Increased Opiorphin in Burning Mouth Syndrome: Possible Disbalanced Androgen Regulation

Opiorphin, a rat sialorphin analog, is a mature product of proline rich, lacrimal 1 (PROL1) protein. It is an endogenous QRFSR-peptide that suppresses pain from chemically-induced inflammation and physical pain with efficiency similar to morphine, yet with fewer adverse effects. Burning mouth syndrome (BMS) is a painful chronic condition of unknown etiology, most often affecting menoupausal women. Levels of estrogen, progestones and androgens decrease following menopause. We suggest a relationship between disbalanced androgen regulation in menopausal women, BMS and opiorphin. It is known that SMR1 protein, PROL1 analog in rats, is encoded by the Vcsa1 gene, hormonally regulated by androgens. Expression of PROL1 gene in humans may be similarly regulated. Aim of this study was to measure opiorphin levels in patients with BMS in whole unstimulated saliva (WUS) and whole stimulated saliva (WSS) and to look for possible differences in opiorphin secretion between BMS patients and healthy controls, which could result from neuroendocrine disturbance.

Method:

Saliva was sampled from 29 patients with BMS (24 female, 5 male) and 29 age- and sex-matched control subjects (20 female, 9 male). Original methods comprising specimen deproteinization, freeze-drying, and liquid chromatography–electrospray ionization tandem mass spectrometry (LC–ESI-MS/MS) were used for quantification of salivary opiorphin.

Result:

Mean opiorphin concentrations in WUS and WSS in BMS were 8.13±6.45 and 5.82±3.59ng/ml, respectively. Mean opiorphin concentrations in WUS and WSS in control group were 5.02±2.59 and 4.99±3.21ng/ml, respectively. Salivary opiorphin was found to be significantly higher in the WUS of the BMS patients compared to the control group (t=2.413; p=0.0191). No statistical difference was found in the WSS samples between the two groups (t=0.924; p=0.3595).

Conclusion:

Increased opiorphin could play a role in the mechanism and symptoms of BMS. A further study measuring androgens in relation to opiorphin levels is planned to corroborate our hypothesis.