Follicle-stimulating hormone signal transduction: Role of carbohydrate in aromatase induction in immature rat Sertoli cells

Abstract

Receptor activated adenylate cyclase acts as a major transmembrane signalling system. It is widely accepted that upon binding to its receptor, follicle-stimulating hormone (FSH) activates the cAMP-dependent pathway which in turn mediates FSH-induced estradiol production in Sertoli cells. Studies utilizing several chemically derived variants of FSH have demonstrated that these variants bind to the FSH receptors with equal avidity but differ in their ability to activate cAMP-dependent pathways. Since cAMP is believed to be the second messenger responsible for FSH signal transduction, we tested two hypotheses: (1) that the effects of different oFSH variants on cAMP production and aromatase induction (as measured by estradiol production) would be in parallel; and (2) that deglycosylated ovine FSH (DG-oFSH) would antagonize the ability of intact oFSH to stimulate aromatase induction, similar to its reported antagonistic effect on cAMP production. Immature rat (7- to 10-day-old) Sertoli cells were cultured and the effects of several different oFSH variants on cAMP production and/or aromatase induction were tested. The variants tested were native oFSH, DG-oFSH, asialo oFSH (AS-oFSH), a recombinant of intact LH alpha and FSH beta (alpha + beta) and a recombinant of deglycosylated LH alpha and intact FSH beta (DG alpha + beta). Both native oFSH and alpha + beta recombinant at relatively large doses (10 ng) elicited a significant increase in extracellular cAMP accumulation as well as total cAMP production. In contrast, DG-oFSH did not produce an increase in cAMP even at 10-fold higher doses than native oFSH. Intracellular cAMP concentrations did not increase following stimulation with native oFSH, DG-oFSH or DG alpha + beta. In contrast to the divergent effects of oFSH and DG-oFSH on cAMP production all variants of oFSH stimulated estradiol production from Sertoli cells albeit with varying potencies. The sensitivity (minimal effective dose) and ED50 (dose at which half maximal response is achieved) of the estradiol (E2) response curve to increasing concentrations of native oFSH were 0.025 +/- 0.01 and 0.33 +/- 0.05 ng, respectively. Asialo-oFSH (AS-oFSH) increased E2 production with a potency (comparative dose required for effect) similar to that of native oFSH.(ABSTRACT TRUNCATED AT 400 WORDS)

Efficacy of a combined protocol of urinary and recombinant follicle-stimulating hormone used for ovarian stimulation of patients undergoing ICSI cycle

“…Furthermore, several studies have documented the occurrence of significant changes in FSH heterogeneity during certain physiological conditions including puberty and the menstrual cycle [19][20][21][22][23]. Acidic FSH isoforms are produced during follicular and luteal phases when the E2 level is low whereas less acidic FSH isoforms are produced during mid-cycle i.e.…”

Ovarian stimulation protocols based on follicle-stimulating hormone glycosylation pattern: impact on oocyte quality and clinical outcome

“…Several studies have documented the occurrence of significant changes in FSH heterogeneity during certain physiologic conditions, including puberty and the menstrual cycle (16)(17)(18)(19)(20). Acidic FSH isoforms are produced during the follicular and luteal phases when the estradiol level is low whereas less-acidic FSH isoforms are produced during the midcycle (i.e., when the estradiol level is high).…”

Androgen Regulation of Immunological and Biological Activities of Pituitary Follicle-Stimulating Hormone Isoforms inMale Rats

“…Gonadotropins are N-glycosylated protein hormones where carbohydrates are needed for the full expression of their biological activity [1, 2]. These carbohydrates also determine the circulating half-life of the hormone [3].…”