| Abstrakt: |
The expression of the proenkephalin gene has been demonstrated in the reproductive tissues of several animal species. The objectives of the experiments reported here were to (a) examine the presence of immunoreactive methionine-enkephalin (ir-MENK) in rabbit ovary, oviduct, and uterus and in a rabbit endometrial cell line (HRE-H9), (b) characterize ir-MENK biochemically, (c) investigate the effect of eCG + hCG treatment on the synthesis and secretion of ir-MENK in vivo, and (d) study the effect of K+depolarization on the secretion of ir-MENK from HRE-H9 cells.Uterine fluid was collected by flushing the uterine lumen with saline. Reproductive tissues and HRE-H9 cells were extracted with 0.1 N acetic acid. Both the uterine fluid and extracts of uterus, ovary, oviduct, and HRE-H9 cells exhibited inhibition curves parallel to that of authentic MENK in the MENK RIA system. Sephadex G-15 gel filtration profiles indicated that in the extracts of rabbit uterus and HRE-H9 cells, most ir-MENK co-eluted with standard MENK, with a minor portion eluting near the void volume (Vo). Reverse-phase-HPLC (RP-HPLC) profiles showed a major peak coinciding with standard MENK, plus a minor peak of highly hydrophilic ir-MENK. The effect of eCG + hCG treatment was studied by i.m. injection of eCG (150 IU), followed by i.v. injection of hCG (75 IU) 4 days later. Ir-MENK concentration in the uteri and ovaries was significantly (p< 0.05) increased (9.06 ± 1.89 and 2.05 ± 0.32 ng/mg protein, respectively), compared to control levels (2.31 ± 0.86 and 0.24 ± 0.77). Treatment with eCG + hCG did not cause significant changes in ir-MENK concentrations in oviducts and uterine fluids. Secretion of ir- MENK from HRE-H9 cells increased due to depolarization by 15 mM of KCI after 1 h of incubation and reached its maximum level after 4 h. These results showed that ir-MENK is present in rabbit uterus, ovary, oviduct, and uterine fluid and also in HRE. H9 cells. The synthesis of ir-MENK in the ovary and uterus may be influenced by ovarian steroids, Secretion of ir’MENK from HRE-H9 cells can be stimulated by depolarization of cells with KCI. |
