Expression and Action of Neurotropin-3 and Nerve Growth Factor in Embryonic and Early Postnatal Rat Testis Development

Abstract

The current study examines the expression and potential actions of neurotropin-3 (NT3), nerve growth factor (NGF), and their receptors during morphological sex determination (seminiferous cord formation) and perinatal rat testis development. The expression of neurotropins and their receptors was analyzed with immunohistochemistry. Cellular localization of neurotropin ligand and receptor proteins changed during embryonic testis development. Neurotropin-3 was localized to Sertoli cells at Embryonic Day 14 (E14), was present in gonocytes at Postnatal Day 0 (P0), and after birth became localized to the interstitium and Sertoli cells (P3-P5). The expression of trk C (the high affinity receptor for NT3) was localized to mesonephric ducts and cells surrounding the cords (E14-E18). In addition, Sertoli cells and preperitubular cells surrounding the cords at E14 also stained for trk C. Neurotropin-3 was expressed in gonocytes and Sertoli cells at P0-P5. Nerve growth factor was detected in Sertoli cells at E14, was clearly in Sertoli and interstitial cells at E16 and E18, and in Sertoli, germ, and interstitial cells from P0-P5. The expression of trk A (the high affinity receptor for NGF) was located in Sertoli and interstitial cells at E16-P5. To determine the actions of neurotropins during embryonic and perinatal testis development, experiments were conducted on E13 and P0 testis. Antisense oligonucleotide experiments with NT3 were used on E13 testis organ cultures to determine effects on seminiferous cord formation. Cord formation was inhibited in 40% of the organ cultures treated with the antisense NT3 oligonucleotides, while no inhibition was observed with sense oligonucleotides. In P0 testis cultures, both NT3 and NGF alone and in combination stimulated thymidine incorporation into DNA. Therefore, the neurotropins are involved in embryonic morphological events (cord formation; NT3) and in growth of the perinatal testis (P0; NT3 and NGF). To define further the growth effects of neurotropins on testis development, expression of transforming growth factor alpha and beta (TGF alpha and TGF beta) were examined in response to neurotropins. The P0 testis cultures were treated with neurotropins, and expression of mRNA for TGF alpha and TGF beta was analyzed utilizing a quantitative reverse transcription-polymerase chain reaction assay. Nerve growth factor and NT3 alone or in combination inhibited expression of mRNA for TGF alpha while NT3 increased mRNA expression of epidermal growth factor receptor. The combination treatment of neurotropins inhibited expression of TGF beta 1 and increase expression of TGF beta 3. In summary, observations suggest that NT3, NGF, trk A, and trk C are localized to cells critical to seminiferous cord formation and appear to be important regulators of morphological sex determination. In addition to these morphological effects, both NT3 and NGF stimulate P0 testis growth and may elicit their action through altering the expression of locally produced growth factors such as TGF alpha and TGF beta. Ta...

Effect of NGF on the Motility and Acrosome Reaction of Golden Hamster Spermatozoa In Vitro

“…For instance, previous data show that TrkA is expressed in Sertoli and interstitial cells of the testis at embryonic and early postnatal ages in the rat [16]. Our data suggest that the high affinity receptor TrkA is localized only in Sertoli cells, whereas p75 showed dispersed expressions in the testis of the adult male golden hamster.…”

Fibroblast growth factor (FGF) 2 and FGF9 mediate mesenchymal–epithelial interactions of peritubular and Sertoli cells in the rat testis

“…It should also be pointed out that several growth factors are morphogens during embryonic testis development, i.e., the hepatocyte growth factor (HGF) (Ricci et al 2002), the PDGF (Uzumcu et al 2002, Brennan et al 2003, Puglianielli et al 2004, Ricci et al 2004) and the neurotropins (Cupp et al 2000(Cupp et al , 2003. Such an apparent redundancy may explain the lack of a severe testicular phenotype (at least with respect to embryonic testis development) in mice deleted for c-Met, the HGF receptor (Ricci et al 2002), for PDGF receptor- (Soriano 1994) and for trkA and trkC neurotropin receptors (Cupp et al 2002).…”

Vascular Endothelial Growth Factor and Kinase Domain Region Receptor Are Involved in Both Seminiferous Cord Formation and Vascular Development During Testis Morphogenesis in the Rat1

“…All male organs, as confirmed by PCR for Sry expression in tail samples from each embryo [20], were imaged before processing for whole-mount immunohistochemistry to verify the presence of seminiferous cords in control organs and to analyze testis area. Brightfield images of whole organs from the VEGFR-TKI and Je-11 treatments were obtained with a Spot camera and Spot imaging capture system (Diagnostic Instruments; Spot Advance, Sterling Heights, MI).…”

“…Because germ cell deficient mice have normal cord formation [15][16][17], the Sertoli cells logically produce the paracrine growth factor(s) that induce mesonephric cell migration [15][16][17][18]. Several factors, including the activity of Sertoli-derived chemokines, have been proposed, because of alterations in seminiferous cord formation in vitro [19][20][21][22][23] and altered testis morphogenesis in vivo [24,25].…”