title: Effect of conjugated linoleic acid on testosterone levels in vitro and in vivo after an acute bout of resistance exercise.
abstract: The purposes of the present study were to investigate the effect of conjugated linoleic acid (CLA) supplementation on testosterone levels in vitro on a cell line derived from Leydig cells (R2C) and in vivo in the blood of physically active subjects before and after a resistance exercise bout. In vitro R2C cells were treated with different CLA concentrations (0-30 μM) for 24 and 48 hours. After treatment, supernatant media were tested to determine testosterone secretion. The CLA increased the testosterone secretion only after 48 hours. In vivo, 10 resistance-trained male subjects, in a double-blind placebo-controlled and crossover study design were randomized for 3 weeks of either 6 g·d⁻¹ CLA or placebo. Blood was drawn pre and post each resistance exercise bout to determine the total testosterone and sex hormone-binding globulin (SHBG) levels. No significant differences were observed for total testosterone or SHBG pre and post each resistance exercise bout; although after the resistance exercise bouts, total testosterone increased moderately (effect size = moderate), whereas after CLA supplementation, there was a large increase in total testosterone (effect size = large). CLA supplementation induced an increase in testosterone levels in Leydig cells in vitro after 48 hours but not in vivo before and after a resistance exercise bout. These findings suggest that CLA supplementation may promote testosterone synthesis through a molecular pathway that should be investigated in the future, although this effect did not have an anabolic relevance in our in vivo model.
authors.affiliation: Department of Physiological Science, Stellenbosch University, Stellenbosch, South Africa. filippo.mac@libero.it
authors.forename: Filippo
authors.initials: F
authors.lastname: Macaluso
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Morici
authors.forename: Patrizia
authors.initials: P
authors.lastname: Catanese
authors.forename: Nella M
authors.initials: NM
authors.lastname: Ardizzone
authors.forename: Antonella
authors.initials: A
authors.lastname: Marino Gammazza
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Bonsignore
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lo Giudice
authors.forename: Tomaso
authors.initials: T
authors.lastname: Stampone
authors.forename: Rosario
authors.initials: R
authors.lastname: Barone
authors.forename: Felicia
authors.initials: F
authors.lastname: Farina
authors.forename: Valentina
authors.initials: V
authors.lastname: Di Felice
mesh_terms: D000328:Adult; D000818:Animals; D002460:Cell Line; D018592:Cross-Over Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007985:Leydig Cells / Q000187:drug effects* / Q000378:metabolism; D019787:Linoleic Acid / Q000494:pharmacology*; D008297:Male; D051381:Rats; D055070:Resistance Training; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism*; D013739:Testosterone / Q000096:biosynthesis / Q000097:blood*
chemical_list: D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D019787:Linoleic Acid