Exp Clin Endocrinol Diabetes 2007; 115 - P01_005
DOI: 10.1055/s-2007-972261

Is there a role of Dopamine in the ovary? Functional studies in human granulosa cells

V Rey-Ares 1, C Mayer 1, C Roggors 1, D Berg 2, U Berg 2, L Kunz 1, A Mayerhofer 1
  • 1Anatomisches Institut der LMU am Biederstein, München, Germany
  • 2IVF-Labor A.R.T. Bogenhausen, München, Germany

Objectives: High levels of dopamine (DA) were described in human ovary (Lara et al., Endocrine, 2001) and DA receptors, namely D1 receptors in human granulosa cells (GCs; Mayerhofer et al., JCEM, 1999) and D1 and D2 receptors in horse follicles and Corpora lutea (King et al., Domest Anim Endocrinol, 2005) have hinted to a specific role of ovarian DA. Human GCs derived from women undergoing IVF are an adequate model for the follicle and the corpus luteum and were therefore employed in an attempt to decipher DA receptors and their functions.

Methods: Cells were obtained from patients undergoing IVF and examined using cDNA-array, RT-PCR, Western blotting and immunocytochemistry. In addition electron microscopy, a CASY cell counter and a commercial ATP assay were used, as well as calcium measurement (with FLUO-4) and confocal microscopy.

Results: We readily found D2 and D5 receptors in GCs, in addition to the expected D1 receptor. With regard to D2 receptor, two splice variants (D2L, D2S) were found by PCR and Western blot. The addition of the trophic hormone hCG (10 IU/ml) for several days to the culture medium did not affect mRNA or protein levels of D1/2/5 receptors. D1 receptors of GCs have been shown to be connected to cAMP and the same can be assumed for the related D5 type. D2 receptors also were functional, as DA raised intracellular Ca2+ levels. This Ca2+ mobilizing effect of DA was observed in the absence of extracellular Ca2+ and was abolished by a D2 blocker (L741626). When GCs were exposed to DA (1µM) for 48 hrs, we observed cells significantly bigger (about 20%) and metabolically more active. Furthermore, these cells exhibited ultrastructural features of active cells, implying a trophic action of DA. The D1/5 blocker (SCH23390) inhibited this action of DA, while a D2 blocker (L741626) was ineffective.

Conclusions: DA is present in human ovary and may act as a trophic factor on GCs. This action is attributable mainly to D1/5 receptors. The consequences of functional D2 receptors in the ovary remain to be elucidated.