced blood flow response. Arrows indicate nasal administration of agonist. (B, D) Compared to vehicle treated controls, blood flow response to nasal acrolein or capsaicin was diminished at one week of treatment and significantly decreased at two and three weeks of RTX treated. Similar diminished blood flow responses were observed with capsaicin in RTX treated animals. Values are means ± S.E.M. Number of animals per group is indicated. P<0.05 compared to blood flow changes in saline-injected animals.
Figure 5.
Retrograde double labeling in the trigeminal ganglion.
Representative images two weeks following retrograde labeling of the nasal epithelium (Fluorogold; blue) and middle cerebral artery (MCA) (DiI; red). Numerous labeled cells were observed throughout the trigeminal ganglion and frequently retrograde labeled cells from the nasal mucosa were observed near to or adjacent to those from the MCA. Scale bar 100 µm.
Table 1.
Distance measurements between nasal epithelium sensory afferents (FG) and middle meningeal sensory afferents (DI) in the rat trigeminal ganglion.