Paracrine regulation of cellular interactions in the testis: factors in search of a function

Abstract

Throughout evolution, gamete generation and sex hormone production are the two processes combined in the testis. The local proximity of sex steroid-producing cells and spermatogenic cells allows multiple cellular interactions to occur and thereby facilitates the modulation and/or synchronisation of both testicular functions. This mini review provides an introduction to the vast variety of different testicular cell types, the unique bi-compartmental organisation of the testis, the many factors being released in the testis and the different forms of cellular interactions occurring between testicular cells. Selected members of two groups of signal molecules (sex steroids, growth factors) are described in detail and specific examples for the intratesticular actions of signalling factors are presented.

Interbular space characterization in adult capybara (Hydrochoerus hydrochaeris) testis

“…In addition to the already well-known endocrine control through the hypothalamus-hypophysistesticle axis, an elaborated system of intercellular communication is developed in the testicle to assure the perfect functioning of the spermatogenic process (Roser, 2000). Thus, the cells directly or indirectly involved in the production of the male gametes, that is, Sertoli cells, germ cells, Leydig cells, peritubular mioid cells, leukocytes, etc, maintain a paracrinous/autocrine system that modulates this intricate net of cellular interaction, which is fundamental for the perfect functioning of the testicle (Schlatt, 1997;Zirkin and Chen, 2000;Rothschild et al, 2003). The contribution of the Leydig cell for this paracrine communication involves the production of different substances (Lejeune et al, 1997;Roser, 2000;França et al, 2000).…”

Pharmacological profile of inhibition of the chloride channels activated by extracellular acid in cultured rat Sertoli cells

“…The principal findings of this study were (i) ICl acid can be stimulated by various acid species (HCl, aspartic acid and the physiologically relevant lactic acid) suggesting that the most important determinant is the concentration of protons itself rather than the nature of the acid; (ii) the profile for inhibition of ICl acid was DIDS ≈ glibenclamide > DPC >> TS-TM calix [4]arene, 9-AC; (iii) an ATP-activated Cl − channel ICl ATP was inhibited by DIDS ≈ DPC ≈ 9-AC >> glibenclamide; (iv) a swellingactivated Cl − channel ICl swell was inhibited by DIDS ≈ DPC >> 9-AC, glibenclamide. Thus glibenclamide appears to be a relatively good discriminator of ICl acid compared to ICl ATP or ICl swell whereas 9-AC is a good discriminator of ICl ATP compared to ICl acid or ICl swell .…”

“…Thus the Cl − channel inhibitors DIDS, DPC and glibenclamide inhibit ICl acid , independently of the presence of extracellular calcium. The profile for inhibition of ICl acid was therefore DIDS ≈ glibenclamide > DPC >> TS-TM calix [4]arene, 9-AC. The same inhibitory profile was obtained when ICl acid was stimulated by lactic acid (Fig.…”

“…The sulfonated calixarene TS-TM calix [4]arene (5,11,17,23-tetrasulfonato-25,26,27,28-tetramethoxy-calix [4]arene) [28] is a highly potent inhibitor of outwardly rectifying Cl − channels (so called ORCC). Figure 3C shows that 100 nM TS-TM calix [4]arene did not block the iodide efflux activated by HCl in the presence of extracellular calcium. Thus the Cl − channel inhibitors DIDS, DPC and glibenclamide inhibit ICl acid , independently of the presence of extracellular calcium.…”

“…The structure of Sertoli cells and the specialized junctions between them and the neighboring germ cells create an immunologically protected space [4], a barrier to protect developing germ cells against harmful agents and a sophisticated microenvironment providing all the nutrients, a variety of hormones [5] and growth factors required for the full development of germ cells [1][2][3]. In the rat, Sertoli cells proliferate during the fetal and early neonatal periods before assuming a terminally differentiated state [6,7].…”