Endothelin-1 inhibits basal and human chorionic gonadotrophin-stimulated progesterone production.

Endothelin-1 (ET-1) is a peptide classically produced by endothelial cells and known for its powerful vasoconstrictor activity. However, recent data suggest an involvement of ET-1 also in reproductive function. This study was designed to examine the possible presence and role of ET-1 in human luteal cells. Purified luteal cells were incubated for different times with ET-1 (10(-9)-10(-6) M) or ET-3 (10(-9)-10(-6)) alone or associated with human chorionic gonadotrophin (HCG) (100 ng/ml). Both basal and HCG-induced progesterone production were significantly reduced by ET-1 at all examined times whereas preincubation of luteal cells with BQ485 (10(-9)-10(-6) M), an ET-A receptor antagonist, prevented the inhibitory effect of ET-1. Conversely, no effect on progesterone synthesis was observed when ET-3 was added to the cultures. Luteal cells were then incubated for 24 h with phorbol 12-myristate-13 acetate (PMA) (100 ng/ml), an activator of protein kinase C. Inhibition of progesterone synthesis by PMA was similar to that induced by ET-1 alone. This study demonstrates that ET-1 negatively affects, at physiological concentrations, basal and HCG-induced progesterone synthesis. These effects seem to be exerted through the ET-A receptors and the protein kinase C pathway. Conversely, ET-3 was not able to influence human luteal steroidogenesis.

Effect of pituitary adenylate cyclase-activating peptide on meiotic maturation in follicle-enclosed, cumulus-enclosed, and denuded rat oocytes.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a novel bioactive peptide isolated from ovine hypothalamus. Recently, its presence and action have been demonstrated also in peripheral tissues such as testis and ovary. On the basis of sequence similarity, PACAP is included in the vasoactive intestinal peptide (VIP)/glucagon/secretin/growth hormone-releasing factor (GRF) family of neuropeptides. Because both VIP and GRF stimulate oocyte maturation in the rat ovary, we wanted to evaluate whether PACAP also could influence this process. Granulosa cells and follicle-enclosed, cumulus-enclosed, and denuded oocytes were obtained from immature eCG-treated rats. The addition of PACAP-38 significantly accelerated meiotic maturation in follicle- and cumulus-enclosed oocytes from treated rats and in follicle enclosed-oocytes from immature untreated rats, while VIP was effective only on follicle-enclosed oocytes. Interestingly, when used on denuded oocytes, PACAP was able to directly affect the meiotic process. In fact, the neuropeptide delayed oocyte maturation by maintaining elevated levels of intracellular cAMP. Our results clearly demonstrate an involvement of PACAP in oocyte meiotic maturation. Furthermore, for the first time, a direct effect of a peptide on the oocytes has been shown. Moreover, the differences in the action of PACAP and VIP on granulosa cells and oocytes suggest the presence of PACAP type I receptors on both cell types. Our results, along with the data demonstrating the presence of the peptide in the ovary, strongly suggest a potential relevance of PACAP in ovarian physiology.

Control of human luteal steroidogenesis: role of growth hormone-releasing hormone, vasoactive intestinal peptide, and pituitary adenylate cyclase-activating peptide.

OBJECTIVE: To examine the possible effect of growth hormone-releasing hormone (GHRH), vasoactive intestinal peptide, and pituitary adenylate cyclase-activating peptide on basal and hCG-stimulated P production by human luteal cells. DESIGN: Cultures of human luteal cells from the early and midluteal phase. SETTING: All corpora lutea were obtained from the Obstetrics and Gynecology Department of the Università Cattolica, a public care center. PATIENT(S): Ten nonpregnant women between 35 and 47 years of age underwent surgery for various nonendocrine disorders, such as leiomyomatosis. INTERVENTION(S): Corpora lutea were obtained at the time of hysterectomy. MAIN OUTCOME MEASURE(S): Luteal cells were incubated with GHRH, vasoactive intestinal peptide, and pituitary adenylate cyclase-activating peptide with or without hCG at different concentrations. RESULT(S): Pituitary adenylate cyclase-activating peptide stimulated P production in a dose- and time-dependent manner, whereas GHRH and vasoactive intestinal peptide did not affect luteal steroidogenesis. None of the three peptides were found to synergize with hCG. CONCLUSION(S): Pituitary adenylate cyclase-activating peptide can influence human luteal steroidogenesis.

