Developmental Changes of Testicular Gonadotropin Receptors and Serum Gonadotropin Levels in Two Strains of Mice

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The relationship between testicular gonadotropin receptors and serum gonadotropin concentrations during sexual maturation was studied in two inbred mouse strains ( BALB/cAJcl and ICR/Jcl strains). The specific binding of [^<125>I]iodo-FSH per unit testicular weight was the highest at 21 days of age in the BALB/cAJcl strain and 7 days in the ICR/Jcl strain, followed by a rapid decrease thereafter. The total FSH binding in the ICR/Jcl strain was significantly decreased at 35 days from the level at 28 days and remained low thereafter. However, such decrease was not observed in the BALB/cAJcl strain. Scatchard plot analyses showed that the changes in FSH binding were due to the changes in the number of binding sites and not in the affinity of binding. The specific binding of [^<125>I]iodo-LH per unit testicular weight reached a peak around puberty, and the total LH binding tended to remain constant after puberty in both strains. During early testicular developmental stages, the increase in the serum FSH levels was well correlated with the number of FSH receptors. Prepubertal increase in LH binding sites occurred after the rise in the serum FSH levels. To conclude, we found a strain difference in the regulation of the number of FSH receptors, indicating that down-regulation is not unique to the C57BL/6NCrj strain, but that it is not universal among strains of mice.
社団法人日本動物学会の論文
1993-06-15