title: Green tea polyphenols inhibit testosterone production in rat Leydig cells.
abstract: This study investigated the acute effects of green tea extract (GTE) and its polyphenol constituents, (-)-epigallocatechin-3-gallate (EGCG) and (-)-epicatechin (EC), on basal and stimulated testosterone production by rat Leydig cells in vitro. Leydig cells purified in a Percoll gradient were incubated for 3 h with GTE, EGCG or EC and the testosterone precursor androstenedione, in the presence or absence of either protein kinase A (PKA) or protein kinase C (PKC) activators. The reversibility of the effect was studied by pretreating cells for 15 min with GTE or EGCG, allowing them to recover for 1 h and challenging them for 2 h with human chorionic gonadotropin (hCG), luteinizing hormone releasing hormone (LHRH), 22(R)-hydroxycholesterol or androstenedione. GTE and EGCG, but not EC, inhibited both basal and kinase-stimulated testosterone production. Under the pretreatment conditions, the inhibitory effect of the higher concentration of GTE/EGCG on hCG/LHRH-stimulated or 22(R)-hydroxycholesterol-induced testosterone production was maintained, whereas androstenedione-supported testosterone production returned to control levels. At the lower concentration of GTE/EGCG, the inhibitory effect of these polyphenols on 22(R)-hydroxycholesterol-supported testosterone production was reversed. The inhibitory effects of GTE may be explained by the action of its principal component, EGCG, and the presence of a gallate group in its structure seems important for its high efficacy in inhibiting testosterone production. The mechanisms underlying the effects of GTE and EGCG involve the inhibition of the PKA/PKC signalling pathways, as well as the inhibition of P450 side-chain cleavage enzyme and 17beta-hydroxysteroid dehydrogenase function.
authors.affiliation: Department of Physiology and Pharmacology, Federal University of Pernambuco, 50607-901 Recife, PE, Brazil.
authors.forename: Marina S
authors.initials: MS
authors.lastname: Figueiroa
authors.forename: Juliany S B
authors.initials: JS
authors.lastname: César Vieira
authors.forename: Disleide S
authors.initials: DS
authors.lastname: Leite
authors.forename: Ruben C O Andrade
authors.initials: RC
authors.lastname: Filho
authors.forename: Fabiano
authors.initials: F
authors.lastname: Ferreira
authors.forename: Patrícia S
authors.initials: PS
authors.lastname: Gouveia
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Udrisar
authors.forename: Maria I
authors.initials: MI
authors.lastname: Wanderley