Site-dependent survival in cancer of the oral cavity.

A series of 100 patients affected by primary squamous cell carcinoma of the oral cavity treated at the Ear, Nose, and Throat Clinic of Ferrara from January 1980 to December 1989 was considered in this retrospective study. Data set was classified according to Union Internationale Contre le Cancer staging system. Results showed a crude survival rate at 5 years of 54%. Tumor site of origin and N, adjusted for sex and age of patients were the most important prognostic variables for survival rate. T stage and therapy did not achieve a significant value in the correlation with survival rate when used as covariates in multivariate analysis. The present study demonstrates that survival decreases the closer the tumor origin is to the inner sites of the mouth and in relation to N status. In cases with these characteristics, multimodality treatment protocols are useful in improving survival.

Growth hormone stimulates androsterone synthesis by rat theca-interstitial cells.

The aim of this study was to assess the possible role of growth hormone (GH) on androsterone synthesis. This effect was analyzed in theca-interstitial cells obtained from immature female rats. The addition of GH to the cultures significantly stimulated androsterone (A) synthesis in a dose- and time-dependent way and this effect was not due to a cellular number increase. When added to the hCG cultures, GH significantly enhanced androgen production even though it did not synergyze with the chorionic gonadotropin. The addition of antibodies anti-IGF-I to the GH cultures did not modify the growth hormone effect suggesting that GH probably does not require IGF-I to achieve its effect on A production. Finally, no effect of GH on cAMP levels were observed in the cultures at the end of the treatment. Our results demonstrate that GH is able to significantly induce A synthesis by rat theca-interstitial cells. Since the presence of GH and its receptors in the ovary is now well established the present data strongly suggest a potential relevance of GH in reproductive biology.

Growth hormone-releasing factor stimulates meiotic maturation in follicle- and cumulus-enclosed rat oocyte.

This study was designed in order to assess the possible role of growth hormone-releasing factor (GRF) on oocyte maturation. This effect was analyzed in follicle-enclosed, cumulus-enclosed and denuded oocytes obtained from immature pregnant mare's serum gonadotropin-treated rats. The addition of GRF to the cultures significantly accelerated maturation in follicle- and cumulus-enclosed oocytes while no effect was seen on denuded oocytes. Also, the neuropeptide was able to induce maturation in follicle-enclosed oocytes obtained from immature untreated rats. The GRF action was probably not mediated by the vasoactive intestinal peptide (VIP) receptors since the two hormones had different effects on oocyte maturation and on cAMP production by granulosa cells. In addition the disappearance of the GRF effect observed in the presence of antibodies anti-GH suggested that GRF required the intermediacy of GH to accomplish its effect on oocyte maturation. Finally, GRF did not affect meiotic maturation when dbcAMP was added to the cultures. Our results demonstrate the ability of GRF to accelerate maturation in oocytes from both primed and unprimed rats. Since the presence and the involvement of GRF at the ovarian levels is now well established, the present data strongly suggest an important potential role of GRF in the ovarian physiology.

Growth hormone induces in vitro maturation of follicle- and cumulus-enclosed rat oocytes.

The aim of this study was to assess the possible role of growth hormone (GH) on rat oocyte maturation. This effect was analyzed in follicle-enclosed, cumulus-enclosed and denuded oocytes obtained from immature pregnant mare's serum gonadotropin (PMSG)-treated rats. The addition of GH to the cultures significantly accelerated maturation in both follicle- and cumulus-enclosed oocytes while no effect was seen on denuded oocytes maturation. Also, GH accelerated meiotic maturation in follicle-enclosed oocytes from immature untreated rats. The GH action was not mediated by lactogenic receptors since prolactin (Prl) did not affect the maturation process while it was mediated by insulin growth factor-I (IGF-I) as suggested by the block of GH action observed in the presence of antibodies anti-IGF-I. Finally, no GH effect was found when dbcAMP was added to the cultures. Our results demonstrate that GH is capable of inducing maturation in oocytes from both primed and unprimed rats. Since the presence of physiological levels of GH in the ovary is now well established, the present data strongly suggest a potential relevance of GH in the reproductive biology.