Signaling and Signal Transduction in Endocrine Tissues
(T734) DIFFERENTIAL DISTRIBUTION OF ADENYLYL CYCLASES IN THE RAT OVARY.
Grimshaw, S.1, Bagavandoss, P.1, 1 Kent State University Stark, Canton, OH
ABSTRACT- The development of mammalian ovary is regulated by a multitude of signals that act via both intracellular and plasma membrane receptors. Many hormones and cytokines acting through the G-protein coupled receptors, critically regulate the intracellular cyclic adenosine monophosphate (cAMP) by modulating the activity of adenylyl cyclases. At least, nine distinct isoforms of membrane-bound adenylyl cyclases have been characterized to date. However, the distribution of these enzymes in the ovary is not well understood. Therefore, in this study, we have examined the rat ovary for the presence of different adenylyl cyclases. Immature female Sprague-Dawley rats were primed with equine chorionic gonadotropin (eCG, 15 IU) in 100 microliters of phosphate buffered saline (PBS). Two days later, to induce ovulation, the rats were injected with human chorionic gonadotropin (hCG, 5 IU/100 microliters of PBS). The animals were sacrificed at selected intervals, the ovaries were removed and processed for cryostat sectioning. The sections were immunostained with various adenylyl cyclase antibodies. The control sections were incubated with antibodies preincubated with respective blocking peptides. ACI was localized to the granulosa cell plasma membrane (PM) and luteal cells. In the oocyte, only the nucleus showed ACI immunoreactivity. ACII was also found in the granulosa cells and the corpus luteum. ACIII was found primarily in the theca and in the interstitial blood vessels. ACIV was widely distributed in many cells. AC VIII was present in the granulosa cells. AC V/VI, VII, & IX were not consistently detectable in the ovary. Thus, the adenylyl cyclases are uniquely distributed within the rat ovary. Further, the presence of multiple isoforms of AC in granulosa and luteal cells indicates a potential for complex intracellular regulation of cAMP in these cells in response to multiple signals. The nuclear compartmentalization of AC in the oocyte also suggests the existence of subcellular amplification mechanisms for cAMP within the oocyte.
KEY WORDS: adenylyl cyclases, ovary