Exposure to paclobutrazol disrupts spermatogenesis in male Sebastiscus marmoratus

Paclobutrazol (PBZ) is triazole-containing fungicides and widely used in agriculture as an efficient plant growth retardant. However, far fewer studies addressing the reproductive toxicity of PBZ on fishes are available. The present study was conducted to investigate the effects of PBZ at environmentally relevant concentrations on testicular development in male rockfish Sebastiscus marmoratus and to gain insight into its mechanism of action. After exposure to 10, 100 and 1000 ng/L PBZ for 50 d, although the gonadosomatic index did not show a significant alteration, there was a reduced number of mature sperm and an abundance of the late stages of spermatocysts in the testes. The activity of γ-glutamyl transpeptidase (which is used as a Sertoli cell marker) was decreased in a dose-dependent manner after PBZ exposure, which might be a result of the reduction in FSHβ expression in the brain. The toxicity induced by accumulation of PBZ in the brain might be primary cause impacting the spermatogenesis via brain-pituitary-gonad pathway.