Gonadotropin-Independent Regulation of Steroidogenesis: RESULTS(1)

9 Nov


Pituitary and Plasma LH in Male Fetal Rats

Fetal pituitary LH was undetectable on E15.5, whereas it was 3.25 pg/gland on El6.5 and increased thereafter significantly with fetal age (Fig. 1). The fetal plasma concentration of LH was very low on E17.5 (0.005 ± 0.001 |xg/ L), and it increased marginally on El8.5 and El9.5. There was a significant increase in the LH concentration only between E19.5 and E20.5, from 0.010 ± 0.002 |xg/L to 0.043 ± 0.01 |xg/L (p < 0.001). The sex difference in plasma LH concentrations (females 1.8-fold higher than males) was statistically significant from E19.5 onward (data not shown).
Fig1Gonadotropin-independent regulation
FIG. 1. Pituitary and plasma (serum) concentrations of LH and testicular contents of testosterone (T) in male rat fetuses. The values are mean ± SEM of 7-10 samples. Individual samples were analyzed of all pituitary samples and plasma of Days E20.5 and E21.5. The plasma samples of E17.5-E19.5 were pooled from 2-4 fetuses. Each testicular testosterone content was measured from a pool of two pairs of testes. * Significant difference from the previous age group (*p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001).

LH(3 Subunit Gene Expression

In order to identify the exact onset of LH$ subunit gene expression, LH(3 mRNA in fetal pituitaries was measured by RT-PCR. To ascertain the specificity of the cDNA fragments, the RT-PCR products were transferred onto nylon membranes and subjected to Southern hybridization with a nested cDNA probe. The cDNA fragment with the expected 247-base pair (bp) size was not found on E15.5, but it was faintly detectable on E16.5, and a clear message was found from El7.5 onward, together with a smaller transcript (120 bp) (Fig. 2). The latter was possibly due to alternative splicing, but its exact sequence was not studied. ventolin inhaler
Fig2Gonadotropin-independent regulation
FIG. 2. Southern hybridization analysis of the RT-PCR products of LHfS-subunit transcripts in the fetal rat pituitary of El 5.5-El 8.5 and in adult pituitary. The migration of the expected cDNA products (247 and 120 bp) is depicted on the right of the panel.