Effects of 2-hydroxyoestradiol, oestradiol and testosterone on FSH-induction of catecholamine- and gonadotrophin-responsive progesterone biosynthesis in rat granulosa cell cultures.

Catecholamine- and gonadotrophin-responsive progesterone biosynthesis increases during FSH-induced granulosa cell maturation. In this study, we compared in vitro effects of interrelated classes of follicular steroid on both endpoints: an androgen (testosterone), an oestrogen (oestradiol) and an oestradiol metabolite (2-hydroxyoestradiol). Granulosa cells from diethylstilboestrol-pretreated, immature rat ovaries were cultured for 48 h (pretreatment) in serum-free medium containing human FSH with or without steroid. The cell monolayers were then washed and reincubated for a further 24 h (test-treatment) in fresh medium with and without a catecholamine (isoproterenol or norepinephrine) or a gonadotrophin (FSH or hCG); test-treatment culture medium was collected and assayed for progesterone content. At concentrations up to 10(-6) M, each steroid enhanced dose-dependently basal and catecholamine-responsive progesterone production with a ranked potency-order of testosterone greater than 2-hydroxyoestradiol much greater than oestradiol. All three compounds also enhanced FSH and hCG responsiveness but this endpoint was affected most markedly by oestradiol. Pretreatment in the presence of specific antiandrogen (hydroxyflutamide; SCH16423) blocked the stimulatory effects of testosterone and 2-hydroxyoestradiol but did not inhibit stimulation by oestradiol, highlighting similarities between the actions of testosterone and the catechol oestrogen distinct from that of oestradiol. Test-treatment in the presence of beta-adrenergic antagonist (propranolol) blocked the stimulatory action of isoproterenol and reduced the response to FSH, suggesting the involvement of beta-adrenergic receptors in FSH as well as catecholamine action on steroidogenesis. We conclude that testosterone and catechol oestradiol have major effects on FSH-induced development of catecholamine responsive steroidogenesis whereas oestradiol mainly affects gonadotrophin responsiveness in this granulosa cell culture system. All three steroid types could interact with gonadotrophins and locally produced catecholamines to influence granulosa cell function in vivo.

Catechol oestradiol control of FSH-stimulated granulosa cell steroidogenesis.

Catechol oestrogens are formed in the ovary but it is not known if they have a local function. Working with primary granulosa cell cultures prepared from immature rat ovaries, we found that the presence of 2-hydroxyoestradiol in the culture medium (48 h incubation) dramatically enhanced the steroidogenic response (progesterone production) to human FSH (100 ng/ml). The effect of 2-hydroxyoestradiol was dose-dependent and maximal (approximately 40 times the response to FSH alone) at 3.0 microM. The stimulatory action of 1.0 microM 2-hydroxyoestradiol was greater than 10 times more than that of 1.0 microM oestradiol but only half that of 1.0 microM testosterone; other catechol oestrogens (2-hydroxyoestrone, 4-hydroxyoestradiol, 2-methoxyoestradiol and 2-methoxyoestrone) were not stimulatory. The stimulatory actions of 2-hydroxyoestradiol and testosterone were partially additive and each was antagonized in the same way by the presence of a specific antiandrogen (SCH16423). These observations suggest a role for intrafollicular catechol oestradiol in modulating FSH-stimulated granulosa cell steroidogenesis; its mechanism of action may be similar to that of testosterone.

Cardiopulmonary responses to combined lateral and vertical acceleration.

To investigate the effects of a lateral G force, eight stress panel members were each subjected to a series of stresses using +/- 1.5, 2, or 2.5 Gy combined with either +/- 1 or +/- 2 Gz, for 30 s followed by a 60-s recovery period. Peripheral arterial oxygen saturation, utilizing a Hewlett-Packard 47201A ear oximeter and heart rate were recorded. A consistent fall in arterial oxygen saturation (SaO2) was observed during all the Gy/Gz exposures with the +Gy direction giving the lowest value of 90.1% SaO2 (PaO2 of less than 60 mmHg). A small but consistent increase in heart rate (HR) was also observed during, and for 15 to 20 s after the Gy/Gz exposure. These results indicate that the cardiopulmonary system is stressed during combined Gy/Gz acceleration and the most important change occurs in SaO2.