The ovulatory process in mammals involves gross physiological events in the ovary that cause transient deterioration of the ovarian connective tissue and rupture of the apical walls of mature follicles. This gonadotropin-induced process has features similar to an acute inflammatory reaction that affects most of the ovary. The present study reveals that the ovulatory events include induction of mRNA for pancreatitis-associated protein-III (PAP-III). Immature Wistar rats were primed with 10 IU equine chorionic gonadotropin s.c., and 48 h later the 12-h ovulatory process was initiated by 10 IU human chorionic gonadotropin (hCG) s.c. Ovarian RNA was extracted at 0, 2, 4, 8, 12 and 24 h after the animals were injected with hCG. The RNA extracts were used for RT-PCR differential display to detect PAP-III gene expression in the stimulated ovarian tissue. Northern blotting showed that transcription was significantly greater at 4-12 h after the ovaries had been stimulated by hCG. In situ hybridization indicated that PAP-III mRNA expression was limited mainly to the hilar region of the ovarian stroma, with most of the signal emanating from endothelial cells that lined the inner walls of blood vessels, and from small secondary follicles. Treatment of the animals with ovulation-blocking doses of indomethacin (an inhibitor of prostanoid synthesis) or epostane (an inhibitor of progesterone synthesis) revealed that ovarian transcription of PAP-III mRNA was moderately dependent on ovarian progesterone synthesis. In conclusion, the present evidence of an increase in PAP-III gene expression in gonadotropin-stimulated ovaries provides further evidence that the ovulatory process is comparable to an inflammatory reaction.
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S Yoshioka, S Fujii, JS Richards, and LL Espey
T. Endo, H. Fukue, M. Kanaya, M. Mizunuma, M. Fujii, H. Yamamoto, S. Tanaka, and M. Hashimoto
ABSTRACT
The present studies were carried out to investigate the effect of several growth factors on human endometrial stromal cells.
In human endometrial stromal cells, bombesin and bradykinin provoked an increase in intracellular free Ca2+ and in labelled inositol phosphates when pre-incubated with [3H]myoinositol. Some or possibly all of the initial increase in intracellular free Ca2+ represented a mobilization of Ca2+ from intracellular stores and the second phase of the response depended on Ca2+ influx from the extracellular medium.
[3H]Thymidine was added to human cultured endometrial stromal cells with bombesin, bradykinin, epidermal growth factor (EGF), prostaglandin F2α, vasopressin and platelet-derived growth factor. Bombesin, bradykinin and EGF stimulated the incorporation of [3H]thymidine into DNA in quiescent cells.
In conclusion, bombesin and bradykinin are growth factors which activate phospholipase C in human endometrial stromal cells, while EGF stimulates DNA synthesis without the activation of phospholipase C.
Journal of Endocrinology (1991) 131, 313–318
T. Tominaga, J. Fukata, Y. Naito, Y. Nakai, S. Funakoshi, N. Fujii, and H. Imura
ABSTRACT
We have examined the mechanism by which corticostatin-I (CS-I) acts to attenuate ACTH-induced steroidogenesis in rat adrenal cells. CS-I inhibited ACTH-induced corticosterone production in a dosedependent manner, without any effects on the basal corticosterone level in adrenal cells. When the cells were stimulated by 100 pg ACTH/ml, the minimum effective concentration of CS-I was 100 ng/ml, and 0.3–1.0 μg CS-I/ml produced a 50% reduction of the stimulated corticosterone production. The inhibitory effect of CS-I on ACTH-stimulated corticosterone production became apparent within 15 min of incubation, and the effect was reversed quickly by the removal of CS-I from the media. CS-I had no effect on angiotensin II-stimulated aldosterone production by adrenal zona glomerulosa cells. CS-I also did not affect cyclic AMP- or forskolin-stimulated corticosterone production. In an in-vitro binding study using 125I-labelled CS-I, CS-I showed considerable specific binding to rat adrenal cells, and the binding competed with ACTH in a dose-dependent manner. These experiments suggest that CS-I competes with ACTH on their binding sites and exerts an inhibitory effect on the adrenal cells.
Journal of Endocrinology (1990) 125, 287–292
Lawrence L Espey, Rebecca A Garcia, Haruhiro Kondo, Bunpei Ishizuka, Shinya Yoshioka, Shingo Fujii, Stephen Hampton, and JoAnne S Richards
This study assesses the relatively high incidence of the expression of paralogs of several pseudogenes within the cascade of expression of functional genes in the rat ovary in response to an ovulation-stimulating dose of gonadotropin. Immature Wistar rats were primed with 10 IU equine chorionic gonadotropin subcutaneously, and 48 h later the 12-h ovulatory process was initiated by 10 IU hCG subcutaneously. Ovarian RNA was extracted at 0, 2, 4, 8, 12, and 24 h after injecting the animals with hCG. The RNA extracts were used for RT-PCR differential display to detect gene expression in the ovarian tissue. Sequence analyses of differentially expressed cDNAs revealed that ∼27% (i.e. 22/82 clones) of the transcripts were fragments of paralogs of known pseudogenes. Out of the 22 clones reported here, 12 have high sequence similarity to the cytochrome P450 pseudogene Cyp21a1-ps, and 5 have high sequence similarity to both the Cyp21a1-ps and the aldo-keto reductase gene Akr1c6. The remaining five clones were paralogs of the endogenous retrovirus SC1 that has heavily infested the rat genome. Northern analyses reveal that peak expression of all the 22 paralogs occurs at 4–8 h into the ovulatory process. In situ hybridization shows that expression of these pseudogenes is primarily in the granulosa layer of ovulatory follicles. In summary, the results reveal that ovarian expression of Cyp21a1-ps- and SC1-like pseudogenes occurs concurrently with the ovulatory process.
