Leydig cell development in boars
Geiger, Tammy Lynn
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Three waves of Leydig cell development are found in the pig testes Clearly defined periods of cell proliferation and differentiation occur during fetal, perinatal and pre-pubertal periods. Luteinizing hormone (LH) regulates Leydig cell proliferation via growth factors in the rat. However, it is not known how LH affects Leydig cell development in the neonatal pig testis. The purpose of the study was to identify growth factors involved in Leydig cell proliferation in neonatal pigs In this study we investigated the effects of hCG and the following growth factors; EGF (TGFa), SEP, IL-lp, IGF-1 and TGFP in vitro on DNA synthesis in neonatal Leydig cells. Leydig cells were isolated from 3- to 5-day-old pigs using coUagenase dispersion and a Percoll® gradient centrifligation. The cells were then cultured for 48 hours in serum free media, washed and treated with growth factors and or hCG for 18 hours. Tritiated thymidine incorporation into DNA was assessed over a subsequent four hour incubation period. Incorporation of ['^Hj-thymidine was stimulated by hCG treatment with a 2.3-fold increase over control cultures. SIP also induced a significant increase ( p <.0001) in the incorporation of ["'HJ-thymidine into Leydig cell DNA. Similarly, EGF and IGF-1 also increased DNA synthesis in porcine Leydig cells. When IGF-1 and SIP were added together, they had an additive effect on Leydig cell DNA synthesis. TGFp had very little, if any, etTect on DN.A synthesis when added alone, but inhibited the stimulatory effects of other growth tactor and mitogens (SIP, hCG, EGF, and IGF-1) on DN.A. synthesis Our results indicate thai these growth factors may play a role in proliferation of Leydig cells during the perinatal period of development.