Gonadotropin-Independent Regulation of Steroidogenesis: RESULTS(2)

10 Nov
2012

Testicular Testosterone

Testicular testosterone content was measured between Days E15.5 and E21.5 (Fig. 1). It was 12.0 ± 2.0 pg/testis on E15.5 and increased on E16.5, E17.5, and E18.5 slightly to 32.2 ± 5.0, 45.6 ± 7.6, and 61.1 ± 6.9 pg/testis, respectively. A sharp and significant increase occurred between E18.5 and E19.5, to 126 ± 28.4 pg/testis (p < 0.05). Thereafter, there was a slight decline between E19.5-E20.5, and E20.5-E21.5 accompanied by a reciprocal increase in plasma LH. When the testicular testosterone data were reexpressed as concentrations in pg/mg of tissue, similar trends were observed (data not shown).

Stimulation of Fetal Testes by hCG and LH

The basal and hCG-stimulated rates of testosterone production were measured at 1, 2, 3, and 5 h of incubation of whole fetal testes and dispersed Leydig cells, and compared at different fetal ages (Figs. 3 and 4). The degree of stimulation in fetal testes and dispersed Leydig cells was much lower at early fetal ages (1.4-fold on El6.5) and increased dramatically at later ages (7.7-fold on E20.5). We found that the maximum steroidogenic capacity per unit weight of tissue was highest on El8.5 (data not shown). birth control pills
Fig3Gonadotropin-independent regulation
FIG. 3. The effect of hCG on testosterone production by incubated intact fetal testes on E16.5-E20.5. One testis from each fetus was incubated for 5 h in the absence (dotted bars) and the other in the presence of 1.0 jxg/L hCG (solid bars). Testosterone concentration in the medium was measured by RIA. Data points represent the mean ± SEM (n = 8-10 pairs of incubations). * Significant difference from the previous time point (*p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001).

Fig4Gonadotropin-independent regulation
FIG. 4. The effect of hCG on testosterone production by dispersed fetal rat Leydig cells on E16.5-E20.5. Fetal rat Leydig cells were dispersed as described in Materials and Methods, and incubated for 5 h in the absence (dotted bars) and the presence (solid bars) of 1.0 |j,g/L hCG. Testosterone concentrations in the media were measured by RIA. Data points represent the mean ± SEM (n = 6-8). * Significant difference from the previous time point (*p< 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001).

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