[Neurotrophins and pain in endometriosis]

To evaluate the expression of five members of the neurotrophins family in ovarian endometriotic cyst (endometrioma) (OMA), compared to eutopic endometrium (EE) and to examine the correlation between the levels of induction and the pain intensity.

Twelve Caucasian women in luteal phase, operated for painful stage IV endometriosis were assigned to 2 groups according to a total Visual Analog Scale (tVAS) score above 15 or below 10. tVAS takes into account all VAS scores for dysmenorrhea, deep dyspareunia, non cyclic chronic pelvic pain, gastrointestinal and lower urinary symptoms. Samples of OMA and EE were processed by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) for NGF, BDNF, NT-3, NT-4/5 and NTRK2 mRNA expression. Expression levels in OMA were compared to those in EE on one hand and between two groups of 6 mild painful and 6 highly painful patients on the other.

All neurotrophins were significantly higher expressed in OMA than in EE, in particular NGF and BDNF (induction ratios: 20.6 and 9.7, respectively). In contrast, no correlation was observed between induction ratios and pain intensity.

This is the first study reporting an over-expression of all neurotrophins in endometriosis, as only NGF was previously documented. It confirms the central role of this family in the genesis and modulation of pain in endometriosis. Anti-neurotrophin selective therapy might be a promising way of analgesia in the future.