Nitric oxide (NO) is involved in the regulation of endocrine functions, but only a few studies have been reported about its role in placental hormone secretion. We investigated whether NO has any function in the release of human chorionic gonadotropin (hCG) in two different choriocarcinoma cell lines, JEG-3 and BeWo. First, nitric oxide synthase (NOS) was characterized in the choriocarcinoma cells. NOS activity was localized mainly in the particulate fraction and depended on calcium/calmodulin. Activity was inhibited by the presence of the l-arginine analog, NG-monomethyl-l-arginine (L-NMMA; 1 × 10−4 m). Western blot analysis showed that the choriocarcinoma cells contained an endothelial isoform of NOS.
The NO donor, sodium nitroprusside (SNP; 1 × 10−5 and 1 × 10−4 m), significantly inhibited hCG secretion in both choriocarcinoma cell lines. The suppression of hCG release by SNP (1 × 10−5 m) was blocked by the addition of an NO scavenger, hemoglobin (1 × 10−6 m). l-Arginine (1 × 10−2 m), a NOS substrate, inhibited basal hCG secretion in JEG-3 cells. Incubation of the cells with L-NMMA (1 × 10−4 and 1 × 10−3 m) significantly increased hCG release. Exposure of both cell lines to increasing concentrations of a cyclic GMP analog (8-bromo-cyclic GMP; 1 × 10−4 to 1 × 10−2 m) caused a dose-dependent inhibition of hCG release. Cyclic GMP accumulation in response to SNP (1 × 10−4 m), however, was not detected in either JEG-3 or BeWo cells. These data demonstrated that the endothelial isoform of NOS and a functional l-arginine-NO pathway are present in the choriocarcinoma cell lines. In addition, these findings support the hypothesis that NO produced in these cell lines is involved in the regulation of hCG secretion. We assume that although cyclic GMP is likely to play a role as a second messenger, a cyclic GMP-independent pathway cannot be excluded as a possible physiological mechanism in the attenuation of hCG release by NO.
Journal of Endocrinology (1996) 150, 243–253
Journal of Endocrinology is committed to supporting researchers in demonstrating the impact of their articles published in the journal.
The two types of article metrics we measure are (i) more traditional full-text views and pdf downloads, and (ii) Altmetric data, which shows the wider impact of articles in a range of non-traditional sources, such as social media.
More information is on the Reasons to publish page.
| Sept 2018 onwards | Past Year | Past 30 Days | |
|---|---|---|---|
| Full Text Views | 3 | 2 | 0 |
| PDF Downloads | 3 | 1 | 0 |
Online ISSN: 1479-6805
Print ISSN: 0022-0795
Strengthening biomedical communities
to advance science and health
CONTACT US
Bioscientifica Ltd | Starling House | 1600 Bristol Parkway North | Bristol BS34 8YU | UK
Bioscientifica Ltd | Registered in England no 3190519
