Critical role of nitric oxide in expression of porcine LH receptor at transcription and post-transcription levels.

The present study was performed to clarify the involvement of nitric oxide (NO) in the expression of LH receptor in porcine granulosa cells. The granulosa cells, prepared from porcine ovarian follicles, were developed in the presence of FSH. LH receptor mRNA was induced to reach a maximal level after a 24-h culture with FSH, as determined by semi-quantitative reverse transcriptase-PCR (RT-PCR). In our previous report (Nishida et al., 2000), we found that NO was released from granulosa cells after a 40-48 h culture with FSH. When 200 microM NO scavenger was added to cultures before the NO release (30 h), the content of LH receptor on the cells decreased to 28% that of the control. However, the receptor content was not influenced by addition of NO scavenger at 46 h, or by 50 microM NO donor at 30 or 46 h. During transformation of mature granulosa cells to luteal cells, LH receptor mRNA was induced after a 24-h culture with LH, which induction was inhibited by removal of endogenous NO. However, the expression was not influenced by addition of either NO scavenger at 46 h or by NO donor. During the period of these treatments, cellular DNA contents were constant. Consequently, the transient generation of NO may play a critical role in expression of the LH receptor at transcription and post-transcription levels.