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Title: Follicle-stimulating hormone receptor-mediated uptake of sup 45 Ca sup 2+ by cultured rat Sertoli cells does not require activation of cholera toxin- or pertussis toxin-sensitive guanine nucleotide binding proteins or adenylate cyclase

We have previously reported that FSH stimulates flux of 45Ca2+ into cultured Sertoli cells from immature rats via voltage-sensitive and voltage-independent calcium channels. In the present study, we show that this effect of FSH does not require cholera toxin (CT)- or pertussis toxin (PT)-sensitive guanine nucleotide binding (G) protein or activation of adenylate cyclase (AC). Significant stimulation of 45Ca2+ influx was observed within 1 min, and maximal response (3.2-fold over basal levels) was achieved within 2 min after exposure to FSH. FSH-stimulated elevations in cellular cAMP paralleled increases in 45Ca2+ uptake, suggesting a possible coupling of AC activation to 45Ca2+ influx. (Bu)2cAMP, however, was not able to enhance 45Ca2+ uptake over basal levels at a final concentration of 1000 microM, although a concentration-related increase in androstenedione conversion to estradiol was evident. Exposure of Sertoli cells to CT (10 ng/ml) consistently stimulated basal levels of androstenedione conversion to estradiol but had no effect on basal levels of 45Ca2+ uptake. Similarly, CT had no effect on FSH-induced 45Ca2+ uptake, but potentiated FSH-stimulated estradiol synthesis. PT (10 ng/ml) augmented basal and FSH-stimulated estradiol secretion without affecting 45Ca2+ influx. The adenosine analog N6-phenylisopropyladenosine, which binds to Gi-coupled adenosine receptors on Sertoli cells, inhibited FSH-stimulatedmore » androgen conversion to estradiol in a dose-related (1-1000 nM) manner, but FSH-stimulated 45Ca2+ influx remained unchanged. Our results show that in contrast to FSH-stimulated estradiol synthesis, the flux of 45Ca2+ into Sertoli cells in response to FSH is not mediated either directly or indirectly by CT- or PT-sensitive G protein, nor does it require activation of AC. Our data further suggest that the FSH receptor itself may function as a calcium channel.« less
Authors:
;  [1]
  1. (Albany Medical College, NY (USA))
Publication Date:
OSTI Identifier:
6530374
Resource Type:
Journal Article
Resource Relation:
Journal Name: Endocrinology; (USA); Journal Volume: 127:2
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; CALCIUM COMPOUNDS; MEMBRANE TRANSPORT; ESTRADIOL; BIOSYNTHESIS; FSH; BIOCHEMICAL REACTION KINETICS; AMP; CALCIUM 45; CYCLASES; RATS; RECEPTORS; TESTES; TOXINS; TRACER TECHNIQUES; ALKALINE EARTH ISOTOPES; ALKALINE EARTH METAL COMPOUNDS; ANIMALS; ANTIGENS; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; BODY; CALCIUM ISOTOPES; DAYS LIVING RADIOISOTOPES; ENZYMES; ESTRANES; ESTROGENS; EVEN-ODD NUCLEI; GONADOTROPINS; GONADS; HORMONES; HYDROXY COMPOUNDS; INTERMEDIATE MASS NUCLEI; ISOTOPE APPLICATIONS; ISOTOPES; KINETICS; LYASES; MALE GENITALS; MAMMALS; MATERIALS; MEMBRANE PROTEINS; NUCLEI; NUCLEOTIDES; ORGANIC COMPOUNDS; ORGANS; PEPTIDE HORMONES; PITUITARY HORMONES; PROTEINS; RADIOISOTOPES; REACTION KINETICS; RODENTS; STEROID HORMONES; STEROIDS; SYNTHESIS; TOXIC MATERIALS; VERTEBRATES 550201* -- Biochemistry-- Tracer Techniques