Negative feedback control of the spermatogenic progression by testicular oestrogen synthesis: insights from the shark testis model

APMIS : Acta Pathologica, Microbiologica, Et Immunologica Scandinavica
M Betka, G V Callard

Abstract

The organisation of the testis of the dogfish shark is technically advantageous for stage-by-stage analysis of spermatogenesis in vivo and in vitro. Prior studies using this model show that total oestrogen receptors (ER) are concentrated in regions where spermatocysts ("follicle-like" germ cell-Sertoli cell units) are in stem cell and spermatogonial stages: respectively, germinal zone (GZ) and premeiotic (PrM) regions. By contrast, key enzymes regulating oestrogen (E) concentrations (aromatase, 17 alpha-hydroxylase) are maximal in meiotic (M) and postmeiotic (PoM) regions, respectively, which are upstream in the intratesticular vascular pathway. To investigate the hypothesis that E is part of a signalling mechanism between stages of development, studies were undertaken to test direct effects of oestradiol-17 beta (E2) on processes in ER-rich regions. As measured by [3H]thymidine (-Tdr) incorporation. DNA synthesis in GZ and PrM regions was inhibited by E2 (0-1000 nM) in a dose-response fashion. The maximal response (30-40%) was significant, reproducible and observed within 72 hr of treatment. Insulin differentially affected DNA synthesis and the response to E2 in GZ in GZ and PrM regions. As measured by [3H]Tdr release after pr...Continue Reading

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Citations

Jun 19, 2001·Molecular and Cellular Endocrinology·R A HessJ Bahr
Aug 12, 1999·International Journal of Andrology·S CarreauJ Levallet
Aug 9, 2003·Reproductive Biology and Endocrinology : RB&E·Rex A Hess
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May 26, 2017·Physiological Reviews·Paul S CookeRex A Hess
Sep 25, 2004·Experimental Biology and Medicine·Sharada KaranthSamuel M McCann

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