Depletion of mucosal substance P in acute otitis media.
OBJECTIVE
The neuropeptide substance P (SP) is an inducer of neurogenic inflammation and bone resorption in the middle ear. Resorption of the bone tissue structures surrounding the middle ear cavity is a distinct feature of the initial stage of acute otitis media (AOM), which may be due to nerve fiber release of SP.


METHODS
To investigate possible release of SP in the middle ear mucosa during AOM, we used a well-established rat model of AOM caused by Streptococcus pneumoniae. Following tissue extraction on Days 1, 3 and 6 post-inoculation, the mucosal concentration of SP was measured using a radioimmunoassay.


RESULTS
Compared to sham-inoculated control ears, the concentration of SP was significantly reduced on Day 1 and even further reduced on Day 3, whereas partial replenishment was found on Day 6.


CONCLUSIONS
SP seems to be depleted in the rat middle ear mucosa in the hyperacute phase of AOM. This depletion is followed by replenishment and the concentration of SP approaches its normal level 6 days post-inoculation. The release of SP may be the trigger of the concurrent bone resorption and may further augment the inflammatory response to the bacterial colonization.
Cayé-Thomasen
Per
P
Department of Otorhinolaryngology, Head and Neck Surgery, Gentofte University Hospital of Copenhagen, Hellerup, Denmark. percaye@dadlnet.dk
Schmidt
Peter Thelin
PT
Hermansson
Ann
A
Holst
Jens Juul
JJ
Thomsen
Jens
J
D000208:Acute Disease; D000818:Animals; D001862:Bone Resorption; D004195:Disease Models, Animal; D008297:Male; D009092:Mucous Membrane / Q000378:metabolism*; D010033:Otitis Media / Q000378:metabolism*; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D013373:Substance P / Q000378:metabolism*; D013997:Time Factors
D013373:Substance P