CHRONIC ADMINISTRATION OF INSULIN LIKE GROWTH FACTORS (IGFS) MODULATES RESPONSE TO HUMAN CHRONIC GONADOTROPIN (hcg) BY LEYDIG CELLS OF HUMAN PREPUBERTAL TESTIS IN CULTURE

MARIANA COSTANZO; ESPERANZA B. BERENSZTEIN; MARÍA SONIA BAQUEDANO; NORA I. SARACO; R DOMÁNICO; M MURANO; MARCO A RIVAROLA; ALICIA BELGOROSKY

Lima, Perú

Congreso; XX Reunión Anual de la Sociedad Latinoamericana de Endocrinología Pediátrica; 2008

Sociedad Latinoamericana de Endocrinología Pediátrica (SLEP)

We have previously published (Berensztein et al, Ped Res 2008) the characterization of the expression of IGF1, IGF2, IGF receptor type 1 (IGFR1) and insulin receptor (IR) in HPT OF 3 age groups (GR): GR1, neonates; GR2, postnatal activation; GR3, early prepuberty, as well as the effect of IGF1 on cell proliferation and apoptosis, P450scc expression ´and testosterone (T) secretion, in primary culture. A role for IGFs in the modulation of Leydig cell differentiation was proposed. In this study, we have analyzed the effect of chronic stimulation by IGF1 on hCG acute response. HPTs, collected at necropsy, were grouped for culture, as published. Pre-incubation with IGF1 significantly increased T res pon se to acute hCG stimulation (396 ± 133 % of basal; mean ± MSE; n=7; p< 0.05). Moreover, in one culture of GR1, IGF2 significantly increased T secretion (175%, p<0.05) in the absence of other stimuli, real time RT-PCR of type 2 3beta-hydroxysteroid-dehydrogenase and 17alphahydroxylase enzymes on day 6 of culture (5.7 and 8.2 times respectively; 2-deltadeltaCT), and T response to acute hCG stimulation (237 %, p<0.05). This last effect was blocked by the presence of picropodophyllin, a selective inhibitor of IGFR1. These results are in favor ofthe hypothesis that the IGF system modulates functional differentiation of Leydig cells, in HPT.