ESTROGENS ACT AS PARACRINE/AUTOCRINE FACTORS IN HUMAN PREPUBERTAL TESTIS

ESPERANZA B. BERENSZTEIN; NORA I. SARACO; MARIELA SCIARA; CANDELA R. GONZALEZ; MARCO A. RIVAROLA; ALICIA BELGOROSKY

Angra dos Reis. Brasil

Congreso; XVII Encuentro Anual de la SLEP; 2004

Sociedad Latinoamericana de Endocrinología Pediátrica

Estrogens act as paracrine/autocrine factors in human prepubertal testis- Berensztein E, Saraco N, Sciara M, Gonzalez C, Rivarola M A, Belgorosky A. Research Laboratory, Garrahan Pediatric Hospital, Buenos Aires, Argentina. We have recently described that during the newborn period there is a vigorous growth of the testis in normal subjects. This cell growth seems to be secondary to a decreased apoptosis of somatic and germ cells (GC). We have proposed that these changes, taking place during the newborn period, might be important to define testicular cell mass in human (h) adults (Berensztein E., JCE&M 87: 5113-5118, 2003). In various models, estrogens are potent modulators of proliferation and apoptosis, but in the h testes, their role is not well defined. Aim: In order to study if estrogens (in terms of cell biosynthesis and human testicular cell biological response) might be involved in the regulation of h prepubertal testicular apoptosis and growth we have evaluated: 1) in h prepubertal testicular tissue, immunolocalization of estrogen receptor (ER) a, ERb and aromatase (ARO), as well as mRNA expression of ARO by semiquantitative RT-PCR as a function of age; and 2) in h prepubertal testicular cells in culture: effect of estradiol (2 nM) on apoptosis (TUNEL) of cells maintained in culture for six days. Patients and Methods: Testes collected at necropsy were divided in three age groups (Gr): Gr1, newborns (1- to 21-day-old neonates), Gr2, post natal activation (1- to 7-month-old infants) and Gr3, early childhood period (12- to 36-month-old boys). Results: Expression of  ERa in interstitial cells (IC) was less than 5% in all age groups. ERb was detected in IC, peritubular (PeC), Sertoli (SC) and GC. The percentage of positive cells in the IC in Gr1 (26.2±4.41) was significantly higher than in Gr2 (12.3±1.56) and Gr3 (13.7±0.50), p< 0.05, but no change according to age was found in the other cell compartments. ARO immunolocalization was detected in IC, PeC and GC but not in SC. No significant differences were detected among age groups. When we compared cell types, we observed that the percentage of ERb positive cells in GC (44.7±2.99,42.2±2.62 and 57.3±1.10, in Gr1, Gr2 and Gr3, respectively) was significantly higher than in PeC (15.2±5.71) in Gr1, IC (12.3±1.56) and PeC (7.89±5.15) in Gr2 and IC (13.7± 0.50), PeC (7.78±5.47) and SC (28.1±1.51) in Gr3. ARO mRNA abundance in Gr1 was higher than in Gr2 + Gr3 (5.29±5.75 AU, and 1.90±7.02 AU,  respectively, p=0.008). In cell culture, day 6 apoptotic index under estradiol treatment (2.7±2.17%) was significantly lower than in control (8.97±3.45 %). Conclusions: 1) Since ERa is very low in h testicular tissue at any age and cell compartment, the effect of estrogens might be mediated through ERb , 2) since ARO is poorly detected in SC at any age, we proposed that IC represent the main source of estrogens, particularly in the neonatal period. Possibly, a non identified estrogen-regulated factor secreted by neonatal IC could be involved in the inhibition of  apoptosis  detected in all cell types in the neonatal group. However, a direct effect of estrogens on GC through ERb, inhibiting apoptosis and arresting the spermatogenesis development, can be proposed at all prepubertal ages studied.