EFFECT OF SUBSTANCE-P ADMINISTRATION ON VASCULAR-PERMEABILITY IN THE RAT ORAL-MUCOSA AND SUBLINGUAL GLAND

Neuropeptides, including substance P (SP) may play a role in neurogeni c inflammation. Although SP-immunoreactive (SP-IR) axons are known to be present within the oral mucosa (OM) and salivary glands, the functi onal significance of SP in oral mucosa and sublingual salivary gland ( SLG) is not fully understood. The present experiments were carried out to study the effects of SP infused into the left common carotid arter y on vascular permeability in the OM and in the SLG of male rats. Vasc ular permeability was assessed on the basis of Evans Blue extravasatio n. Separate groups of animals received histamine (Hi) receptor antagon ist (chloropyramine, 10 mg kg(-1) i.v.) or prostaglandin synthesis inh ibitor (indomethacin, 4 mg kg(-1) i.v.) prior to SP infusions. Infusio n of SP in doses of 30 and 74 pmol min(-1) increased the vascular perm eability of OM by 162.3+/-16.3% (n=8, p<0.05) and 482.7+/-46.7% (n=8, p<0.001), respectively. SP in a dose of 15 pmol min(-1) did not increa se Evans Blue extravasation in OM (38.3+/-4.0 pg g(-1), n=8, compared to the control: 44.0+/-7.9 mu g g(-1) n=8, NS). Although SP increased plasma extravasation in OM, it failed to affect vascular permeability in SLG (15 pmol min(-1) SP: 46.9+/-6.9 mu g g(-1), n=6, NS; 30 pmol mi n(-1) SP: 54.1+/-6.2 mu g g(-1), n=11 NS; 74 pmol min(-1) SP: 49.7+/-2 .3 mu g g(-1) n=7, NS; compared to the control: 48.9+/-5.8 mu g g(-1), n=8). After chloropyramine administration the SP effect on vascular p ermeability decreased in OM by 41.5+/-5.9% (n=10, p<0.05). Indomethaci n pretreatment similarly diminished the effect of SP on the dye extrav asation in OM by 43.9 +/- 6.1% (n=8, p<0.01). Our results suggest that the effect of SP on plasma extravasation in the oral mucosa is partly elicited via the release of vasoactive agents (histamine, prostagland ins), and the microvasculature of SLG has lower sensitivity of SP than that of the oral mucosa.