[Synthesis of proteoglycans by purified Leydig cells in immature rats and mature rats].

In Percoll purified Leydig cells from mature rat incubated for 24 h in Ham F12/DME medium, we demonstrated that the testosterone production (6 ng/10(6) Leydig cells/24 h) is increased 11 fold by a saturating amount of hCG whereas rat Leydig cells the basal output of testosterone is 4.5 ng and increased 2.5 fold by hCG. In the sulfate-free Ham F12/DME medium used for the proteoglycan (PG) studies, the productions of testosterone are lower but the cells remain sensitive to hCG. Whatever the age, the Leydig cells synthesize labeled PG after 24 h of incubation in the presence of [3H] glucosamine and [35S] sulfate. In immature rat, the quantity of synthesized PG is 20% higher than in mature animal; the secreted PG represented respectively 70 and 85% of the immature and mature Leydig cells PG outputs. In addition, the immature Leydig cell HSPG represents 15% of the secreted PG whereas it is 5% in mature rat; irrespective of the age the associated-HSPG account for 10% of the PG. The addition of hCG improves the production of HSPG especially in the immature Leydig cells. Therefore we evidenced a rat Leydig cell synthesis of PG, especially HSPG which are likely involved in the regulation of the Leydig cell function.