In Vitro Stimulation of Stage-Specific Deoxyribonucleic Acid Synthesis in Rat Seminiferous Tubule Segments by Inter leukin- lα*

Abstract

Levels of rat testicular interleukin-1-like factor (tIL-1) have been shown to correlate with DNA synthetic activity during the cycle of the rat seminiferous epithelium, suggesting its role as a spermatogonial or meiotic growth factor. To explore this further, a new in vitro model system was developed. Rat seminiferous tubule segments from stages I, V, VIIa, and VIII-IX of the cycle were isolated by transillumination-assisted microdissection, cultured in chemically defined serum-free medium supplemented with human recombinant IL-1 alpha, and labeled with [3H]thymidine. During incubation, spontaneous progression of spermatogenesis was noted. Inactive stage VIIa tubule segments differentiated to stage VIII and initiated DNA synthesis, and concomitantly started to secrete IL-1-like factor. DNA synthesis of stages VIII-IX ceased through differentiation of spermatocytes to leptotene-zygotene (stages XII-XIII of the cycle). IL-1 alpha stimulated DNA synthesis significantly in spermatogonia of stage I. Meiotic DNA synthesis at stage VIIa was stimulated (48 h/34 C) and maintained at stages VIII-IX (48 h/34 C). IL-1 alpha seems to act as a regulator of spermatogenic DNA synthesis in both mitotic and meiotic phases. It has mainly stimulating and maintaining effects, but it may also be inhibitory under certain conditions.

Immunocytochemical Tools Reveal a New Research Field Between the Boundaries of Immunology and Reproductive Biology in Teleosts

“…Moreover, in 180 dph juveniles, acidophilic granulocytes and mesenchymal cells and a few germ cells produced Il1 , while in 270 dph males, in which the spermatogenesis process is active, Il1 was only located in acidophilic granulocytes and spermatocytes as occurs in one year old fish (Chaves-Pozo et al, 2008a). Our observations of the gonadal primordial support the hypothesis that Il1 is a testicular germ cell growth factor, as is also the case in mammals, since Il1 is not produced in the developing ovarian area (Khan and Rai, 2007;Parvinen et al, 1991;Pollanen et al, 1989). The appearance of Mcsfr was only observed in the well-developed testicular areas of 240-300 dph males, produced by the same cell types as in the adult testis (Chaves-Pozo et al, 2008a).…”

Immunohistochemical and hybridocytochemical study on ghrelin signalling in the rat seminiferous epithelium.

“…Pituitary adenylate cyclase-activating polypeptide (PACAP) is most intensely expressed in spermatids steps 3 -12 but not in maturation phase spermatids, its receptor in spermatids step 7 -12, and expression of the PACAP gene occurs in spermatogonia and primary spermatocytes [14,15]. Stage-specific expression was recognized also for other molecules as for IGF-I, activin, inhibin, NGFβ, transcriptional factors, interleukins [4][5][6]8,10,11]. We also believe that expression of GHSR-1a isoforms illustrates conditions for a response of spermatogenic cells to ghrelin whithin the seminiferous epithelium and the process in which spermatozoa are furnished receiving receptor to respond, for instance, to seminal plasma ghrelin or to the ghrelin of female reproductive tract fluid available in the course of movement and capacitation of spermatozoa or acrosome reaction and fertilization.…”

“…The local regulatory mechanism has been defined during last two decades and the list of its messengers, the local signalling molecules, has been growing with years. The list includes growth factors, polypeptides of hormonal and paracrine nature, transcriptional modulators, interleukins and receptors of these molecules, all of them being the mediators in a cross talk between somatic and germ cells [4][5][6][7][8][9][10][11][12][13][14][15][16][17].…”

Rôle des facteurs de croissance et cytokines dans le testicule normal et pathologique

“…Ces facteurs pourraient contr61er la survie (SCF, [38]), la m u l t i p l i c a t i o n des s p e r m a t o g o n i e s (EGF/TGFa, bFGF, IGF I ; [23,30,61,64,73]), l'arr6t de la multiplication de ces cellules (TGFb, [18] ; inhibine, [16,81] de signalisation vis-a-vis des hormones (FSH, testosterone) ( Figure 3). Cependant, rexpression de ces facteurs sertoliens peut ~tre aussi sous le contrSle de facteurs locaux comme le TNFa, l'ILla ou le NGF, provenant des cellules germinales.…”