PROTEOGLYCAN SYNTHESIS BY PURIFIED LEYDIG -CELLS FROM IMMATURE 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 am ount of hCG whereas in immature rat Leydig cells the basal output of t estosterone in 4.5 ng and increased 2.5 fold by hCG. In the sulfate-fr ee Ham F12/DME medium used for the proteoglycan (PG) studies, the prod uction 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 [H-3] glucosamine and [S-35] sulfate. In immature rat, the quantity of synthesized PG is 20% higher than in mature animal; the secreted PG represent respectively 70 and 85% of t he immature and mature Leydig cells PG outputs. In addition, the immat ure Leydig cell HSPG represents 15% of the secreted PG whereas it is 5 % in mature rat; irrespective of the age the associated-HSPG account f or 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.