Publication | Closed Access
Changes in Testicular Gonadotropin Receptors and Steroid Content through Postnatal Development until Puberty in the Lamb*
26
Citations
0
References
1983
Year
SpermatogenesisFertilityComparative EndocrinologyFsh Receptor NumbersFemale Reproductive FunctionReproductive BiologyReproductive EndocrinologyReproductive PhysiologyPublic HealthTesticular TestosteroneAnimal PhysiologyHormonal ReceptorSteroid ContentDevelopmental EndocrinologyEndocrinologyTesticular Gonadotropin ReceptorsTheriogenologyDevelopmental BiologyTesticular LhPhysiologyReceptor BiologyPostnatal DevelopmentMedicineEndocrine ResearchReproductive HormoneGonadotropin Biology
Changes in testicular LH and FSH receptor numbers were studied in lambs from 10–120 days of age and in 2-yr-old rams. Testicular testosterone and 17β-estradiol were also measured, and a histological examination of testicular parameters was performed in 20-day-old and 2-yr-old animals. The binding affinities of testicular LH receptors (1.4 ± 0.1 × 1010 M-1) and FSH receptors (3.7 ± 0.2 109 M-1) did not differ with age. The concentration of LH receptors (expressed per milligram of membrane protein) decreased from 31 to 6 fmol between 10– 120 days of age, but that of FSH receptors increased from 65 to 95 fmol. The total number of LH receptors per testis increased from 0.06 to 0.6 pmol between 10–80 days of age, then to 2.0 pmol by 120 days of age. The total number of LH receptors per testis did not differ between 120-day-old and 2-yr-old rams, but this was the result of a concomitant increase in the number of Leydig cells and a decrease in the number of LH receptors per Leydig cell. The change in the total number of FSH receptors per testis showed a pattern similar to that of LH receptors except that it was more pronounced (0.18–26.4 pmol per testis between 10–120 days of age). The total number of FSH receptorswas 7 times greater in 2-yr-old rams as compared to 120-day-old lambs. Up to 80 days of age, the testicular content of testosterone remained constant; it then rose from 0.5–2.3 ng per testis during puberty. There was no difference in testicular testosterone content in 120-day-old and 2-yr-old rams. The testicular content of 17(8-estradiol paralleled that of testosterone at all stages of development. In particular, it did not differ between 120-old-day and 2-yr-old animals despite the increase in the number of FSH receptors. It is concluded that: 1) between 10–120 days of age, the increase in the number of LH receptors results from both an increase in the number of Leydig cells and an increase in LHreceptors per Leydig cell. 2) Beyond day 50, the increase in the number of FSH receptors reflects only a variation per Sertoli cell. 3) After 120 days of age, the number of FSH receptors continues to increase but the number of LH receptors is maximal.4) The prepubertal rise in LH and FSH receptor numbersis related to the rise in testosterone production and to the activation of spermatogenesis (as shown by testicular weight). 5) The production of 17β-estradiol follows the production of testosterone and seems to be independent of variations in the number of FSH receptors per Sertoli cell.