Previous studies have shown that macromolecules in ovine RTF (oRTF) are beneficial for maintenance of the ability to metabolize testosterone by cultured principal cells from the proximal epididymal regions , and these macromolecules can stimulate protein secretion in the initial segment of the rat epididymis . Ovine RTF contains a growth factor , and a number of growth factors are produced by the testis . Therefore, we hypothesize that testicular factors such as growth factors are involved in the regulation of GGT catalytic activity and GGT protein level in the initial segment.

Basic fibroblast growth factor (bFGF) has been shown to be produced by the testis . Germ cell media contain bFGF-like protein , and bFGF-like activity is present in the homogenate of calf and human epididymis . Basic FGF has also been shown to be involved in the development of the epididymis, and may act as an autocrine or paracrine mediator of the actions of androgen in the development of the rat epididymis . Furthermore, bFGF-like proteins appear to be involved in the regulation of GGT catalytic activity in Sertoli cells . A previous study in this laboratory has shown that the expression of GGT mRNA-IV in the rat initial segment is under the regulation of testicular factor(s) . It is possible that bFGF is one of the testicular factors that act to regulate epididymal GGT catalytic activity and GGT protein level in the initial segment. ventolin inhalers

The objectives of this study were to determine whether GGT catalytic activity and GGT protein in the initial segment are regulated by testicular factors, as well as to determine which factors in RTF are involved in the regulation of GGT catalytic activity and protein level in the initial segment of the rat epididymis.