STRONG IMMUNOEXPRESSION OF IGF2 AND INSULIN RECEPTOR (IR) IN LEYDIG AND GERM CELLS OF THE HUMAN POSTNATAL TESTIS

6. BERENSZTEIN E, GONZALEZ C, PONZIO R, BAQUEDANO MS, SARACO N, RIVAROLA MA, BELGOROSKY A

Viña del Mar, Chile.

Congreso; XVIII Reunión de la Sociedad Latinoamericana de Endocrinología Pediátrica; 2006

Sociedad Latinoamericana de Endocrinología Pediátrica (SLEP)

The GH/IGF axis may be involved in the differentiation of Leydig cell (LC) precursors, and in the maintenance of the immature germ cell (GC). Three age groups (Gr) were defined:Gr1(n=11),1-to 21-day-old newborns,Gr2 (n=11),1- to 7-month-old infants and Gr3(n=10),12-to 36-month-old children.IGF1, IGF2, IGFR, IR and GH receptor (GHR) immunoexpression was studied in testes after necropsy. Percentage of positive cells was estimated. In Interstitial cells (IC), low IGF1 and GHR, and moderate IR was detected in all Grs. IGF2 was higher in Gr1 than in Gr3 (7.0±1.3 vs 2.68±2.49 %,p=0.02). IGFR was higher in Gr1 and Gr2 than in Gr3 (11.7±4.5, 7.2±2.9 and 2.8±0.8%, p=0.046). In LC, IGF1 in Gr1 and Gr2 was undetectable, IGF2 was high (36 and 44.8%) and IGFR moderate (8.6 and 4.4%) in Gr1 and Gr2, IR was moderate in Gr1 (8.0 %), but increased in Gr2 (36.7%). GHR was only found in LC of Gr2 (13.7%). In GC, IGF1 was moderate while a strong label of IGF2, IGFR and IR was found in all Grs. In testicular cell cultures, rhGH increased Testosterone (T) secretion in 4/8 cultures of Gr2. IGF1 stimulated T in all Grs (n=13). In conclusion, in LC of Gr1, local IGF2 acting through IGFR or IR might modulate steroidogenesis, before the LH peak. In Gr2, serum GH through GHR expressed in LC might modulate IGF2 production. Since IR increased in LC of GR2, we propose that IGF2, through type A IR, might be involved in functional LC differentiation. In some IC, probably LC precursors, IGF2 could stimulate cell proliferation or inhibit apoptosis, mainly in Gr1. Local production of IGFs and the expression of receptors in GC suggest an autocrine role of IGFs to preserve spermatogonia in human prepubertal testis.