Increase in calcitonin gene related peptide (CGRP) and decrease in mast cells in dihydroepiandrosterone (DHEA)-induced polycystic rat ovaries

The polycystic ovary is reported to correspond with a high density in intraovarian nerve fibers and their sympathetic hyperresponsiveness. Peptidergic nerves may also be involved in this process. An interaction between nerve fibers and mast cells is assumed because of nerve growth-factor production by mast cells. Here we investigated CGRP-positive nerve fibers and mast cells in polycystic ovaries induced in immature rats with dihydroepiandrosterone (DHEA). The DHEA treated ovaries contained less corpora lutea than controls (mean±SEM: 4.3±0.6 versus 11.3±0.9, P >0.001) and less intact antral follicles (4.7±0.7 versus 8.1±1.1; P< 0.05) according to the histometric approach. By immunolabelling more CGRP-positive nerve fibers were found in the DHEA treated ovaries than in controls (mean±SEM per one section: 23.2±5.8 fibers versus 10.3±0.9 and 171±44.7 varicosities versus 84±9.5). This was confirmed by dot blot analysis, showing a significant higher CGRP signal intensity per microgram homogenized ovaries of the DHEA treated group compared to the untreated (P< 0.05). Toluidine-blue-stained mast cells populated the medulla in both groups, yet had strikingly decreased in the DHEA treated ovaries (23.5±3.9 versus 89±5.6, P< 0.005). Conclusion: the increase in CGRP-positive nerve fibers and the decrease of toluidine-blue-stained mast cells points to an altered neuroimmune function in DHEA-induced polycystic rat ovaries.