Direct influence of rooibos-derived compound on rabbit ovarian functions and their response to gonadotropins

Rooibos is widely used in folk medicine, but its influence on reproductive processes has been studied insufficiently. The aim of present study was to examine possible involvement of rooibos on the release of progesterone (P4), testosterone (T) and insulin-like growth factor I (IGF-I), as well as its response to gonadotropin–follicle-stimulating and luteinizing hormone (FSH+LH), the most known hormonal regulators for reproduction. Rabbit ovarian fragments were cultured in the presence of rooibos (1, 10 and 100 μg/mL medium), FSH+LH (0.01, 0.1 and 1 IU/mL medium) and rooibos (10 μg/mL medium) in combination with FSH+LH (0.01, 0.1 and 1 IU/mL medium). The release of hormones was evaluated by using radioimmunoassay. It was observed that rooibos addition to culture medium stimulated P4 and inhibited T release. IGF-I release was significantly stimulated by rooibos at all doses added. FSH+LH when given alone promoted IGF-I, but not P4 or T release. The addition of rooibos induced the suppressive effect of FSH+LH on P4 release, the stimulatory action of FSH+LH on T output and reduced the response of IGF-I to FSH+LH treatment. These data suggest that rooibos is able to directly affect the release of steroid (P4 and T) and peptide (IGF-I) hormones by rabbit ovarian cells and to modulate their response to gonadotropins.